Graphical Abstract

Previous Issue

JMSJ, 2021, Vol. 99, No. 1 (February)

Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Aoki and Shige (2021)

Aoki, S., and S. Shige, 2021: Large precipitation gradients along the south coast of Alaska revealed by spaceborne radars. J. Meteor. Soc. Japan, 99, 5-25.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary
https://doi.org/10.2151/jmsj.2021-001Graphical Abstract

Plain Language Summary: At high latitudes, discriminating the phase of precipitation, as well as amount, is crucial in grasping the hydrological cycle. This study investigates the horizontal and vertical distribution of precipitation along the south coast of Alaska, using two spaceborne radars: the Dual-frequency Precipitation Radar (DPR) KuPR onboard the Global Precipitation Measurement (GPM) Core Observatory and the Cloud Profiling Radar (CPR) onboard CloudSat. It reveals that the precipitation phase and amount considerably change with the distance from the coastline.

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Article

Suzuki et al. (2021)

Suzuki, K., T. Iwasaki, and T. Yamazaki, 2021: Analysis of systematic error in numerical weather prediction of coastal fronts in Japan’s Kanto Plain. J. Meteor. Soc. Japan, 99, 27-47.
https://doi.org/10.2151/jmsj.2021-002Graphical Abstract

Plain Language Summary: Coastal fronts tend to be forecast on the inland side of their actual positions by the operational Numerical Weather Prediction (NWP with a horizontal grid spacing of 5 km) model at the Japan Meteorological Agency. This study confirms a systematic NWP error through statistical validations of coastal fronts, and the numerical experiments reveal that the systematic error may be caused primarily by an underestimation of the mountain barrier surrounding the Kanto Plain in the model.

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Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Le and Chandrasekar (2021)

Le, M. and V. Chandrasekar, 2021: Graupel and hail identification algorithm for the Dual-Frequency Precipitation Radar (DPR) on the GPM core satellite. J. Meteor. Soc. Japan, 99, 49-65.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary
https://doi.org/10.2151/jmsj.2021-003Graphical Abstract

Plain Language Summary: This paper aims to develop a graupel and hail identification algorithm for GPM DPR. This algorithm is constructed using a precipitation type index (PTI) defined for DPR. The PTI is effective in separating hydrometeor types and is calculated using measurements of reflectivity, dual-frequency ratio, and storm top height data. The output of the algorithm is a Boolean product representing the existence of graupel or hail along with the vertical profile for each Ku- and Ka-band matched footprint. Cross validation is performed with the Weather Service Radar (WSR-88D) network over continental United States as well as during the Remote sensing of Electrification, Lightning, and Mesoscale/Microscale Processes with Adaptive Ground Observations (RELAMPAGO) experiment. Evaluation of this identification algorithm is performed on a global basis, which illustrates promising comparisons with the global lightning and hail precipitation maps generated using radar and radiometer.

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Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Yu et al. (2021)

Yu, T., V. Chandrasekar, H. Xiao, and S. S. Joshil, 2021: Snowfall estimation using dual-wavelength radar during the PyeongChang 2018 Olympics and Paralympic winter games. J. Meteor. Soc. Japan, 99, 67-77.
https://doi.org/10.2151/jmsj.2021-004Graphical Abstract

Plain Language Summary: This paper aims to develop S-Z and S-Z-DFR relationships for snow estimation using D3R radar in a coastal area. The velocity and diameter measured by the disdrometer is used to derive the snow density directly. Evaluation of the two snow estimation methods is performed at three sites (YPO, CPO, and DGW), and the results show that the radar snowfall estimation agrees well with the ground observations at the three sites and S-Z-DFR algorithm performs better compared with S-Z algorithm.

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Article

Kusunoki and Mizuta (2021)

Kusunoki, S. and R. Mizuta, 2021: Future changes in rainy season over East Asia projected by massive ensemble simulations with a high-resolution global atmospheric model. J. Meteor. Soc. Japan, 99, 79-100.
https://doi.org/10.2151/jmsj.2021-005Graphical Abstract

Plain Language Summary: Future changes in the rainy season in East Asia are projected based on massive ensemble simulations of about 100 members with a 60-km mesh global atmospheric model called the “Database for Policy Decision-Making for Future Climate Change (d4PDF)”. Summer precipitation will generally increase in most regions of East Asia, but will decrease over western Japan, where the onset of rainy season will delay and the retreat will occur earlier, resulting in a shorter rainy season.

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Notes and Correspondence

Ohigashi et al. (2021)

Ohigashi, T., T. Maesaka, S. Suzuki, Y. Shusse, N. Sakurai, and K. Iwanami, 2021: Clear-air echoes observed by Ka-band polarimetric cloud radar: A case study on insect echoes in the Tokyo metropolitan area, Japan. J. Meteor. Soc. Japan, 99, 101-112.
https://doi.org/10.2151/jmsj.2021-006Graphical Abstract

Plain Language Summary: The clear-air echoes (CAEs), that appeared on May 21, 2016 in the Tokyo metropolitan area, Japan, were investigated to establish the potential for distinguishing CAEs and hydrometeor echoes in the initial stage of cloud formation using Ka-band polarimetric cloud radar. The polarimetric variables obtained by Ka-band polarimetric cloud radar are useful in distinguishing between clear-air echoes and hydrometeor echoes.

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Article: Special Edition on Years of the Maritime Continent (YMC)

Seiki et al. (2021)

Seiki, A., S. Yokoi, and M. Katsumata, 2021: The impact of diurnal precipitation over Sumatra Island, Indonesia, on synoptic disturbances and its relation to the Madden-Julian Oscillation. J. Meteor. Soc. Japan, 99, 113-137.
Special Edition on Years of the Maritime Continent (YMC)
https://doi.org/10.2151/jmsj.2021-007Graphical Abstract

Plain Language Summary: Summary: Upscale effects of diurnal precipitation over Sumatra on synoptic disturbances are examined. The strong diurnal cycle is followed by the development of synoptic disturbances over the eastern Indian Ocean for several days, and apparent twin synoptic disturbances straddling the equator develop only when the convective center of the Madden–Julian Oscillation (MJO) lies over the Indian Ocean. Furthermore, the MJO events with the strong diurnal cycle tend to have continuing eastward propagation of active convection across the Maritime Continent, suggesting that the strong diurnal cycle facilitate the smooth eastward propagation of the MJO.

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Article

Huang et al. (2021)

Huang, X.-G., X.-D. Peng, J.-F. Fei, X.-P. Cheng, J.-L. Ding, and D.-D. Yu, 2021: Evaluation and error analysis of official tropical cyclone intensity forecasts during 2005-2008 for the western North Pacific. J. Meteor. Soc. Japan, 99, 139-163.
https://doi.org/10.2151/jmsj.2021-008Graphical Abstract

Plain Language Summary: This study systematically evaluates the accuracy, trends, and error sources of three centers as the China Meteorological Administration (CMA), Joint Typhoon Warning Center (JTWC), and Regional Specialized Meteorological Center Tokyo-Typhoon Center (RSMC-Tokyo) for western North Pacific tropical cyclone (TCs) intensity forecasts between 2005 and 2018. The results of the study confirm the steady progress of the intensity forecast in the three centers in recent years. Meanwhile, the intensity forecast skill still needs to be greatly improved for the rapidly intensification (RI) TCs.

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Article: Special Edition on Extreme Rainfall Events in 2017 and 2018

Unuma and Takemi (2021)

Unuma, T., and T. Takemi, 2021: Rainfall characteristics and their environmental conditions during the heavy rainfall events over Japan in July of 2017 and 2018. J. Meteor. Soc. Japan, 99, 165-180.
Special Edition on Extreme Rainfall Events in 2017 and 2018
https://doi.org/10.2151/jmsj.2021-009Graphical Abstract

Plain Language Summary: Precipitating cloud systems during the heavy rainfall events in July of 2017 and 2018 were categorized into five types, based on the intensity, area, and lifetime of rainfall. Organized convective systems having larger rainfall areas and longer lifetimes play a major role in generating the heavy rainfalls. Column moisture content and tropospheric relative humidity characterize the environmental conditions for the occurrence of the present heavy rainfall events.

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Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Meneghini et al. (2021)

Meneghini, R., H. Kim, L. Liao, J. Kwiatkowski, and T. Iguchi, 2021: Path attenuation estimates for the GPM Dual-Frequency Precipitation Radar (DPR). J. Meteor. Soc. Japan, 99, 181-200.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary
https://doi.org/10.2151/jmsj.2021-010Graphical Abstract

Plain Language Summary: Estimation of the path-integrated attenuation (PIA) is a critical part of retrieving precipitation parameters using measurements from the Dual-Frequency Precipitation Radar (DPR) on board the Global Precipitation Measurement Mission (GPM) satellite. In this paper, we describe and evaluate different techniques used to estimate the PIA using both single- and dual-frequency DPR radar data. The resulting algorithm forms part of the present operational system used to process the DPR data.

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JMSJ, 2021, Vol. 99, No. 2 (April)

Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Seto et al. (2021)

Seto, S., T. Iguchi, R. Meneghini, J. Awaka, T. Kubota, T. Masaki, and N. Takahashi, 2021: The Precipitation rate retrieval algorithms for the GPM Dual-frequency Precipitation Radar. J. Meteor. Soc. Japan, 99, 205-237.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary,
https://doi.org/10.2151/jmsj.2021-011Graphical Abstract

Plain Language Summary: New precipitation rate retrieval algorithms (version 06A) for the GPM Dual-frequency Precipitation Radar are developed. Major changes from the previous algorithms (version 03B) include the introduction of the relation between precipitation rate and mass-weighted mean diameter (R−Dm relation), non-uniform beam filling correction, DSD database (single-frequency algorithms only), and the ZfKa method (dual-frequency algorithm only).

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Review Article

Hitchman et al. (2021)

Hitchman, M. H., S. Yoden, P. H. Haynes, V. Kumar, and S. Tegtmeier, 2021: An observational history of the direct influence of the stratospheric Quasi-biennial Oscillation on the tropical and subtropical upper troposphere and lower stratosphere. J. Meteor. Soc. Japan, 99, 239-267.
https://doi.org/10.2151/jmsj.2021-012Graphical Abstract

Plain Language Summary: The history of observational studies regarding the influence of the quasi-biennial oscillation (QBO) on the tropical and subtropical upper troposphere and lower stratosphere (UTLS) is described. The seasonal and geographical variation of QBO westerly (W) minus easterly (E) differences in UTLS temperature, pressure, and zonal wind is presented. Results from the periods 1958-1978 and 1978-2000 using National Centers for Environmental Prediction (NCEP) reanalyses are compared with modern updates using Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA2) data for 1980-2017, and European Centre for Medium Range Weather Forecasting Reanalysis – Interim (ERA-Interim) data for 1979-2018.

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Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Jian et al. (2021)

Jian, H.-W., W.-T. Chen, P.-J. Chen, C.-M. Wu, and K. I. Rasmussen, 2021: The synoptically- influenced extreme precipitation systems over Asian-Australian monsoon region observed by TRMM Precipitation Radar. J. Meteor. Soc. Japan, 99, 269-285.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary
https://doi.org/10.2151/jmsj.2021-013Graphical Abstract

Plain Language Summary: This study investigates the synoptic-scale flows associated with extreme rainfall systems over the Asian-Australian monsoon region observed by precipitation radar onboard TRMM satellite. The extreme rainfall systems are classified into four categories based on the synoptic flow patterns and the vicinity to coastlines. The spatial-temporal variation of the four categories and their internal structures are examined.

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Article

Yamashita et al. (2021)

Yamashita, Y., M. Takigawa, D. Goto, H. Yashiro, M. Satoh, Y. Kanaya, F. Taketani, and T. Miyakawa, 2021: Effect of model resolution on black Carbon transport from Siberia to the Arctic associated with the well-developed low-pressure systems in September. J. Meteor. Soc. Japan, 99, 287-308.
https://doi.org/10.2151/jmsj.2021-014Graphical Abstract

Plain Language Summary: Atmospheric transport of black carbon (BC) affects the absorption/scattering of solar radiation, precipitation, and snow/ice cover, especially in areas of low human activity such as the Arctic. The resolution dependency of simulated BC transport from Siberia to the Arctic, related to the well-developed low-pressure systems in September, was evaluated using the Nonhydrostatic Icosahedral Atmospheric Model–Spectral Radiation Transport Model for Aerosol Species (NICAM-SPRINTARS) with fine (∼ 56 km) and coarse (∼ 220 km) horizontal resolutions.

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Article

Chandra et al. (2021)

Chandra, N., P. K. Patra, J. S. H. Bisht, A. Ito, T. Umezawa, N. Saigusa, S. Morimoto, S. Aoki, G. Janssens-Menhout, and R. Fujita, M. Takigawa, S. Watanabe, N. Saitoh, and J. G. Canadell, 2021: Emissions from the oil and gas sectors, coal mining and ruminant farming drive methane growth over the past three decades. J. Meteor. Soc. Japan, 99, 309-337.
https://doi.org/10.2151/jmsj.2021-015Graphical Abstract

Plain Language Summary: Methane (CH4) is an important greenhouse gas and plays a significant role in tropospheric and stratospheric chemistry. CH4 growth rate (i.e., year to year change) in atmosphere varied in three distinct phases in the past three decades (1988-2016); namely, the periods of slowed (1988-1998), quasi-stationary (1999-2006) and renewed (2007-2016) growth phases. These distinct growth rate phases are explained by the anomalies in global and regional emissions that are estimated with an atmospheric chemistry-transport model (ACTM) based inverse modelling framework and observations from 19 sites worldwide. The anomalies in global and regional emissions are further attributed into different sectorial categories with the help of emission inventory.

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Article

Takemura et al. (2021)

Takemura, K., T. Enomoto, and H. Mukougawa, 2021: Predictability of enhanced monsoon trough related to the meandered Asian jet and consequent Rossby wave breaking in late August 2016. J. Meteor. Soc. Japan, 99, 339-356.
https://doi.org/10.2151/jmsj.2021-016Graphical Abstract

Plain Language Summary: Predictability of an enhanced monsoon trough south of Japan seen in late August 2016 is diagnosed. The monsoon trough is found to be enhanced by a meandering of the Asian jet and by a subsequent Rossby wave breaking east of Japan (Fig. 1). Japan Meteorological Agency (JMA)’s operational one-month ensemble forecast from 12 UTC 16 August 2016 fails to predict the enhanced monsoon trough. The main findings obtained from the predictability assessment are summarized as follows.

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Article

Chandra et al. (2021)

Chandra, N., P. K. Patra, J. S. H. Bisht, A. Ito, T. Umezawa, N. Saigusa, S. Morimoto, S. Aoki, G. Janssens-Menhout, and R. Fujita, M. Takigawa, S. Watanabe, N. Saitoh, and J. G. Canadell, 2021: Emissions from the oil and gas sectors, coal mining and ruminant farming drive methane growth over the past three decades. J. Meteor. Soc. Japan, 99, 357-377.
https://doi.org/10.2151/jmsj.2021-017Graphical Abstract

Plain Language Summary: Methane (CH4) is an important greenhouse gas and plays a significant role in tropospheric and stratospheric chemistry. CH4 growth rate (i.e., year to year change) in atmosphere varied in three distinct phases in the past three decades (1988-2016); namely, the periods of slowed (1988-1998), quasi-stationary (1999-2006) and renewed (2007-2016) growth phases. These distinct growth rate phases are explained by the anomalies in global and regional emissions that are estimated with an atmospheric chemistry-transport model (ACTM) based inverse modelling framework and observations from 19 sites worldwide. The anomalies in global and regional emissions are further attributed into different sectorial categories with the help of emission inventory.

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Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Seiki (2021)

Seiki, T., 2021: Near-global three-dimensional hail signals detected by using GPM-DPR observations. J. Meteor. Soc. Japan, 99, 379-402.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary
https://doi.org/10.2151/jmsj.2021-018Graphical Abstract

Plain Language Summary: Hail is a large dense ice particle and its particle size often reaches more than 1 cm. Hail is known to be associated with intense storms and causes severe damage to cars, buildings, and croplands. In general, hail has been observed by weather radar systems or reported from visual check on the ground. Such the observations are limited to developed countries and populated regions and, hence, global three-dimensional structure of hail has not been analyzed yet. This study proposed a method to detect hail signals using space-borne radar observations and successfully illustrated a near-global three-dimensional hail map. This new dataset for hail is to be utilized for improving weather forecasting and risk management of hail disasters in the global scale.

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Article

Shibata and Sai (2021)

Shibata, K., and A. Sai, 2021: Long-term trends and variations in surface humidity and temperature in the Japanese archipelago over 100 years from 1880s. J. Meteor. Soc. Japan, 99, 403-422.
https://doi.org/10.2151/jmsj.2021-019Graphical Abstract

Plain Language Summary: The surface observation data in Japan, beginning around the 1880s, are analyzed focusing on the long–term trends and variations in humidity and temperature. It is found that the annual–mean temperature trend exhibits statistically significant warming of 1.0°C–2.5°C century-1, while the annual–mean relative humidity shows significantly decreasing trend of −2% to −12% century-1. On the other hand, the annual–mean mixing ratio trend displays a different spatial distribution compared to the temperature or relative humidity trend. In this study, three types of trends exist: significantly positive and negative values, and virtually zero. Significantly negative trends of about −0.2 to −0.3 g kg-1 century-1 are located approximately in the Pacific side of Honshu from the middle Tohoku through Shikoku to the eastern Kyushu. Significantly positive trends of about 0.2 to 0.4 g kg-1 century-1 are observed over Hokkaido, the western Japan along Sea of Japan, the western Kyushu, and the remote islands including Okinawa.

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Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

De Meyer and Roca (2021)

De Meyer, V., and R. Roca, 2021: Thermodynamic scaling of extreme daily precipitation over the tropical ocean from satellite observations. J. Meteor. Soc. Japan, 99, 423-436.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary
https://doi.org/10.2151/jmsj.2021-020Graphical Abstract

Plain Language Summary: Extreme precipitation is expected to increase in a warmer climate at the same rate of the surface humidity, that is the Clausius-Clapeyron rate (~6%/K in the tropics). This study investigates the scaling of the extreme precipitation over the tropical ocean using an ensemble of satellite-based precipitation products and SST analysis. The microwave constellation-based products show a very robust positive scaling range between 300K to 302.5K, with an ensemble mean very close to the 6%/K theoretical expectation.

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Article

Jain et al. (2021)

Jain, S., R. Chhin, R. M. Doherty, S. K. Mishra, and S. Yoden, 2021: A new graphical method to diagnose the impacts of model changes on climate sensitivity. J. Meteor. Soc. Japan, 99, 437-448.
https://doi.org/10.2151/jmsj.2021-021Graphical Abstract

Plain Language Summary: Equilibrium climate sensitivity (ECS) is defined as the change in global-mean surface air temperature (ΔT) due to the quadrupling of CO2 in a climate model simulation (Fig.1a). In this paper, we propose a new graphical method, which is based on Gregory’s linear regressions (Fig.1b), to visualize the impact of a model change on ECS, climate forcing (RF), and feedbacks (Rα) in a single diagram (Fig.1c), and demonstrate its usefulness with an example of climate sensitivity simulations with interactive (ACTIVE) and prescribed (FIXED) chemistry model.

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Notes and Correspondence

Maeda et al. (2021)

Maeda, S., K. Takemura and C. Kobayashi, 2021: Planetary wave modulations associated with the Eurasian teleconnection pattern. J. Meteor. Soc. Japan, 99, 449-458.
https://doi.org/10.2151/jmsj.2021-022Graphical Abstract

Plain Language Summary: This study analyzes the modulation of planetary waves associated with the Eurasian pattern through composite analyses to reveal its dynamic mechanism, including wave-mean flow interaction. In the positive phase of the Eurasian pattern (EU+), corresponding to the enhanced Asian monsoon, the upward and eastward propagation of the planetary wave from the Central Eurasia to the North Pacific in the troposphere is enhanced. The enhanced upward and eastward propagating planetary wave converges in the upper troposphere, thereby causing anomalous extratropical direct circulation and cold outflow toward the mid-latitude lower troposphere.

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Article

Takemura and Mukougawa (2021)

Takemura, K., and H. Mukougawa, 2021: Relaxation experiments for predictability assessment of enhanced monsoon trough in late August 2016. J. Meteor. Soc. Japan, 99, 459-472.
https://doi.org/10.2151/jmsj.2021-023Graphical Abstract

Plain Language Summary: Predictability of an enhanced monsoon trough south of Japan seen in late August 2016 is diagnosed using an atmospheric general circulation model. The trough is found to be enhanced by a Rossby wave propagation over Eurasia and the subsequent Rossby wave breaking east of Japan. Three types of relaxation experiments are conducted, with nudging the model forecast toward reanalysis, for regions of the Rossby wave breaking, Rossby wave propagation, and both the regions. The main findings obtained from the experiments are summarized as follows.

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Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Sawada and Ueno (2021)

Sawada, M., and K. Ueno, 2021: Heavy winter precipitation events with extratropical cyclone diagnosed by GPM products and trajectory analysis. J. Meteor. Soc. Japan, 99, 473-496.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary
https://doi.org/10.2151/jmsj.2021-024Graphical Abstract

Plain Language Summary: The mechanisms for producing heavy precipitation regarding the structure of an occluding extratropical cyclone during the cold seasons were analyzed using the products of the Dual-frequency Precipitation Radar (DPR) onboard the Global Precipitation Measurement (GPM) core satellite and trajectory analysis on the European Centre for Medium-range Weather Forecasts atmospheric reanalysis data.

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Article

Voelger and Dalin (2021)

Voelger, P and P. Dalin, 2021: A case study of a quasi-stationary, very long polar stratospheric cloud layer edge. J. Meteor. Soc. Japan, 98, 497-504.
https://doi.org/10.2151/jmsj.2021-025Graphical Abstract

Plain Language Summary: A very long (more 600 km) straight edge of a Polar Stratospheric Cloud (PSC), located at 24-26 km altitude, was observed east of the Scandinavian Mountain Range both by an optical camera and by lidar. The cloud edge remained unchanged for several hours. We investigated the atmospheric conditions during observation which led to the unusual feature.

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Article: Special Edition on Years of the Maritime Continent (YMC)

Feng et al. (2021)

Feng, L., T. Zhang, T.-Y. Koh, and E. M. Hill, 2021: Selected years of monsoon variations and extratropical dry-air intrusions compared with the Sumatran GPS array observations in Indonesia. J. Meteor. Soc. Japan, 99, 505-536.
Special Edition on Years of the Maritime Continent (YMC)
https://doi.org/10.2151/jmsj.2021-026Graphical Abstract

Plain Language Summary: Although the Global Positioning System (GPS) has been widely used to study long-term trends or diurnal and subdiurnal cycles of precipitable water vapor (PWV), it has been rarely used for the intra-seasonal scale. We used the zenith wet delay (ZWD) data from the Sumatran GPS Array (SuGAr) in Indonesia, with help from reanalysis data, to study the summer intra-seasonal variability of PWV over Sumatra in years without strong inter-annual variability, and to probe the underlying atmospheric processes that control the variability.

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Article

Li and Wang (2021)

Li, T.-H., and Y. Wang, 2021: The role of boundary layer dynamics in tropical cyclone intensification. Part I: Sensitivity to surface drag coefficient. J. Meteor. Soc. Japan, 99, 537-554.
https://doi.org/10.2151/jmsj.2021-027Graphical Abstract

Plain Language Summary: Most previous studies have found that the intensification rate of a tropical cyclone (TC) simulated in high resolution numerical models is often insensitive to surface drag coefficient (CD) or surface friction. A new explanation to this finding has been provided in this study based on the hypothesis that although surface friction has dual opposite effects: negative direct frictional dissipation effect and indirect positive effect by strengthening and inwardly shifting eyewall updrafts/convection. We have demonstrated that the increased/reduced positive indirect effect of surface friction is roughly offset by the increased/reduced negative direct dissipation effect due to increased/reduced CD. As result, the intensification rate of the simulated TC is insensitive to CD (Figure 1). However, increased CD can result in earlier onset of the intensification stage through increasing frictional moisture convergence and Ekman pumping and thus moistening of the inner-core column of the TC vortex, but would lead to a weaker storm in the mature stage.

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Article: Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains

Li and Wang (2021)

Li, T.-H., and Y. Wang, 2021: The role of boundary layer dynamics in tropical cyclone intensification. Part II: Sensitivity to initial vortex structure. J. Meteor. Soc. Japan, 99, 555-573.
Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains
https://doi.org/10.2151/jmsj.2021-028Graphical Abstract

Plain Language Summary: Typhoons and hurricanes (collectively known as tropical cyclones) are one of the most destructive natural phenomena, and their prediction is an important task of weather and climate models. In this study, we evaluated nine global storm-resolving models, that is, models with high enough resolution to explicitly simulate the thunderstorms that make up the cyclone power engine, in their ability to simulate tropical cyclones. We found that the models are able to simulate cyclones more realistically than previous generations of global models. For example, unlike current-generation global models, the tested models are able to capture the cyclone eyewall and its extreme winds. But the models are not perfect, and continued work in improving the models is needed to exploit their full potential in tropical cyclone prediction.

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JMSJ, 2021, Vol. 99, No. 3 (June)

Article: Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains

Judt et al. (2021)

Judt, F., D. Klocke, R. Rios-Berrios, B. Vanniere, F. Ziemen, L. Auger, J. Biercamp, C. Bretherton, X. Chen, P. Düben, C. Hohenegger, M. Khairoutdinov, C. Kodama, L. Kornblueh, S.-J. Lin, M. Nakano, P. Neumann, W. Putman, N. Röber, M. Roberts, M. Satoh, R. Shibuya, B. Stevens, P. L. Vidale, N. Wedi, and L. Zhou, 2021: Tropical cyclones in global storm-resolving models. J. Meteor. Soc. Japan, 99,
Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains
https://doi.org/10.2151/jmsj.2021-029.Early Online ReleaseGraphical Abstract

Plain Language Summary: Localized heavy rainfall events with 3-houly accumulated precipitation amounts larger than 200 mm are often observed in Japan. Such events are majorly brought from quasi-stationary band-shaped precipitation systems, named as “senjo-kousuitai” in Japanese. Senjo-kousuitai is defined as a band-shaped heavy rainfall area with the length of 50-300 km and the width of 20-50 km, produced by successively formed and developed convective cells, lining up to organize multi-cell clusters, and passing or stagnating at almost the same place for a few hours.

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Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Kobayashi et al. (2021)

Kobayashi T., M. Nomura, A. Adachi, S. Sugimoto, N. Takahashi, and H. Hirakuchi, 2021: Retrieval of attenuation profiles from the GPM dual-frequency radar observations. J. Meteor. Soc. Japan, 99, 603-620.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary
https://doi.org/10.2151/jmsj.2021-030Early Online ReleaseGraphical Abstract

Plain Language Summary: A new method retrieving attenuation profiles using a Dual-Frequency Precipitation Radar equipped on the Global Precipitation Mission (GPM) is proposed. The method utilizes the differential frequency ratio (DFR), which is the difference in the measured reflectivity in the log scale between Ka and Ku bands. The range variations of relative values of differential attenuation between two frequencies are estimated and can be used for identifying hydrometeor types. Simulations indicate that estimated attenuation profiles agree with the shape of theoretical ones for rain, melted snow. The method was applied to identify rain and dry snow regions in the GPM measurements. High and low correlation coefficients between attenuated part of DFR and radar range were observed for rain and dry snow, respectively.

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Article

Cheng and Suzuki (2021)

Cheng, C. T., and K. Suzuki, 2021: Size-resolved aerosol microphysics in a global nonhydrostatic atmospheric model: Model description and validation. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-031.Early Online ReleaseGraphical Abstract

Plain Language Summary: Particle size determines the aerosol transport and removal processes, as well as how aerosol interacts with clouds and climate. In this study, we develop a sectional aerosol scheme for Spectral Radiation-Transport Model for Aerosol Species (SPRINTARS-bin) which explicitly simulates the variations in size distributions due to microphysical processes. SPRINTARS-bin is implemented in NICAM (Nonhydrostatic ICosahedral Atmospheric Model) as an alternative to the original mass-based SPRINTARS-orig aerosol module. Both schemes are evaluated by comparing year-long simulation results to ground-based measurements and satellite observations to find that the sectional scheme with better representations of ultra-fine particles largely alleviates underestimates of the aerosol number concentration in the original scheme.

Highlights:

 

Article

Cui et al. (2021)

Cui, Y., Z. Ruan, M. Wei, F. Li, R. Ge, and Y. Huang, 2021: Vertical evolution of microphysical properties during snow events in middle latitudes of China observed by a C-band vertically pointing radar. J. Meteor. Soc. Japan, 99, 649-671.
https://doi.org/10.2151/jmsj.2021-032Early Online ReleaseGraphical Abstract

Plain Language Summary: The snow clouds were divided into upper generating cell (GC) and lower stratiform (St) regions according to their vertical structure. The growth of particle size and mass mainly occurred in the St regions. The increases of ice particle number concentration (N) were usually observed near −5°C accompanied by bimodal Doppler spectra, which might be caused by ice multiplication. The average ratios of the median N, median mass diameter (Dm), and ice water content (IWC) inside GCs to those outside GCs are 2, 1.3, and 2.5 respectively for shallow events, with 1.7, 1.2, and 2.3 respectively for deep events. These values were basically the same as those for the fall streaks (FSs), implying the importance of GCs to the enhanced ice growth subsequently found in FSs. The larger values of N, Dm, and IWC inside GCs could be related to the upward air motions inside GCs. The first Ze–IWC relationship suitable for snow clouds in the midlatitudes of China was also established.

Highlights:

 

Notes and Correspondence: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Yamaji et al. (2021)

Yamaji, M., T. Kubota, and M. K. Yamamoto, 2021: An approach to reliability characterization of GSMaP near-real-time precipitation product. J. Meteor. Soc. Japan, 99, 673-684.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary,
https://doi.org/10.2151/jmsj.2021-033
Early Online ReleaseGraphical Abstract

Plain Language Summary: Reliability information of satellite precipitation products is required for various applications, such as agricultural monitoring, public health, and education, as well as weather monitoring and disaster prevention. This study confirms effectiveness for a reliability flag of the Global Satellite Mapping of Precipitation Near-Real-Time precipitation product (GSMaP_NRT), which is developed to characterize the reliability of GSMaP_NRT data “simply” and “qualitatively”.

Highlights:

 

Notes and Correspondence

Takata and Hanasaki (2021)

Takata, K., and N. Hanasaki, 2021: Investigating runoff sensitivity in the land-surface model MATSIRO to reduce low runoff bias. J. Meteor. Soc. Japan, 99, 685-695.
Early Online Releasehttps://doi.org/10.2151/jmsj.2021-034Graphical Abstract

Plain Language Summary: Runoff calculated with the Minimal Advanced Treatments of Surface Interaction and RunOff (MATSIRO) on the basis of TOPography-base MODEL (TOPMODEL) tends to be too low and its response to precipitation be too low, compared to observation for instance in Thailand. We conjectured that those biases could be attributed to the water table's excessive depth, which was diagnosed from grid-mean soil moisture using a saturation parameter. The results of Sensitivity for the parameter were then investigated aiming to make the response more active at a catchment in Thailand. The results presented marked increases in runoff accompanying reduction in water table depth. The preliminary global sensitivity experiments indicated spatial variations of the sensitivity with climate zones.

Highlights:

 

Review Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Nakamura, K. (2021)

Nakamura, K., 2021: Progress from TRMM to GPM. J. Meteor. Soc. Japan, 99, 697-729.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary,
https://doi.org/10.2151/jmsj.2021-035Early Online ReleaseGraphical Abstract

Plain Language Summary: The Tropical Rainfall Measuring Mission (TRMM) satellite was launched in 1997, and the observations continued for more than 17 years. The features of TRMM observation were as follows:

  1. It followed a non-sun synchronized orbit that enabled the diurnal variation of precipitation to be investigated.
  2. It carried a precipitation radar (PR) and microwave and infrared radiometers along with a lighting sensor and a radiation budget sensor, which enabled the study of the global characteristics of precipitation systems, as an example shown in Fig. 1.
  3. It worked as a standard reference for precipitation measurements for other spaceborne microwave radiometers, which enabled global rain maps to be developed.
On the basis of the great success of TRMM, the Global Precipitation Measurement (GPM) was designed to expand TRMM’s coverage to higher latitudes. The core satellite of GPM is equipped with a Ku/Ka dual-frequency precipitation radar (DPR) and a microwave radiometer. DPR can discriminate solid from liquid precipitation. The period of the precipitation measurement from space extended to more than 23 years, which deepens the understanding of global precipitation climatology. This paper attempts to highlight Japan’s contributions to the science of these missions.

Highlights:

 

Notes and Correspondence

Yamada (2021)

Yamada, Y., 2021: An efficient practical post-processing algorithm for the quality control of dual-PRF Doppler velocity data. J. Meteor. Soc. Japan, 98, 707-733.
https://doi.org/10.2151/jmsj.2021-036Early Online ReleaseGraphical Abstract

Plain Language Summary: In this study, the impacts of Typhoon Morakot’s (2009) vortex structure on the extreme rainfall in Taiwan are investigated through modeling with an application of piecewise potential vorticity (PV) inversion. The control experiment (C0), starting at 0000 UTC 7 August or 15 h before landfall, reproduces the event realistically and is validated against the observations. By altering the PV perturbation inside 750 km from its center, we conduct sensitivity experiments in which the size and/or circulation strength of Morakot is reduced/weakened in the initial field in several different ways.

Highlights:

 

Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Kumar et al. (2021)

Kumar, P., R. M. Gairola, T. Kubota, and C. M. Kishtawal, 2021: Hybrid assimilation of satellite rainfall product with high density gauge network to improve daily estimation: a case of Karnataka, India. J. Meteor. Soc. Japan, 99, 741-763. Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary,
https://doi.org/10.2151/jmsj.2021-037Early Online ReleaseGraphical Abstract

Plain Language Summary: After initial verification of GSMaP rainfall product against dense rain gauge network over a southwestern state of India, a hybrid assimilation method is developed in this study to prepare merge rainfall product. The hybrid assimilation method, a combination of variational method and Kalman filter, demonstrated importance of advance data assimilation over objective analysis and optimal interpolation methods, widely used for generating merge rainfall product. Moreover, study suggested that both assimilation technique and density of rain gauges are crucial for preparing final rainfall product.

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Article

Moroda et al. (2021)

Moroda, Y., K. Tsuboki, S. Satoh, K. Nakagawa, T. Ushio, and S. Shimizu, 2021: Structure and evolution of precipitation cores in an isolated convective storm observed by phased array weather radar. J. Meteor. Soc. Japan, 99, 765-784.
https://doi.org/10.2151/jmsj.2021-038Early Online ReleaseGraphical Abstract

Plain Language Summary: An isolated convective storm was observed by two phased array weather radars (PAWRs) that can perform one volume scan in just 30 seconds. The storm caused localized heavy rainfall on 7 August 2015 in the Kinki District, western Japan. We described the evolution of the storm in terms of precipitation cores and updraft cores that were clearly defined using threshold values of radar reflectivity and vertical velocity. We found that the isolated storm exhibited structures of multi-precipitation cores and multi-updraft cores.

Highlights:

 

JMSJ, 2021, Vol. 99, No. 4 (August)

Article

Bui and Yu (2021)

Bui, H. X., and J.-Y. Yu, 2021: Impacts of model spatial resolution on the simulation of convective spectrum and the associated cloud radiative effect in the tropics. J. Meteor. Soc. Japan, 99, 789-802.
https://doi.org/10.2151/jmsj.2021-039Graphical Abstract

Plain Language Summary: In this study, we examine the resolution dependence of convective spectrum in CAM5 (Community Atmospheric Model version 5) simulations, focusing on the transition from shallow to deep convection and the associated cloud radiative effect (CRE) change. We find that the convective spectrum is sensitive to model spatial resolution, with more deep convection in the coarser resolution runs. Moreover, the longwave component of CRE (LWCRE) is more sensitive to the change of model resolution compared to the shortwave component of CRE (SWCRE), characterized by a stronger response in the coarser resolution runs over the heavy-rain regime. The resolution dependence of convective spectrum and CRE changes highlights the importance of scale-aware cumulus parameterization design in climate models, which is not yet implemented in CAM5.

Highlights:

Review Article

Haynes et al. (2021)

Haynes, P., P. Hitchcock, M. Hitchman, S. Yoden, H. Hendon, G. Kiladis, K. Kodera, and I. Simpson, 2021: The influence of the stratosphere on the tropical troposphere. J. Meteor. Soc. Japan, 99, 803-845.
https://doi.org/10.2151/jmsj.2021-040Graphical Abstract

Plain Language Summary: Observational and model studies suggest that the stratosphere exerts a significant influence on the tropical troposphere. Such influence requires both communication of dynamical effects from stratosphere to troposphere and feedbacks within the troposphere which enhance the tropospheric response. This review summarises the current observational and modelling evidence for stratospheric influence on the tropical troposphere, on timescales ranging from diurnal to centennial, identifies outstanding scientific questions and discusses implications for weather and climate prediction.

Highlights:

 

Review Article

Mapes (2021)

Mapes, B., 2021: Toward form-function relationships for mesoscale structure in convection. J. Meteor. Soc. Japan, 99, 847-878.
https://doi.org/10.2151/jmsj.2021-041Graphical Abstract

Plain Language Summary: Mesoscale patterns are always observed in convective cloud fields. But there is a gap in theory and understanding about whether and how these patterns matter to the larger-scale weather in its entirety. This review essay spotlights that gap, and offers a formal framework for research to address it. Could patterns and textures detected by imagery artificial intelligence, become a tangible and useful new form of semi-quantitative data? Perhaps, but only if we can better understand what the patterns signify.

Highlights:

 

Article

Takemura et al. (2021)

Takemura, K., H. Mukougawa, and S. Maeda, 2021: Decrease of Rossby wave breaking frequency over the middle North Pacific in boreal summer under global warming in large-ensemble climate simulations. J. Meteor. Soc. Japan, 99, 879-897.
https://doi.org/10.2151/jmsj.2021-042Graphical Abstract

Plain Language Summary: Future change of Rossby wave breaking (RWB) frequency over the middle North Pacific (MNP) in August under global warming and related features of large-scale atmospheric circulation are examined using large-ensemble simulations of current and future climates with a global circulation model. The main findings are summarized as follows.

Highlights:

 

Article

Hirata et al. (2021)

Hirata, H., R. Kawamura, M. Nonaka, and K. Tsuboki, 2021: Kuroshio-enhanced convective rainband associated with an extratropical cyclone in the cold season. J. Meteor. Soc. Japan, 99, 899-912.
https://doi.org/10.2151/jmsj.2021-043Graphical Abstract

Plain Language Summary: A convective rainband developed along a non-classic front (outer front), which formed to the north of a warm front, associated with an extratropical cyclone. The rainband produced record-breaking heavy rainfall to Miyake Island, Japan, on 8 January 2017. This study examined roles of surface latent and sensible heat fluxes from the Kuroshio Current in the intensification of the rainband using cloud-resolving numerical experiments. Results derived from the numerical experiments indicated that the heat fluxes, especially the latent heat fluxes, enhanced the rainband by increasing the moisture content and convective instability.

Highlights:

 

Article

Chien et al. (2021)

Chien, F.-C., Y.-C. Chiu, and C.-H. Tsou, 2021: A Climatological study of southwesterly flows and heavy precipitation in Taiwan during Mei-yu seasons from 1979 to 2018. J. Meteor. Soc. Japan, 99, 913-931.
https://doi.org/10.2151/jmsj.2021-044Graphical Abstract

Plain Language Summary: During active years of southwesterly flow events, the Pacific high weakens and moisture is transported from the South China Sea to the Taiwan area in the early mei-yu season. The moisture-laden air results in a large equivalent potential temperature gradient to the north of Taiwan, favoring the formation of mei-yu fronts and low pressure systems. The pressure gradient thus increases and southwesterly flows develop. More moisture is transported toward Taiwan, resulting in heavy rainfall as well as a further increase of equivalent potential temperature.

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Review Article

Kikuchi (2021)

Kikuchi, K., 2021: The Boreal summer intraseasonal oscillation: A review. J. Meteor. Soc. Japan, 99, 933-972.
https://doi.org/10.2151/jmsj.2021-045Graphical Abstract

Plain Language Summary: The tropical intraseasonal oscillation (ISO) is one of the most pronounced atmospheric variability in the tropics. The ISO is characterized by a slowly eastward moving convective envelope along the equator from the Indian Ocean to the western Pacific that tends to recur with an interval of 30-90 days. Within the envelope, a variety of organized mesoscale convective systems develop. Although the ISO is pronounced throughout the year, it exhibits a significant seasonal cycle. The ISO during boreal winter, often referred to as the Madden-Julian oscillation, displays the simple eastward propagating feature mentioned above. In contrast, the ISO during boreal summer, referred to here as the boreal summer ISO (BSISO), displays more complicated propagation features: in addition to the eastward propagation, northward propagation of the convective envelope over the Northern Indian Ocean and the western North Pacific is pronounced. It exerts a strong influence on a broad range of tropical weather and climate phenomena such as tropical cyclogenesis, monsoon onset and active/break cycles, among others. There are many review articles on the MJO, whereas there are few, if any, review articles on the BSISO to the author’s knowledge. This paper attempts to provide an up-to-date review on some of the fundamental aspects of the BSISO from the viewpoint of observation, theory, and modeling.

Highlights:

 

Article: Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains

Shibuya et al. (2021)

Shibuya, R., M. Nakano, C. Kodama, T. Nasuno, K. Kikuchi, M. Satoh, H. Miura, and T. Miyakawa, 2021: Prediction skill of the boreal summer intra-seasonal oscillation in global non-hydrostatic atmospheric model simulations with explicit cloud microphysics. J. Meteor. Soc. Japan, 99, 973-992.
Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains
https://doi.org/10.2151/jmsj.2021-046Graphical Abstract

Plain Language Summary: This study assessed a prediction skill of the Boreal Summer Intra-Seasonal Oscillation (BSISO) mode using one-month simulations by a global non-hydrostatic atmospheric model. It was found that the model showed an BSISO prediction skill of approximately 24 days, while the prediction skill tended to be higher (~2 days) when the BSISO events began in the initial phases where a major convective center was located over the Philippine Sea.

Highlights:

 

Notes and Correspondence

Sato & Kusaka (2021)

Sato, T., and H. Kusaka, 2021: Statistical intercomparison of similarity metrics in sea level pressure pattern classification. J. Meteor. Soc. Japan, 99, 993-1001.
https://doi.org/10.2151/jmsj.2021-047Graphical Abstract

Plain Language Summary: We compare the accuracy of five representative similarity metrics in extracting sea level pressure (SLP) patterns for accurate weather chart classification. We use a large amount of teacher data to statistically evaluate the accuracy of each metric. The evaluation results reveal that S1 and SSIM have the highest accuracy in terms of both average and maximum scores. Their accuracy does not change even when non-ideal data are used as the teacher data.

Highlights:

 

Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Komatsu et al. (2021)

Komatsu, K. K., Y. Iijima, Y. Kaneko, and D. Oyunbaatar, 2021: Validation of GSMaP products for a heavy rainfall event over complex terrain in Mongolia captured by the GPM core observatory. J. Meteor. Soc. Japan, 99, 1003-1022.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary,
https://doi.org/10.2151/jmsj.2021-048Graphical Abstract

Plain Language Summary:Detailed comparisons with rainfall products by Global Satellite Mapping of Precipitation (GSMaP) were conducted using summer precipitation over Mongolia and a heavy rainfall event near Ulaanbaatar. The measurement by the core-satellite of the Global Precipitation Measurement mission (GPM) and the regional atmospheric modeling also cooperated the comparison for the rainfall event. As a result, the gauge-calibrated GSMaP effectively moderates the enormous error of the ungauged ones. However, the gauge-calibrated GSMaP over mountainous areas may be affected by a potential underestimation of gauge analysis due to the missing localized precipitation occurring in the significant gaps of the routine observation network.

Highlights:

 

Article

Wu et al. (2021)

Wu, Y.-J., Y.-C. Liou, Y.-C. Lo, S.-L. Tai, S.-F. Chang, and J. Sun, 2021: Precipitation processes of a thunderstorm occurred on 19 August 2014 in northern Taiwan documented by using a high resolution 4DVar data assimilation system. J. Meteor. Soc. Japan, 99, 1023-1044.
https://doi.org/10.2151/jmsj.2021-049Graphical Abstract

Plain Language Summary: The evolution of a heavy rainfall event occurred on 19 August 2014 in northern Taiwan is investigated with observed data and analyses from a newly-developed 4DVar data assimilation system named IBM_VDRAS. This event possesses different precipitating processes and track from those frequently observed in that region. The kinematic, thermodynamic, and microphysical fields of the convective cells are analyzed in details to explain the mechanisms which help to maintain the structure of the convective system and lead to heavy precipitation.

Highlights:

 

Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Barreyat et al. (2021)

Barreyat, M., P. Chambon, J.-F. Mahfouf, G. Faure, and Y. Ikuta, 2021: A 1D Bayesian inversion applied to GPM Microwave Imager observations: Sensitivity studies. J. Meteor. Soc. Japan, 99, 1045-1070.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary,
https://doi.org/10.2151/jmsj.2021-050Graphical Abstract

Plain Language Summary: The assimilation of cloudy and rainy microwave observations is under investigation at Météo- France with a method called ’1D-Bay+3D/4D-Var’. This method consists of two steps: (i) a Bayesian inversion of microwave observations and (ii) the assimilation of the retrieved relative humidity profiles in a 3D/4D-Var framework. In this paper, two estimators for the Bayesian inversion are used: either a weighted average (WA) or the maximum likelihood (ML) of a kernel density function. Sensitivity studies over the first step of the method are conducted for different degrees of freedom: the observation error, the channel selection and the scattering properties of frozen hydrometeors in the observation operator. Observations over a two-month period of the Global Precipitation Measurement (GPM) Microwave Imager (GMI) on-board the GPM-Core satellite and forecasts of the convective scale model Application of Research to Operations at Mesoscale (AROME) have been chosen to conduct these studies.

Highlights:

 

Article

Song et al. (2021)

Song, J., P. J. Klotzbach, and Y. Duan, 2021: Recent weakening of the interannual relationship between ENSO Modoki and boreal summer tropical cyclone frequency over the western North Pacific. J. Meteor. Soc. Japan, 99, 1071-1088.
https://doi.org/10.2151/jmsj.2021-051Graphical Abstract

Plain Language Summary: Early studies reported that there was a significant relationship between the summertime ENSO Modoki and the simultaneous tropical cyclone (TC) frequency over the western North Pacific. However, this study show that the impact of ENSO Modoki on WNP TC formation has experienced decadal changes during the past few decades. The correlation between the ENSO Modoki index and WNP TC frequency is weak during 1975–1989, becomes strong and significant during 1990–2004, and becomes weak again during 2005–2019. This change results from the different ENSO Modoki sea surface temperature patterns among the aforementioned three sub-periods. The typical tripolar feature is only observed in 1990–2004, whereas it is not obvious in other two sub-periods.

Highlights:

 

Article

Sekiyama (2021)

Sekiyama, T. T., 2021: Sekiyama, T. T. and M. Kajino, 2021: Performance of a 250-m grid Eulerian dispersion simulation evaluated at two coastal monitoring stations in the vicinity of the Fukushima Daiichi Nuclear Power Plant. J. Meteor. Soc. Japan, 99, 1089-1098.
https://doi.org/10.2151/jmsj.2021-052Graphical Abstract

Plain Language Summary: A super-high-resolution Eulerian dispersion model is sometimes defeated by a lower-resolution model in the vicinity of emission sources; in that case, a plume augmentation (max pooling) process is effective for the higher-resolution model to improve the statistical scores.

Highlights:

 

Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Nakamura et al. (2021)

Nakamura, K., Y. Kaneko, K. Nakagawa, and H. Hanado, 2021: Radiowave scattering characteristics of melting layer measured by a dual Ka-band radar system. J. Meteor. Soc. Japan, 99, 1099-1114.
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary,
https://doi.org/10.2151/jmsj.2021-053Graphical Abstract

Plain Language Summary: Specific attenuation and equivalent radar reflectivity in a melting layer were measured using a dual Ka-band radar system. When the two radars are arranged to face each other and a precipitation system comes between the two radars, they observe the system from opposite directions. The radar echoes suffer from rain attenuation, which appears symmetrically in both radar echo profiles. By differentiating measured radar reflectivity with range, the specific attenuation (k) can be estimated. After obtaining the specific attenuation, the equivalent radar reflectivity (Ze) is estimated. Melting layer observations were conducted on a slope of Mt. Zao, Japan. The relationship between k and Ze showed interesting characteristic which appears in a loop-shape on a k-Ze diagram. A simple theoretical study explained this characteristic.

Highlights:

 

Notes and Correspondence: Special Edition on Years of the Maritime Continent (YMC)

Yoneyama et al. (2021)

Yoneyama, K., M. Fujita, A. Seiki, R. Shirooka, S. Yokoi, E. O. Cayanan, C. O. Iglesia, and O. C. Cabrera, 2021: Evaluation of LMS6 and RS41 radiosonde humidity data obtained during YMC-Boreal Summer Monsoon study in 2018 and 2020. J. Meteor. Soc. Japan, 99, 1115-1125.
Special Edition on Years of the Maritime Continent (YMC),
https://doi.org/10.2151/jmsj.2021-054Graphical Abstract

Plain Language Summary: Quality control of radiosonde humidity data was performed for the data obtained in the international field campaign called the Years of the Maritime Continent (YMC) - Boreal Summer Monsoon study in 2018. This was done based on the intercomparison between two radiosonde types. We also used precipitable water vapor data derived from Global Navigation Satellite System signals for assessment. In addition, we proposed a method to determine whether our correction procedures can be applied to other data or not.

Highlights:

 

Article

Kodera et al. (2021)

Kodera, K., N. Eguchi, R. Ueyama, B. M. Funatsu, M. Gaetani, and C. M. Taylor, 2021: The impact of tropical tropopause cooling on Sahelian extreme deep convection. J. Meteor. Soc. Japan, 99, 1127-1139.
https://doi.org/10.2151/jmsj.2021-055Graphical Abstract

Plain Language Summary: There has been a recent increase in heavy precipitation over Sahel in West Africa following decades of severe drought. This study shows that West Africa exhibited a cooling trend in the tropical lower stratosphere and tropopause layer since the 1980s, combined with a warming in the troposphere. These temperature changes destabilized the atmosphere and induced extreme deep convection over the Sahel where penetrating convection is frequent. In contrast, tropospheric warming suppressed the shallower convection over the neighboring Guinea Coast. This feature is similar to that which might result from increased greenhouse gas levels.

Highlights:

 

JMSJ, 2021, Vol. 99, No. 5 (October)

Article

Nguyen et al. (2021)

Nguyen, T. H., K. Ishijima, S. Sugawara, and F. Hasebe, (2021): Application of a nudge general circulation model to the interpretation of the mean age of air derived from stratospheric samples in the tropics. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-056.Early Online ReleaseGraphical Abstract

Plain Language Summary: The age of air is a transport characteristic of the stratospheric general circulation. Vertical profile of the age of air estimated from cryogenic air samples taken over Biak, Indonesia is investigated by applying the boundary impulse evolving response (BIER) method and Lagrangian backward trajectories to the transport field simulated by a general circulation model nudged to reanalysis.

Highlights:

 

Article

Uda et al. (2021)

Uda, T., T. Sakajo, M. Inatsu, and K. Koga, 2021: Identification of atmospheric blocking with morphological type by topological flow data analysis. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-057Early Online ReleaseGraphical Abstract

Plain Language Summary: We propose an algorithm detecting atmospheric blockings by extracting topological features of geo-potential height data at 500 hPa. The method is based on Topological Flow Data Analysis (TFDA), providing a unique symbolic representation (COT representation) and a discrete graph structure (Reeb graph) to every structurally stable Hamiltonian vector field. The algorithm objectively detects not only the period of blocking events but also the morphological types such as an Omega shape and a dipole pattern.

Highlights:

 

Article

Si et al. (2021)

Si, D., Y. Ding, and D. Jiang, 2021: A low-frequency downstream development process leading to the outbreak of a mega-cold wave event in East Asia. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-058.Early Online ReleaseGraphical Abstract

Plain Language Summary: An unprecedented cold wave swept through most parts of East Asia in January 2016, leading to record–breaking low temperatures and widespread snowfall in several regions. Our analysis indicated that this East Asian cold wave was triggered by a low-frequency downstream development process in the Northern Hemisphere from late 2015 to early 2016.

Highlights:

 

Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Hirose et al. (2021)

Hirose, M., S. Shige, T. Kubota, F. A. Furuzawa, H. Minda, and H. Masunaga, 2021: Refinement of surface precipitation estimates for the Dual-frequency Precipitation Radar on the GPM Core Observatory using near-nadir measurements. J. Meteor. Soc. Japan, 99,
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary,
https://doi.org/10.2151/jmsj.2021-060.Early Online ReleaseGraphical Abstract

Plain Language Summary: This study attempts to improve surface precipitation estimates from GPM Core Observatory Dual-Frequency Precipitation Radar (DPR). We updated the low-level precipitation rate profiles (LPPs) using an a priori near-nadir database. The angle-bin difference in the detectability of shallow storms was examined to estimate the effect of missing shallow storms. We constructed a priori lookup tables constrained by the clutter-free bottom level and spatially averaged shallow precipitation fractions for the shallow precipitation deficiency (SPD) correction. Overall, these two corrections increase precipitation by 8% over land and 11% over ocean. These corrections mitigate approximately half of the incidence angle dependency over land and reduce the discrepancies from other global precipitation datasets.

Highlights:

 

Article: Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary

Awaka et al. (2021)

Awaka, J., M. Le, S. Brodzik, T. Kubota, T. Masaki, V. Chandrasekar, and T. Iguchi, 2021: Development of precipitation type classification algorithms for a full scan mode of GPM Dual-Frequency Precipitation Radar. J. Meteor. Soc. Japan, 99,
Special Edition on Global Precipitation Measurement (GPM): 5th Anniversary,
https://doi.org/10.2151/jmsj.2021-061.Early Online ReleaseGraphical Abstract

Plain Language Summary: The Global Precipitation Measurement (GPM) Dual-Frequency (DF) Precipitation Radar (DPR) has operated in full scan (FS) mode in both the Ku-band and Ka-band since May 2018. For the first time in the DPR level 2 (L2) version V06X experimental algorithms, the DF processing has been made on the 245 km wide full swath data. In previous versions up to V06A, the DF processing is limited to the 125 km wide inner swath data only. This paper describes the V06X precipitation type classification algorithm that detects bright-band (BB) and classifies precipitation as stratiform, convective, and other.

Highlights:

 

Article: Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains

Heim et al. (2021)

Heim, C., L. Hentgen, N. Ban, and C. Schär, 2021: Inter-model variability in convection- resolving simulations of subtropical marine low clouds. J. Meteor. Soc. Japan, 99,
Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains
https://doi.org/10.2151/jmsj.2021-062.Early Online ReleaseGraphical Abstract

Plain Language Summary: We analyse the set of 40-day-long kilometre-resolution global atmospheric simulations of the DYAMOND model intercomparison project over the South-East Atlantic to study how this new family of models simulate subtropical marine low clouds. Such clouds represent a critical uncertainty in climate-change projections. The simulations produce low cloud fields that look in general realistic in comparison to satellite images, but there are considerable inter-model differences. Detailed analyses show that the relevant dynamical and physical processes of the marine boundary layer are consistently represented by the analysed models, indicating that there is a potential to improve the simulated low cloud cover through model calibration.

Highlights:

 

Article

Yamada et al. (2021)

Yamada, H., K. Ito, K. Tsuboki, T. Shinoda, T. Ohigashi, M. Yamaguchi, T. Nakazawa, N. Nagahama, and K. Shimizu, 2021: The double warm-core structure of Typhoon Lan (2017) as observed through the first Japanese eyewall-penetrating aircraft reconnaissance. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-063Early Online ReleaseGraphical Abstract

Plain Language Summary: Eyewall-penetrating upper-tropospheric aircraft reconnaissance was carried out for Typhoon Lan (2017). This was the first case of a Japanese research group observing the inner core of an intense typhoon using dropsondes. We captured a double warm-core structure persisted in an environment with a strengthening vertical wind shear. Based on analyses of thermodynamics, we hypothesize the contribution of a high enthalpy air transported from the eye boundary layer into the upper warm core via the eyewall for the continuous eye warming.

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Article

Hioki and Tsuboki (2021)

Hioki, T., and K. Tsuboki, 2021: Trajectory Analyses on the warm core development and pressure falls of a developing typhoon as simulated by a cloud-resolving model. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-064Early Online ReleaseGraphical Abstract

Plain Language Summary: The central pressure fall of a typhoon is associated with the development of the warm core in the eye and mass divergence of the eye. The purpose of this study is to examine (i) the origins and paths of the air comprising the warm core, and (ii) the paths followed by air leaving the eye in the troposphere. We performed trajectory analyses based on a high-resolution (2-km) numerical simulation of a developing typhoon Wipha (2007) using the cloud-resolving model CReSS.

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Article: Special Edition on Extreme Rainfall Events in 2017 and 2018

Ohara et al. (2021)

Ohara, R., T. Iwasaki, and T. Yamazaki, 2021: Impacts of evaporative cooling from raindrops on the frontal heavy rainfall formation over western Japan on 5-8 July 2018. J. Meteor. Soc. Japan, 99,
Special Edition on Extreme Rainfall Events in 2017 and 2018,
https://doi.org/10.2151/jmsj.2021-065Early Online ReleaseGraphical Abstract

Plain Language Summary: This study examines impacts of evaporative cooling in the heavy rainfall event in early July 2018 to deepen our knowledge about when and how evaporative cooling affects Baiu frontal precipitation systems. Results of sensitivity experiments reveal that the raindrop evaporation maintains the position of the heavy front-induced precipitation by suppressing the northward retreat of the frontal surface.

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Article: Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains

Inoue et al. (2021)

Inoue, T., K. Rajendran, M. Satoh, and H. Miura, 2021: On the semidiurnal variation in surface rainfall rate over the tropics in a global cloud-resolving model simulation and satellite observations. J. Meteor. Soc. Japan, 99,
Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains
https://doi.org/10.2151/jmsj.2021-066.Early Online ReleaseGraphical Abstract

Plain Language Summary: A 3.5-km mesh Non-hydrostatic Icosahedral Atmospheric Model (NICAM) for 26–31 December 2006 simulates the dual peak semidiurnal variation in surface rainfall rate over the tropics. We confirmed this semidiurnal variation of surface rainfall rate from 17-year winter precipitation climatology of Tropical Rainfall Measuring Mission (TRMM) TMI (TRMM Microwave Imager), Precipitation Radar (PR), and the same 6-day data of Global Satellite Mapping of Precipitation (GSMaP), as well as infrared data from geostationary satellites.

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JMSJ, 2021, Vol. 99, No. 6 (December)

Article

Ikeda & Kusaka (2021)

Ikeda T., and H. Kusaka, 2021: Development of models for predicting the number of patients with heatstroke on the next day considering heat acclimatization. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-067.Early Online ReleaseGraphical Abstract

Plain Language Summary: Some models for predicting the number of ambulance transport due to heatstroke cause underestimation in early summer. This study’s model reduces underestimation in early summer, using the number of days since June 1 and the number of ambulance transport due to heatstroke on the previous day.

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Article

Nguyen et al. (2021)

Nguyen, T. H., K. Ishijima, S. Sugawara, and F. Hasebe, (2021): Application of a nudge general circulation model to the interpretation of the mean age of air derived from stratospheric samples in the tropics. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-068.Early Online ReleaseGraphical Abstract

Plain Language Summary: The age of air is a transport characteristic of the stratospheric general circulation. Vertical profile of the age of air estimated from cryogenic air samples taken over Biak, Indonesia is investigated by applying the boundary impulse evolving response (BIER) method and Lagrangian backward trajectories to the transport field simulated by a general circulation model nudged to reanalysis.

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Article: Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains

Roh et al. (2021)

Roh, W., M. Satoh, and C. Hohenegger, 2021: Intercomparison of cloud properties in DYAMOND simulations over the Atlantic Ocean. J. Meteor. Soc. Japan, 99,
Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains
https://doi.org/10.2151/jmsj.2021-070.Early Online ReleaseGraphical Abstract

Plain Language Summary: We intercompared the cloud properties of the seven atmospheric general circulation models with a grid spacing of less than about 5 km over the Atlantic Ocean. The domain averaged outgoing longwave radiation was found to be similar across the models. The vertical structure of cloud water, cloud ice and cloud fraction exhibited large variations across models.  

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Article: Special Edition on Typhoons in 2018–2019

Wada (2021)

Wada, A., 2021: Roles of oceanic mesoscale eddy in rapid weakening of Typhoons Trami and Kong-Rey in 2018 simulated with a 2-km-mesh atmosphere-wave-ocean coupled model. J. Meteor. Soc. Japan, 99,
Special Edition on Typhoons in 2018–2019,
https://doi.org/10.2151/jmsj.2020-071Early Online ReleaseGraphical Abstract

Plain Language Summary: To understand the role of a cold-core eddy in the intensity change of Typhoons Trami and Kong-Rey (2018), numerical simulations were performed with a 2-km-mesh nonhydrostatic atmosphere model and an atmospheric-wave-ocean coupled model. The ocean’s role in the simulated rapid weakening of two typhoons was related to the low upper-ocean heat content caused by typhoon-induced sea surface cooling. The reductions in downward motion in the center of two typhoons and the associated adiabatic heating were closely related to the weakening. The difference of ocean’s role between the two typhoons were discussed.

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Article: Special Edition on DYAMOND: The DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains

Bao and Stevens (2021)

Bao, J. and B. Stevens, 2021: The elements of the thermodynamic structure of the tropical atmosphere. J. Meteor. Soc. Japan, 99,
Special Edition on Typhoons in 2018–2019,
https://doi.org/10.2151/jmsj.2021-072Early Online ReleaseGraphical Abstract

Plain Language Summary: The two foundations of the tropical atmosphere are that the horizontal temperature in the free troposphere is homogeneous, and the vertical structure follows a moist-adiabatic lapse rate. This study uses simulations from global storm-resolving models to investigate the accuracy of these ideas. Our results show that horizontally the density temperature appears to be homogeneous, but only in the mid- and lower troposphere. Vertically, the tropical atmosphere in saturated convective regions tends to be isentropic (condensed water remaining in the updraft) below the freezing level and pseudo-adiabatic (condensed water/rain falling immediately upon formation) above. However, the tropical mean temperature is substantially colder than that in saturated convective regions because of the impact of entrainment, a process that the saturated air mixes with dry environment, in the lower troposphere.

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Article

Endo et al. (2021)

Endo, H., A. Kitoh, R. Mizuta, and T. Ose, 2021: Different future changes between early and late summer monsoon precipitation in East Asia. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-073.Early Online ReleaseGraphical Abstract

Plain Language Summary: Future changes in East Asian summer monsoon (EASM) precipitation and the associated atmospheric circulation changes are investigated with a 60-km-mesh atmospheric general circulation model (AGCM). The results highlight a distinct difference between early and late summer in future changes of EASM precipitation (Fig. 1a). Sensitivity experiments with the AGCM reveal that the precipitation changes in early summer are dominated by the effects of sea surface temperature (SST) warming, resulting in an intensification and a southward shift of the Baiu rainband (Figs. 1d and 1f), whereas the influence of land warming and successive large SST warming in the extratropics is evident in late summer (Figs 1c and 1e).

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Article

Yang et al. (2021)

Yang, W.-T., S.-M. Fu, J.-H. Sun, F. Zheng, J. Wei, and Z. Ma, 2021: Comparative evaluation of the performances of TRMM-3B42 and CMORPH precipitation estimates over Thailand. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-074.Early Online ReleaseGraphical Abstract

Plain Language Summary: Thailand plays an important role in ensuring the global food security. To understand precipitation features over Thailand is of great importance to agriculture in Thailand. This study conducted a detailed comparative evaluation between the TRMM-3B42v7 and CMORPH precipitation products, and showed the relative performances quantitatively. We found that, overall, the TRMM-3B42v7 displayed a better performance than that of CMORPH.

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Article

Ikuta et al. (2021)

Ikuta, Y., T. Fujita, Y. Ota, and Y. Honda, 2021: Variational data assimilation system for operational regional models at Japan Meteorological Agency. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-076Early Online ReleaseGraphical Abstract

Plain Language Summary: The regional data assimilation system at the Japan Meteorological Agency employs a variational data assimilation system on the basis of the non-hydrostatic model ASUCA (named ASUCA-Var). As a system for operational use, ASUCA-Var is designed for sustainable development. This paper reviews configurations, workflow of operational systems, and performances of ASUCA-Var.

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Article

Steppeler et al. (2021)

Steppeler, J., J. Li, F. Fang, and J. Zhu, 2021: The o2o3 Local Galerkin method using a differentiable flux representation. J. Meteor. Soc. Japan, 99,
https://doi.org/10.2151/jmsj.2021-077Early Online ReleaseGraphical Abstract

Plain Language Summary: Local Galerkin methods, in particular the spectral elements (SE) solve the difficulty in classic Galekin methods for applying to multiprocessor system and have been found to be scalable up to millions of processors. The present study investigates improvements of SE under the name o2o3 which substitutes the irregular Gauss-Lobatto grid in SE by a regular collocation grid to compute Galerkin integrals with the potential to improve the computational efficiency and simplify the physical parameterization.

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