Special Issue on weather and environmental studies using the geostationary meteorological satellite Himawari-8
Oyama et al (2018)
Oyama, R., M. Sawada, and K. Shimoji, 2018: Diagnosis of tropical cyclone intensity and structure using upper tropospheric atmospheric motion vectors. J. Meteor. Soc. Japan, 96B, 3-26.
https://doi.org/10.2151/jmsj.2017-024 Graphical Abstract
- This study identified the characteristics of cloud-top winds that indicate tropical cyclone (TC) intensification by analysis of the upper tropospheric atmospheric motion vectors (AMVs) of TCs occurring in the western North Pacific basin (Fig. 1).
- It was noteworthy that the maximum tangential wind of upper tropospheric AMVs was highly correlated with the best-track maximum sustained wind (Fig. 2), suggesting that the cyclonic circulation near the cloud top was intensified by the upward transport of the absolute angular momentum from the surface to the upper troposphere within TC inner core. Meanwhile, the radial outflow near the cloud top captured by the AMVs represented the outward movement of upper tropospheric clouds such as anvils from deep convection in TC inner core.
- The case study using Typhoon Lionrock (1610) showed a capability of Himawari-8’s high-resolution AMVs to support TC intensity and structure analyses.
Iwabuchi et al (2018)
Iwabuchi, H., N. S. Putri, M. Saito, Y. Tokoro, M. Sekiguchi, P. Yang, and B. A. Baum, 2018: Cloud property retrieval from multiband infrared measurements by Himawari-8. J. Meteor. Soc. Japan, 96B, 27-42.
https://doi.org/10.2151/jmsj.2018-001 Graphical Abstract
- An algorithm for retrieving the macroscopic, physical, and optical properties of clouds from thermal infrared measurements is applied to the Himawari-8 multiband observations.
- A comparison of retrieved cloud properties with collocated active remote sensing counterparts with small time lags shows reasonable agreements for single-layer clouds. Multilayer cloud systems with optically thin upper clouds overlying lower clouds are the major source of error in the present algorithm.
- The present cloud analysis investigates cloud evolution through separation of different cloud types and reveals typical features of diurnal cycles related to the topography in the vicinity of the New Guinea (Fig. 1). Over land, middle clouds increase from 0900 to 1200 local solar time (LST), deep convective clouds develop rapidly during 1200–1700 LST with a subsequent increase in cirrus and cirrostratus cloud amounts.
Yamamoto et al (2018)
Yamamoto, Y., and H. Ishikawa, 2018: Thermal land surface emissivity for retrieving land surface temperature from Himawari-8. J. Meteor. Soc. Japan, 96B, 43-58.
https://doi.org/10.2151/jmsj.2018-004 Graphical Abstract
- The land surface emissivity (LSE) maps for AHI (Advanced Himawari Imager) bands, Band 13, 14 and 15 were developed, which is used in the land surface temperature retrieval.
- The LSE is estimated by a semi-empirical method, which is a combination of the classificationbased method and a normalized difference vegetation index (NDVI) thresholds method (Figure 1).
- The new method basically follows the work of Peres and DaCamara (2005), and some advanced considerations are added. These considerations are the phenology of vegetation, flooding of paddy fields, snow/ice coverage, and internal reflections (cavity effect) in urban areas (Figure 1).
- The average cavity effect on LSE in urban canopies is approximately 0.01, but it reaches 0.02 in built-up areas.
- The sensitivity analysis shows that the LSE errors for the three bands are less than 0.02. The LSE estimation is especially stable at the vegetation area, where the error is less than 0.01 (Figure 2).
Yamamoto et al (2018)
Yamamoto, Y., H. Ishikawa, Y. Oku, and Z. Hu, 2018: An algorithm for land surface temperature retrieval using three thermal infrared bands of Himawari-8. J. Meteor. Soc. Japan, 96B, 59-76.
https://doi.org/10.2151/jmsj.2018-005 Graphical Abstract
- A nonlinear three-band algorithm (NTB) was developed which makes the best use of these bands to estimate the land surface temperature (LST). The NTB requires the brightness temperatures and the land surface emissivities (LSE) for three thermal infrared bands as input data.
- It was shown that the NTB has the highest robustness against the uncertainties in input data compared with other retrieval algorithms (Figure 1).
- This LST retrieval algorithm is applicable to the clear-sky pixels. An operational LST-observation method is proposed in combination with newly constructed cloud masking and LSE estimation methods in this study (Figure 2).
Sekiguchi et al (2018)
Sekiguchi, M., H. Iwabuchi, T. M. Nagao, and T. Nakajima, 2018: Development of gas absorption tables and an atmospheric radiative transfer package for applications using the Advanced Himawari Imager. J. Meteor. Soc. Japan, 96B,Sekiguchi, M., H. Iwabuchi, T. M. Nagao, and T. Nakajima, 2018: Development of gas absorption tables and an atmospheric radiative transfer package for applications using the Advanced Himawari Imager. J. Meteor. Soc. Japan, 96B, 77-89.
https://doi.org/10.2151/jmsj.2018-007 Graphical Abstract
- We developed an atmospheric gas absorption table for the Advanced Himawari Imager (AHI) based on the correlated k-distribution (CKD) method with the optimization method, which was used to determine quadrature weights and abscissas.
- We incorporated the table and band information of the AHI into a multi-purpose atmospheric radiative transfer package, Rstar. We updated the package so that users could easily specify the satellite and band number. Use of this update made it possible for the optimized CKD method to carry out calculations rapidly and accurately.
- Cloud retrieval tests using different numbers of quadrature points showed that cloud retrievals could be significantly affected by the accuracy of the CKD model. (Fig. 1).
Okuyama et al (2018)
Okuyama, A., M. Takahashi, K. Date, K. Hosaka, H. Murata, T. Tabata, and R. Yoshino, 2018: Validation of Himawari-8/AHI radiometric calibration based on two years of in-orbit data. J. Meteor. Soc. Japan, 96B, 91-109.
https://doi.org/10.2151/jmsj.2018-033 Graphical Abstract
- This paper reports on the radiometric calibration performance of all AHI-8’s IR and VNIR bands and introduces an image quality monitoring approach.
- The estimated Tb biases for IR bands are less than 0.3 K in standard scenes (Fig.1). The IR calibration approach developed under Global Space-based Inter-Calibration System (GSICS) framework revealed undesirable diurnal calibration variations in IR data during AHI-8’s early commissioning phase.
- VNIR band calibration was validated via ray-matching approach with S-NPP/VIIRS and radiative transfer calculation approach with Aqua/MODIS as a reference. The results indicated that AHI-8 Bands 1 to 4 have no significant biases with reference to VIIRS and MODIS but exhibit trends of sensor sensitivity degradation at approximately 0.5% a year, while Bands 5 and 6 exhibit positive and negative biases of about 5% with no clear degradation. These validation outcomes also show close correspondence with solar calibration target observation analysis results.
Otsuka et al (2018)
Otsuka, M., H. Seko, K. Shimoji, and K. Yamashita, 2018: Characteristics of Himawari-8 rapid scan atmospheric motion vectors utilized in mesoscale data assimilation. J. Meteor. Soc. Japan, 96B, 111-131.
https://doi.org/10.2151/jmsj.2018-034 Graphical Abstract
- Data assimilation experiments on a cold vortex event in June 2016 were conducted using AMVs derived from Himawari-8 2.5 min rapid scan imagery over Japan (RS-AMVs).
- RS-AMVs in ALL experiment distinctly represent the wind field near the cold vortex over northern Japan with much denser data than hourly AMVs routinely computed from 10 min full disk scans (RTN-AMVs) in CNTL experiment, which also indicated the location of the vortex but less clearly with many fewer data (Fig. 1).
- The wind forecasts in ALL improved slightly in early forecast hours before 12 hours in northern Japan, over which the vortex passed during the assimilation period. They also showed small improvements at low levels when averaged over the whole forecast period. (Fig. 2).
Yumimoto et al (2018)
Yumimoto, K., T. Y. Tanaka, M. Yoshida, M. Kikuchi, T. M. Nagao, H. Murakami, and T. Maki, 2018: Assimilation and forecasting experiment for heavy Siberian wildfire smoke in May 2016 with Himawari-8 aerosol optical thickness. J. Meteor. Soc. Japan, 96B, 133-149.
https://doi.org/10.2151/jmsj.2018-035 Graphical Abstract
- The first application of aerosol optical thickness (AOT) provided by Himawari-8, a Japanese third-generation geostationary meteorological satellite launched by Japanese Meteorological Agency, to an operation-oriented aerosol assimilation and forecasting system is demonstrated.
- To effectively utilize the observational capability of Himawari-8, the system assimilated 1-h merged AOTs generated through the combination of six AOT snapshots taken over 10-min intervals, three times per day.
- An assimilation and forecasting experiments for a heavy Siberian wildfire smoke event show that data assimilation with the Himawari-8 AOTs successfully improved the underestimation of the smoke in the forecast without assimilation and resulted in a better forecast performance (Fig. 1).
- Our results also indicate that the inheritance of assimilation cycles and the assimilation of more recent observations let to better forecasting in this case of a continental smoke outflow.
Khatri et al (2018)
Khatri, P., T. Hayasaka, H. Iwabuchi, T. Takamura, H. Irie, and T. Y. Nakajima, 2018: Validation of MODIS and AHI observed water cloud properties using surface radiation data. J. Meteor. Soc. Japan, 96B, 151-172.
https://doi.org/10.2151/jmsj.2018-036 Graphical Abstract
- The study implements long-term surface observed radiation data (pyranometer observed global flux and sky radiometer observed spectral zenith transmittance data) of multiple SKYNET sites to validate water cloud optical properties (cloud optical depth COD and effective radius Re) observed from space by MODIS onboard TERRA and AQUA satellites and AHI onboard Himawari-8 satellite.
- In general, CODs from both satellite sensors are found to overestimated when clouds are optically thin. The Re values from the sky radiometer and satellite sensor are generally poorly correlated than COD values.
- Among a number of factors (spatial and temporal variations of cloud, sensor and solar zenith angles), the solar zenith angle (SZA) is found to have an impact on COD difference between reflectance based satellite sensor and transmittance based sky radiometer.
- The difference in Re between the sky radiometer and satellite sensor is negatively correlated with COD difference between them.
Kazumori, M., 2018: Assimilation of Himawari-8 Clear Sky Radiance data in JMA's global and mesoscale NWP systems. J. Meteor. Soc. Japan, 96B, 173-192.
https://doi.org/10.2151/jmsj.2018-037 Graphical Abstract
- In data assimilation experiments using JMA’s global NWP system, the assimilation of Himawari-8’s three water vapor bands (TEST) significantly improved the tropospheric humidity field in analysis, especially in the lower troposphere, as compared to assimilation of the single MTSAT-2 water vapor channel (CNTL). First-guess (FG) departure statistics for microwave humidity sounders indicated an improvement in the water vapor field, especially over Himawari-8 observation areas (Fig. 1).
- In data assimilation experiments using JMA’s mesoscale NWP system, a single water vapor band of Himawari-8 CSR corresponding to MTSAT-2 was assimilated, resulting in enhanced contrast of the water vapor field between moist and dry areas, as well as a realistic representation of moist air flows from the ocean in analysis. The changes also improved mesoscale model heavy precipitation forecasts (Fig. 2).
Yoshida et al (2018)
Yoshida, M., M. Kikuchi, T. M. Nagao, H. Murakami, T. Nomaki, and A. Higurashi, 2018: Common retrieval of aerosol properties for imaging satellite sensors. J. Meteor. Soc. Japan, 96B, 193-209.
https://doi.org/10.2151/jmsj.2018-039 Graphical Abstract
- We developed a common algorithm (common aerosol models and lookup tables, and automatic selection of the optimum channels) to retrieve aerosol properties for various satellite sensors over land and ocean.
- This method was applied to the Advanced Himawari Imager (AHI) on board the Japan Meteorological Agency’s geostationary satellite Himawari-8, showing a continuous estimate of aerosol optical thickness over land and ocean (Fig.1).
- In addition, we applied our algorithm to MODIS onboard the Aqua satellite and compared the retrieval results to that obtained from the AHI (Fig.2). The comparison of the two retrievals using the common algorithm could evaluate the assumptions in the aerosol model (e.g., sphericity or size distribution).
Murata et al (2018)
Murata, H., K. Saitoh, and Y. Sumida, 2018: True color imagery rendering for Himawari-8 with a color reproduction approach based on the CIE XYZ color system. J. Meteor. Soc. Japan, 96B, 211-238.
https://doi.org/10.2151/jmsj.2018-049 Graphical Abstract
- A new type of true color imagery for Himawari-8, termed True Color Reproduction (TCR), was rendered by an approach, which aimed to reproduce colors seen by the human eye based on the CIE XYZ color system. In this approach, RGB signals observed by AHI are converted into XYZ tristimulus values and then reconverted into RGB signals for output devices via the application of 3 × 3 conversion matrices.
- An objective technique developed for the evaluation of XYZ accuracy indicated that the combination of AHI native RGB bands (Fig. 1a) is suboptimal for obtaining accurate XYZ values as is (Fig 2a), whereas a combination in which the green band is replaced by a pseudo band with a central wavelength of around 0.555 μ is optimal. The pseudo green band is generated via regression with existing visible and near-infrared bands as predictor variables.
- Figure 1b shows TCR imagery, which is rendered with the new RGB band combination and the matrix application, whose colors are dramatically improved and appear more realistic. There are no significant deviations in the evaluation results as a whole (Fig. 2b) and this imagery is considered to reproduce colors as accurately as possible with current best efforts.
Notes and Correspondence
Putri et al (2018)
Putri, N. S., H. Iwabuchi, and T. Hayasaka, 2018: Evolution of Mesoscale Convective System properties as derived from Himawari-8 high resolution data analyses. J. Meteor. Soc. Japan, 96B, 239-250.
https://doi.org/10.2151/jmsj.2018-020 Graphical Abstract
- Mesoscale convective systems (MCSs) in two subregions of Indonesia were studied by using the infrared (IR) data from Himawari-8 satellite. The MCSs were tracked by using a modified “Grab 'em Tag 'em Graph 'em” (GTG) tracking algorithm. The Detect and Spread (DAS) method was integrated in the process of cloud element (CE) delineation of GTG algorithm (hereafter GTG-DAS) to obtain an improved representation of the MCSs of interest. Although more exploration in GTG-DAS is possible, our current configuration yielded satisfactory results for MCS tracking in the two selected case studies. Figure 1 demonstrates the better segmentation of MCSs by GTG-DAS compared to the default GTG.
- The physical properties of the identified MCSs were evaluated by employing a cloud retrieval algorithm, namely the Integrated Cloud Analysis System (ICAS), which uses multiband IR radiances of Himawari-8 as the input. As suggested by Fig. 2, compared to the Sumatra case, the MCS in Java case generally reached higher cloud top height (CTH) and its anvil exhibited a larger CTH variation and a slightly larger cloud-particle effective radius (CER). The differences of MCS physical properties between the two cases may be partly attributable to the background wind profiles: the Sumatra case showed a strong upper level wind persisting throughout the MCS lifetime, while such wind was not present consistently in Java case.