JMSJ, 2014, Vol. 92, No. 1 (February)
Chowdary et al. (2014)
Chowdary, J. S., R. Attada, J.-Y. Lee, Y. Kosaka, K.-J. Ha, J.-J. Luo, C. Gnanaseelan, A. Parekh, and D.-Y. Lee, 2014: Seasonal prediction of distinct climate anomalies in the summer 2010 over the tropical Indian Ocean and South Asia. J. Meteor. Soc. Japan, 92, 1-16.
http://dx.doi.org/10.2151/jmsj.2014-101 Graphical Abstract
- This study reveals that the predictive skill of rainfall and circulation anomalies during summer 2010 over the TIO and South Asia is largely attributable to the Indian Ocean basin-wide warming during the decay phase of El Niño (Fig. 1).
- Coupled models well predicted the positive rainfall anomalies over the west coast of India, southern Peninsular India and central Bay of Bengal and the suppressed rainfall over northeast Bay of Bengal associated with northwestward extension of northwest Pacific ridge one month ahead (Fig. 2).
- Coupled models failed to predict the anomalous positive rainfall in the northern Pakistan due to their inability in predicting the mid-latitude circulation anomalies (Fig. 2).
Shimada et al. (2014)
Shimada, T., M. Sawada, T. Iwasaki, 2014: Indices of cool summer climate in northern Japan: Yamase indices. J. Meteor. Soc. Japan, 92, 17–35.
http://dx.doi.org/10.2151/jmsj.2014-102 Graphical Abstract
- This study examined seven indices of cool summer climate in northern Japan associated with the cool easterly wind or Yamase in terms of spatial representativeness and interannual variability. Based on the common and different characteristics of the indices, we can now choose a suitable index for the intended use.
- Atmospheric fields represented by the indices show the following features in common: (1) northwestward tilting of the vertical axis of the Okhotsk high, a ridge in the mid-troposphere, and the developed Okhotsk high at the surface; (2) southward extensions of low SAT, high SLP, low specific humidity, and high cloud water along the Pacific coast of northern Japan and along the Japan Sea coast of the Eurasian continent; and (3) high speeds of the easterly/northeasterly surface winds to the east and west of northern Japan.
- The differences between the indices lie in (1) locations of the ridge in the mid-troposphere and the vertical structure of the Okhotsk high, (2) center locations of the low SAT and the enhanced easterly/northeasterly surface winds, and (3) degree of the southward extension of the cool air along the Pacific coast of northern Japan and the resulting contrast between the Pacific/Okhotsk Sea and the Japan Sea.
Kubokawa et al. (2014)
Kubokawa, H., T. Inoue, M. Satoh, 2014: Evaluation of the tourism climate index over Japan in a future climate using a statistical downscaling method. J. Meteor. Soc. Japan, 92, 37-54.
http://dx.doi.org/10.2151/jmsj.2014-103 Graphical Abstract
- This is the first study that examines the relationship between tourism and climate change over Japan. We used the tourism climate index (TCI) to evaluate the effect of meteorological factors on tourism. We estimated TCI using data from observatories of the Japan Meteorological Agency (JMA), and compared it with monthly changes in tourist number at Morioka city, and annual variations in tourists at 38 areas in Japan.
- We found that rainfall influences the number of tourists; the contribution of rainfall to the number of tourists is approximately 17% at maximum.
- In future climate, spring and autumn may become the preferred seasons for tourists.
Niwa et al. (2014)
Niwa, Y., K. Tsuboi, H. Matsueda, Y. Sawa, T. Machida, M. Nakamura, T. Kawasato, K. Saito, S. Takatsuji, K. Tsuji, H. Nishi, K. Dehara, Y. Baba, D. Kuboike, S. Iwatsubo, H. Ohmori, and Y. Hanamiya, 2014: Seasonal variations of CO2, CH4, N2O and CO in the mid-troposphere over the western North Pacific observed using a C-130H cargo aircraft. J. Meteor. Soc. Japan, 92, 55–70.
http://dx.doi.org/10.2151/jmsj.2014-104 Graphical Abstract
- Seasonal variations of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO) and nitrous oxide (N2O) in the mid-troposphere over the western North Pacific are investigated using air samples collected onboard a C-130H aircraft between Atsugi Base and Minamitorishima.
- The C-130H aircraft observed high CH4 concentration events in the mid-troposphere concomitantly with high CO concentrations, for both winter–spring and summer-fall. Average enhancement ratios of CH4 to CO suggest that the high CH4 concentrations originated primarily from fossil fuel combustions in winter–spring, while there could be an additional contribution from increased biogenic sources during summer–fall.
- Because a surface station rarely observed the summer–fall high CH4 concentration values in the mid-troposphere, the aircraft measurements could provide a powerful constraint on the CH4 emission estimates for Asia, in addition to that provided by the surface measurements.
Ohigashi et al. (2014)
Ohigashi, T., K. Tsuboki, Y. Shusse, and H. Uyeda, 2014: An intensification process of a winter broad cloud band on a flank of the mountain region along the Japan-Sea coast. J. Meteor. Soc. Japan, 92, 71–93.
http://dx.doi.org/10.2151/jmsj.2014-105 Graphical Abstract
- A broad cloud band formed along the northern coastal region of western Japan and persisted for about 2 days from 25 to 27 January 2009, during a cold-air outbreak. In the band, snowfall was remarkably intensified along a flank of a high mountain region in central Japan. The intensification caused local concentration of substantial precipitation (Figure 1).
- It can be theoretically explained that the winds are blocked at least below a height of 900 m by a high mountain region in Hokuriku. The southwesterlies caused by the blocking made a convergence with the predominant westerlies, the area of which corresponded to the intensified precipitation region.
- For the intensified precipitation region, time-averaged specific differential phase (KDP) had negative values (Figure 2), which indicates the predominance of prolate graupel in the intensified precipitation region.
Kondo et al. (2014)
Kondo, H., S. Murayama, Y. Sawa, K. Ishijima, H. Matsueda, A. Wada, H. Sugawara and S. Onogi, 2014: Vertical diffusion coefficient under stable conditions estimated from variation in the near-surface radon concentration. J. Meteor. Soc. Japan, 92, 95–106.
http://dx.doi.org/10.2151/jmsj.2014-106 Graphical Abstract
- The time variations of estimated vertical diffusivity for radon (KC) are shown in Fig.1, where assumed boundary layer height h = 25 m. As a reference, h for KC = 0 at each time is also shown in Fig. 1. KC and h are related in a quadratic equation for h.
- The relationship of φ(ς)∝ς1/3 may be seen under a particularly strong stable condition because the term of friction velocity u* is included both in φ(ς) and in ς (self-correlation or spurious correlation). Figure 2 shows the relationship between φ(ς) and ς for the three groups of the data; ensemble averaged time series datasets grouping on time variation of radon concentration used in the present analysis (group 1), original 10-min averaged data (group 2), and randomly disordered dataset (group 3).
- Figure 2 demonstrates that the scatter of group 1 is rather small, that of group 2 is very large, and the scatter of φ(ς) in group 3 is correlated to ς1/3 for a large value of ς with large scatter. The proposed formula of φ(ς) by Högström (1988) (φ(ς) = 1+6ς ) and another formula which suits the result of group 1 (φ(ς) = 1+2ς ) are added in Fig. 2 as a reference.
Koshiro et al. (2014)
Koshiro, T., and M. Shiotani, 2014: Relationship between low stratiform cloud amount and estimated inversion strength in the lower troposphere over the global ocean in terms of cloud types. J. Meteor. Soc. Japan, 92, 107–120.
http://dx.doi.org/10.2151/jmsj.2014-107 Graphical Abstract
- Low stratiform clouds (LSCs) are of three types: stratocumulus (Sc), stratus (St), and sky-obscuring fog (FOG). Using a long-term ship-based cloud report archive, this paper demonstrates relationships between the amount of each LSC type and the estimated inversion strength (EIS) over the global ocean.
- The relationships are clearly divided into two regimes at a sea surface temperature (SST) of approximately 16°C: Sc is the only dominant type and its amount is strongly correlated with EIS in the warm SST regime, whereas the St and FOG amounts increase with EIS in the cold SST regime.
- Examination of vertical layers contributing to EIS reveals that an increase in the inferred inversion strength between 850- and 925-hPa levels corresponds to that in the Sc amount in the warm SST regime. In the cold SST regime, as EIS increases, relatively high values of inferred inversion strength between 700- and 850-hPa levels change to a rapid increase in that between 925-hPa level and the surface, which coincides with the transition from Sc to FOG. Temperature advection implied by the air–sea temperature difference provides favorable conditions to the variations in the two regimes: general occurrence of cold advection in the warm SST regime and cold-to-warm transition of advection in the cold SST regime.
Ohashi et al. (2014)
Ohashi, Y., S. Shimada, and T. Ohsawa, 2014: Numerical simulations of summer mesoscale heat-stress around the Seto Inland Sea, Japan. J. Meteor. Soc. Japan, 92, 121–136.
http://dx.doi.org/10.2151/jmsj.2014-108 Graphical Abstract
- From numerical simulations (Fig. 1), we specified five regions, the Osaka, Tokushima, Okayama, Sanuki, and Nakatsu Plains, where undesirably high daytime Heat Index (HI) with a “danger” HI rank of above 41 °C was found around the Seto Inland Sea in western Japan in August 2007. However, simulated Mousho-bi days, having a daily maximum air temperature (AT) of 35 °C or more, appeared most frequently on the Osaka Plain.
- Daytime differences between HI and AT were large on all the aforementioned plains except the Osaka Plain; those showed differences of 5–7 °C in our simulation. The difference between HI and AT was caused by the different relative humidity in regions.
- Sensitivity experiments revealed that mountains and SST increased the daytime HI in some regions through thermal effects induced by valley-like terrain and warm and moist air transports from the sea, respectively. These were related to the development of daytime sea breezes or valley winds attributable to topographic sources. From the experimental results, increases of 1–2 °C in HI were confirmed in the aforementioned four regions except the Osaka Plain.