(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 65, No. 1, pp. 5-23, 2018
A heavy rainstorm occurred in the area ranging from Hirakata City of Osaka to Uji City of Kyoto on 13 and 14 August 2012, causing flooding of small rivers and giving serious damage to residents in the cities; we call this storm "the Uji rainstorm". This is the first part of the two-series papers concerning the Uji rainstorm, describing meteorologically analyzed results using mainly surface data and weather radar data. The second part of the series shows simulation results on flooding of a small-scale river due to the Uji rainstorm using a hydrological runoff model.
This paper has revealed the following evidences. 1) There are two types of Yodogawa-channel rainstorms: cold-front type and stationary-front type. The Uji rainstorm was classified into the stationary-front type and generated as a weak-forced convection in the deep convectively unstable layer with a low-level jet. 2) During the storm period of thirteen hours, six mesoscale line systems were organized and slowly moved along the Yodo River. Taking into account of the behavior and kinematic structure of the convective systems, they were classified into three types: back-building (BB) convection, back-and-side-building (BSB) convection and squall line convection. 3) At first stage of the Uji storm, convective cells in the mesoscale line systems were produced by the topography-forced uplifting of warm moist air around the the Rokko Mountains. At the middle stage, convective cells were generated at the western edge of the stationary cold pool near the surface, which was produced by the mesosocale line systems. At the final stage, the mesoscale line system merged with a stratified mesosocale system, and the merging might intensify the convective activity of the mesoscale line system. 4) The intensity of the southwesterly low-level wind over the Kii-channel correlated with convective activity of the mesoscale line systems.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 65, No. 1, pp. 35-41, 2018
The values of atmospheric optical depth on three sites in Nepal were derived from observations of global solar radiation from 2012 to 2014, and then the aerosol turbidity coefficients β were evaluated from the values. One of these sites is Parasi located in Terai Belt of Indo-Gangetic Plain, and other two sites are Kathmandu, the capital city of Nepal, and Pokhara, the typical resort area of Nepal.
It is considered that the variations of β in these sites are attributed not only to regional aspects but also to seasonal conditions in these sites. For instance, the characteristic variations of β are found in the sites depending on precipitation and wind system in the each season, that is, pre-monsoon, monsoon, post-monsoon and winter.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 65, No. 3, pp. 145-157, 2018
A heavy rainstorm occurred in the area ranging from Hirakata City of Osaka to Uji City of Kyoto on 13 and 14 August 2012, causing flooding of small rivers and giving serious damage to residents in the cities. We call this storm "the Uji rainstorm". This is the second part of the two-series papers concerning the Uji rainstorm, describing simulation results on the flooding of the Shizu River: a small-scale river of 9 km in length and 11 km2 in area, using the hydrological runoff models of Kojima et al. (1998) and Tachikawa et al. (2004).
When the Analysis Precipitation data of Japan Meteorological Agency (JMA) are used as the rainfall amount data, the true water flow rate was simulated with the error of 16% at the time of the peak of water flow. The water level of the Shizu River at the site where a house was washed away by the flooding was estimated with the accuracy enough for practical use for issuing flooding warning. In case of using the JMA precipitation forecast data, the best simulation result showed that the water flow rate was well forecasted up to one hour later.
These results have indicated that flooding information could be issued to residents around small rivers, if the runoff models which have been applied to larger rivers are used.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 65, No. 6, pp. 417-423, 2018
Significant differences between reanalysis data (ERA40, JRA55) and observation data are found about the Baiu-frontal depression that brought intense rainfalls over Kyushu (southwestern Japan).
The differences in the sea-level pressure field are small, while significant differences are seen for the 500-hPa height field; a weak trough associated with the depression is not properly analyzed in JRA55. Significant difference between ERA40 and JRA55 is found for the 700-hPa vertical velocity. The comparison with satellite observation (cloud top black body temperature) indicated that the smaller patterns of vertical velocity in JRA55 are erroneous.
The present report suggests that examination of reanalysis data on the basis of observation data is needed for the depression-scale analysis.