(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 62, No. 1, pp. 5-15, 2015
The spatial distribution and long-term variation of occurrence risks for rice leaf blast for 34 years in the Tohoku Region were analyzed using "BLASTAM" (a forecasting model for rice leaf blast). The downscaled 1-km resolution meteorological data from the AMeDAS stations by linear interpolation were applied to the BLASTAM.
Infectious conditions for leaf blast occurred frequently indeed in years of cool summer. The climatic composite analyses for high risk years and low risk years estimated by the BLASTAM showed that the lasting of wet condition caused by stagnant subtropical jet stream and frontal zone over the Tohoku Region seems to contribute to increase the possibilities of leaf blast infection.
The forecast of rice leaf blast by BLASTAM was more accurate in widespread flatland areas. This geographical characteristic was considered to be due to both of the imprecision of downscaling with linear interpolation and the inner problems in BLASTAM such as disregard of non-rainy wet duration by dew condensation.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 62, No. 2, pp. 97-103, 2015
We investigated diurnal and seasonal relationships between nocturnal cooling and meteorological parameters by using 5-year observation data from the NARO Tohoku Agricultural Research Center, Japan. Multiple regression analysis between nocturnal cooling (Tnoc) and meteorological parameters (total net radiation, Rn tot; total weak-wind duration, Wd tot; and snow depth, SD) revealed that Rn tot and Wd tot dominantly contributed to Tnoc. Diurnal relationships among Tnoc, Rn tot, and Wd tot suggested that a strong temperature drop occurred not only on calm nights but also at nights when weak wind conditions lasted at least a few hours. In addition, in the warm season, correlation coefficients between Tnoc and Rn tot were nearly the same in every Wd tot category. In the cold season, however, those coefficients varied with Wd tot. We attributed this difference to the strong, synoptic-scale winds that accompanied cold and warm advection in the cold season.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 62, No. 3, pp. 187-199, 2015
The "Seasonal Snow Depth Index (SSDI)" was defined for the quantitative evaluation of the distribution and variation of snow depth. SSDI distribution maps were examined for 31 winters. The snow depth distribution differed among winters. A quantitative expression of the areal distribution tendency was proposed. The relations between SSDI and both the winter East Asian monsoon and global circulation were examined. Low temperatures, or a strong winter Asian monsoon were related to a snow-rich winter. A snow-rich winter was more likely to occur in a warmer winter in the 2010s than in the 1980s. The multiple regression coefficient of indices of the Arctic oscillation, West Pacific Pattern, and Niño3.4 to SSDI were all negative, and the ratio of their contribution was slightly less than 0.5.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 62, No. 3, pp. 201-208, 2015
Measurements of SO2 and sulfate aerosol concentrations in the atmosphere were performed in Suzu City, the Noto Peninsula, Ishikawa Prefecture in the summer of 2012. High concentrations of SO2 and sulfate aerosols in PM2.5 were observed in late July when CO and O3 concentrations did not increased. The high SO2 and sulfate particles may not be due to anthropogenic air pollution. According to the atmospheric pressure pattern in summer and the results of trajectory analyses, the air mass over the Noto Peninsula was transported from the southern part of Kyushu. The large eruption of Sakurajima occurred on 24 July in 2012, and the fumes were transported to the Hokuriku district. Recently, the volcanic eruptions of Sakurajima have increased in activity and may highly affect the air environment, such as PM2.5, over Japan.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 62, No. 5, pp. 403-409, 2015
In order to clarify the influence of obstacles on temperature measurement, two years' continuous observation was made in the meteorological enclosure of the Japan Meteorological Agency in central Tokyo (Otemachi), by installing an extra thermometer at a spot that was surrounded by trees and was 20 m distant from the thermometer for operational observation. In the early afternoon of the warm season, the temperature at the spot surrounded by trees was found to be higher than the operational temperature. The temperature difference at 15JST was about 0.5 degrees Celsius on the average, and was correlated with daily solar radiation with a correlation coefficient of over 0.7 from March to September. On the other hand, difference of nighttime temperature was generally small, so that the monthly mean difference of daily mean temperatures was less than 0.1 degree Celsius for all the months of the year.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 62, No. 8, pp. 627-639, 2015
The Atmospheric Environmental Regional Observation System (AEROS) of the Japanese Ministry of the Environment provides high resolution surface meteorological observation data. In this paper, AEROS data in the Kanto region was compared with reference data, such as the hourly analyses of the Japan Meteorological Agency and SYNOP data, for applications of local scale analyses and data assimilations.
First, evaluation criteria were determined statistically from differences between the AEROS data and reference data. Second, data quality control was conducted with reference to the evaluation criteria. The results showed that data at approximately 70 % of the AEROS sites in the Kanto region were consistent with the reference data. AEROS sites which were not consistent with reference data were removed properly during quality control. Finally, we investigated the reason why some stations failed to meet the criteria, with large errors, by considering their geographical locations and site conditions. It was suggested that the large differences were likely caused when their environments were not appropriate for a meteorological measurement or when the spatial scale that the AEROS data represents was much smaller than the reference data.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 62, No. 9, pp. 749-757, 2015
The human civilization started since the agricultural revolution in about 10 thousand years ago, but particularly after the industrial revolution the human activity has been changing the climate and environment of our planet earth. Some recent studies have suggested the earth environment is approaching a "tipping point", crossing over our "planetary boundaries" when the earth environment would drastically and irreversibly be changed. The four global environmental change programs (WCRP, IGBP, DIVERSITAS and IHDP) have been conducted to understand the earth environment change including the impact of human activities. However, to pursue the sustainable basis of the biosphere and human society, we need to promote interdisciplinary studies of natural, social and humanity sciences. Furthermore, to promote transformation to sustainable society we need to collaborate with many stakeholders of society through trans-disciplinary research and activity. Future Earth has been designed for these inter-disciplinary and trans-disciplinary studies toward global sustainability. In Asia, where the recent urbanization and economic development have been extremely rapid, and the environment has also been extremely deteriorated, the Japanese leadership role is highly expected in the Future Earth in Asia.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 62, No. 9, pp. 759-764, 2015
This study attempted to make a probabilistic prediction of rice leaf blast over Tohoku region using ensemble hindcast data from 2000 to 2009. In this paper, accuracy of the probability forecast was assessed by comparing the probability value and occurrence rate which were calculated from forecast and observed outcome of the rice leaf blast, respectively. Our result suggested that forecast accuracy of the ensemble data accounted for accurate probability forecast for rice leaf blast. In the cases when the ensemble data could properly predict future state of meteorological field, the occurrence rate of the rice leaf blast increased with an increase in the probability value, which suggested practical use of our forecasting approach.
(Tenki is the bulletin journal of the Meteorological Society of Japan in Japanese.)
TENKI, Vol. 62, No. 10, pp. 881-894, 2015
Upper-tropospheric Atmospheric Motion Vectors (AMV) for 16 tropical cyclones (TCs) in 2011-2013 were derived using rapid-scan imagery of MTSAT-1R infrared (IR) and water vapor (WV) channels at intervals of 5 minutes, and their characteristics were examined. This study particularly investigated on how such short time intervals of imagery affect the number of the derived AMVs with Quality Indicator (QI) above 0.3, and validated the quality of the AMVs with reference to sonde observations of the Japan Meteorological Agency (JMA) and the Ministry of Defense (MOD). The results showed that: (i) the rapid-scan imagery at intervals of 5 minutes enabled to derive spatially high-density AMVs even in the TC area where the spatial and temporal variations of wind field were generally large, (ii) the tangential and radial winds of the AMVs in the TC area were consistent with those of drop sonde observations near cirrus cloud layer which were obtained by a preceding research, and (iii) the upper-tropospheric IR-AMV and WV-AMV could mutually complement each other regarding data coverage. In addition, this study suggested that the difference between the heights of wind fields captured by IR-AMV and WV-AMV tends to be small near the TC center.