Utilization of GMS Data for Estimation of Ganges River Run-off

GMS-WEFAX数据采集的硬件和基本处理的软件在上一财政年度提供。进一步开发并实现了对红外图像云面温度分布进行统计分析的程序。对于与恒河流域相关的大尺度水文研究，云覆盖可以用FC分布来恰当地表示，其中FC是在1个<s:1>纬度/经度的小正方形框架中表示温度低于215 K的像素率。该指标已成功地应用于本地区的短期和长期气象试验分析中。在追踪1996年5月袭击孟加拉国的龙卷风时指出了时间分辨率的不足。然而，在龙卷风的东南边缘发现了明显陡峭的FC梯度。这一大规模气象学的发现对未来的龙卷风预报具有重要意义。对1996年季风季节（5月至9月）FC分布的广泛分析显示，在孟加拉国及其毗邻的恒河和孟加拉湾的广大地区，每天都有规律的云层生成和衰减。利用伪向量表达式对云量变化进行了综合描述。这项技术将有助于季风和相关降水的宏观研究。汇编了关于区域地形、降水和河流径流的现有数据，尽管这些数据在质量和数量上都不充分。然而，京都大学灾害预防中心在地面真实数据的积累方面付出了可观的努力，GMS数据的汇编也已成为一项既定的例行工作。这些数据有望在几年内用于预测恒河径流。

Hardware for GMS-WEFAX data acquisition and software for their fundamental processing were provided within the last fiscal year. Programs were further developed and implemented for statistical analyzes of cloud-surface temperature distribution obtained from IR image. For widescale hydrological studies associated with Ganges River basin, cloud coverage is properly represented by FC distribution, where FC is the rate of pixels indicating lower temperature than 215ﾟK in a small square frame of 1ﾟ latitude/longitude. This index was successfully introduced into trial analyzes on both short-term and long-term meteorology in the present region.Insufficiency in time resolution was pointed out in tracing May 1996 tornado which attacked Bangladesh. Notably steep FC gradient, however, was detected along the south-east edge of the tornado. Such a finding in large-scale meteorology is important for future tornado forecasting.Extensive analysis of FC distrbutions in 1996 monsoon season (May through september) revealed regular diurnal generation and decay of clouds over a wide area of Bangladesh and adjoining Ganges River and Bengal Bay. Variation in cloud coverage in comprehensively described by means of pseudo-vector expression. This technique will contribute to the macroscopic study of monsoon and associated precipitation.Existing data on regional topography, precipitation and river run-off were compiled, although they are sufficient neither in quality nor in quantity. The Disaster Prev.Res.Center of Kyoto Univ., however, has been paying appreciable efforts toward accumulation of ground truth data, and compilation of GMS data has also become an established routine work. These data will hopfully be correlated for forecasting of Ganges River run-off within several years.