Time change of water cycle in Huaihe River Basin

淮河流域位于重要的副热带锋，即所谓的梅雨锋，在初夏停滞的地方。那里经常发生水灾和旱灾。HUBEX（淮河流域试验）是GAME （GEWEX亚洲季风试验）的子项目之一，将从1996财政年度开始进行，目的是阐明淮河流域周围的水循环及其变化，以建立淮河流域洪涝和干旱的可预测性。本研究项目是在1995财政年度进行的，目的是通过日本和中国的气象学家和水文学家之间的合作，澄清其机制，作为HUBEX的一项试验性研究。在HUBEX中，我们将在1998年进行密集的野外观测，如为输入区域四维数据同化而进行的密集的雷达探空观测，以及为制作雷达-雨量复合数据和检索中尺度热力场而进行的日本3部多普勒雷达观测。中尺度大气-地面耦合模式的建立。本研究利用现有资料，包括1991年夏季淮河流域大洪水的试点分析，对上述问题进行了考察，并在日本科学家访问淮河流域时对资料资料进行了调查。1996年3月在名古屋举行的HUBEX讲习班总结了这些结果和今后的问题。主要发现如下。(1)在1991年汛期，不仅持续有大量水汽从南方流入流域，而且还存在有效的宏观尺度辐合（北界流出量很小）。即使在这一时期，局地蒸散发对面积降水的贡献也不算小。(2) 1979年夏季在白球锋面附近的几个地区观测到具有显著日变化的积雨云团（以傍晚最多）。地表加热的作用在这些区域之间有很大的不同。3)利用1988年7月日本列岛周围多普勒雷达观测资料和常规观测资料，通过对这些资料的检索，澄清了一个中尺度系统的维持过程。针对这种情况，进行了不同积云参数化的敏感性试验。以琵琶湖流域为例，对包含城市冠层的简单生物圈模型（SiBUC）进行了签约和验证。并对分布式水文模型进行了改进，使其能够预测河流流量。(5)提出了利用常规地面气象资料估算陆地表面热湿通量的方案。少

Huaihe River Basin is located where the significant subtropical front, so-called the Meiyu (Baiu) front, stagnates in early summer. Floods and drought occur very often there. HUBEX (Huaihe River Basin Experiment) is one of the sub-project of GAME (GEWEX Asian Monsoon Experiment) and will be carried out from 1996 fiscal year to clarify the water cycle around the basin and its variation toward the establishment of predictability of the floods and the drought there. The present research project was carried out in 1995 fiscal year to clarify and their mechanisms by collaborating between the meteorologists and the hydrologists in Japan and China, as a pilot study of HUBEX.In the HUBEX,we will make intensive field observations in 1998, such as intensive rawinsonde observation for input the regional 4-dimensional data assimilation, three Doppler Radars observation by the Japanese side for producing the Radar-Raingauge Composite Data and for retrieval of thermodynamic fields of meso-beta-scale … More cloud systems, special field observations on interaction processes between land-surface and atmosphere including hydrology, and construction of the coupled meso-scale atmosphere and land-surface model.The present study examined the above mentioned items with use of the data available so far, including the pilot analysis of the case in summer of 1991 when the big flood occurred in the Huaihe River Basin The survey of data and informations was also made with visit of the basin by the Japanese scientists. These results and the future problems were summarized at the HUBEX workshop in Nagoya in March 1996. Main finding are as follows.1) In the flood period in 1991, not only large moisture inflow from the south into the basin persisted, but also effective macro-scale convergence (outflow from the northern boundary was very small) was also remarked. Contribution of local evapotranspiration to the areal precipitation was not so small even in that period.2) Cumulonimbus clusters with remarkable diurnal variation (maximum in the evening) was observed in the several regions adjacent to the Baiu frontal zone in summer of 1979. The role of the surface heating suggested to be rather different among these regions.3) With use of the Doppler Radar observation data together with the conventional ones around the Japan Islands in July 1988, maintenance process of a meso-beta-scale system was clarified by the retrieval of these data. Sensitivity test of the different cumulus parameterization was made for that case.SiBUC (Simple Biosphere Model including Urban Canopy) was contracted and checked by applying for the Biwa Lake basin. The distributed hydrological model, which can predict the river discharge, was also tried to be improved.5) Scheme for evaluating the surface heat and moisture fluxes over land with use of conventional surface meteorological data was contracted. Less