青海省海东市不同等级降水和旱涝关系研究

利用1961～2015年青海省海东市5气象站逐日降水资料,根据中国气象局降水等级划分标准和旱涝Z指数的计算方法,分别统计海东市夏、冬半年不同等级雨量和雨日及计算Z指数,利用线性回归法分析海东市55年来不同等级雨日和雨量和Z指数的变化趋势,并采用偏相关系数、相对贡献率和合成分析等方法研究不同等级雨日和雨量对旱涝的影响。得出以下结论：①海东市夏(冬)半年降水以小雨(雪)和中雨(雪)为主,雨日和雨量及占年比例均呈现自南向北递增的空间分布。②夏半年小雨和大到暴雨的雨量及雨日呈减小趋势,中雨雨量和雨日呈增加趋势,冬半年小雪、中雪和大到暴雪的雨量及雨日均呈减小趋势。③夏、冬半年Z指数均表现为不显著的减小趋势。④夏、冬半年不同等级雨量和雨日与Z指数偏相关系数和相对贡献率分析,夏半年中雨和大到暴雨的雨量及雨日对Z指数有显著的影响,冬半年小雪的雨量和雨日对Z指数变化影响最大。⑤采用合成分析法的标准化值,无论是夏半年还是冬半年,在偏涝年,不同等级降水雨日和雨量基本都为正值,在偏旱年,不同等级降水雨日和雨量基本都为负值。在偏涝年,不同等级降水雨日和雨量差异夏半年主要表现在大到暴雨和中雨雨日及雨量,小雨雨日及雨量差异较小,而冬半年主要表现在小雪雨日及雨量,中雪次之,大到暴雪最小；在偏旱年,不同等级降水雨日和雨量差异夏半年主要表现在中雨雨日及雨量,大到暴雨次之,小雨最小,冬半年主要表现在小雪和中雪雨日及雨量,大到暴雪差异较小。

The Relationship Between Different Grades of Precipitation and Drought and Flood in Haidong, Qinghai

Haidong is an important grain production base in Qinghai, and drought directly affects the orderly development of agriculture. Based on the daily precipitation data of 5 meteorological stations in Haidong from 1961 to 2015, we analyzed the variation trend of rain days and precipitation of different grades and Z index, and studied the effects of rain days and precipitation of different grades on drought and flood. The results showed that: (1) half-year precipitation in summer (winter) was dominated by light rain (snow) and moderate rain (snow), the precipitation and rain days of light rain and heavy rain (moderate rain) in summer half year were decreasing (increasing) and the precipitation and rain days at all grades in winter half year were decreasing; (2) the Z index in summer, winter half year showed an insignificant trend of decrease; (3) according to the analysis of partial correlation coefficient and relative contribution rate, the precipitation and rain days of medium rain and heavy rain in summer half year had significant influence on Z index, while the precipitation and rain days of light snow in winter half year had the greatest influence on Z index change; (4) the synthetic analysis showed that the precipitation and rain days of different grades were basically positive in flood years, the differences of precipitation and rain days of different grades was mainly shown in the heavy rain and moderate rain in summer half year, and the differences in winter half year was mainly reflected in the precipitation and rain days of light snow; in the dry year, the precipitation and rain days at all grades were basically negative, the differences in summer half year was mainly reflected in precipitation and rain days of moderate rain, while the differences in winter half years was mainly reflected in the precipitation and rain days of light snow and moderate snow.