甘肃河东地区春小麦生育期干旱指数的时空特征

nalysis on the Spatiotemporal Characteristics of Drought Indexes during the Growth Period of Spring Wheat in the Regions of Gansu Province East from the Yellow River

利用甘肃河东地区1960-2001年42个台站逐日降水资料,统计出各站逐年春小麦生育期(3-7月)总降水量和无雨日数,并根据它们呈显著负相关的特点,定义了无雨日数-降水均一化干湿指数,然后对该干湿指数场进行时空特征分析。结果表明：甘肃河东地区春小麦生育期干旱指数既存在一致性异常分布特征,同时也存在次区域性分布特点；在不同的次区域内干旱指数的变化趋势不完全一致；另外,还发现甘肃河东地区春小麦生育期干旱指数存在年际和年代际周期振荡特征。

Gansu Province （32°31′～42°57′N, 92°13′～108°46′E） is located in a junction of the Qinghai-Tibetan Plateau, Loess Plateau and Mongolian Plateau, and there is no so much precipitation in the province. There are some oases in the Hexi Corridor, and the irrigation agriculture is developed by relying on the continental rivers rising in the Qilian Mountains. However, the growth of crops dominated by spring wheat in the regions of Gansu Province east from the Yellow River is completely relied on rainfall. In this paper, the statistical data of the total precipitation and the rainless days during growth period of spring wheat from March to July are derived based on the daily precipitation data observed by 42 meteorological stations in the regions of Gansu Province east from the Yellow River during the period of 1960- 2001. Moreover, the rainless-day-precipitation drought indexes in these regions are defined based on the characteristics of their significant negative correlation, and the spatiotemporal change of the drought indexes is analyzed. The results show that there is an abnormity in the distribution of drought indexes in the regions of Gansu Province east from the Yellow River during growth period of spring wheat, and there is also a subregional distribution feature. The change trends of drought indexes are different from the different subregions, and there are also the interdecadal and interannual periodical fluctuations in drought indexes in the regions of Gansu Province east from the Yellow River during the growth period of spring wheat.