乌鲁木齐降水分布型及其40多年来的变化

Distribution Patterns of Precipitation and Their Change in Urumqi since Recent 40 Years

使用乌鲁木齐站1961-2003年的月降水值,分析了降水的年分布型及其随时间的变化。年降水距平数据经过标准化处理并计算了对应于R+1.17σ、R+0.33σ,R-0.33σ和R-1.17σ的值,以分析该年份是否为很干、干、正常、湿和很湿的年份。对年内暖半年和冷半年的降水分布型及其趋势也作了分析。结果表明,年降水显示出了增加趋势,尤其是20世纪80年代初期以来最为明显;冷暖2个半年的降水也都呈增加趋势。60年代和70年代早中期,干旱和很干旱年份出现频率很高,此后湿润和很湿润年份的数量显著增加。过去40多年里,冷暖2个半年可能出现的25种降水分布型中出现了20种。其中,以下7种出现频率最高:(a)干旱冷半年-很干暖半年的年份;(b)干旱冷半年-干旱暖半年的年份;(c)干旱冷半年-正常暖半年的年份;(d)正常冷半年和正常暖半年的年份;(e)湿润冷半年和干旱暖半年的年份;(f)湿润冷半年和湿润暖半年的年份;(g)很湿润冷半年和湿润暖半年的年份。分布型(a),(c),(d),(g)具有相同的频率(9.3%),而分布型(b),(e),(f)具有约7%的频率。降水的增多和分布型转向湿润对区域环境建设会产生明显的正面影响。

In arid areas, precipitation is the main water source for economic development and ecological environment improvement, and the change in both quantity and spatiotemporal distribution of precipitation affects the economic development and ecological environment regeneration in an area. In this paper, the temporal distribution and change of precipitation in Urumqi are analyzed using monthly precipitation data recorded in Urumqi during the period of 1961 - 2003. in Urumqi, the annual, extremely maximum and extremely minimum temperatures are 6.2 ℃, 40.5 ℃ and -41.5 ℃ respectively, the annual precipitation varies in a range of 131.3-419.2 mm, and the precipitation occurs mainly in spring and summer. In the study, the precipitation data are normalized, and the values corresponding to R ＋ 1.17σ, R ＋ 0. 33σ, R - 0. 33σ and R - 1.17σ are calculated to analyze whether the years are extremely arid, arid, normal, humid or extremely humid. Annual precipitation and the precipitation in the warm half-year （from April to October） and the cold half-year （from November to next March ） and their trends are also analyzed. The results show that the annual precipitation in Urumqi has trended to increase, especially since the early-1980s, and the precipitation in both the warm half-year and the cold half-year has also trended to increase. Arid and extremely arid years occurred frequently in the 1960s and the early -and mid-1970s, and then the humid and extremely humid years have significantly increased. Among the 25 possible distribution patterns of precipitation in both the warm half-year and the cold half-year, 20 patterns occurred in recent 40 years, in which the occurring frequency of 7 patterns was high. Precipitation increase in Urumqi will bring about a positive effect on regenerating the regional ecological environment.