古尔班通古特沙漠腹地与周边的降水特征分析

Precipitation characteristics at the hinterland of Gurbantunggut Desert and the surrounding areas

沙漠腹地的降水问题历来是研究中的难点。多数学者利用沙漠周边气象站资料或短期科学考察数据来研究新疆沙漠环境及气候变化,有些研究涉及到沙漠腹地短时降水过程及降水云系特征,但很少有人利用沙漠腹地长期的实测气象资料对其降水特征进行相关研究。根据1996-2005年古尔班通古特沙漠腹地人工气象站获取的长期连续气象资料,使用变差系数和相对差分析技术,分析沙漠腹地10 a降水量的年、季、月的分布及变化,并与同期沙漠周边地区的资料进行对比分析,结果表明:(1)古尔班通古特沙漠腹地10 a平均降水量为123.4 mm,比沙漠周边地区平均偏少32%。(2)沙漠腹地降水的年、月、季的分布与沙漠周边地区基本一致。10 a来沙漠腹地降水量总体呈增加趋势,但冬季为下降趋势,夏季呈增加趋势,其它两季变化不明显,说明夏季降水对年降水的增加贡献显著。(3)沙漠腹地年和季降水量、水汽压、相对湿度的变差系数均大于沙漠周边地区,说明沙漠腹地气象要素变率大,相对不稳定。(4)沙漠腹地10 a各月平均降水量均小于沙漠周边的同期值,其中3月降水偏少最多,降水相对差为52.3%。(5)观测资料表明10 a间沙漠腹地只出现过一次日降水量大于25 mm的降水。最长连续降水日数为8 d;最长连续无降水日数共计44 d。

It is always a challenge to study and understand precipitation characteristics in inner desert area due to the uninhabited conditions and the scarcity of observation data.Most relevant work in the literature employed data from weather stations located on the peripheral area of the desert and/or measurements from short-term scientific field explorations to study desert environment and climate change in Xinjiang.A few studies have examined short-term precipitation and clouds characteristics in the inner desert;however,it is not common to encounter studies using long-term meteorological data that were obtained in the inner desert area.This paper is one of the first of using the long-term,continuous measurements collected at the meteorological weather stations in the inner Gurbantunggut Desert between 1996 and 2005 to examine the annual,seasonal and monthly precipitation patterns and possible changes inside the desert with the variation coefficient and relative difference technique.Comparisons with the precipitation data obtained from the surrounding areas of the desert are also conducted.The results show as follows：（1） The annual precipitation in the inner Gurbantunggut Desert is 123.4 mm,about 32% less than the surrounding areas;（2） The annual,seasonal,and monthly distributions of the precipitation inside the desert are rather similar to those of the surrounding areas,with increase trend in summer and decrease trend in winter but no significant changes in the other two seasons.This implies that the total increase trend in precipitation comes primarily from summer increase;（3） The variation coefficients of the annual and seasonal precipitation,vapor pressure and relative humidity in the inner desert are larger than those of the surrounding areas,suggesting larger variability and instability of meteorological conditions inside the desert when compared to the peripheral areas;（4） The monthly precipitation of this decade in inner desert is less than that in surrounding area.In March the precipitation is minimal and the precipitation relative difference is 52.3%.（5） Observation data shows that there is only one day with precipitation more than 25 mm in this decade.The longest period with continuous precipitation is 8 days while the longest period without precipitation is 44 days in the inner desert in this decade.