基于湿润指数的近35年青海省干湿状况变化分析

Analysis on Dry Trend Based on Moisture Index in Qinghai Province in the Recent 35 Years

利用青海省1971—2004年1km分辨率空间插值气象资料,计算了基于FAO推荐的Penman-Monteith方法的潜在蒸散及Thornthwaite湿润指数,分析了近35a来气温、降水量及湿润指数的时空变化格局及趋势。结果表明:青海省总体上表现为较为显著的暖化和不显著的干旱化趋势;增温趋势以西部较高,而东南部较低;降水在西部的唐古拉和中部的柴达木盆地表现为增加趋势,而东南大部分地区表现为减少趋势;综合考虑辐射、气温和降水等气候要素的湿润指数表明,在西部唐古拉地区、柴达木盆地等干旱区表现为暖湿化趋势,而东南部的澜沧江源、黄河源等地区表现为干旱化趋势,但与降水变化趋势一样,其变化趋势的统计学特征并不显著。

This study analyzes the spatiotemporal trends of wetness of Qinghai Province in the recent 35 years （1971 -2004） by using the potential evapotranspiration and Thornthwait moisture index （MI） derived from the Penman-Monteith methods recommended by FAO and 1 km spatially interpolated meteorological data. The results suggested a significant warming and indistinctive drying trend overall, while the degree of warming decreases from west to southeast in recent 35 years. Precipitation increases significantly in Tanggula and Chaidamu in the west and decreases in the southeast. However, the moisture index, which integrated the effect of solar radiance, temperature, precipitation, has almost the same spatial patterns of inter-annual variation as the precipitation. In the desert areas, such as Tanggula of western Qinghai and Chaidamu of central Qinghai, the MI increases with a warmer and wetter trend, while in well vegetated regions near Lantsang, Yellow River, a dryer trend exits with insignificant statistics.