1971-2010年若尔盖湿地潜在蒸散量及地表湿润度的变化趋势

利用若尔盖、红原、玛曲3个气象站1971-2010年的地面气象观测资料,根据Penman-Monteith模型计算了若尔盖湿地的潜在蒸散量,发现若尔盖湿地年潜在蒸散量呈明显上升的趋势,上升趋势为9.1 mm/10a;若尔盖湿地潜在蒸散量在2001年出现了增大突变,2001-2010年平均潜在蒸散量比1971-2000年上升了28.6 mm;各季节潜在蒸散量均呈上升趋势,其中以秋季上升最明显,上升趋势为4.3 mm/10a。导致若尔盖湿地潜在蒸散量上升的主要气象因子是温度上升、相对湿度下降和降水量的减少,虽然日照时数减少和风速减小有利于潜在蒸散量的下降,但由于气温上升的趋势更明显,影响更大,所以若尔盖湿地潜在蒸散量呈明显的上升趋势。近40 a若尔盖湿地地表湿润度以-0.03/10a的趋势减小,其中2001-2010年比1981-1990年下降了0.11,下降十分明显;与此同时,年平均气温以0.41℃/10a的趋势上升,降水量以-13.5 mm/10a的趋势减少,虽然若尔盖湿地仍属于湿润区,但出现了明显的暖干化趋势。

The Variety Characters of Potential Evapotranspiration and Soil Surface Humidity Index in the Zoige Wetland in 1971-2010

The meteorological data of the Zoige, Hongyuan and Maqu weather observation stations were used, the potential evapotranspiration was computed by using Penman-Monteith model. The results indicated that the potential evapotranspiration variation in the Zoige wetland shows an obvious increasing tendency with the tendency ratio of 9.1 mm/10a,An abrupt change of the potential evapotranspiration was detected in the 2001,the mean potential evapotranspiration during 2001-2010 has increased by 28.6 mm compared with that of 1971-2000. The autumn potential evapotranspiration increased with the tendency ratio of 4.3mm/10a,its more higher than the other seasons. The annual potential evapotranspiration’s minimum period is 1980s, it obviously increased from 1990s, the variety of seasonal potential evapotranspiration in spring, summer and autumn is very similar to that of annual. The winter potential evapotranspiration minimum period is 1990s, it obviously increased in the 21st.The cycle change is 7-8 a during 1970s and 1980s, from the end of 1980s to the end of 1990s, it is an obviously adjusted period, the cycle change is 5a from the beginning of 21st. The temperature rising, relative humidity and precipitation decreasing are the major contributors to the potential evapotranspiration increased. Although the decreasing of the sunshine duration and mean wind velocity is help to the potential evapotranspiration decreased, but the temperature rising plays a more important role to the potential evapotranspiration increased. The decreasing tendency of soil surface humidity index is -0.03/10a,the soil surface humidity index has decreased 0.11 during 2001-2010 compared with that of 1981-1990. meanwhile, the increasing tendency of the mean temperature is 0.41℃/10a , the decreasing tendency of the precipitation is -13.5 mm/10a, the climate change of the Zoige wetland shows an obviously warm-drying tendency .