1966—2015年天山南北坡空气湿度差异及其影响因素

Spatial variation of humidity and its influencing factors in the north and south slopes of the Tianshan Mountains,China during 1966-2015

利用天山地区近50年(1966—2015年)逐日气象资料,采用Mann-Kendall趋势检验法研究了天山南北坡相对湿度(RH)的时空变化特征,分析了天山南北坡RH对平均气温、降水量、平均风速、参考蒸散量、日照时数的敏感性,并探讨了引起RH变化的主导因素。结果表明:(1)整个天山地区RH变化有略微上升的趋势但不显著,北坡RH总体呈下降趋势,南坡RH总体呈上升趋势。(2) RH空间分布呈自北向南递减趋势,南北坡全年及春季以下降趋势为主,而夏、秋、冬三季均以上升趋势为主,且南坡变化趋势的显著性高于北坡。(3) RH对风速、气温、日照时数及参考蒸散量均为负敏感,对降水量为正敏感。北坡RH对各气象因子的敏感程度依次为日照时数>参考蒸散量>风速>气温>降水量,南坡敏感程度依次为日照时数>风速>参考蒸散量>气温>降水量。空间分布上,仅降水量敏感系数高值区位于北坡伊犁河谷,其余要素敏感系数高值区均位于南坡。(4)参考蒸散量是影响天山地区RH变化的主导因子,整个天山地区参考蒸散发贡献率较高,日照时数贡献率高值区集中于北坡伊犁河谷,风速、降水量、气温贡献率高值区均集中于南坡克孜勒苏地区。

Daily meteorological data during 1966-2015 were used to analyze the spatio-temporal distribution characteristics of relative humidity(RH) in the north and south slopes of the Tianshan Mountains by using MannKendall trend test. In addition, sensitivity coefficient and relative contribution were calculated to assess the impact of temperature, precipitation, reference evapotranspiration, wind speed and sunshine duration on RH. The results revealed that RH in the north slope exhibited fluctuating downward trend, but in the south slope it showed the opposite trend. Furthermore, the RH showed a rising gradient from south to north slope. As for seasonal RH, an upward trend was found in summer, autumn and winter, but a downward trend was observed in spring in the entire Tianshan Mountains. Sensitivity analysis indicated that RH was negatively related to temperature, reference evapotranspiration, wind speed and sunshine duration, but positively related to precipitation. Moreover, RH was the most sensitive to sunshine duration, reference evapotranspiration and wind speed, but precipitation was most insensitive, whether in north or south slope. Spatially, the high value area of sensitivity coefficient of precipitation was located in the Ili Valley, while others were located in the south slope. Contribution analysis suggested that the impact of reference evapotranspiration on RH was much larger than other factors. The high contribution area of sunshine duration was distributed in the Ili Valley(north slope), but that of wind speed, precipitation and temperature in Kizilsu(south slope).