中国北方干旱区降雨与相对湿度变化趋势的非一致性研究

Inconsistent change trends between precipitation and relative humidity in arid areas of north China

降雨量(P)和相对湿度(RH)是反映全球干湿变化最常用的气象因子,掌握二者在不同干旱区、不同时段(全年、雨季和非雨季)的变化趋势及其非一致性规律,对于准确认识全球变暖背景下干旱区干湿变化状况具有重要指导意义。基于中国北方干旱区20个气象站点1951-2018年的日气象数据,采用M-K趋势检验法研究了各站点P和RH在全年、雨季和非雨季时段的长期变化趋势,着重讨论了两者变化趋势的非一致性。结果表明:不同时段P呈增加趋势的站点占总站点个数的70%~100%,其在全年、雨季和非雨季的增幅分别为0.02~4.42、0.01~3.96和0.03~0.84 mm/a;不同时段RH的变化趋势大多与P相反,其在全年、雨季和非雨季呈降低趋势的站点比例分别为85%、85%和90%,降幅为0.01%/a~0.19%/a、0.01%/a~0.17%/a和0.01%/a~0.21%/a;P和RH在全年和非雨季时段的非一致性均高达90%,而在雨季时段的非一致程度较低,仅为65%;且气温T(全年和雨季)及其增量ΔT(非雨季)可能是导致P与RH呈非一致性的关键因子;未来气候变暖背景下,气温的升高将加剧雨季的降雨-蒸散发过程,且这一问题将覆盖越来越多的干旱区。

Precipitation(P)and relative humidity(RH)are the most commonly used meteorological factors in the study of global dry and wet changes.It is of great significance for the researchers to grasp the change trends and their inconsistent patterns in different arid regions and different periods(annual,rainy and non-rainy seasons),in order to accurately acknowledge the dry and wet changes in arid regions under the background of global warming.Based on the daily meteorological data of 20 meteorological stations in arid regions of north China from 1951 to 2018,the M-K trend test method was used to study the long-term trends of P and RH at each station in the whole year,rainy season and non-rainy season,and the inconsistency of the two trends was emphatically discussed.The results demonstrated that the stations with increasing P in different periods accounted for 70%-100%of the total number of stations,and the P of the annual,rainy and non-rainy seasons increased by 0.02-4.42,0.01-3.96 and 0.03-0.84 mm/a,respectively.Whereas the change trend of RH in different periods was almost opposite to that of P,and the proportion of stations with decreasing trend in the whole year,rainy season and non-rainy season accounted for 85%,85%and 90%,with a decrease of 0.01%/a-0.19%/a,0.01%/a-0.17%/a and 0.01%/a-0.21%/a,respectively.The inconsistency of P and RH in the whole year and non-rainy season periods reached 90%,whereas that in the rainy season period only accounted for 65%.It is found that the temperature T(annual and rainy season)and its incrementΔT(non-rainy season)may be the key factors leading to the inconsistency between P and RH.In the context of future climate warming,the rising temperature will exacerbate the precipitation-evapotranspiration process during the rainy season and this problem will inflict an increasing number of arid areas.