浑善达克沙地气候及沙漠化规律的研究

RESEARCHES INTO CLIMATE AND DESERTIFICATION IN HUNSHANDAKE SANDY LAND IN CHINA

本文选用浑善达克沙地及其边缘巴彦郭勒、正镶白旗等七个气象站的30年的气象资料,通过均权合并统计,获得一组表征整个沙区气候状况的气象要素时间序例,并依此分析了与沙漠化有关的各气象因子的演变趋势,探讨了该区温度、降水以及干燥系数的准周期振动规律及其影响因子。

According to recent 30 years' (1960-1989) spring climatic data of 7 stations near Hunshandake sandy land, we have discussed in detail the evolution tendencies in these climatic factors which are related to deser- tification process. The quasi-periodic variation of spring precipitation, temperature and aridity coefficient have been studied by using power spectrum and cross spectrum methods. we also set up mutiple linear regre- ssion models to analyze the influential factors on the 3 elements mentioned in above text. we have obtained the following conclusions. (1) Climatic conditions was relatively nice in early 1960's, but turned worse and worse since middle 1960's owing to blind reclaimation, cultivation and excessive grazing. In 1980's, however, the sandstorm days and gale days are markedly reduced by protecting vegetation and affores- tation. This indicates the significant effects of human activities on deser- tification process. (2) Quasi-triennial cycle and eight-year cycle commonly exist in the variations of spring precipitation, temperature and aridity coefficient in Hunshandake. Cospectrum of spring precipitation and temperature rea- ches the peak at 6.7 years of the cycle with significant condense spectrum. precipitation lags behind temperature for 1.07 years. (3) Three factors affect spring aridity coefficient: frequency of simultaneously-occured cold air, earlier stage (last autumn)EL Nino index of central equatorial Pacific Ocean, and the same period southern oscilla- tion index, which are negatively correlated with the dependent variable. Spring precipitation is mainly influenced by the frequency of simul- taneously-occured cold air and the earlier stage northern position of sub- tropical high, the former is positively and the latter is negatively corre- lated with the dependent variable. Influencial factors on spring tempera- ture are the same stage 500 hpa zonal circulation index within the scope of Asia and the earlier stage northern position of subtropical high, they both are positively correlated with the dependent variable.