| Using the linear regression, wavelet analysis and Mann-Kendall methods, we carried out the trends, cycles and mutation analysis for the water vapor changing characteristics in near-surface of the oasis agricultural areas, according to the observed water vapor pressure information come from the nine stations of Dunhuang, Guazhou, Yumen, Jiuquan, Gaotai, Zhangye, Shandan, Wuwei and Minqin, which had the longest ground meteorolocial observations in the Hexi Corridor. The results shown that: In recent 60 years, the near-surface water vapor pressure in the oasis agricultural areas of the Hexi Corridor has been shown a wavy increasing trend, the linear increase was 0.123 hPa·10a-1. The maximal rise extent was in summer and autumn, with the linear increasing rate was 0.192 hPa·10a-1 and 0.198 hPa·10a-1, respectivesly. The minimal increasing rate was
in spring with the rate only 0.056 hPa·10a-1. The yearly water vapor change existed a 3-year main cycle and a 30-year longer main period, also a 10-year weaker cycle. In spring and summer season, there was a 5-year main cycle and a 20～30-year longer period cycle for the water vapor change scale. In autum, there was a 5-year main cycle, also existed a 30～40-year longer cycle. The w
ater vapor change in winter also existed a 5-year cycle, but with the time sequence extended, the cycle was extended too. there was a 15-year cycle after 2000. The yearly water vapor content was emerged mutation in 1985, For the four seasons as spring, summer, autum and winter, the water vapor content was emerged mutation in 1980, 1986, 1994 and 1983, respectively. The response of water vapor
content to climate warming was apparent. There were statistically significant correlations between annual and seasonal water vapor pressure with the mean temperature. The correlation coefficients in annual mean, spring, summer, autum and winter were 0.592, 0.192, 0.551, 0.532 and 0.285, respectively. This indicated that the near-surface water vapor changes was sgnificant positive correlation with the mean temperature in Hexi Corridor. |