The Changes of the Average Relative Humidity in Southwest China

Relative humidity is an important factor on on human health and animal and plant growth. In this study,the average relative humidity in southwest China is analyzed during the period 1966 ~ 2013. The following conclusions are obtained:The average relative humidity of 48 years in southwest of China is 66. 44%,and had a weak increasing trend during 1966-2000,after that an obviously decreasing trend was showing,from 68% to 62%. Mann-Kendall test shows that the interannual variation of annual mean relative humidity in 1990 ~ 2000 was rapid growth,the mutation occurred in 2007. Wavelet analysis shows that the interannual variation of annual mean relative humidity has about the periodic variation of short period of 3a,7a,and 24 a in southwest mountains. The type of monthly average relative humidity changes is "single peak and single valley",where the valley value is 57. 62% in the March,the peak value is 74. 82% in September. From the new century,the average annual relative humidity decreased rapidly to approximately 62%,which is very close to the 61. 8% of the best comfort value for human.