The Penman-Monteith
model was applied to estimate the values of evapotranspiration (ET0) in the
Qaidam Basin during the period of 1961-2017
based on the meteorological data from 8 meteorological stations. Then the values
of surface humid index were derived, and the climate tendency rate, IDW
interpolation, M-K test, Morlet wavelet and principal component analysis were
used to analyze the spatiotemporal variation of humid index and its affecting
factors in the study area. The results showed that the humid index in recent 57
years was in an increase trend 0.007·(10a) -1, which revealed that
the regional climate became wetter in the Qaidam Basin, the interannual
variation of the humid index was significant, and the variable coefficient was
30.73%. Seasonally, the humid indexes in spring, summer, autumn and winter were
all in an increase trend, and the tendency rates were 0.003·(10a)-1,
0.009·(10a)-1, 0.004·(10a)-1 and 0.003·(10a)-1 respectively. Spatially, difference of the variation was very significant, and
the increase of humid index in the eastern part of the basin was more
significant than that in the western part. Mutation of humid index occurred in
1981 and 1986, and there were 2.8-and
3.6-year
periods of humid index variation (α≥0.05), which was relatively identical with
the 2-4-year periodicity of general atmospheric circulation.
Principal component analysis showed that precipitation and average temperature were
the main factors affecting the variation of humid index in the Qaidam Basin. In
addition, the correlation coefficients between the humid index and the PVA,
PVI, APVI and APVII were -0.46,
-0.36,
-0.49
and -0.47
(α≥0.01) respectively.
