The impact of atmosphere circular system on coupling features of spring net primary productivity with precipitation in East Asia.

In many East Asia regions, spring (from March to May) precipitation is an important restricting factor to vegetation growth. By analyzing the coupling features of spring NPP with precipitation, the result was found that the response features of NPP to precipitation were mainly embodied within the leading six NPP-precipitation paired-modes. The explanation rates of the leading six paired-modes to the covariance of NPP-precipitation were 42.91, 23.29, 9.96, 5.60, 5.04 and 3.95%, respectively and total to 90.75%. The temporal correlation coefficients of the leading six paired-modes were 0.830, 0.889, 0.841, 0.747, 0.912 and 0.923, respectively and all the correlations were significant at the level of 0.001. In some high altitude regions, there was no obviously corresponding relationship between NPP and precipitation in the leading two paired-modes and the reason of it may be that spring temperature was the main restricting factor to NPP. In middle and low altitude regions, the effect of precipitation on NPP was relatively more notable. Nine atmospheric circulation factors in spring affected the patterns of NPP and precipitation greatly and the affected regions with explanation rate to precipitation and NPP changes over 50% shared 65.58 and 60.41% to the whole study area, respectively.