The evident linkage of springtime NDVI over Eurasia with East Asian atmospheric circulation in summer

Vegetation can feedback on climate, both directly on the energy budget through surface albedo and exchanges of heat, water, and momentum and indirectly on the biogeochemical process. The purpose of this paper is to provide the statistical linkage of springtime vegetation variations over the Eurasia with summer East Asian atmospheric circulation using observational data. We firstly apply the European Center for MediumRange Weather Forecasts reanalysis data sets (ERA40) and the UMD GLCF GIMMS Normalized Difference Vegetation Index(NDVI) dataset from 1982 to 2002 to reveal the association of the NDVI over Eurasia with the zonal wind at 200 hPa level (U 200) over East Asia using singular value decomposition (SVD) analysis. The results show that there is a significant relation between the spring NDVI in the sensitive area (55°-65°N，60°-100°E) west of Baikal Lake and summer East Asian atmospheric circulation, and the most important NDVI U 200 connection accounts for 33.39% of the total squared covariance. When the spring NDVI in the sensitive area is above the normal, there are remarkable positive zonal wind anomalies in summer in upper troposphere over the Balchas Lake Baikal Lake northern Japan area, and over South China and the Indo China Peninsula, and distinctive negative zonal wind anomalies over North China and the ChangjiangHuaihe River Valley, and therefore the anomalous centers exhibit a positivenegativepositive sign distribution from north to south, which indicate that the summer 200 hPa westerly axis lies south of the normal position. In middle troposphere, the westerly is stronger between 15°N and 25°N accompanied with a stronger ascending motion, but weaker between 25°N and 42°N with a distinctive descending motion over about 32°N. In lower troposphere, there are evident anomalous anticyclonic wind anomalies over the Changjiang Huaihe River Valley, North China and the area east of Baikal Lake, and anomalous northeasterly anomalies over South China. Those circulation characters suggest that the East Asian summer monsoon (EASM) is weaker than normal, and the summer rainband lies south of the normal position, which result in excessive summer rainfall in South China and deficit rainfall in the most areas north of South China. Correspondingly, summer temperature is lower than normal over southeast China and the southeastern Tibet Plateau, and higher over northern China and the Changjiang Huaihe River Valley. The possible association between the NDVI over the Eurasian continent and the EASM could provide some help for forecast of EASM.