Links between the late wintertime North Atlantic Oscillation and springtime vegetation growth over Eurasia

In the present study, the linkages between the late wintertime (January–February–March; JFM) North Atlantic Oscillation (NAO) and springtime (April–May–June; AMJ) vegetation growth over Eurasia is investigated. Here, the proxy of vegetation growth is represented by normalized difference vegetation index (NDVI) gridded data, obtained from the advanced very high resolution radiometer. Over the period 1982–2006, the NAO (JFM) correlated well with the NDVI (AMJ) over Eurasia, wherein a positive NAO tended to increase the NDVI (AMJ) over Eurasia and vice versa. The results show that a positive phase of the late wintertime NAO leads to an increase in surface air temperature, soil temperature and rainfall in most parts of Eurasia in winter. These changes tend to produce weaker and thinner snow cover in spring compared to that that forms in a negative NAO phase. Corresponding to this, the albedo decreases and the surface air temperature increases over Eurasia in spring, which contributes an earlier snowmelt. Subsequently, the land surface over Eurasia becomes warmer and wetter earlier, as the snow melts. These conditions can then facilitate higher than average vegetation growth over Eurasia, in comparison to the conditions that occur in a negative NAO phase.