East Asian–WNP summer monsoon index

U850 (22.5–32.5°N, 110–140°E) − U850 (5–15°N, 90–130°E) (Wang et al. 2008 EASM index; positive = strong Meiyu/Baiu). Roughly the negative of WNPMI; the sign convention is from memory and should be checked against the paper. — Wang et al. 2008, J. Climate 21, 4449–4463, doi:10.1175/2008JCLI2183.1