[1] Tsinghua Univ, Dept Earth Syst Sci, Beijing 100048, Peoples R China
[2] Univ Maryland, Dept Geog Sci, College Pk, MD 20742 USA
[3] Tsinghua Univ, Inst Interdisciplinary Informat Sci, Beijing 100084, Peoples R China
[4] Univ Groningen, ESRIG, Ctr Energy & Environm Sci IVEM, NL-9747 AG Groningen, Netherlands
[5] Int Inst Appl Syst Anal, Schlosspl 1, A-2361 Laxenburg, Austria