This work was supported in part by the NASA Earth Science Enterprise. The views expressed herein are those of the authors and do not necessarily reflect the views of NASA. The authors are thankful to Dr. Guiling Wang and another anonymous reviewer for their constructive comments and suggestions. CMAP precipitation data were provided by the NOAA–CIRES ESRL/PSD Climate Diagnostics branch, Boulder, Colorado, from their Web site (http://www.cdc.noaa.gov/). CPC U.S. UNIFIED Precipitation data were provided by the NOAA–CIRES ESRL/PSD Climate Diagnostics branch, Boulder, Colorado, from their Web site (http://www.cdc.noaa.gov/). We also would like to thank Dr. C. J. Tucker for providing the GIMMS NDVI data.
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