A Global Respondence Analysis of LAI Versus Surface Air Temperature and Precipitation Variations

In this study, we use the newly released ISLSCP-II / LAI (Leaf area index) dataset, and temperature and precipitation datasets which were produced by ECMWF and CMAP, respectively. Correlations of the 9-year monthly time series of LAI with those of temperature and precipitation are calculated separately using statistical linear correlations. Both monthly total (seasonal cycle included) and monthly anomaly (seasonal cycle removed) correlations are calculated. The results show that the high correlation between the annual cycles of temperature and LAI in the regions of middle and high latitudes of the Northern Hemisphere. The largest anomaly correlations, approximately 0.4 to 0.6, tend to occur in the tropics. The other relatively large values occur in the Qinghai-Xizang Plateau, Siberia, other mostly northern regions, and northwestern U.S.. The largest extra tropical LAI- precipitation correlations (>0.78) occur in eastern Asia, the interior of northern North America, and Sahel region of northern Africa. The strongest negative correlations occur over some regions of middle and high latitudes, e.g., northwestern U.S., middle Asia, and Chile. The most significant feature of LAI-precipitation anomaly correlations is the negative anomaly correlations in Siberia, northern Asia, and northwestern North America. These results indicate that sensitivity of LAI to climatic index is different in various ecosystems with a global scale. In addition, it could be useful for us to understand the LAI role in land surface process as well as climate model and ecosystem research.