Using the coupled WRF-Noah model, we conducted two experiments to investigate impacts of the interannual variability of leaf area index (LAI) on the surface air temperature (SAT) in eastern China. The Moderate Resolution Imaging Spectroradiometer (MODIS) observed dynamic LAI data from 2002 to 2009 were used in one modeling experiment, and the climatological seasonal cycle of the MODIS LAI was used in the other experiment. The results show that the use of dynamic LAI improves model performance. Compared with the use of climatological LAI, the use of dynamic LAI may reduce the warm (cool) bias in the years with large positive (negative) LAI anomalies. The reduction of the warm bias results from the modeled cooling effect of LAI increase through reducing canopy resistance, promoting transpiration, and decreasing sensible heat flux. Conversely, the reduction of cool bias is a result of the warming effect of negative anomaly of LAI. The use of dynamic LAI can improve model performance in summer and to a lesser extent, spring and autumn. Moreover, the dynamic LAI exerts a detectable influence on SAT in the WRF model when the LAI anomaly is at least 20% of the climatological LAI. 1. Introduction A large amount of evidence shows that terrestrial vegetation is an important dynamic component of the climate system [1–4]. Terrestrial vegetation regulates the local/regional weather and climate through modifying the surface energy budget, modifying partition of surface net radiation between latent heat flux and sensible heat flux, modifying surface wind, as reviewed by Notaro et al. [5]. For instance, coupling a dynamic vegetation model could upgrade the ability of the climate model to capture low-frequency variability of precipitation in the Amazon region [6]. The coupled WRF-Noah model could simulate climate warming closer to ground measurements by using a dynamical green vegetation fraction rather than by using a climatological fraction [7]. Therefore, it would be valuable to accurately describe vegetation properties in climate models to improve model performance. In climate models, the land surface submodel is used to simulate the dynamics of moisture and heat within soil and surface heat and moisture fluxes to the atmosphere. The Noah land surface scheme (Noah LSM) is an intermediate-complexity land surface model that can provide reasonable diurnal and seasonal variations of surface heat fluxes [8]. The Noah LSM is employed in the National Centers for Environmental Prediction (NCEP) operational mesoscale Eta model [9], the Mesoscale Model (MM5) [8], the Weather
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