Prescribed versus dynamic leaf area index in simulating surface energy and water budgets: experiments with NCAR LSM and CLM using field data from an agriculture site

There are three methods of determining leaf area index (LAI) in land surface modeling. (1) the temporal variation of LAI is prescribed based on literature survey, field data, or satellite data; (2) only the maximum and minimum values of LAI are prescribed in the same fashion as in (1), but the temporal variation follows the variation in deep soil temperature provided an empirical formula is given; (3) LAI is predicted based on the photosynthesis and carbon assimilation so that the direct interaction of LAI and evapotranspiration is possible during the integration of land surface models. The merits and shortcomings of these three methods have not been evaluated thoroughly because the detailed sequence of LAI measurements are lacking. In this study, we are using daily measurements of LAI and the data of meteorological variables for two years from an agriculture site to evaluate the above three methods with NCAR LSM and CLM.