We will present some of the recent improvements in the unified Noah Land Surface model (LSM) and its impact on the coupled WRF-Noah model results. For these numerical experiments we used the new WRF V.2 release with nesting capability. The finer grid was used at a resolution of 4 km. The improvements in Noah LSM include (a) introduction of surface emissivity as function of landuse types in the Noah LSM surface energy balance calculation and enhancing Noah LSM with a modest treatment of urban landuse (b) further refinement in the surface emissivity treatment of certain landuse types. We tested this upgraded unified Noah LSM coupled with WRFV2 for summer and winter cases. We have used soil data from AFWA AGRMET at 47 km grid spacing and NCEP’s EDAS at 40km grid spacing. Numerical experiments were performed with (a) Upgraded Noah LSM (b) Noah and (c) Slab models. The results were evaluated by surface and aircraft data obtained from IHOP-2002 field campaign. The preliminary results show that upgraded Noah LSM produces higher 2m temperature as compared to observations in the afternoon hours. On comparing the mixing ratio, we found the upgraded Noah LSM gives higher 2m mixing ratio as compared with Noah and Slab models. Comparison with IHOP aircraft boundary layer data shows that this new coupled system is able to capture important features in the boundary layer depth and fluxes induced by surface heterogeneity. Further investigation in this direction, in order to improve the results, are in progress and would be presented in the conference.