We have developed the Korea Land Data Assimilation System (KLDAS) to produce realistic fields (within the context of the LSM) of soil moisture, temperature and other land surface conditions. KLDAS is useful tool in that it is uncoupled land surface modeling system that generates observation-based forcing data, runs at high resolution (5km), and can produce results in real-time. We carried out (1) generation of grid input forcings over East Asia using analysis-based near-surface meteorological conditions and observed precipitation and satellite derived shortwave radiation at the ground surface, and (2) long-term integration of Noah Land surface model with these conditions for spin-up. East Asia land surface fields provided by KLDAS will be used to initialize weather and climate prediction models and will promote various hydrometeorological studies and applications. Few case studies have been selected to understand the impact on Weather Research and Forecasting (WRF) model forecasts of using KLDAS land surface states as initial land surface conditions. Preliminarily case study shows some significant impacts of KLDAS on rainfall and other meteorological fields.