Climate models and global reanalysis datasets have provided long term climate simulations and reanalysis of past, present, as well as projections for future climate change. The available IPCC AR4 climate assessments are at spatial scales that are too coarse for some of the regional studies.

With the support from NASA, the IPCC present and projected climate from the NASA GISS AO model is downscaled to 30-km resolution covering the CONUS area and is further downscaled to 10-km resolution for the southeastern United States for two climate periods: present climate of 1970~2000 and future climate of 2040~2070.

In this work, we analyzed the downscaled climate by focusing on the drought and wetness conditions in the United States. The downscaled regional climate data is cross compared to original GISS model projections, North American Regional Reanalysis (NARR) data, and Climate Research Unit (CRU) gridded observations data for the present climate (1970~2000). We are focusing on the analysis of drought and wetness indices, precipitation, temperature, and soil temperature and moisture output from the models. Regional areas (e.g. western and eastern US) are also studied separately in an attempt to study the patterns and variability of dry and wet events that may relate to large scale climate patterns.

The results reflect the drought and wetness conditions within the present climate, which is a dominant factor in influencing the ecosystem health and evolution. The by-product of the bias analysis will be a critical contribution in the application of the downscaled future climate (2040~2070) in ecosystem modeling and other related studies.