Evaluation of Model Simulated Soil Moisture Using Long-term In Situ Data from Iowa

Soil moisture plays an important role in land-atmosphere interactions through both surface energy and water balances. However, in spite of its importance, there are few long-term records of in situ soil moisture for model validation. Hence, most studies use soil moisture simulated by land surface models. Accurate simulation and evaluation of soil moisture can provide proper initial conditions for land surface and numerical weather prediction models. The primary objective of this study is to evaluate the performance of Noah LSM, Variable Infiltration Capacity (VIC) and Community Land Model (CLM) using in situ observations from 62 stations in Iowa that have long record (1954 to 1990). All the statistical analysis and comparisons of model outputs with observed soil moisture will be made at 0.1m, 0.1-0.4m, 0.4-1m and 1-2m, respectively. We will focus the ability of the three models to resolve the seasonal cycle in soil moisture, mean soil moisture conditions, and interannual variability. The evaluation will provide information about the strengths and weaknesses of existing land surface models and will help to improve our ability to accurately simulate soil moisture. Improving model accuracy will lead to an improved understanding of soil moisture-precipitation interactions and the causes of drought.