Entin et al., 1999

Entin, Jared, Alan Robock, Konstantin Y. Vinnikov, Shuang Qiu, Vladimir Zabelin, Suxia Liu, A. Namkhai, and Ts. Adyasuren, 1999: Evaluation of Global Soil Wetness Project soil moisture simulations. J. Meteorol. Soc. Japan, 77, 183-198. (Invited paper)


To produce a global soil moisture "data set," ten different land surface models were forced with meteorological observations for a two year period (1987-88) for the Global Soil Wetness Project (GSWP). We compare observed plant-available soil moisture in the top 1-m soil layer to the same quantity generated by the models. Our soil moisture observations are from grasslands and agricultural regions in Russia, Illinois (USA), China, and Mongolia.

None of the models does a good job of producing the actual soil moisture value for any of the regions. Thus, GSWP has not yet demonstrated the ability to produce global soil wetness data sets. Once the bias is removed, the models do a fairly good job at reproducing the seasonal cycle of soil moisture from the various areas. The model biases are different in different locations, so correcting them with a simple adjustment of the mean will not produce correct results. Better specification of parameters or better representation of physical and biological processes are still needed to improve these models.

Future GSWP experiments should be conducted for a longer time period and should include emphasis on catchment scale validation and higher time resolution of model output. In addition, increased soil moisture observations, possibly incorporating satellite measurements, would greatly improve a second project.

Prepared by Alan Robock (robock@envsci.rutgers.edu ) - Last updated on September 29, 1999