The Second Global Soil Wetness Project (GSWP-2) is an ongoing environmental modeling research activity of the Global Land-Atmosphere System Study (GLASS) and the International Satellite Land-Surface Climatology Project (ISLSCP), both contributing projects of the Global Energy and Water Cycle Experiment (GEWEX). One of the major goals of this project is to help to improve future Land Surface Schemes (LSSs) performance through the inter-comparison of LSSs and sensitivity studies of specific parameterizations and forcings. LSS simulations in GSWP-2 will encompass the same core 10-year period as ISLSCP initiative II (1986-1995). More than 20 LSSs will participate in this project.

In this study a 10-year simulation of the NCEP Noah LSM will be carried out with the same configuration of GSWP-2 baseline experiment but using traditional NCEP rather than GSWP-2 specified surface parameters. The parameters with different values in these two simulations include surface albedo, greenness, leaf area index, surface roughness, surface slope, field capacity, wilting point, saturated water content, B exponent, saturated hydraulic conductivity, and saturated matric potential. With more recent data adopted by GSWP-2 to prescribe surface conditions, we should anticipate that GSWP-2 baseline simulation yields better results. Based on this we will make some necessary updating or replacing of surface parameters in Noah LSM. The comparison between these two simulations will be also used to guide the tuning of parameters in formulations for infiltration and runoff scheme in Noah LSM with some auxiliary short-term sensitivity simulations.

Future GSWP-2 sensitivity studies to prescribed surface conditions will provide further guidance on such updating and tuning.