Under the second Global Soil Wetness Project (GSWP2), the global energy and water balance is estimated by a simple bucket hydrology model using atmospheric forcing data and land surface parameters from International Satellite Land-Surface Climatology Project initiative 2 (ISLSCP2) for 10 years(1986-1995). The forced data has temporal resolution of 3 hourly and spatial resolution of 1 degree x 1 degree.

The model is identical to that was described by Robock et al (1995). The model has single soil layer with 1m depth and thermal inertia is assumed to be 0. The difference between field capacity and wilting point is assumed to be 15% of the total soil volume and soil moisture is represented as water in a bucket of 15cm depth. The snow layer is 0 dimensional and fractional cover, density and thermal conductivity of snow is not considered. Snow albedo is represented by a linear function of surface temperature and snow water equivalent.

The resulting global energy and water balance is discussed. The bucket model is quite simple and non-biological, however, its simplicity enable us to analyze the processes and the results easily and the characteristics are suited for the base line simulation of GSWP2 that aims at intercomparison of more complex, biological land surface schemes.