Schlosser, C. A., A. G. Slater, A. Robock, A. J. Pitman, K. Y. Vinnikov, A. Henderson-Sellers, N. A. Speranskaya, K. Mitchell, and the PILPS 2(d) contributors, 2000: Simulations of a boreal grassland hydrology at Valdai, Russia: PILPS Phase 2(d). Mon. Weather Rev, 128, 301-321.

The Project for the Intercomparison of Land-surface Parameterization Schemes (PILPS) aims to improve understanding and modeling of land-surface processes. PILPS Phase 2(d) uses a set of meteorological and hydrological data spanning 18 years (1966-1983) from a grassland catchment at the Valdai water-balance research site in Russia. A suite of standalone simulations is performed by 21 land-surface models (LSMs) to explore the LSMs' sensitivity to downward longwave radiative forcing, timescales of simulated hydrologic variability, and biases resulting from single-year simulations that use recursive spin-up. These simulations are the first in PILPS to investigate the performance of LSMs at a site with a well-defined seasonal snow cover and frozen soil. Considerable model scatter for the control simulations exist. However, nearly all of the LSMs are within the spatial variability of root-zone soil water observed inside the catchment. A greater sensitivity of simulated snow melt, compared to snow accumulation, to the choice of snow parameterization is found. All models show a consistent sensitivity to longwave forcing for the simulation of the snow pack, which during the spring melt affects runoff, melt-water infiltration, and subsequent evapotranspiration. Sensitivity simulations starting at prescribed conditions with no spin-up demonstrate that the treatment of frozen soil (moisture) processes can affect the long term variability of the models. The single-year recursive runs show large biases, compared to the corresponding year of the control run, that can persist through the entire year and further emphasize the importance of performing multi-year simulations.

Prepared by Alan Robock (robock@envsci.rutgers.edu ) - Last updated on April 14, 2000