A revised hydrology for the ECMWF model: Verification from field site to terrestrial water storage and impact in the Integrated Forecast System

TitleA revised hydrology for the ECMWF model: Verification from field site to terrestrial water storage and impact in the Integrated Forecast System
Publication TypeMiscellaneous
Year of Publication2008
AuthorsBalsamo, G, Viterbo, P, Beljaars, ACM, van den Hurk, BJJ, Hirschi, M, Betts, A, Scipal, K
Secondary TitleTechnical Memorandum
Number563
Abstract

The Tiled ECMWF Scheme for Surface Exchanges over Land (TESSEL) is used operationally in the Integrated Forecast System (IFS) for describing the evolution of soil, vegetation and snow over the continents at diverse spatial resolutions. A revised land surface hydrology (HTESSEL) is introduced in the ECMWF operational model, to address shortcomings of the land surface scheme, specifically the lack of surface runoff and the choice of a global uniform soil texture. New infiltration and runoff schemes are introduced with a dependency on the soil texture and standard deviation of orography. A set of experiments in stand-alone mode is used to assess the improved prediction of soil moisture at local scale against field site observations. Comparison with Basin-Scale Water Budget (BSWB) and Global Runoff Data Centre (GRDC) datasets indicates a consistently larger dynamical range of land water mass over large continental areas, and an improved prediction of river runoff, while the impact on atmospheric fluxes is fairly small. Finally the ECMWF data assimilation and prediction systems are used to verify the impact on surface and near-surface quantities in atmospheric-coupled mode. A mid-latitude error reduction is seen both in soil moisture and in 2m temperature.