Operational Implementation of the ISBA Land Surface Scheme in the Canadian Regional Weather Forecast Model. Part I: Warm Season Results
- 1 April 2003
- journal article
- Published by American Meteorological Society in Journal of Hydrometeorology
- Vol. 4 (2), 352-370
- https://doi.org/10.1175/1525-7541(2003)4<352:oiotil>2.0.co;2
Abstract
The summertime improvement resulting from the operational implementation of a new surface modeling and assimilation strategy into the Canadian regional weather forecasting system is described in this study. The surface processes over land are represented in this system using the Interactions between Soil–Biosphere–Atmosphere (ISBA) land surface scheme. Surface variables, including soil moisture, are initialized using a sequential assimilation technique in which model errors of low-level air temperature and relative humidity are used to determine analysis increments of surface variables. It was found that the magnitude and nature of the analysis increments applied to the surface variables depended on the surface and meteorological conditions observed in each region. In regions characterized by weak meteorological activity (i.e., no clouds or precipitation), model errors of low-level air characteristics are more likely to be related to an incorrect representation of surface processes due to either erroneous initial conditions or inaccurate parameterizations in the land surface scheme. In other regions characterized by more frequent and more intense precipitation events, surface corrections are mainly associated with inaccurate atmospheric forcing. Objective evaluation against observations from radiosondes and surface stations showed that the amplitude of the diurnal cycle of near-surface air temperature and humidity is larger with the new surface system, in better agreement with observations. This type of improvement was found to extend higher up in the boundary layer (up to 700 hPa) where cold and humid biases were significantly reduced by introducing the new surface system. The model precipitation was also found to be significantly influenced by the new representation of surface fluxes. The problematic increase of a positive bias in precipitation with integration time was found to be significantly reduced with the new system, due to the warmer and drier boundary layer.Keywords
This publication has 72 references indexed in Scilit:
- Impact of Horizontal Resolution on the Numerical Simulation of a Midlatitude Squall Line: Implicit versus Explicit CondensationMonthly Weather Review, 2001
- The Influence of the Inclusion of Soil Freezing on Simulations by a Soil–Vegetation–Atmosphere Transfer SchemeJournal of Applied Meteorology and Climatology, 2000
- Operational Implementation of the Fritsch–Chappell Convective Scheme in the 24-km Canadian Regional ModelWeather and Forecasting, 2000
- Inclusion of a Third Soil Layer in a Land Surface Scheme Using the Force–Restore MethodJournal of Applied Meteorology and Climatology, 1999
- FIFE Surface Climate and Site-Average Dataset 1987–89Journal of the Atmospheric Sciences, 1998
- The Anomalous Rainfall over the United States during July 1993: Sensitivity to Land Surface Parameterization and Soil Moisture AnomaliesMonthly Weather Review, 1996
- Sequential Assimilation of Soil Moisture from Atmospheric Low-Level Parameters. Part I: Sensitivity and Calibration StudiesJournal of Applied Meteorology and Climatology, 1993
- Sequential Assimilation of Soil Moisture from Atmospheric Low-Level Parameters. Part II: Implementation in a Mesoscale ModelJournal of Applied Meteorology and Climatology, 1993
- Inclusion of a TKE Boundary Layer Parameterization in the Canadian Regional Finite-Element ModelMonthly Weather Review, 1989
- Numerical Experiments on the Computation of Ground Surface Temperature in an Atmospheric General Circulation ModelJournal of Applied Meteorology, 1975