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- Author or Editor: L.M. Druyan x
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Abstract
The impact of satellite radiometric soundings on numerical forecasts with the Israel Meteorological Service's three-parameter, haroclinic model is evaluated. Two sets of experiments are performed. One set (26 forecasts) uses experimental VTPR (Vertical Temperature Profile Radiometer) temperature profiles retrieved by the Goddard Institute for Space Studies during January 1974; the second set (13 forecasts) uses operational VTPR temperature profiles transmitted over the global meteorological telecommunications system in January 1976. In both sets of experiments the VTPR soundings are used to enhance the initial analyses over the Atlantic Ocean. Parallel forecasts with and without the VTPR data are verified against operational analyses over a region that includes most of Europe, the Middle East and North Africa. The results indicate that, on the average, there is a small improvement in the forecasts that utilize the satellite temperature soundings. For example, the root-mean-square height errors of the 48 h 500 mb forecast are reduced by ∼4% in the cases utilizing experimental VTPR data and by ∼3% in the cases using operational VTPR data. In both sets of experiments, this average effect is composed of a combination of marginally influenced, positively influenced and negatively influenced forecasts.
Abstract
The impact of satellite radiometric soundings on numerical forecasts with the Israel Meteorological Service's three-parameter, haroclinic model is evaluated. Two sets of experiments are performed. One set (26 forecasts) uses experimental VTPR (Vertical Temperature Profile Radiometer) temperature profiles retrieved by the Goddard Institute for Space Studies during January 1974; the second set (13 forecasts) uses operational VTPR temperature profiles transmitted over the global meteorological telecommunications system in January 1976. In both sets of experiments the VTPR soundings are used to enhance the initial analyses over the Atlantic Ocean. Parallel forecasts with and without the VTPR data are verified against operational analyses over a region that includes most of Europe, the Middle East and North Africa. The results indicate that, on the average, there is a small improvement in the forecasts that utilize the satellite temperature soundings. For example, the root-mean-square height errors of the 48 h 500 mb forecast are reduced by ∼4% in the cases utilizing experimental VTPR data and by ∼3% in the cases using operational VTPR data. In both sets of experiments, this average effect is composed of a combination of marginally influenced, positively influenced and negatively influenced forecasts.
Abstract
A model description and numerical results are presented for a global atmospheric circulation model developed at the Goddard Institute for Space Studies (GISS). The model version described is a 9-level primitive-equation model in sigma coordinates. It includes a realistic distribution of continents, oceans and topography. Detailed calculations of energy transfer by solar and terrestrial radiation make use of cloud and water vapor fields calculated by the model. The model hydrologic cycle includes two precipitation mechanisms: large-scale supersaturation and a parameterization of subgrid-scale cumulus convection.
Results are presented both from a comparison of the 13th to the 43rd days (January) of one integration with climatological statistics, and from five short-range forecasting experiments. In the extended integration, the near-equilibrium January-mean model atmosphere exhibits an energy cycle in good agreement with observational estimates, together with generally realistic zonal mean fields of winds, temperature, humidity, transports, diabatic heating, evaporation, precipitation, and cloud cover. In the five forecasting experiments, after 48 hr, the average rms error in temperature is 3.9K, and the average rms error in 500-mb height is 62 m. The model is successful in simulating the 2-day evolution of the major features of the observed sea level pressure and 500-mb height fields in a region surrounding North America.
Abstract
A model description and numerical results are presented for a global atmospheric circulation model developed at the Goddard Institute for Space Studies (GISS). The model version described is a 9-level primitive-equation model in sigma coordinates. It includes a realistic distribution of continents, oceans and topography. Detailed calculations of energy transfer by solar and terrestrial radiation make use of cloud and water vapor fields calculated by the model. The model hydrologic cycle includes two precipitation mechanisms: large-scale supersaturation and a parameterization of subgrid-scale cumulus convection.
Results are presented both from a comparison of the 13th to the 43rd days (January) of one integration with climatological statistics, and from five short-range forecasting experiments. In the extended integration, the near-equilibrium January-mean model atmosphere exhibits an energy cycle in good agreement with observational estimates, together with generally realistic zonal mean fields of winds, temperature, humidity, transports, diabatic heating, evaporation, precipitation, and cloud cover. In the five forecasting experiments, after 48 hr, the average rms error in temperature is 3.9K, and the average rms error in 500-mb height is 62 m. The model is successful in simulating the 2-day evolution of the major features of the observed sea level pressure and 500-mb height fields in a region surrounding North America.
