Initialization of Cloud Water Content and Cloud Cover for Numerical Prediction Models

Xiang-Yu Huang Danish Meteorological Institute, Denmark

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Hilding Sundqvist Department of Meteorology, Stockholm University, Stockholm, Sweden

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Abstract

An initialization scheme for numerical models containing treatment of cloudiness is presented. The dynamic type of initialization scheme is based on the digital filtering technique, which requires integration of the model backward and forward about the analysis time. As the numerical model contains an advanced condensation-cloud parameterization, the initialization procedure renders initial cloud water and cloud cover fields, yet no cloud observations have been available. The initial cloud fields obtained are in a good agreement with the weather situations as they appear on satellite imagery and in synoptic analyses. The cloud water content is of the same order of magnitude as the one obtained from a 24-h forecast with the model. Improvements are observed in the spinup of the model cloud and of the precipitation rate.

Abstract

An initialization scheme for numerical models containing treatment of cloudiness is presented. The dynamic type of initialization scheme is based on the digital filtering technique, which requires integration of the model backward and forward about the analysis time. As the numerical model contains an advanced condensation-cloud parameterization, the initialization procedure renders initial cloud water and cloud cover fields, yet no cloud observations have been available. The initial cloud fields obtained are in a good agreement with the weather situations as they appear on satellite imagery and in synoptic analyses. The cloud water content is of the same order of magnitude as the one obtained from a 24-h forecast with the model. Improvements are observed in the spinup of the model cloud and of the precipitation rate.

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