Data Assimilation of GPS Precipitable Water Vapor into the JMA Mesoscale Numerical Weather Prediction Model and its Impact on Rainfall Forecasts (3.Application of GPS Data to Atmospheric Science)

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概要

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• Precipitable water vapor (PWV), which was obtained from the nation wide GPS (Global Positioning System) network over Japan, operated by the Geographical Survey Institute (GSI), was assimilated into the meso data assimilation (DA) system of the Japan Meteorological Agency (JMA). Two different methods were examined; one is an optimum interpolation (OI) method, and the other is a 4-dimensional variational (4D-Var) method. Using the analysis data derived from both systems, a number of forecast experiments for rainfall events in Baiu and summer seasons were carried out using the JMA meso scale numerical weather prediction model (MSM). Remarkable improvements in rainfall forecast were seen in several cases, both for the OI and 4D-Var experiments. A statistical score of the 4D-Var experiments, however, showed that the impact of GPS PWV was almost neutral for rainfall forecast, and no substantial improvements were obtained. One of the reasons might be that GPS sites used for the experiments were too few, and sparsely distributed compared to the rainfall systems. Another reason specific for the 4D-Var is that, although the 4D-Var improved PWV analyses, it sometimes modified vertical profiles of water vapor significantly, which brought about different static stability from the first guess of the model (MSM) or from the observations. These results suggested the importance of correct assimilation of vertical profiles of water vapor.

• 社団法人日本気象学会の論文
• 2004-03-25

著者

• Mannoji Nobutaka

  Forecast Division Japan Meteorological Agency

• NAKAMURA Hajime

  Numerical Prediction Division, Japan Meteorological Agency

• Koizumi K

  Numerical Prediction Division Japan Meteorological Agency

• Koizumi Ko

  Numerical Prediction Division Japan Meteorological Agency

• Nakamura Hajime

  Numerical Prediction Division Japan Meteorological Agency

関連論文

• Dry Biases of Humidity Measurements from the Vaisala RS80-A and Meisei RS2-91 Radiosondes and from Ground-Based GPS (1.Ground-Based GPS Meteorology)
• Impact of GPS and TMI Precipitable Water Data on Mesoscale Numerical Weather Prediction Model Forecasts (3.Application of GPS Data to Atmospheric Science)
• Data Assimilation of GPS Precipitable Water Vapor into the JMA Mesoscale Numerical Weather Prediction Model and its Impact on Rainfall Forecasts (3.Application of GPS Data to Atmospheric Science)
• Temperature and Water Vapor Profiles Derived from Downward-Looking GPS Occultation Data (2.Space-Borne GPS Meteorology and Related Techniques)

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