Application of Optical Flow Method to Heavy Precipitation Forecast Verification
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Abstract:
The optical flow method is an important method in motion image analysis, which is mainly used to determine the motion information of a target. The element forecast fields produced by numerical models are gridded spaces, which are also a kind of images, and the optical flow method used in image analysis can be applied to the numerical model verification. The optical flow method is used to the heavy precipitation forecast verification. The principles of the optical flow method are described by using the theoretical simulation, and then through the verification on the 24 h precipitation forecast of ECMWF and T639 models for three different types of heavy precipitation process, the practical application of the optical flow verification method in heavy precipitation forecast verification is discussed. The results show: (1) By decomposing the forecast error into intensity, displacement, and angular errors, the optical flow verification method can give an accurate quantitative analysis of the heavy precipitation forecast errors. (2) Based on the application of the optical flow verification method for three different types of heavy precipitation processes such as plum rain, southwest vortex, and typhoon, it can be found that for the same precipitation process, different numerical models usually have different performance in strength, displacement, and angular errors. The optical flow verification results have high reference value in reflecting the differences of the precipitation strength, precipitation belt deviation angle, and distance of different models.
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.