DEVELOPMENT OF CELL-TRACKING ALGORITHM IN THE CZECH HYDROMETEOROLOGICAL INSTITUTE

Abstract. Precipitation and convective storms now-casting based on weather radar data has been studied in the CHMI (Czech Hydrometeorological Institute) for a long period. Two methods of radar echo prediction on entire radar domain were implemented in 2003 into the operational processing of the Czech Weather Radar Net-work. The methods work very well but they have some limitations mainly for severe convective storms nowcast-ing. These limitations resulted into development of cell-oriented algorithm of radar echo prediction. Cell identification is based on single minimum thresh-olding of maximum reflectivity data. Wind field from operational prediction algorithm (calculated for entire radar domain) is used as a first guess of cell assignment algorithm in subsequent images. Splitting and merging are also considered within the cell assignment algorithm. Simple calculation of cell motion vector from reflectiv-ity core centres displacement is too inaccurate. Thus, to calculate cell motion vector, special local similarity algorithm is applied on each assigned cell pair. The paper describes this algorithm and shows evalu-ation of the algorithm performance. Comparison with operationally implemented algorithm is showed.