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Abstract: This paper uses high resolution WRF model to simulate a number of heavy rainfall events in summer in Ho Chi Minh city using radar data to assimilation initial conditions with 3DVAR method, the WRF3Dvar running simulation with two modes: cold start and warm start combine with three cases: only Reflectivity of radar; Reflectivity and Doppler radar radial wind observations; Reflectivity, Doppler radar radial wind, and GTS data. The background error used was CV7 created from 6 months forecast in South Vietnam. Radar data before assimilation was quality control and thinned to remove noise and create the best observation. 24 station rainfall in South Vietnam using to an evaluation of WRF model simulation. Results show assimilation only reflectivity will affect to variable Qcloud, Qvapor and Qrain on the initial condition of model and assimilation only Doppler radar radial wind improve wind. Compare each case show warm start simulation precipitation better than the cold start, assimilation both Doppler radar radial wind observations, the reflectivity of radar and GTS better than another case.
Keywords: WRFDA, RADAR.
 Dư Đức Tiến và cộng sự , Nghiên cứu đồng hóa số liệu Radar Đông Hà để nâng cao chất lượng dự báo mưa lớn cho khu vực miền Trung. Tạp chí Khí tượng Thủy văn 2013, số 632 tr.12-19. – 2013
 Trần Hồng Thái và cộng sự, Phương pháp đồng hóa số liệu nudging cho quan trắc Radar và tác động tới dự báo mưa lớn trên khu vực Bắc Bộ. tạp chí Khí tượng Thủy văn 2016, số 670 tr.1-6. – 2016.
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