基于BDA扰动法的台风路径集合预报试验研究

EXPERIMENTS OF ENSEMBLE FORECAST OF TYPHOON TRACK USING BDA PERTURBING METHOD

关键词:  集合预报  台风路径  BDA扰动方法  台风数值预报

Key words:  ensemble forecast  typhoon’s track  BDA perturbing method  typhoon numerical forecast

摘要:

提出一种新的方法(BDA扰动方法)对台风路径进行集合预报。BDA扰动方法是基于BDA同化方案,通过扰动台风的中心位置和台风强度得到一系列模型台风,将之分别同化到同一环境场中得到一系列扰动初始场,从而对台风进行集合预报的方法。本文选取四个台风个例进行数值试验,将直接用BDA方案同化初始场的模拟结果与采用BDA扰动方法模拟的结果进行比较,发现:利用BDA扰动方法对台风路径进行集合预报能进一步提高路径预报精度;同时发现:对于BDA扰动方法,若与初始定位扰动相结合,5 hPa的台风强度扰动幅度可能比10 hPa的

Abstract:

A new method,BDA perturbing,is used in ensemble forecasting of typhoon track.This method is based on the Bogus Data Assimilation scheme.It perturbs the initial position and intensity of typhoons and gets a series of bogus vortex.Then each bogus vortex is used in data assimilation to obtain initial conditions.Ensemble forecast members are constructed by conducting simulation with these initial conditions.Some cases of typhoon are chosen to test the validity of this new method and the results show that: using the BDA perturbing method to perturb initial position and intensity of typhoon for track forecast can improve accuracy,compared with the direct use of the BDA assimilation scheme.And it is concluded that a perturbing amplitude of intensity of 5 hPa is probably more appropriate than 10 hPa if the BDA perturbing method is used in combination with initial position perturbation.