Assimilation of radar radial velocity data with the WRF Hybrid ETKF-3DVAR system for the prediction of Hurricane Ike (2008)

作者：Shen Feifei; Min Jinzhong^*; Xu Dongmei

来源：Atmospheric Research, 2016, 169: 127-138.

DOI：10.1016/j.atmosres.2015.09.019

• Radial velocity data
• WRF data assimilation
• Hybrid ETKF-3DVAR
• Numerical simulation

The impacts of assimilation of radar radial velocity (Vr) data for the application of analyses and forecasts for Hurricane Ike (2008) are investigated using hybrid ensemble transform Kalman filter-three-dimensional variational data assimilation method (Hybrid ETKF-3DVAR) in this study. Radar Vr observations are pre-processed with quality control procedures before they are assimilated using Weather Research and Forecasting and Data Assimilation model (WRFDA) with three-dimensional variational data assimilation (3DVAR) and hybrid method respectively. With the hybrid method, the ensemble mean is updated with the variational method, while the ensemble perturbations are updated by the ETKF. It seems that assimilating Radar Vr data with Hybrid ETKF-3DVAR method is able to adjust the hurricane initial position and dynamic structure significantly, yielding better track and intensity forecast in the data assimilation experiments. Positive temperature increments are found in Hybrid ETKF-3DVAR experiment, indicating a more realistic thermal structure of Hurricane Ike, while 3DVAR experiment produces much smoother and weaker increments with cold temperature increments near the hurricane vortex center at lower levels. Hybrid ETKF-3DVAR further improves the track and intensity forecast accuracy compared to 3DVAR. The ability of the hybrid method in providing flow-dependent background error covariance is the primacy reason for its superior performance.

• 出版日期2016-3-1
• 单位南京信息工程大学