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Shanhong Gao. Data assimilation for sea fog over the Yellow Sea. 中国海洋大学 海洋气象学系. MODIS, MTSAT, FY images. Three aspects are important. model. ● initial conditions ● micro-physics ● PBL scheme. Obs. fog area. inversion. Observations. sound. synop. ships. QuikSCAT. airs. gps.
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Shanhong Gao Data assimilation for sea fog over the Yellow Sea 中国海洋大学 海洋气象学系 MODIS, MTSAT, FY images
Three aspects are important model ● initial conditions● micro-physics●PBL scheme Obs fog area inversion
Observations sound synop ships QuikSCAT airs gps others
Obs DA result model analysis first guess (bg) Data assimilation methods DA methods:OA, 3DVAR, 4DVAR, Kalman Filters
(a) 3DVAR (3 dimensional varational ) analysis first guess obs Observation error Background error
EnKF yo time 3DVAR xb xa xb 3DVAR + ETKF (b) Hybrid-3DVAR ( ETKF + 3DVAR ) xb xb xa xa xb xb Xb: bgyo: obsXa: analysis 3DVAR: 3-dimensional variational Advantages: • based on the existed frame of 3DVAR • flow –dependent background error EnKF: Ensemble Kalman Filter ETKF: Ensemble Transform Kalman Filter
(c) flow-dependent background error (BE) 3DVAR uses static BE. In fact, flow-independent is better. Temporal mean Non-flow dependent flow dependent (Hamillet al., 2006)
Data assimilation Tools • Based on the WRF model, we have developed • Cycling-3DVAR DA module • Hybrid-3DVAR Da module
create_my_case 子系统主要目录结构
2. Two study cases Case1: Observed fact(Year 2006) 20 LST 06 Mar 02 LST 07 Mar 08 LST 07 Mar 20 LST 07 Mar 12 LST 07 Mar 14 LST 07 Mar 02 LST 08 Mar 05 LST 08 Mar MTSAT IR(Gaoet al., 2009) TBB of IR1
Model configuration Specifications of WRF run Domains
Obs Comparison of simulated results Exp-A FNL only Single 3DVAR Exp-B Cycling 3DVAR Exp-C Hybrid Ens=12 Exp-D Hybrid Ens=24 Exp-E
Model configuration Specifications of WRF run Domains
Assimilating MTSAT-derived humidity MTSAT-IR Dual-channel detection Step1 Step2 Step3 DA
Result Single 3DVAR Cycling 3DVAR Cycling 3DVAR + MTSAT
Assimilating MTSAT-derived humidity Wang et al. (2014)