气象卫星资料同化研究进展

资料同化研究进展：
1 Overview

2 Approaches to assimilation
Infrared radiances
(15.5–3.7 μm)：

()cldLf云量，云顶高度
1、单一层假设
2、简化的云参数，来自观测的估计，而在实际大气中，它们是不均匀和非线性的。
3、按线性组合来解释云辐射

NWP centre Model Global Regional In the study
Infrared Microwave
ECMWF IFS HIRS/AIRS/IASI (4D-Var) SSMI(S)/AMSR-E/TMI (4D-Var)“all-sky system”AMSU-A ch 3、4
ground-based
radar
precipitation in
the global 4D-Var
system

JMA GSM MSM
AMSR-E/TMI (4D-Var in MSM) Ground-based radar precipitation in MSM (4D-Var (2002)

MF (France) ARPEGE AROME AIRS/IASI
Ground radar network (1D+3D-Var) (April 2010)

UKMO
UK NAE AIRS/IASI (1D-Var/4D-Var) AMSU-A ch 1 、2 (4D-Var) （‘Total’ RH） Radar rain rate(LHN) SEVIRI(1D+4D-Var) radar rain data in
NAE 4D-Var

NCEP GFS NAM WRF
TMI-retrieved surface rainrate/ AMSU-A radiance data affected by clouds over ocean in GDAS （Normalized RH and cloud water mixing ratio）
,+()cldcldcldocld
LLLp（1-N）N

N(1-)=N

几何因子N≠模式（物理）云量

N

≠物理发射率

cld
p
≠物理云顶

MMR
（the Multi-variate Minimum Residual）

MMR Cloud detection
:

3k
N

001ncldkk

kRNRNR




2k
N

ECMWF’s IFS

NCAR’s WRF

1kN NCEP’s GSI

Pixel
Cloud-top pressure(hPa) derived from Aqua MODIS
Cloud-top pressure(hPa)derived from AIRS using the NCAR MMR method
Mean temperature analysis impact (K) of cloud-affected infrared sounder radiance data assimilation
experiments :
700hpa 850hpa
ECMWF:(September–November 2009)

M´et´eo-France:(September 2010)
Environment Canada:(September 2010)

Relative change in RMS forecast errors for selected parameters between clear + cloud-affected and clear-sky
only infrared radiance data assimilation experiments:
Met Office(December 2008):
M´et´eo-France(December2008):
Microwave radiances：
Quality Control in WRF-Var :
•AIRS: Multivariate Minimum Residual (MMR) scheme for cloud detection
•AMSU, MHS, SSMIS: Scatter Index（SI）and Background CLWP for precipitation check
云检测：
对AMSU-A：散射因子、降水概率和小雨检测
对AMSU-B：通道2亮温模拟观测误差、Bennartz散射因子

UKMO：
AMSU-A channels 1 and 2

ECMWF：
“all-sky system”：AMSU-A ch 3、4，区域主要是中纬度洋面。
AMSU-A channels 5 and 6: 700hpa，400hpa，对流性云水汽凝结现象

Mean first-guess departure difference (K) of Metop AMSU-A channel 4 radiances in the radiative transfer
calculations（1–8 February 2010）
(a) cloud effects are ignored VS (b) cloud effects are included
UKMO and ECMWF 的优点：进行精确的辐射传输计算，而不是直接影响模式的物理湿度参数，只需初
猜场的云特性,与模式物理量之间的相互关系不活跃。控制矢量、背景场误差统计、线性化的物理量等不
受影响。

USA：
JCSDA and NCEP：
AMSU-A radiance data /TMI affected by clouds over ocean in GDAS
控制变量： T、Q、P、地表风 +Normalized RH and cloud water mixing ratio，total moisture（water vapour
+ cloud liquid + cloud ice + hydrometeors）
背景误差协方差矩阵：1、NMC
2、集合预报成员与集合平均之差作为预报误差近似