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)：

()cld L f 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/I ASI (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-V ar) 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 ）

,+()cld cld cld o cld L L L p εε

=（1-N ）N

τε

N(1-)=N

几何因子N ≠模式（物理）云量

εN ≠物理发射率

cld p ≠物理云顶

MMR （the Multi-variate Minimum Residual ）

MMR Cloud detection :

3

k N

1

n

cld

k

k

k R N R N R ν

νν

==+∑

2

k N

ECMWF’s IFS

NCAR’s WRF 1

k N

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