AIRS Sounding and Cloud Property Study

Xuebao Wu, Jun Li, Paul Menzel,Allen Huang In collaboration with CIMSS colleagues

National Satellite Meteorology Center, Beijing, China CIMSS, University of Wisconsin-Madison, Madison, U.S.A.

Mar.6, 2006

Outline

( Clear Sounding Study) 1. Algorithm---Regression&Physical 2. Two Experiments 3. Validation (Cloud Property Study) 4. MR Retrieval Method 5. Case Study: MPACE 6. Validation

(Courtesy of Lee et al., 2005）

Part 1. Clear IR Sounding Retrieval

RegressionPhysical retrieval (regularization) which needs

--Radiance measurements and observation errors --First guess from regression or other sources --Fast Radiative Transfer Model

-- Others

Regularization Inversion

202)()( XXXYYXJ m

Equations

,X

Unknowns

Solutions

X Newton Iteration

Discrepancy Principle (Li and Huang 1999)

22))(()( mYXYG

Discrepancy Principle

)(G

Residual = Observation error

γ

1688 AIRS Channels

394 AIRS Channels

Sept.6, 2002, G193

1km MODIS Cloud Mask

AgainstECMWF

500 hPa T difference 500 hPa q (g/kg) difference

Validation with match up dataset

• Match up dataset at ARM SGP Site AIRS/Best Estimate (Sept. of July 2002 – Aug. of 2004) )

• Use AIRS retrieval algorithm developed at CIMSS (regression + physical)

Part 2 Cloud Property Study

Some features:

1. Minimum Residual Retrieval Method

2. Ping Yang’s fast cloud RT model

3. MODIS cloud mask and cloud phase to characterize the AIRS SFOV

][][)]([)]([)( 11B

TB

mTm XXBXXXRREXRRXJ

1DVAR algorithm for cloud retrieval

Fast Cloudy Radiative Transfer Model: coupled

Observed AIRS Radiance Measurements

),,,...,,,,( 10321 COTCPSECAECAECAECACTPX

CTP: Cloud-Top Pressure; ECA: Effective Cloud AmountCPS: Cloud Particle Size; COT: Cloud Optical Thickness at 0.55µmCTP and ECA: 720 – 790 cm**-1COT and CPS: 790 – 1130 cm**-1

Background Information from MODIS

)]([)]([)()( 1 XRREXRRXRRXJ mTmm

Minimum Residual (MR) algorithm for cloud retrieval

( Courtesy of Chianyi LIU)

MODIS Cloud Phase

AIRS CTH (m)

Barrow

Conclusion?

• Clear sky sounding retrieval algorithm has been tested using AIRS data. Physical retrieval work reliably. One day MPACE study.

• Ongoing works and Remaining issues(Esfc,BiasCorr)

• Acknowledge: HalW, KevinB, JinglongL,SeeBor, DaveT

Reference:

Wu Xuebao, Li Jun, Zhang Wenjian, and Wang Fang, Atmospheric Profile Retrieval with AIRS Data and Validation at the ARM CART Site, Advances in Atmospheric Sciences, 2005, Vol. 22, No. 5, 647–654.

Wu, X., J. Li, W. P. Menzel, A. Huang, K. Baggett, and H. Revercomb, Evaluation of AIRS cloud properties using MPACE data, Geophys. Res. Lett., 2005, 32, L24819.