Infrared satellite data assimilation at ncar
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Infrared Satellite Data Assimilation at NCAR. Tom Auligné , Hui-Chuan Lin, Zhiquan Liu, Hans Huang, Syed Rizvi, Hui Shao, Meral Demirtas, Xin Zhang National Center for Atmospheric Research. Work supported by AFWA, NASA, NSF, KMA. Outline. Introduction to satellite data assimilation at NCAR

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Infrared satellite data assimilation at ncar

Infrared Satellite Data Assimilation at NCAR

Tom Auligné,Hui-Chuan Lin,Zhiquan Liu, Hans Huang, Syed Rizvi, Hui Shao, Meral Demirtas, Xin Zhang

National Center for Atmospheric Research

Work supported by AFWA, NASA, NSF, KMA


Infrared satellite data assimilation at ncar

Outline

Introduction to satellite data assimilation at NCAR

Practical issues with AIRS data assimilation

Current developments on infrared radiances


Infrared satellite data assimilation at ncar

Introduction:Data assimilation at NCAR

  • WRF-ARW: Local Area Model (with global version) + TL/ADJ version

  • DART: Ensemble Data Assimilation (EnKF, ETKF, …) (no radiance yet)

  • WRF-Var: Variational Data Assimilation (3DVar, FGAT, 4DVar) + Hybrid system

  • Community support


Infrared satellite data assimilation at ncar

Satellite DA:WRF-Var capabilities

  • Retrievals (T / Q profiles)

    • SATEM (from AMSU)

    • AIRS retrievals (NASA version 5)

  • GPS Radio Occultation

    • Retrieved refractivity from COSMIC

  • Winds

    • Retrieved winds: polar MODIS, SATOB

    • Active sensors: Quikscat

  • Radiances(BUFR format from NCEP/NRL/AFWA/NESDIS)

    • HIRS from NOAA16, 17, 18

    • AMSU-A from NOAA15, 16, 18, EOS-Aqua, METOP-2

    • AMSU-B from NOAA15, 16, 17

    • MHS from NOAA18, METOP-2

    • AIRS from EOS-Aqua

    • SSMIS from DMSP16


Infrared satellite data assimilation at ncar

Satellite DA:WRF-Var capabilities

  • Retrievals (T / Q profiles)

    • SATEM (from AMSU)

    • AIRS retrievals (NASA version 5): NASA-EOS Project to assess impact over Antarctica

  • GPS Radio Occultation

    • Retrieved refractivity from COSMIC

  • Winds

    • Retrieved winds: polar MODIS, SATOB

    • Active sensors: Quikscat

  • Radiances(BUFR format from NCEP/NRL/AFWA/NESDIS)

    • HIRS from NOAA16, 17, 18

    • AMSU-A from NOAA15, 16, 18, EOS-Aqua, METOP-2

    • AMSU-B from NOAA15, 16, 17

    • MHS from NOAA18, METOP-2

    • AIRS from EOS-Aqua: AFWA Project to incorporate in operational 3DVar

    • SSMIS from DMSP16


Infrared satellite data assimilation at ncar

ModelTop

ModelTop

Solarcontamination

Ozone

AIRS

T Jacobians

AIRS Channel Selection:10hPa model top

RTTOV

(v 8.7)

CRTM

(REL-1.1)

T

Surface

O3

Q

T


Infrared satellite data assimilation at ncar

Observation Error:Tuning of statistics

NCEP

ECMWF

NCEP (and most ECMWF) observation errors statistics consistent with innovations

Error factor tuning from objective method (Desrozier and Ivanov, 2001)

Channel number`


Infrared satellite data assimilation at ncar

Quality Control & Thinning

  • Pixel-level QC

    • Reject limb observations

    • Reject pixels over land and sea-ice

    • Cloud/Precipitation detection (NESDIS)

    • Synergy with imager (AIRS/VIS-NIR)

  • Channel-level QC

    • Grosscheck(innovations <15 K)

    • First-guess check(innovations < 3o).

  • ThinningWarmest Field of View

Thinning (120km)

345 active data

Warmest FoV

696 active data


Infrared satellite data assimilation at ncar

Parameters

Predictors:

  • Offset

  • 1000-300mb thickness

  • 200-50mb thickness

  • Surface skin temperature

  • Total column water vapor

  • Scan, scan2, scan3

Cost Function

Bias Correction:Static and Variational

Modeling of errors in satellite radiances:

“Offline” bias correction

“Variational” bias correction


Infrared satellite data assimilation at ncar

VarBC:Issues with regional models

No Inertia Constraint

Inertia Constraint

VarBC Timeseries

Innovations for AIRS window channel #787

After BC

Before BC


Infrared satellite data assimilation at ncar

Parameter estimation:in CRTM & RTTOV

gmodulates atmospheric absorption to compensate for:

  • poor knowledge of gas concentrations (CO2, …)

  • errors in definition of ISRF

  • errors in mean absorption coefficient

Gamma sensitivity

Timeseries of  estimations

-1(%)

Analysis cycle


Infrared satellite data assimilation at ncar

Cloud Detection:MMR scheme

AIRS

2378 channels

… to identifying clear channels(insensitive to the cloud).

From « hole hunting » (identifying clear pixels)…

= Radiance calculated in clear sky

RTM

= Radiance calculated for overcast cloud at level k

/

Nk3

Nk2

Cloud fractionsNk are ajusted variationally to fit observations.

Nk1

Vertical Level

No

Pixel

Channel Number (LW band)


Infrared satellite data assimilation at ncar

Cloud Detection:Initial validation for AIRS

MODIS NASA Level 2 Product

AIRS Cloud Detection

Cloud Top Pressure (hPa)


Infrared satellite data assimilation at ncar

Current Developments:Cloudy Radiances

Cloud Top Pressure


Infrared satellite data assimilation at ncar

Current Developments:Observation Impact

Analysis

(xa)

Observation

(y)

Forecast

(xf)

WRF-VAR

Data Assimilation

WRF-ARW

Forecast

Model

Define

Forecast

Accuracy

Background

(xb)

Forecast

Accuracy

(F)

Observation Impact

<y-H(xb)> (F/ y)

Gradient

of F

(F/ xf)

Observation

Sensitivity

(F/ y)

Analysis

Sensitivity

(F/ xa)

Adjoint of WRF-ARW Forecast

TL Model

(WRF+)

Adjoint of

WRF-VAR

Data

Assimilation

Derive

Forecast

Accuracy

Background

Sensitivity

(F/ xb)

STATUS: DONE

ONGOING

Obs Error

Sensitivity

(F/ eob)

Bias Correction

Sensitivity

(F/ k)

Figure adapted

from Liang Xu


Infrared satellite data assimilation at ncar

More plans…

  • AIRS/AMSU (v.5) Retrievals over Antarctica

    • Collocate with COSMIC retrievals

    • Assess impact in AMPS system

  • AFWA Cloud Analysis

    • Introduce cloud hydrometeors in control variable

    • Study background error covariances for clouds

    • Include cloud microphysics into WRF-ARW TL/ADJ

    • Assess the accuracy/linearity of radiative transfer in cloudy conditions

  • IASI, CrIS


Infrared satellite data assimilation at ncar

Thanks for your attention…

[email protected]


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