Kein Folientitel

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Towards passive microwave radiance assimilation
of clouds and precipitation Ralf Bennartz1, Tom
Greenwald2, Andrew Heidinger3, Chris ODell1,
Martin Stengel1, Kenneth Campana4, Peter
Bauer5 1 Atmos. Oceanic Sci.,University
of Wisconsin 2 CIMSS,University of Wisconsin 3
NOAA/NESDIS 4 NOAA/NCEP 5 ECMWF
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• Outline
• Introduction
• Comparison of different models for cloud/precip
  assimilation
• Accuracy
• Speed
• Phase function
• Slant path
• Including Cloud liquid water/precipitation
  First results
• Biases GFS/AMSR under cloud-free and cloudy
  conditions
• MSG SEVIRI
• Status
• Plans for year 3

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Definitions
Gas Absorption properties
Radiative Transfer
Particle scattering properties
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GFS interface against OPTRAN-RT (gas absorption
only) (Sanity check for our implementation)
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OPTRAN-RT versus Eddington (gas absorption only)
Difference 89 GHz
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Speed Test (SOI versus Eddington)
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Accuracy of Results (Eddington and SOI versus
Monte-Carlo model)
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• Comparisons satellite/simulations including cloud
  liquid water
• Screening strategy
• Stay within 1.0 hours between GFS forecast and
  AMSU/ AMSR observation
• Use CLAVR-X (Heidinger, 2003) AVHRR gridded cloud
  product to find boxes that are at least 95
  cloudy (or at maximum 5 cloudy for cloud-free)
• Compare AMSU-A/B window frequencies and AMSU-B
  183 X GHz water vapor absorption channels

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• First assessment of AMSR versus GFS (period Jan
  2004)
• (cloud-free 6.9, 10.7, 18.7 GHZ versus scan
  position)

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• First assessment of AMSR versus GFS (period Jan
  2004)
• (cloud-free 23, 36, 89 GHZ versus scan position)

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• Simulation example forward and adjoint

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• Simulation example forward and adjoint

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• HG versus Mie phase function

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• Comparison MSG-SEVIRI versus GFS
• June 2004
• SOI
• RTTOV-8 gas absorption
• Only cloud-free so far

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• Infrared MSG SEVIRI No. of cloud-free obs,
• June 2004

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• Infrared MSG SEVIRI

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• Infrared MSG SEVIRI

Channel RMSE K Bias K
6.2 1.93 0.22
7.3 1.91 -1.25
8.7 1.54 1.17
10.8 1.38 0.73
12.0 1.37 0.64
13.4 1.37 1.06
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• Infrared MSG SEVIRI BIAS mid-trop WV

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• Infrared MSG SEVIRI BIAS window

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• Infrared MSG SEVIRI BIAS CO2

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• Status after year 2
• Fast RT models (SOI) developed, tested and
  integrated in CRTM
• Tangent linear and adjoint model developed,
  tested, and integrated in CRTM
• Bias statistics for passive microwave
• Initial results also for infrared SEVIRI
  cloud-free

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• Plans for year 3
• Monitor bias statistics over longer time
  period,especially
• Fully include scattering (need more complete GFS
  input data)
• Biases in IR including scattering
• Precipitation assimilation
• Include cloud diagnostics to generate
  precipitation rate
• 1DVAR loop to optimize moisture profiles versus
  direct assimilation?