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Towards Passive Microwave Radiance Assimilation of Clouds and Precipitation

Towards Passive Microwave Radiance Assimilation of Clouds and Precipitation Ralf Bennartz 1 , Tom Greenwald 2 , Andrew Heidinger 3 , Chris O’Dell 1 , Martin Stengel 1 , Kenneth Campana 4 , Peter Bauer 5 1: Atmos. & Oceanic Sci. ,University of Wisconsin 2: CIMSS ,University of Wisconsin

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Towards Passive Microwave Radiance Assimilation of Clouds and Precipitation

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  1. Towards Passive Microwave Radiance Assimilation of Clouds and Precipitation Ralf Bennartz1, Tom Greenwald2, Andrew Heidinger3, Chris O’Dell1,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

  2. Outline • SOI model and applications • Cloud/precipitation overlap • 3-year accomplishments • Further plans

  3. SOI Radiative Transfer Model • Hybrid multi-stream solution method (doubling plus iteration) (Heidinger et al. 2006; O’Dell et al. 2006) • Implementation - Less scattering: 2-stream solution - More scattering: 4-stream solution • Forward, tangent linear and adjoint models integrated into CRTM

  4. Accuracy of Results (Eddington and SOI versus Monte-Carlo model)

  5. Forward and adjoint simulation example GFS Simulations AMSR-EObservations

  6. Infrared Applications: MSG SEVIRI

  7. MSG SEVIRI Comparison Results

  8. Different cloud/precipitation overlap models • Conventional approach uses cloud cover to subdivide NWP pixel in cloudy/precipitation • New approach derives two or three optimal columns based on subscale distribution of precipitation columns with similar optical properties • Numerically efficient (2-3 radiative transfer calculations per NWP grid point) • Highly accurate against independent column/Max-Random-overlap reference • Optimal approach reduces errors due to cloud overlap from maximum values of 5-10 K to values < 1K

  9. Different cloud/precipitation overlap models 1Column 2Columns 3columns 3 optimal Currently operational at ECMWF O’Dell, Bauer, Bennartz, JAS, 2006, submitted

  10. Different cloud/precipitation overlap models 1Column 2Columns 3columns 3 optimal New scheme with much better error characteristics Currently operational at ECMWF O’Dell, Bauer, Bennartz, JAS, 2006, submitted

  11. 3-year Accomplishments • Fast forward RT model (SOI) developed, tested and integrated in CRTM (3 publications) • Tangent linear and adjoint model developed, tested, and integrated in CRTM • Bias GFS/SOI statistics for passive microwave and infrared • Fast and accurate new cloud overlap scheme for use in NWP radiance assimilation (forward/adjoint); manuscript submitted

  12. Further plans • 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 • Further test and integrate cloud overlap with NCEP/GFS.

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