Towards Passive Microwave Radiance Assimilation of Clouds and
- Slides: 12
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 3: NOAA/NESDIS 4: NOAA/NCEP 5: ECMWF
Outline Ø SOI model and applications Ø Cloud/precipitation overlap Ø 3 -year accomplishments Ø Further plans
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
Accuracy of Results (Eddington and SOI versus Monte-Carlo model)
Forward and adjoint simulation example GFS Simulations AMSR-E Observations
Infrared Applications: MSG SEVIRI
MSG SEVIRI Comparison Results Channel RMSE [K] Bias [K] 6. 2 m 1. 93 0. 22 7. 3 m 1. 91 -1. 25 8. 7 m 1. 54 1. 17 10. 8 m 1. 38 0. 73 12. 0 m 1. 37 0. 64 13. 4 m 1. 37 1. 06
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 < 1 K
Different cloud/precipitation overlap models 1 Column Currently operational at ECMWF 2 Columns 3 columns 3 optimal O’Dell, Bauer, Bennartz, JAS, 2006, submitted
Different cloud/precipitation overlap models 1 Column Currently operational at ECMWF 2 Columns 3 columns New scheme with much better error characteristics 3 optimal O’Dell, Bauer, Bennartz, JAS, 2006, submitted
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
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.
- Active and passive microwave devices
- Microwave passive devices
- Passive microwave repeater
- Radiance equation
- Total radiance
- Radiance vs reflectance
- Total radiance
- Radiance to irradiance conversion
- Spherical harmonics lighting
- Radiance map
- Precomputed radiance transfer
- 4 parts of digestive system
- Absorption and assimilation