Cloud rain partitioning using modis and amsr e
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Cloud/Rain partitioning using MODIS and AMSR-E. Matt Lebsock. Aqua AMSR- E & MODIS. The world is a drizzly place. Drizzle defined where 750 meter reflectivity exceeds -15 dBZ Area and Low cloud fraction weighted oceanic mean is 19.2%. Physical Basis For Cloud/Rain Separation.

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Cloud/Rain partitioning using MODIS and AMSR-E

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Cloud rain partitioning using modis and amsr e

Cloud/Rain partitioning using MODIS and AMSR-E

Matt Lebsock

Aqua

AMSR-E & MODIS


The world is a drizzly place

The world is a drizzly place

  • Drizzle defined where 750 meter reflectivity exceeds -15 dBZ

  • Area and Low cloud fraction weighted oceanic mean is 19.2%


Physical basis for cloud rain separation

Physical Basis For Cloud/Rain Separation

  • The water path can be partitioned between cloud and Precipitation

  • @ Visible/Near-Infrared wavelengths Qext->2

  • @ Microwave frequencies

    • Tb are sensitive to both cloud and precipitation water

Small


Spatial resolution

Spatial Resolution

  • MODIS

    • 1km

  • AMSR-E

  • Use Backus-Gilbert method to resample the AMSR-E footprints to a common resolution @ 23 GHz (31km x 18km)

  • Average the MODIS cloud products to the 23 Ghz resolution with the antenna gain function as a weighting parameter.


Optimal estimation retrieval

Optimal Estimation Retrieval

A-Priori Uncertainty

Observational Uncertainty


January 2007 results

January 2007 Results


Cloud rain partitioning using modis and amsr e

No Cloud Fraction


Cloud rain partitioning using modis and amsr e

Cloud Fraction


Cloud rain partitioning using modis and amsr e

Precipitation Water


January 2007 statistics

January 2007 Statistics


Radiative transfer simulations

Radiative Transfer Simulations

Polarization

Brightness Temperatures

Emission Signal

Scattering Signal

Depolarization Signal

There does appear to be a signal in the brightness temperatures


Cloud rain partitioning using modis and amsr e

Land Influence?

Water Vapor?


Continued work

Continued Work

  • Add a realistic DSD

  • Add rain fraction to retrieval

  • Include an optical depth constraint


Summary

Summary

  • It appears possible to place bounds on the ratio of precipitation water to cloud water in liquid clouds.

    • Critical assumptions

      • Precipitation DSD

      • Insensitivity of MODIS to precipitation

  • Applications

    • Improved GPROF database

    • Studies on the control of precipitation production

      • Aerosol indirect effects

      • Thermo-dynamical controls


Gprof algorithm

Radiometer Obs

TMI, AMSR-E, SSM/I

Background retrieval

SST, TPW

Radiometer

Appropriate

Database

Compare Tb with

a-priori database

Rainfall Product

GPROF Algorithm

Does the A-priori database contain

The correct statistics of rain/no-rain


Gprof 2008 database generation

TRMM

Radiometer Obs

TRMM

Radar Obs

Background Retrieval

SST, Wind, TPW,

CLW

Rain?

No

Yes

Radar Rain Profile

CompareTb to Obs

Combine & Compute Tb

Agreement ?

Make Database

Make Database

Yes

No

Add rain below sensitivity of PR

&

Recombine and Compute Tb

CompareTb to Obs

Agreement ?

Yes

No

Modify DSD in PR pixels w/o PIA information

&

Recombine and Compute Tb

CompareTb to Obs

Yes

GPROF 2008 Database Generation

Make Database


Pr cloudsat matchups

PR-CloudSat Matchups

7 Wm-2

10%

50%

Berg et al., 2010


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