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An assessment of data products for studies of clouds and radiation

An assessment of data products for studies of clouds and radiation. (INVITED) Ehrhard Raschke University of Hamburg, Germany William R. Rossow, Yuan-Chong Zhang NASA, GISS & Columbia University, New York NY Paul W. Stackhouse NASA, LaRC Hampton VA

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An assessment of data products for studies of clouds and radiation

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  1. An assessment of data products for studies of clouds and radiation (INVITED) Ehrhard Raschke University of Hamburg, Germany William R. Rossow, Yuan-Chong Zhang NASA, GISS & Columbia University, New York NY Paul W. Stackhouse NASA, LaRC Hampton VA (With contributions by B. Carlson, M. Giorgetta, S. Kinne, M. Wild, R. Cess, G. Potter) 5th GEWEX Science Conference, 20 – 24 June 2005 Orange County, California

  2. Clouds: -50 to +35 Wm-2 ABC ! IPCC 2001

  3. See also GCOS papers

  4. CLOUDS Surface Observations, RAWIN-Sondes, (Neph-Analyses, photographic averages) TOVS, ISCCP, HIRS/2, SAGE, POLDER, and many others To contrast clouds against background of passive measurements: Correlative data sets on state of atmosphere and ground are needed.

  5. ISCCP vs. TOVS Cloud amount 69/46 Cloud top pressure 588/596 Top minus surface temperature –26/-27 Stubenrauch (2005)

  6. Summary for clouds: • There are now several data sets available for geometric and radiometric cloud field properties and for occurrence of clouds covering more than 15 years with largest uncertainties over Polar Regions. • There are further numerous results available for microphysical cloud field properties covering shorter periods. • CONCLUSIONS: • The cloud products are not necessarily compatible due to different techniques of measurements and analyses and sampling. • GEWEX must develop and accept an appropriate terminology on cloud characteristics. • Significant improvements expected when “A-Train data” is included.

  7. RADIATION PRODUCTS Studies of Earth’s Radiation Climatology began in late 19th century. -.-.-.-.- At Top of Atmosphere (TOA) with satellite data since ~1960 Now: ERBE, CERES, ScaRaB, GERB (and ISCCP, SRB, others) At Ground with satellite information since ~1975; Now: ISCCP, GEWEX-SRB, + various shorter time series over regions.

  8. Radiation product Primarily sensitive to … (in some order of priority) Insolation at TOA TSI, Astro-mechanics, spectrum, cut-off angle Planetary albedo Clouds, surface albedo, aerosols, scene identification, angular models Outgoing longwave radiation at TOA Temperature of atmosphere and surface, water vapor, clouds, scene, angular models Downward longwave at surface Atmospheric temperature and water vapor, clouds Upward longwave at surface Surface skin temperature and effective emittance Downward solar radiation at surface Clouds, aerosols, moisture; insolation at TOA Upward solar radiation at surface Downward solar, surface albedo (and spectrum) Longwave budgets at TOA and surface; integral divergence (Temperatures at surface and in the atmosphere; clouds) Solar budgets at TOA and surface; integral divergence (Clouds, aerosols, surface albedo)

  9. Planetary radiation budget 1991 to 1995 1991 - 1995

  10. Validation: Solar (left) and terrestrial (right) at TOA: CERES vs. ISCCP (B.Carlson, GISS)

  11. TSI PMOD-composite 2005 AMIP-2, mean incoming solar radiation at TOA in May and November (1985-1988) (with R. Cess, S. Kinne, M. Giorgetta, M. Wild) DJF

  12. AMIP-2: Deviations monthly (1985-88) insolation at TOA from their zonally averages

  13. Downward solar Downward atmospheric BSRN vs. ISCCP Martin Wild, ETHZ

  14. Total radiative flux divergence 1991 to 1995 1991 - 1995

  15. Summary for Radiation Products • (from models, satellite data and computations with climate data) • At TOA: ALL (!!) radiation climatologies must use “same solar forcing”. Upward fluxes and CE-s need thorough validation vs. CERES and other space-based measurements. • At surface: Atmospheric transmittance and emittance: ISCCP > SRB; surface albedo and emission seasonally different; cloud effects: need comparison between measured and computed ! Use network data ! • Radiative flux divergence: Uncertainties are dominated by errors in the net budgets at both boundaries. • -.-.-.-.- • There is an urgent need to establish and acceptscale dependent uncertainty and stability criteria for cloud and radiation products and data sets must be characterized accordingly. The next workshop should develop mechanisms for a steady quality control (also for correlative data).

  16. GEWEX: develop and apply quality control procedures Thanks to all contributors to the data sets E.R. enjoyed excellent hospitability in Sapporo, and at CCSR and at NIPR in Tokyo.

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