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Can we measure from satellites the cloud effects on the atmospheric radiation budget?

Can we measure from satellites the cloud effects on the atmospheric radiation budget?. Ehrhard Raschke University of Hamburg Institute of Meteorology Dubrovnik 19-23 September 2005.  Quantities at top of the atmosphere (TOA) (ERBE data). Mean values. For cloudless earth.

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Can we measure from satellites the cloud effects on the atmospheric radiation budget?

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  1. Can we measure from satellites the cloud effects on the atmospheric radiationbudget? Ehrhard Raschke University of Hamburg Institute of Meteorology Dubrovnik 19-23 September 2005

  2.  Quantities at top of the atmosphere (TOA) (ERBE data) Mean values For cloudless earth Effect of clouds Outgoing terrestrial radiation Absorbed solar radiation Net radiation Albedo -234 Wm-2 239 Wm-2 +5 Wm-2 30% -266 Wm-2 288 Wm-2 +22 Wm-2 15% +32 Wm-2 -49 Wm-2 -17 Wm-2 +15% If YY = Radiation Budget Quantity at any level Cloud Effect (YY) = Cloudy (YY) – Clear (YY) CE > 0: Clouds increase YY CE < 0: Clouds decrease YY

  3. Estimates of CE are possible : Either by a.) Searching for cloudless sky over a limited area within a small period (typically 1 month) inradiation products at TOA(see ERBE, ScaRaB, CERES and earlier analyses) Or by b.) Direct calculation from multiple ancillary data on radiative transfer properties of atmosphere and ground during each time step of e.g. 3h. (see ISCCP, SRB) forradiation products atTOA and ground, and within the atmosphere.

  4. ISCCP and GEWEX-SRB (and also other related projects) must use various correlative data which contain uncertainties. (details: Zhang et al., 2004; JGR)

  5. Validation: Solar at TOA: CERES vs. ISCCP (B.Carlson, NASA)

  6. A few results from the ISCCP:

  7. Planetary radiation budget Raschke et al, 2005; Int. Journ. Clim. 1991 - 1995

  8. Absorption of solar radiation in the climate system, and cloud effect Raschke et al, 2005; Int. Journ. Clim. 1991 - 1995

  9. Radiation budget at surface Raschke et al, 2005; Int. Journ. Clim. 1991 - 1995

  10. Divergence of solar radiation Raschke et al, 2005; Int. Journ. Clim. 1991 - 1995

  11. Divergence of terrestrial radiation Raschke et al, 2005; Int. Journ. Clim. 1991 - 1995

  12. Cloud effect on vertical divergence high solar middle terrestrial low Raschke et al, 2005; Int. Journ. Clim.

  13. However, the present radiation products of the ISCCP and of the GEWEX-SRB contain serious uncertainties with strong seasonal effects.

  14. Downward solar radiation, ISCCP minus SRB: ISCCP > SRB ! See GEWEX News, Aug. 2005

  15. 1985 - 1988 See GEWEX News, Aug. 2005

  16. SW at surface ISCCP>SRB at higher latitudes CE on solar dw: ISCCP<SRB at lower latitudes

  17. LW at surface ISCCP>SRB over both poles CE on LW-dw: ISCCP<SRB between 60S and 60N

  18. Solar divergence: ISCCP<SRB, except for low values CE on solar divergence: ISCCP<SRB between 60S and 30N

  19. Total vertical radiative flux divergence (Wm-2) As for lw divergence

  20. There are large discrepancies between ISCCP and GEWEX-SRB data sets in the (a)    Solar components: Downward solar radiation at TOA and at ground, the effective surface albedo and all derived quantities. ISCCP>SRB in most cases. Different limits for sunrise and sunset. (b)    Infrared (longwave) components: Skin temperatures in the tropics and polar regions; ISCCP atmosphere is generally warmer during winter and at high latitudes throughout the year. CE : ISCCP<SRB in most cases And there are (c) Various other individual uncertainties: “Spikes”, sudden changes, uncertain quantities, time-dependent “noise”, …. ISCCP and SRB data cannot (yet ?) be used for trend analyses ! Assessment by GRP is overdue!

  21. A general problem: How to include anomalies of atmospheric aerosols? Biomass Burning September 28, 2004

  22. clouds is an international project with silent but very effective co-operations between JMA NASA, NOAA, CSU Meteo France MSC EUMETSAT (+ various individuals)

  23. Validation: Terrestrial at TOA: CERES vs. ISCCP (B. Carlson, NASA)

  24. Raschke et al, 2005; Int. Journ. Clim.

  25. Radiation budget at surface

  26. LW Flux Divergence ISCCP>SRB between 30S and 30N ISCCP>SRB between 60S and 60N

  27. 1991 - 1995 Verhältnis solarer „Wolkeneffekt am Boden“ zu „Wolkeneffekt am TOA“ e.g.: Li et al., Nature 1995

  28. 1991 - 1995 Verhältnis langwelliger „Wolkeneffekt am Boden“ zu „Wolkeneffekt am TOA“

  29. Downward atmospheric radiation Raschke et al, 2005; Int. Journ. Clim. 1991 - 1995

  30. OLR: ISCCP > SRB at high latitudes CE on OLR: ISCCP<SRB at high latitudes Albedo: ISCCP>SRB CE on Albedo: mixed

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