1 / 20

Thermal Radiation Down-welling Long-wave Fluxes at the Surface

Thermal Radiation Down-welling Long-wave Fluxes at the Surface. Isabel F. Trigo. MSG-based Radiation Products Down-welling Long-wave Flux (DSLF) Definition Algorithm Basis The LSA SAF DSLF product from MSG Validation. Solar Radiation. Thermal Radiation. 30%. 23%. 90%. 4%. 47%.

trella
Download Presentation

Thermal Radiation Down-welling Long-wave Fluxes at the Surface

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Thermal Radiation Down-welling Long-wave Fluxes at the Surface Isabel F. Trigo

  2. MSG-based Radiation Products Down-welling Long-wave Flux (DSLF) • Definition • Algorithm Basis • The LSA SAF DSLF product from MSG • Validation

  3. Solar Radiation Thermal Radiation 30% 23% 90% 4% 47% Radiation Budget Earth Surface • Short-Wave Net Radiation • Loss • Gain ? • Long-Wave Net Radiation • Loss • Gain ? Adapted from K. Trenberth, J. Fasullo, and J. Kiehl.

  4. Solar Radiation Thermal Radiation 30% 23% 23% 4% 90% 7% Radiation Budget Earth Surface • Short-Wave Net Radiation • Loss • Gain X • Long-Wave Net Radiation • Loss • Gain X Adapted from K. Trenberth, J. Fasullo, and J. Kiehl.

  5. Surface Down-welling Long-Wave Radiation Down-welling Long-wave Fluxes at the Surface Long-wave Radiation reaching the Surface: • Essentially emitted by the lowest 100 m of the atmosphere Emitted by the atmosphere, Ra • It is controlled by • concentration of abosrbing gases • CO2, CH4, H2O, ... • presence of clouds, clouds phase • temperature profile & temperature of cloud base .... Reflected by the surface, Rrefl Emitted by the surface, Rsup

  6. Surface Down-welling Long-Wave Radiation Total irradiance at the surface within the [4 – 100 m]interval: Spectral irradiance emitted downwards by the atmosphere FLW = Observed Downward Spectra Radiance – a clear sky day 20 15 12.5 10.5 9 8 7 Wavelength (m) (adapated from Turner et al., 2004 in J. Atmos. Sci.

  7. Surface Down-welling Long-Wave Radiation Remote Sensing • Satellite observationsprovide information on variables that control • Down-welling Longwave Fluxes at the surface: • Clouds • Temperature Profiles • Humidity profiles 7

  8. Surface Down-welling Long-Wave Radiation FLW as estimated in theLSA SAF from MSG/SEVIRI Down-welling Longwave Fluxat the Surface (DSLF) SEVIRI/MSG Data: SEVIRI/MSG Cloud identification: channels 1-4, 7, 9 & 10 • Other Information: • atmosphere screen temperature (ECMWF forecast) • total column water vapour (ECMWF forecast)

  9. Surface Down-welling Long-Wave Radiation FLW as estimated in theLSA SAF from MSG/SEVIRI Down-welling Longwave Fluxat the Surface (DSLF) Parameterization based on Stefan-Boltzman Law: Tcloudy-sky , cloudy-sky Cloudcover fraction Tclear-sky , clear-sky

  10. 2m air temperature Total column water vapour 2m dew point depression Surface Down-welling Long-Wave Radiation FLW as estimated in theLSA SAF from MSG/SEVIRI Down-welling Longwave Fluxat the Surface (DSLF) Fraction of Cloud Parameterization based on Stefan-Boltzman Law: Forecasts: (ECMWF)

  11. Surface Down-welling Long-Wave Radiation 15 November 2011 00 UTC 12 UTC Cloud’s signature?

  12. Surface Down-welling Long-Wave Radiation 15 November 2011 00 UTC 12 UTC Clear Sky - Cloudy/Partially Cloudy -

  13. Surface Down-welling Long-Wave Radiation • Generation Frequency - 30 min • MSG projection & resolution • Over land ... • Available since • Europe – Feb 2005 • Full disk – Jul 2005 But ... Algorithm changed in 2008! Also distributed with quality flag (pixel by pixel basis)

  14. Surface Down-welling Long-Wave Radiation Daily Accumulated Long-wave Flux • MSG projection & resolution • Over land ... • Available since • Full disk 2010 Also distributed number of time-slots used for each (pixel) estimation.

  15. DSLF - Validation • Comparison with in situ measurements • Comparison with other satellite products (CERES onboard Aqua and Terra) Location of Ground Observations

  16. clear sky cloudy DSLF - Validation LSA SAF DSLFcolocated in space and time with Ground Stations & CERES (http://aqua.nasa.gov/about/instrument_ceres.php) Northern Europe Stations Jan 2006 - Apr 2007 • Problems: • Cloud identification at the edge of Meteosat disk • DSLF model for ice clouds • Temperature inversions

  17. DSLF - Validation LSA SAF DSLFcolocated in space and time with Ground Stations & CERES (http://aqua.nasa.gov/about/instrument_ceres.php) Central Europe Stations Jan 2006 - Apr 2007 • Problems: • Temperature inversions

  18. DSLF - Validation LSA SAF DSLFcolocated in space and time with Ground Stations & CERES (http://aqua.nasa.gov/about/instrument_ceres.php) Semi-arid & Desert Stations Jan 2006 - Apr 2007 • Problems: • Impact of high aerosol loads

  19. DSLF • LSA SAF estimates DSLF at the original satellite resolution (3 km at the sub-satellite point), every 30 –minutes, covering Meteosat disk • Satellite data provide Cloud information • Comparison with in situ data • -10 Wm-2 < Bias < 10 Wm-2 • Root Mean Square Differences (RMS) ranges from considerably (from ~15 to 25 Wm-2)

  20. DSLF DSLF Applications – Please see presentation in Session 8 As one of the components of the Surface Radiation Budget, DSLF applications include: • Forcing of Land Surface (and Hydrology) models • Model Assessment (surface and atmospherirc) • Case Studies

More Related