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What is the spectrum of the GHI data (POWER Project)?
Posted: Mon Mar 01, 2021 9:35 pm America/New_York
by tsdejong1234
Hi all,
I am wondering what the irradiance spectrum for the 'All Sky Insolation Incident on a Horizontal Surface' data is from NASA's POWER Project? (ie. 300-800nm? 300-3000nm?)
Thank you
Re: What is the spectrum of the GHI data (POWER Project)?
Posted: Tue Mar 02, 2021 9:02 am America/New_York
by ASDCx - mcook
Thank you for your question. A Subject Matter Expert has been notified and will answer your question shortly. Please stand by!
Re: What is the spectrum of the GHI data (POWER Project)?
Posted: Tue Apr 27, 2021 1:24 pm America/New_York
by ASDC - pstackhouse
Dear tsdejong1234,
I think we answered your question, via e-mail, however, for Forum users I thought I'd enter the answer to this question. The surface solar irradiance or "Global Horizontal Irradiance" available at the POWER web site is the full spectrum irradiance spanning the wavelength 225 nm to 4000 nm (0.225 - 4.0 micrometers). The wavenumber span is 2500 to 57000 cm^-1. These spectral ranges are identical to the GEWEX SRB (
https://gewex-srb.larc.nasa.gov) and CERES (
https://ceres.larc.nasa.gov) that are processed and reformatted for POWER web services. Please let us know if you have any additional questions.
Paul and the POWER Team
Re: What is the spectrum of the GHI data (POWER Project)?
Posted: Sun Oct 08, 2023 11:14 pm America/New_York
by chillmo
Dear all,
How about the spectrum of the 'ALLSKY_SFC_SW_DWN' data?
I find the definitions from the Parameter Dictionary:'the total solar irradiance incident (direct plus diffuse) on a horizontal plane at the surface of the earth under all sky conditions. An alternative term for the total solar irradiance is the "Global Horizontal Irradiance" or GHI.'
Is the 'ALLSKY_SFC_SW_DWN' data spanning a full spectrum irradiance? I'm confused because the data name says it is Shortwave Downward Irradiance.
Thank you
Re: What is the spectrum of the GHI data (POWER Project)?
Posted: Tue Oct 17, 2023 11:39 am America/New_York
by ASDC - pstackhouse
Dear Tsdejong,
GHI is the same as ALLSKY_SFC_SW_DWN. It has the same broad spectral region (see the thread below). In the POWER dictionary is the parameter called PAR or Photosynthetically Active Radiation which has the spectral range of 400 nm to 700 nm. Perhaps, this PAR (called All-sky Surface PAR Total) would be useful to assess the integrated visible light. A publication for reference is Su et al., 2006 (
https://doi.org/10.1029/2006JG000290). I hope this helps. POWER is preparing to upgrade to v10 data in the next several months. We plan to clarify the definitions of these parameters. Thanks for your interest and sorry the delay in answering your question.
Sincerely,
Paul and the POWER Team