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SAFARI 2000 SOLAR SPECTRAL FLUX RADIOMETER DATA, SOUTHERN AFRICA, DRY SEASON 2000
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Summary:

The Solar Spectral Flux Radiometer (SSFR) was deployed on the University of Washington CV-580 during the dry season component of the Southern African Regional Science Initiative, August 1 - September 20, 2000. The SSFR made simultaneous measurements of both downwelling and upwelling net solar spectral irradiance at varying flight levels. Data have been provided for twenty flights in netCDF format for the period August 17 - September 16, 2000.

For a complete detailed guide to the extensive measurements obtained aboard the UW Convair-580 aircraft in support of SAFARI 2000, see the UW Technical Report for the SAFARI 2000 Project[ ftp://daac.ornl.gov/data/safari2k/remote_sensing/SSFR_irradiance/comp/SAFARI-MASTER.pdf].

More information about the Solar Spectral Flux Radiometer can be found at Atmospheric Research Branch, NASA Ames Research Center [http://geo.arc.nasa.gov/sgp/sgprad.htm].

Data Citation:

Cite this data set as follows:

Pilewskie, P. 2006. SAFARI 2000 Solar Spectral Flux Radiometer Data, Southern Africa, Dry Season 2000. Data Set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/841.

Table of Contents:

1. Data Set Overview:

Project: SAFARI 2000

The investigators were P. Pilewskie, W. Gore, (NASA Ames Research Center, Moffett Field, CA USA), J. Pommier, S. Howard, (Bay Area Environmental Research Institute) and L. Pezzolo (NASA Ames Research Center, Moffett Field, CA USA)

SSFR Mission Objectives:

Characterize the solar spectral radiation distribution in the lower troposphere.

Related data set with CV-580 navigation data for the SSFR measurements:

Hobbs, P. V. 2004. SAFARI 2000 CV-580 Aerosol and Cloud Data, Dry Season 2000 (CARG). Data set. Available on-line [http://www.daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.

2. Data Characteristics:

Data for twenty flights for the period August 17 - September 16, 2000 are provided. Data files are in netCDF format.

Data File Variable Definitions:

Each NetCDF file is comprised of four arrays: sec, wvl, nad, and zen.

array name      units               description

-------------     ----------        --------------------------

sec                    seconds          UTC time in seconds

wvl                    nm                  wavelengths of spectral data

nad                   Wm-2nm-1     upwelling irradiance

zen                    Wm-2nm-1     downwelling irradiance

Data File Format Basics:

NetCDF (network Common Data Form) is an interface for array-oriented data access and a library that provides an implementation of this interface. The netCDF library also defines a machine-indepent format for representing scientific data. Together, the interface, library, and format support the creation, access, and sharing of scientific data. Information about netCDF can be obtained from the Unidata web site, http://www.unidata.ucar.edu/software/netcdf/.

Data Processing Details:

Raw data were converted to scientific units and quality checked. Dark signal was removed and calibrations applied. Data were filtered to remove measurements acquired when the cosine of the solar zenith angle with respect to the aircraft was more than 3% different from the cosine of the solar zenith angle with respect to an absolute reference plane.

Site boundaries: (All latitude and longitude given in degrees and fractions)

Site (Region) Westernmost Longitude Easternmost Longitude Northernmost Latitude Southernmost Latitude
Southern Africa 5 60 5 -35


3. Data Application and Derivation:

SSFR instruments were flown on both the CV-580 and the ER-2 during SAFARI 2000. The SSFR on the ER-2 was used to characterize the solar spectral radiation distribution in the upper atmosphere, providing a valuable source of data for comparison with spaceborne earth radiation budget sensors. The SSFR on the Convair-580 thoroughly profiled the lower troposphere, providing solar radiation closure in vertical columns containing elevated levels of aerosol loading.

4. Quality Assessment:

None identified.

5. Data Acquisition Materials and Methods:

The SSFR is a moderate resolution spectrometer comprised of an identical pair of Zeiss Monolithic Miniature Spectrometer Modules (MMS 1 and MMS NIR) for simultaneous zenith and nadir viewing.

The MMS-1, with the wavelength range 300 - 1100 nm, is equipped with a flat-field, 366 1/mm grating and a 256 element Hamamatsu Si linear diode array detector. The MMS-NIR, covering the wavelength range 900 - 1700 nm, has a 179 1/mm flat-field grating with a 128-element InGaAs linear diode array. Spectral resolution is 9 nm for the MMS-1 and 12 nm for the MMS-NIR. Data collection rate is nominally 1 Hz.

6. Data Access:

This data set is available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC) [http://www.daac.ornl.gov] or the EOS Data Gateway [https://wist.echo.nasa.gov/~wist/api/imswelcome/].

Data Archive Center:

Contact for Data Center Access Information

E-mail: uso@daac.ornl.gov

Telephone: +1 (865) 241-3952

FAX: +1 (865) 574-4665

7. References:

Pilewskie, P., J. Pommier, R. Bergstrom, W. Gore, S. Howard, M. Rabbette, B. Schmid, P. V. Hobbs, and S. C. Tsay, Solar spectral radiative forcing during the Southern African Regional Science Initiative, J. Geophys. Res., 108(D13), 8486, doi:10.1029/2002JD002411, 2003.

Bergstrom, R. W., P. Pilewskie, B. Schmid, P. B. Russell, Estimates of the spectral aerosol single scattering albedo and aerosol radiative effects during SAFARI 2000, J. Geophys. Res., 108(D13), 8474, doi:10.1029/2002JD002435, 2003.