GEWEX-RFA Data Set Description Before attempting to submit data, please read "How to Participate" (http://eosweb.larc.nasa.gov/GEWEX-RFA/documents/how_to_participate.html) and the "File Convention" document (http://eosweb.larc.nasa.gov/GEWEX-RFA/documents/data_format.html) for detailed instructions on the data submission process. Please maintain a copy of this form for each data product (defined by _ as in the "File Conventions" document) you submit to GEWEX-RFA, and submit an updated copy of the file with EACH upload. This file will serve as the documentation for the entire data product within the assessment effort. ------------------------------------------------------------------------ Project Title: GEWEX-RFA ------------------------------------------------------------------------ Data product name: (ERBEsrb-Li_EdXXX) 1) Contact for scientific questions about data Name: Zhanqing Li Address: 2207 Computer & Space Sciences Bldg, University of Maryland, College Park, MD20742-2425 Telephone: (301) 405-6699 E-mail address: zli@atmos.umd.edu URL: www.atmos.umd.edu/~zli 2) What is the name of the original archived data set from which this GEWEX-RFA subset was produced? N/A 3) Is the original archived data set currently available from another data center or web site? No If so, please list addresses or URLs: 4) Brief data description: A reference or URL for the complete original archived data set documentation, followed by a brief summary of features of particular relevance to the RFA submission (such as gap filling method), is the preferred approach. (Items of interest: input data streams, name of algorithm used to produce data, start and end time of data, gaps in spatial or temporal coverage, and data quality issues, etc.). Li, Z., and H.G. Leighton, 1993, Global climatology of the solar radiation budgets at the surface and in the atmosphere from 5 years of ERBE data, J. Geophy. Res.- Atmosphere, 98, 4919-4930. Data Description of the Shortwave Radiation Budgets at Surface Derived from 4 Years of ERBE Mearsurements I. INTRODUCTION This document describes a set of abbreviated, monthly averaged results of shortwave Surface Radiation Budget (SRB) i.e. the shortwave radiative fluxes absorbed at the surface. They are derived from the Earth Radiation Budget Experiment (ERBE)data set S-4 and the European Centre for Medium-range Weather Forecasts (ECMWF)analysis archive using the algorithm proposed by Li et al (1993). There are three input parameters: reflected flux or albedo on the top of the atmosphere, vertically integrated water vapor content and the solar zenith angle. S-4 data provides monthly-mean reflected fluxes and albedo on the top of the atmosphere at 2.5X2.5 degrees of latitude/longitude. Precipitable water is obtained from ECMWF data by vertical integration of humidity analyses from the bottom to the top of the atmosphere. Solar zenith angle is calculated according to latitude and time. ERBE consists of 3 satellites, NOAA 9, 10 and ERBS. NOAA satellites were in sun-synchronous polar orbits, while ERBS has an orbit inclined 57 degrees relative to the equator which allows observations at different local times. ERBE has both scanning and non-scanning radiometers. Gridded product at 2.5X2.5 degrees was derived from scaner observations. ERBS scaner began observation in Nov. 1984 and failed in February 1990. NOAA 9 scanner operated from Jan 1985 to Jan 1987, while NOAA 10 from Oct 1986 to May 1989. The period covered by the S-4 product is not exactly same as the scanner operation time but a bit shorter. S-4 product contains both single data measured from one satellite and combined data from more than one satellites. The principle of data selection in the acquisition of SRB and ARB is that single data were not used unless combined data were not available. For detailed description of S-4 data, please refer to The Regional, Zonal, and Global Averages, S-4, User's Guide, available from NASA Langley, Hampton, Virginia, USA These globe(i.e. 90S to 90N) shortwave surface radiation budget data contains the results for individual months and years (1985 - 1988) under all-sky condition. The results in polar region (60 north or south) are based on NOAA ERBE observations only, as the ERBS satellite cannot view these areas. THE ORIGINAL DATA FORMAT The original files were written in ASCII consisting of 145X73 numbers. The data are equal latitude/longitude with an increment of 2.5 degrees. Therefore, the data correspond to 145X73 longitude/latitude grids (145=360/2.5+1, 73=180/2.5+1). The grid begins at the South Pole 180W, and progresses eastward and then northward. The following depicts the sequence of the data: (90.0S,180.0W), (90.0S, 177.5W), ... (90.0S, 177.5E), (90.0S, 180.0E), (87.5S,180.0W), (87.5S, 177.5W), ... (87.5S, 177.5E), (87.5S, 180.0E), ....................................................................., (90.0N,180.0W), (90.0N, 177.5W), ... (90.0N, 177.5E), (90.0N, 180.0E). THE CONVERTED DATA DESCRIPTION In these submitted files, the data at four grid boundaries, such as (90.0S,180.0W), (90.0S, 177.5W), (87.5S,180.0W), (87.5S, 177.5W), have been linearly interpolated to the center of the grid, such as (88.75S,178.25W) Therefore, the first grid cell (cell 1) is bounded by latitude -90กใ to -87.5กใ and longitude -180กใ to -177.5กใ. The second grid cell (cell 2) is bounded by latitude -90กใ to -87.5กใ and longitude -177.5กใ to -175กใ. The last grid cell (cell 10368) is bounded by latitude 87.5กใ to 90กใ and longitude 177.5กใ to 180กใ. There are total 10368 (144X72) global grid cells. 5) History of updates and changes. If you resubmit a new version of any part of this data product to GEWEX-RFA, please use this space to record the reasons for the new submission (i.e., fixed error in ___ parameter; changed to area-weighted spatial averaging, etc.) Please specify the parameter(s) affected, new RFA number(s), and the date of the change. 6) Please provide a list of publications and journal articles pertaining to these data (if any); or a link to a bibliography for the product. The procedure of deriving global SRB and ARB and discussion of the results were presented in Li, Z., and H.G. Leighton, 1993, Global climatology of the solar radiation budgets at the surface and in the atmosphere from 5 years of ERBE data, J. Geophy. Res.- Atmosphere, 98, 4919-4930. For detailed description of the algorithm, please refer to Li, Z., H.G. Leighton, K. Masuda and T. Takashima, 1993, Estimation of SW flux absorbed at the surface from TOA reflected flux, J. Climate, 6, 317-330. Validations against surface observations can be found in Li, Z., M. Cribb, F.-L. Chang, A. Trishchenko, L. Yi, 2005, Natural Variability and Sampling Errors in Solar Radiation Measurements for Model Validation over the ARM/SGP Region, /J. Geophy. Res/., 110, D15S19, doi: 10.1029/2004JD005028. Li, Z., H.G. Leighton, and R.D. Cess, 1993, Surface net solar radiation estimated from satellite measurements: Comparisons with tower observations, J. Climate, 6, 1764-1772. Li, Z., C.H. Whitlock, T.P. Charlock, 1993, Assessment of the global monthly mean surface insolation estimated from satellite measurements using global energy balance archive data, J. Climate, 8, 315-328. Quality analysis is also carried out by comparing with an independent data set. Li, Z., Intercomparison between two satellite-based products of net surface shortwave radiation, J. Geophy. Res., 100, 3221-3232. 7) If you would like a specific citation or acknowlegment when these data are used in a publication, please provide that here: 8) Please indicate below all data types currently included in the GEWEX-RFA archive for this data product. A) Top of atmosphere data products _____ Maps (Parameters: list here) _____ Time series (Parameters: list here) B) Surface data products __X__ Maps (Parameters: shortwave surface radiation budget data under all-sky condition) _____ Time series (Parameters: list here) C) Ground-based measurements _____ Time series (Parameters: list here) ------------------------------------------------------------------------ Atmospheric Science Data Center NASA Langley Research Center User and Data Services MS 157D 2 South Wright St. Hampton, VA 23681-2199 Tel: (757) 864-8656 Fax: (757) 864-8807 Internet: larc@eos.nasa.gov URL: http://eosweb.larc.nasa.gov/