---TITLE: 
	      ISCCP Cloud and Radiative Flux in 50km ARCMIP-EASE Grid
	      199709-199809

 ---AUTHORS:
              Prof.  Judith Curry
              School of Earth and Atmospheric Sciences
              Georgia Institute of Technology
              Atlanta, GA  30332-0340
              Phone: (404) 894-3955
              Fax: (404) 894-5638
              Email:  curryja@eas.gatech.edu

              Yuanchong Zhang
	      Goddard Institute for Space Studies
              2880 Broadway, RM 320-B
              New York, NY 10025
              Phone: (212) 678-5514
              Fax: (212) 678-5552
              Email: clyxz@giss.nasa.gov 


              Contact for data questions :

	      Mathew V. Rothstein
	      Program in Atmospheric and Oceanic Sciences
	      University of Colorado
	      Boulder, CO  80309
	      Phone: (303) 492-4035
              Email: Mathew.Rothstein@colorado.edu

              Randolph A. Reeder
              Aerospace Engineering Dept.
              University of Colorado
              Boulder, CO  80309
              Phone: (303) 492-4266
              Email: rreeder@cloud.colorado.edu




 ---DATA SET OVERVIEW:
	      The ISCCP Cloud and Radiative Flux data set is a subset 
              of ISCCP's FDX-P2 Sheba Flux Data set regridded into a 
              50km EASE-Grid.  It contains surface and top-of-atmosphere 
	      radiative fluxes and the important physical quantities used 
	      to calculate them. 

              The data set covers the time period of September, 1997 
	      through September, 1998, which is roughly coincident 
	      with that of the SHEBA project.

	      Spatial coverage includes the polar region of 55N to the 
              North Pole.  Temporal resolution is every 3hrs.

              There are two satellites available for the period:  
              The NOA-14 afternoon (NOA) and NOA-12 morning (NOM) polar 
              orbiters.

              For more information on ISCCP and their products visit:
              http://isccp.giss.nasa.gov/

	      For information on EASE-Grid visit:
              http://www-nsidc.colorado.edu/data/ease/

 
 ---INSTRUMENT DESCRIPTION:
              The following is an excerpt from the ISCCP FDX-P2 readme 
              file:  Shortwave and Longwave Radiative Flux are calculated 
              using the following datasets to specify the properties of 
              Earth's Atmosphere and Surface: ISCCP-DX cloud dataset, 
              TOVS operational sounder products, TOMS ozone products, a 
              climatology of near-surface air temperature diurnal cycle 
              constructed from the WWW Surface Weather reports and the
              first NCEP reanalysis, a climatology of cloud particle sizes 
              from Han et al, a climatology of stratospheric and upper 
              tropospheric water vapor from SAGE-II, a climatology of 
              tropospheric and stratospheric aerosols used in the GISS 
              climate model, and land surface albedo spectral dependence 
              and spectral emissivities from the GISS climate model.


 ---DATA FORMAT:
              The data are stored by two different methods for easy 
              access.  The first set of files contain all cloud and 
              radiative flux variables by 3hr window.  These files 
	      are named: 

              cloud_yymmddhh.sat.nc    and   rflux_yymmddhh.sat.nc 

              where yymmddhh is the timestamp, sat is the satellite 
              of origin (NOA or NOM), and nc indicates these are 
              self-documented NetCDF files.  

              These files are tarred together by month and gzipped 
              into files named:

              isccp_yymm.sat.tar.gz

              The second set of files store the data by variable and 
              contain the entire period of record.  These files are 
              named: 

              isccp_var.sat.nc.gz 
 
              where var is a two to four letter abbreviation of the 
              variables described below. 

              As mentioned, all data are stored in NetCDF files, which 
              contain additional detailed information as metadata.  The 
              basic storage format is a 161x161 grid corresponding to the 
              inner-most square of the 50km ARCMIP-EASE projection of the 
              northern hemisphere.  Converting between this grid and the 
              full 361x361 hemispheric grid is simply a matter of adding/
              subtracting 100 to the column and row.   
           
              A list of variables is provided here:

              radiative flux variables:
              swds     SW downwelling at surface (W/m^2)
              swus     SW   upwelling at surface (W/m^2)
              lwds     LW downwelling at surface (W/m^2)
              lwus     LW   upwelling at surface (W/m^2)
              swdt     SW downwelling at TOA (W/m^2)
              swut     SW   upwelling at TOA (W/m^2)
              lwut     LW   upwelling at TOA (W/m^2)
              skin     surface skin temperature (K)
              alb      surface visible albedo (0-1)

	      cloud variables:
              o3       column O3 (Dobson unit)
              pwc      column PW actually used (cm)
              ctpr     highest cloud layer top pressure (mb) actually used
              cbpr     lowest  cloud layer base pressure (mb) actually used
              tau      total column Tau actually used


 ---DATA REMARKS:
              1) Missing data are represented by -9999.  
              2) There was no data for the NOA satellite during Nov, 1997.
              3) An error was detected in the Shortwave flux calculation 
                 over land.  Therefore, all Shortwave values in land 
                 grid cells are treated as missing (-9999).
              4) In the process of regridding, extreme outliers were 
                 omitted and linear averages used to determine a grid 
                 cell's value.