i2_RadFlux.readme: ----------------- Information For Using ISCCP-FD RadFlux data ---------------------------------------------------- 12/2002 This dataset contains radiative fluxes and a summary of the physical quantities used to calculate them. Shortwave and Longwave Radiative Flux Profiles are calculated using the following datasets to specify the properties of Earth's Atmosphere and Surface: ISCCP cloud dataset, TOVS operational sounder products, TOMS ozone products, a climatology of near-surface air temperature diurnal cyle 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. All of this information is collected into four data products: -------------------------------------------------------------------------- Product Name Definition -------------------------------------------------------------------------- (A) TOA RadFlux Top-of-Atmosphere Radiative Fluxes (B) SRF RadFlux Surface Radiative Fluxes (C) RadFlux Profiles Radiative Flux Profiles including the TOA and SRF fluxes (D) RadFlux Inputs The complete input dataset which is only summarized in the other datasets. -------------------------------------------------------------------------- Our regular global flux datasets have the same temporal resolution as ISCCP D1 (every three GMT's, 0, 3, .. 21) and eventually will cover all the time period as ISCCP D1 (from July 1983 to the current, and beyond). For a month and in the Integer*2 format, which is scaled from the original Real*4 format, the size of all the four datasets is about 0.6 GB, and separately,they have sizes of about 60, 70, 205 and 205 MB, respectively. The scale factors are listed below and, therefore, all the parameters from this newly reformatted integer*2 datasets may have slightly lower precision than the original Real*4: roughtly 0.5*1/(scale factor). Previous versions of the methodology are documented in Rossow and Lacis (1990) J. Climate, 3, 1204-1253, Zhang et al (1995), JGR, 100, 1149-1165 and Rossow and Zhang (1995) JGR, 100, 1167-1197. More information and browse products related to these datasets can be found at http://isccp.giss.nasa.gov/projects/flux.html. *************************************************************************** The SRF Radiative Flux dataset gives the Upwelling and Downwelling, Shortwave (SW = 0.2-5.0 microns) and Longwave (LW = 5.0-200.0 microns) Radiative Fluxes at the surface, and a summary of the physical quantities used to calculate them. All clear-sky fluxes are calculated under mean state for the atmosphere without clouds. The full-sky fluxes are weighted from fluxes calculated for ISCCP-defined 15 types of cloud condition and the clear-sky fluxes by their areas for each cell. The "100% overcast" fluxe exported from this program are reproduced from clear- and full-sky fluxes using Overcast = [(full sky) - (Clear sky)*(1-CF)]/CF where CF is mean cloud cover, if CF > 0; If CF =0, i.e., the cell is fully clear, all the three scenes have identical flux values since there is no cloud information available that can be used to calculate cloudy fluxes. Therefore, such overcast fluxes should be regarded as "apparent" to distinguish from the original overcast fluxes that have not been saved in order to save data storage space. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Read in global ISCCP-FD SRF RadFlux data and output 25 parameters in equal-area (EGA) or square lat-lon (equal-angle) maps. The latter's longitudinal indices start from Dateline (SQD) or Greenwich line (SQG). >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Import: Collective global SRF RadFlux data file in "i2_srfii.YYMMDDHH" where "ii" = version and YY/MM/DD/HH = year/month/date/GMT, e.g., 99071521 is for year=1999, month=July, Date=15th and GMT=21 ......................................................................... Export: 25 parameters as listed below. Users have three options on output maps: EGA, SQD or SQG. The EGA has spatial resolution of equatorial 2.5 X 2.5 degree, about 280 km^2,written in real*4(6596), whose first cell is for latitude of 90 S->87.5 S and longitude of 0 E->2.5 E. Replicated from EGA map, both the SQD and SQG maps are of 2.5 X 2.5 degree, written in real*4(144,72). Their first latitudinal indices are for the cell of 90 S->87.5 S (South Pole), and their first longitudinal indices are for the cells of 180 W->177.5 W (Dateline) and 0 E->2.5 E(Greenwich line), respectively. Value -1000.00 is for no-data grid cells. Output file names are in XXXXXXVV_YYMMDDHH, XXXXXXVV.YYMMDDHH, XXXXXXVV-YYMMDDHH for the above 3 different maps (EGA, SQD and SQG), repectively, where XXXXXX is output parameter name as listed and defined below, VV is version (='ii' now) and YYMMDDHH is from input file. ......................................................................... The 25 parameters for each grid cell are: ----------------------------------------------------------------------- Scale |Serial| | definition factor|number| name| ----------------------------------------------------------------------- 10. (1) ps____ Surface pressure (mb); 10. (2) ts____ Surface skin temperature (Kelven); 10000. (3) al_srf Surface broadband SW (0.2-5.0 micron) albedo (0-1); 10000. (4) em_srf Surface broadband LW (5.0-200.0 micron) emissivity (0-1); 1000. (5) tlpwfl Total column precipitable water for full sky (cm); 10000. (6) mu0___ Cosine solar zenith angle (0-1) 10. (7) tlo3__ Total column ozone (Dobson units); 10. (8) ta____ Surface air temperature (Kelven); 1000. (9) pws200 Precipitable water for 200-mb-thick layer covering the surface for full sky (cm); 1000.(10) cf_m__ Mean cloud fraction (0-1); 10.(11) tau_m_ Mean cloud optical thickness; 10.(12) pc_m__ Mean cloud top pressure (mb); 10.(13) pb_m__ Mean cloud base pressure (mb); 10.(14) sxdwbt SW downwelling for full sky at surface (W/m^2); 10.(15) sxupbt SW upwelling for full sky at surface (W/m^2); 10.(16) txdwbt LW downwelling for full sky at surface (W/m^2); 10.(17) txupbt LW upwelling for full sky at surface (W/m^2); 10.(18) srdbcr SW downwelling for clear sky at surface (W/m^2); 10.(19) srubcr SW upwelling for clear sky at surface (W/m^2); 10.(20) trdbcr LW downwelling for clear sky at surface (W/m^2); 10.(21) trubcr LW upwelling for clear sky at surface (W/m^2); ---------------------------- Derived from above -------------------------- (22) sxdbcl SW downwelling for 100% overcast sky at surface (W/m^2); (23) sxubcl SW upwelling for 100% overcast sky at surface (W/m^2); (24) txdbcl LW downwelling for 100% overcast sky at surface (W/m^2); (25) txubcl LW upwelling for 100% overcast sky at surface (W/m^2); .......................................................................... The sample data files are saved in data directory. The sample gif files are saved in gif directory. All the sample data files are outputted by a float array of size(144,72). "srf1.pro" is the program to read all the data in and plot them. "read_rad.pro" is a simple program to read in the data print the MIN and MAX of the data. If you have any questions, please let us know. ============================================================== Contact Info: Yan Gu (gu@coaps.fsu.edu) Tel: (850)644-6935 FSU, COAPS ==============================================================