INTERNATIONAL SATELLITE CLOUD CLIMATOLOGY PROJECT ISCCP Monthly Cloud Products Lola M. Olsen William B. Rossow International Council of Scientific Unions World Meteorological Organization World Climate Research Programme prepared by NASA Climate Data System Staff Goddard Distributed Active Archive Center NASA - Goddard Space Flight Center Greenbelt, Maryland 20771 The data contained herein are for scientific use only and have no commercial value. MS-DOS is a registered trademark of Microsoft Corporation. VMS is a registered trademark of Digital Equipment Corp. Further information on ISCCP can be obtained by contacting: William B. Rossow or Alison Walker ISCCP Global Processing Center NASA/Goddard Institute for Space Studies 2880 Broadway New York, NY 10025 tel: (212)678-5567 fax: (212)678-5622 email: clwbr@nasagiss.giss.nasa.gov or claww@nasagiss.giss.nasa.gov Further information on the CD-ROM can be obtained by contacting: Lola M. Olsen Project Manager, NASA's Climate Data System Code 935, Distributed Active Archive Center Goddard Space Flight Center Greenbelt, MD 20771 tel: (301) 286-9760 fax: (301) 286-3221 email: olsen@nssdca.gsfc.nasa.gov The International Satellite Cloud Climatology Project Monthly Cloud Products Introduction This CD-ROM contains the global monthly cloud products as produced for the International Satellite Cloud Climatology Project (ISCCP) at the Goddard Institute for Space Studies, New York, New York. ISCCP is sponsored by the World Climate Research Programme for the purpose of ``collecting and analyzing satellite radiance measurements to infer the global distribution of cloud radiative properties and their diurnal and seasonal variations." The data on this CD-ROM are the ISCCP Stage C2 data (ISCCP-C2), at 280 km spatial resolution. There are 72 variables contained within the data set, which are available at monthly and three-hourly monthly resolution. The data available at the time of publication begin in July 1983 and extend through December 1990. Although the official ISCCP Central Archive is located at the Satellite Data Services Division of NOAA/NESDIS, NASA's Climate Data System (NCDS) at the Goddard Space Flight Center has also provided support for ISCCP data for NASA-funded researchers. The mastering of this CD-ROM is a NASA-sponsored effort implemented by the NCDS staff of Goddard's Distributed Active Archive Center (DAAC). ISCCP Data Set These data are processed in several stages by the principal participating national and international agencies: NASA, NOAA, European Space Agency, Japan Meteorological Agency, Canadian Atmospheric Environment Service, Centre de Meteorologie Spatiale, and Colorado State University. The sources for these data are the NOAA Polar Orbiting Satellites, Geostationary Operational Environmental Satellites (GOES), Geostationary Meteorological Satellites (GMS), and METEOSAT weather satellites from which visible and thermal infrared radiances are collected and analyzed. Originally retrieved radiances are first sampled at 30 km and three-hourly resolution and normalized in calibration by reference to the NOAA-7 Advanced Very High Resolution Radiometer (AVHRR). This data set is called the ISCCP Stage B3 (ISCCP-B3) data and has navigation and calibration information appended. These data are then merged and analyzed at 280 km resolution, maintaining the three-hourly temporal resolution to become the ISCCP Stage C1 (ISCCP-C1) data set. Data are available for the hours 00, 03, 06, 09, 12, 15, 18, and 21 UTC for the given months. The NAVY/NOAA Snow/Ice products and the TOVS data are included and make up a portion of the 132 variables contained in ISCCP-C1. The ISCCP-C1 products are then used to create the monthly statistics, at both three-hour-monthly and monthly temporal resolutions. The resulting products reside on this CD-ROM and are called the ISCCP-C2 data set. The variables include time and spatial means and standard deviations for cloud top pressure and temperature, cloud optical depth, and cloud water path. Optical depth, water path, cloud top pressure, cloud top temperature, and frequencies are available for low, middle, and high clouds and for cumulus, stratus, altocumulus, nimbostratus, cirrus, and deep convective clouds. Also offered as part of the C2 product are surface reflectance and snow/ice cover information. Variables derived from the TIROS Operational Vertical Sounder (TOVS) are precipitable water; surface, 500 mb, tropopause, and stratospheric temperatures; and surface and tropopause pressures. Variables derived from visible wavelengths are available only during daylight hours. The CD-ROM Contents There are three major directories on this disk, one which contains the data (DATA), another which holds the documentation (DOCUMENT), and another which offers the source code and a compiled version for the read software (SOFTWARE). Data Directory This directory holds the ISCCP-C2 Monthly Cloud Products for the years 1983 (beginning with July 1983), 1984, 1985, 1986, 1987, 1988, 1989, and 1990 in separate subdirectories. The data reside on the disk in their original format, except that IBM standard header and trailer files have been removed. The first five files in each annual data directory are written in ASCII and are arranged in 80-character strings. File 1 is the volume ID file (VOLID.TXT); file 2 is the table of contents file (TOC.TXT); file 3 is a READ Program (READPROG.FOR) which can be used directly by IBM users to read, decode, and re-map the files; file 4 holds the conversion tables which convert the integer count values to physical quantities (TABLES.TXT); and file 5 contains geographic and map grid information (ANCILLARY.TXT). The remaining data files are written as one-byte binary integers and correspond to the eight UTC time periods for each month of the year and the monthly data for all twelve months. A full year of data will therefore be contained in 108 files. Document Directory The data set is accompanied by a catalog as an ASCII file which describes both the ISCCP-C1 three-hourly and the ISCCP-C2 three-hour-monthly and monthly products. Other catalogs related to ISCCP are those describing the ISCCP TOVS data and the ISCCP Ice/Snow products. Software Directory The data reside on the disk in their original packed format as binary integers. The producer-supplied program has been modified to demonstrate the output of a sample file from the data set. The executable version of this sample program can be found in this directory as ISCCP.EXE. The source program ISCCP.FOR, which also resides in this directory, can be easily modified by a user to read all or any portion of the ISCCP-C2 data. ISCCP Research By providing the ISCCP Monthly Cloud Products on CD-ROM, we hope that these data will reach a larger community and that more extensive research will result in an ``improved understanding of the role of clouds in the radiation balance and the global hydrological cycle." Users of the ISCCP cloud analysis products can continue to access updates of these data interactively through NCDS as they are processed and sent to the archive. Acknowledgements Special thanks are in order to those who assisted in producing this CD-ROM from Hughes STX: Bruce Vollmer, Ke Jun Sun, Archibald Warnock, and Pat Hrubiak worked directly with the premastering of the CD-ROM. Joe Brown and Frances Bergman have been responsible for the inventory and archival of the ISCCP-B3, ISCCP-C1, and ISCCP-C2 data. Jim Closs and Frank Corprew have helped users with online access and requests for ISCCP data over the years. Hank Griffioen and John Vanderpool have provided expert database and system configuration, respectively. Sue Sorlie helped with documentation, and Rob Kilgore and John Hazen assisted with the artwork for the disk. In addition, valuable assistance was offered by Alison Walker from Hughes STX (at Goddard Institute for Space Studies). Support for this effort from the Earth Science and Applications Division, NASA Headquarters was provided by: Dr. Robert A. Schiffer Chief, Climate and Hydrological Systems Branch Earth Science and Applications Division NASA Headquarters, Code SED Washington, DC 20546 tel: (202)453-1680 fax: (202)755-5032