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International Satellite Cloud Climatology Project

Project Description
Scientific Objectives:

- To produce a global, reduced resolution, infrared and visible, calibrated and normalized radiance data set containing basic information on the radiative properties of the atmosphere from which cloud parameters can be derived.

- To stimulate and coordinate basic research on techniques for inferring the physical properties of clouds from the condensed radiance data set and to apply the resulting algorithms to derive and validate a global cloud climatology for improving the parameterization of clouds in climate models.

- To promote research using ISCCP data and contributing to improved understanding of the Earth's radiation budget (top of the atmosphere and surface) and hydrological cycle.

Project Description:

The International Satellite Cloud Climatology Project (ISCCP) was
established as the first project of the World Climate Research Programme
(WCP-2) to collect and analyze satellite radiance measurements to infer
the global distribution of cloud radiative properties and their diurnal
and seasonal variations. The operational phase of ISCCP began in July
1983 and is currently planned to continue through June 2000.

Global coverage for ISCCP is provided by the five geostationary meteorological satellites (GOES-EAST, GOES-WEST, GMS, INSAT, and METEOSAT) and at least one polar orbiting NOAA satellite. The primary data are from the two standard visible (0.6 micrometers) and infrared (11 micrometers) channels common to all of the satellites. The polar orbiter provides coverage of the polar regions not viewed by the geostationary satellites and is used as a basis for normalization of the radiances observed by the different geostationary satellites.

The strategy adopted for implementing ISCCP reflects the diverse nature of the spaceborne observing system and the large volume of imaging and other correlative data. The primary data processing is done by eight institutions: a Satellite Processing Center (SPC) for each satellite (nominally at least one polar orbiter and five geostationary satellites), the Satellite Calibration Center (SCC), and the Global Processing Center (GPC). The SPC's task is to collect raw satellite image data and reduce its volume. The SCC routinely receives special high resolution-image data from each of the SPCs. These data are used to normalize the calibration of each geostationary satellite to the polar orbiter. The resulting normalization coefficients are sent to the GPC to be used in data production. The SPC sends the reduced image data to the GPC for further processing of the ISCCP B3 and C1/C2 data.

In addition to the primary data processing centers, there are three other centers: the Correlative Data Center of which a main function is to coordinate the delivery of other satellite and conventional data (correlative data) to the GPC for use in the cloud analysis, the ISCCP Central Archive (ICA), which is responsible for the archival of all data produced by ISCCP, and the EOSDIS Langley DAAC, which archives and distributes ISCCP B3, C1 and C2 data.

Representatives of the following ISCCP Data Management Centers: SPC, SCC, GPC, Correlative Data Center, and ICA form the ISCCP Working Group on Data Management (WGDM) for the Joint Scientific Committee (JSC). Scientific guidance is provided to the project by the International Radiation Commission of IAMAP and by the JSC Working Group on Radiation Fluxes. ISCCP B3 data are the primary global radiance data product used in the cloud analysis. The ISCCP cloud analysis has three fundamental parts: cloud detection, radiative transfer model analysis, and statistical analysis. The first part determines whether a particular radiance measurement is associated with cloudy or clear conditions. The second part compares the measured radiances, together with other correlative information about the atmosphere and surface, to a radiative model to retrieve several cloud (and surface) parameters. The third part accumulates spatial distribution information about the radiances and retrieved parameters to summarize the analysis, every 3 hours in C1 data and once per month in C2 data.

The ISCCP C1 and C2, along with the previously unavailable CX data
products were made available in 1995. These new products are
called D1, D2 and DX.

Data Used and Produced:
Input Data
----------
1. Radiance measurements from polar orbiting and geostationary operational
meteorological satellites: NOAA/TIROS-N series satellites, METEOSAT,
GOES-EAST, GOES-WEST, GMS and INSAT.
2. Sounding data from the TIROS Operational Vertical Sounder (TOVS) on the
NOAA polar orbiting satellites.
3. Snow and ice data from the joint US NAVY/NOAA analyses.
4. Topographic altitude.
5. Vegetation type and land-use classification.
6. Surface type (land/water/coast).

Data Products
-------------
1) Reduced Resolution Radiance Data (B3)
- Resolution: 30km pixel, 3hr, individual satellites
- Volume: 1.1G per data month, for global coverage
- Contents: Radiances with calibration and navigation appended.
Uniform format for all satellites.
2) Calibration Table Data Set (BT)
- Resolution: 3hr, individual satellites
- Volume: 7G for 8 years
- Contents: Updates of calibration tables for B3 data set.
3) Pixel Level Cloud Product (CX)
- Resolution: 30km mapped pixel, 3 hr, individual satellites
- Volume: 3.4G per data month
- Contents: Calibrated radiances, cloud detection results, cloud and
surface properties from radiative analysis.
4) Pixel Level Cloud Product - Revised algorithm (DX)
- Resolution: 30km mapped pixel, 3 hr, individual satellites
- Volume: 5G per data month
- Contents: Calibrated radiances, cloud detection results, cloud and
surface properties from radiative analysis.
5) Gridded Cloud Product (C1)
- Resolution: 280km equal-area grid, 3hr, global
- Volume: 216M per data month
- Contents: Spatial averages of CX quantities and statistical
summaries. Satellites are merged into a global grid. Atmosphere and
surface properties from TOVS appended.
6) Gridded Cloud Product - Revised algorithm (D1)
- Resolution: 280km equal-area grid, 3hr, global
- Volume: 320M per data month
- Contents: Spatial averages of DX quantities and statistical
summaries, including properties of cloud types. Satellites are merged
into a global grid. Atmosphere and surface properties from TOVS
appended. See list of variables.
7) Climatological Summary Product (C2)
- Resolution: 280km equal-area grid, monthly, global
- Volume: 4M per data month
- Contents: Monthly average of C1 quantities including mean diurnal
cycle. Distribution and properties of total cloudiness and cloud
types.
8) Climatological Summary Product - Revised algorithm (D2)
- Resolution: 280km equal-area grid, monthly, global
- Volume: 7.5M per data month
- Contents: Monthly average of D1 quantities including mean diurnal
cycle. Distribution and properties of total cloudiness and cloud
types. See list of variables.

Project Archive Contact: Langley DAAC User Services Office
Mail Stop 157B
NASA Langley Research Center
Hampton, VA 23681-0001
USA
Phone: (804) 864-8656
FAX: (804) 864-8807 FAX
Email: support-asdc@earthdata.nasa.gov
WWW: http://eosweb.larc.nasa.gov/

Project Archive Contact: Doug Ross
NOAA/NESDIS/NCDC
Satellite Services Group
Federal Building
151 Patton Avenue
Asheville, NC 28801-5001
USA
Phone: (704) 271-4800, option #5
FAX: (704) 271-4876 FAX
Email: satorder@ncdc.noaa.gov
WWW: http://www.ncdc.noaa.gov/

Project Manager Contact: Dr. William B. Rossow
NASA Goddard Space Flight Center
Institute for Space Studies
2880 Broadway
New York, NY 10025
USA
Phone: (212) 678-5567
FAX: (212) 678-5552
Email: wbrossow@ccny.cuny.edu
ISCCP home page: http://isccp.giss.nasa.gov

References:

B3 RADIANCE DATA DOCUMENTATION
Rossow, W.B., E. Kinsella, A. Wolf, and L. Garder, 1987: International
Satellite Cloud Climatology Project (ISCCP) Description of Reduced
Resolution Radiance Data. WMO/TD-No. 58 (Revised). World
Meteorological Organization.

CALIBRATION DOCUMENTATION
Rossow, W.B., Y. Desormeaux, C.L. Brest, and A.W. Walker, 1992:
International Satellite Cloud Climatology Project (ISCCP) Radiance
Calibration Report. WMO/TD-No. 520, WCRP-77, World Meteorological
Organization.

Rossow, W.B., C.L. Brest, and M. Roiter, 1995: International Satellite
Cloud Climatology Project (ISCCP) Update of Radiance
Calibrations. World Meteorological Organization.

C1/C2 CLOUD DATA DOCUMENTATION
Rossow, W.B., L.C. Garder, P.J. Lu, and A.W. Walker, 1991:
International Satellite Cloud Climatology Project (ISCCP)
Documentation of Cloud Data. WMO/TD-No. 266, World Meteorological
Organization, 76 pp. plus appendices.
**All documents above can be downloaded from the ISCCP home page**

OTHER REFERENCES
Rossow, W.B. , L.C. Garder, P-J. Lu and A. Walker, July 1985:
International Cloud Climatology Project (ISCCP) Description of
Reduced Resolution Radiance Data,December 1985 (Revised August 1987).

Rossow, W.B. , L.C. Garder, P-J. Lu and A. Walker, 1988:
International Cloud Climatology Project (ISCCP) Documentation of
Cloud Data WMO/TD-No. 266, December 1988 (Revised April 1991), World
Meteorological Organization, Geneva, 78 pp plus three appendices.

Schiffer, R.A., and W.B. Rossow, 1983: The International Satellite
Cloud Climatology Project (ISCCP) The First Project of the World
Climate Research Program. Bull. Amer. Meteor. Soc., 64, 779-784
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