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Greenhouse Effect Detection Experiment (GEDEX) CD-ROM Released

by Lola M. Olsen and Archibald Warnock III

1992 has been designated as The International Space Year (ISY), the 500th
anniversary of the discovery of America by Christopher Columbus and the
35th anniversary of the International Geophysical Year (IGY). The ISY
effort is intended to stimulate significant contributions to worldwide
scientific research and application activities under the theme "Mission to
Planet Earth". The Space Agency Forum on the International Space Year
(SAFISY) is responsible for coordinating these activities worldwide.

In preparation for the ISY and in support of SAFISY, the Earth Science and
Applications Division of NASA sponsored an initiative, the Greenhouse
Effect Detection Experiment (GEDEX), for which a workshop was organized to
bring together a core group of scientists to share their research and ideas
on the subject of global climate change. Participants in this workshop,
which was designated the GEDEX Atmospheric Temperature Workshop, met in
Columbia, Maryland, in July of 1991 for the purpose of obtaining a measure
of progress and to recommend actions required to better understand the
global atmospheric temperature record and its relationship with climate
forcings and feedbacks.  Dr. Robert A. Schiffer and Dr. Sushel Unninayar
organized the discussions where concepts and hypotheses were exchanged.  A
document entitled, "The Detection of Climate Change Due To The Enhanced
Greenhouse Effect: A Synthesis of Findings Based on the GEDEX Atmospheric
Temperature Workshop," issued by NASA Headquarters in February 1992,
summarizes the discussions which took place during the workshop.

One of the primary objectives of the workshop was to identify existing data
(focusing on temperature) for the analysis of global climate change and to
consolidate selected data sets onto CD-ROMs for distribution nationally and
internationally to promote further research.  With this focus, Dr. Schiffer
requested that NASA's Climate Data System (NCDS) staff prepare for the
acquisition, archiving, implementation, and documentation of data
recommended for distribution.

GEDEX Data Sets

More than 60 data sets were identified by workshop participants for
inclusion, yielding nearly 1 gigabyte of data for this first 2-disk set of
CD-ROMs. The data sets include surface, upper air, and/or satellite-derived
measurements of temperature, solar irradiance, clouds, greenhouse gases,
fluxes, albedo, aerosols, ozone, and water vapor, along with Southern
Oscillation Indices and Quasi-Biennial Oscillation statistics.  Many of the
data sets provide global coverage.  The spatial resolutions vary from zonal
to 2.5 degree grids.  Some surface station data sets span more than 100
years.  Most of the satellite-derived data sets cover only the most recent
12 years.  Temporal resolution, for most data sets, is monthly. The first
disk contains temperature, solar irradiance, cloud, and radiation budget
data. The atmospheric constituent data are on the second disk.  The data
sets, thoroughly documented by standard detailed catalogs, are easily
identified through the use of summaries which provide temporal coverage and
resolution, spatial coverage and resolution, parameters, etc.

Disk 1 --- Temperature, Radiation and Cloud Data

       Temperature --- Surface

The basic surface station temperature data set from NCDC/NCAR contains
monthly temperature and precipitation values and is subdivided by
continent.  A few records date from as early as 1738, and modern station
data extend through 1989.  Other surface temperature anomaly data sets
containing monthly gridded values were provided by Philip Jones, University
of East Anglia Climate Research Unit, and by James Hansen, Goddard
Institute for Space Studies (GISS).  Zonal and station temperature data are
included from the State Hydrologic Institute's (Russia) Konstantin
Vinnikov.  These data sets extend over 100 years of record.  Gridded 2.5
degree monthly sea surface temperature data and anomalies as calculated by
Richard Reynolds from NOAA's Climate Analysis Center also reside on this
disk. These SST values are from AVHRR sensors on NOAA polar orbiters and
are blended with ship and buoy data. Investigating the effect of the El
Nino/Southern Oscillation (ENSO) on the temperature anomaly record, may be
done with the data set provided by the University of East Anglia's Climate
Research Unit containing the Southern Oscillation Index calculations, along
with the Tahiti and Darwin mean sea level pressures from which they are

   Temperature --- Upper Air

NCDC/NCAR contributed comprehensive monthly station rawinsonde data. Both
temperature and humidity profiles are included in this data set. Another
upper air temperature data set was produced by James Angell, NOAA ARL.  It
contains seasonal zonal temperature deviations from rawinsonde data around
the world.  Angell also provided Quasi-Biennial Oscillation temperature and
zonal wind data at 50, 30, and 10 mb. Marshall Space Flight Center's Roy
Spencer provided more than 12 years of mid-tropospheric temperature and
anomaly data from the TIROS Operational Vertical Sounder Microwave Sounding
Unit (TOVS-MSU), flown on NOAA polar orbiters.  Stratospheric temperature
data were provided by Harry van Loon and Karen Labitzke through NCAR.
Although these data are only available for the northern hemisphere, they
provide a valuable monthly zonal product for the years 1957 to 1991.  In
addition, profiles of meteorological data from NMC were provided at 1 km
intervals for the Stratospheric Aerosol and Gas Experiment (SAGE II) time

    Solar Irradiance and Transmission

Solar transmission and surface-measured irradiance data were supplied by
Ellsworth Dutton, NOAA Climate Monitoring and Diagnostics Laboratory
(CMDL).  The daily solar transmission indices from the Mauna Loa
Observatory begin in 1958 and continue through 1990. The hourly solar
irradiance data make up a rare collection of solar data collected at the
surface from 1976 to 1989 at selected sites.  NASA Goddard Space Flight
Center's Lee Kyle provided solar irradiance data from the Nimbus-7 Earth
Radiation Budget (ERB) instrument, and Langley Research Center's Robert
Lee, offered the solar irradiance data from NOAA-9, NOAA-10, and ERBS.
Richard Willson of JPL has collaborated with the NCDS staff over the years
in making 9 years of solar irradiance data from the Solar Maximum Mission's
ACRIM sensor available to users online.  The Dominion Radio Astrophysical
Observatory (DRAO) (formerly Ottawa) 2800 MHz radio flux data from 1947 to
the present are also available on the disk with observed, absolute, and
adjusted variables.

     Radiation Budget and Clouds

Bruce Barkstrom of Langley Research Center provided the Earth Radiation
Budget Experiment's (ERBE S4) combined satellite gridded products,
including the scanner data at 2.5 degree resolution and the
wide-field-of-view monthly averages.  William Rossow, NASA GISS, suggested
and subsequently provided a comprehensive subset of the International
Satellite Cloud Climatology Project's (ISCCP) monthly cloud products at 2.5
degree resolution.  He also assisted in the review and verification of
those data.  Goddard's Lee Kyle worked closely with the staff in the
validation of data on the disk from the Earth Radiation Budget instrument
on board Nimbus-7.  Data from the wide-field-of-view sensor span the period
1978 to 1987 and are monthly in temporal resolution and approximately 4.5
by 5 degrees in spatial resolution. Goddard's Joel Susskind also worked
closely with the NCDS staff, making subsets of his cloud and radiation data
available for the disk.  His data are derived from NOAA Polar Orbiting
satellites using TOVS-HIRS and TOVS-MSU sensors.

Disk 2 --- Atmospheric Constituents

The Carbon Dioxide Information Analysis Center (CDIAC), Department of
Energy, is the source for the "TRENDS '90, A Compendium of Data on Global
Change," providing carbon dioxide and methane values spanning the
geological record (through ice core techniques) and more recent values
collected by NOAA from flask sampling and continuous monitoring techniques.
NOAA ARL's James Angell also contributed seasonal layer ozone data from
Umkehr sounding and ozonesonde from 1957 to 1990 and total ozone from
Dobson spectrophotometers for the period 1967 to 1989. Patrick McCormick's
colleagues at NASA's Langley Research Center worked closely with our staff
in providing ozone, nitrogen dioxide, and aerosol data from the Atmospheric
Explorer Mission's SAGE I instrument, and aerosol, ozone, water vapor, and
nitrogen dioxide data from the Earth Radiation Budget Satellite's (ERBS)
SAGE II instrument beginning with data from the November 1984 launch
through 1991.

The CD-ROM Design

The intention of the CD-ROM design was to deliver a standalone,
operating system-independent package to the researcher:  data for
research, software tools to access the data, and complete
documentation.  The CD-ROM medium is ideally suited to this purpose. 
The large (approximately 650 megabytes) capacity, low cost and
portable directory structure as enforced by the ISO-9660
specification, make it possible to inexpensively deliver large
quantities of data to the end user for use on virtually every computer
in use today. 

While ISO-9660 defines a platform-independent directory structure and file
naming scheme for CD-ROMs, it imposes no requirements on the contents of
the files.  In order to make data accessible under any operating system,
the data must be written in a way which is also independent of the host
system.  The Common Data Format (CDF) was selected for its advantages in
representing the types of data structures found in various kinds of climate
data.  Gridded data maps naturally to the capabilities of CDF, and the
format allows for easy storage of attribute information along with data.
In addition, a software library for CDF data runs under several operating
systems (Unix, VMS and MS-DOS) and provides for system-independent encoding
of the data.  This well-defined representation of the data ensures
consistent access to the data.


The access software provided on the disk allows the user to browse a
table of contents to the disk and to view the summary and detailed
information on the individual data sets.  Additional software,
developed by the CDF staff, provides browse and subsetting
capabilities.  The software runs with the same user interface under
all three target operating systems.  The overall user interface was
designed to look and perform like the current NCDS online system.  The
interface in the current release is character-based but could easily
be ported to standard windowing environments. 

GEDEX Research

The hope is that through this consolidation and documentation of
existing data sets, ambiguities and uncertainties associated with
climate change and greenhouse gas effect will be further explored by
more scientists.  It is also hoped that researchers will continue to
review the relationships between temperature change and plausible
cause-effect factors and that these disks will serve as a test-bed for
future CD-ROMs for EOS. Support for this effort from the Earth Science
and Applications Division, NASA Headquarters was provided by Dr.
Robert Schiffer. 

If you are interested in receiving a copy of the GEDEX CD-ROM, please
contact the Goddard Distributed Active Archive Center (DAAC) User
Support Office [NCDS has become part of the Goddard DAAC] by phone:
(301) 286-2109, via Internet: NCDSUSO@xxxxxxxxxxxxxxxxxxxx or by mail:
NCDS/Goddard Distributed Active Archive Center, Code 935, Goddard
Space Flight Center, Greenbelt, Maryland 20771. 

An update to this CD-ROM disk set will be available for the United
Nations Conference on Environment and Development which will be held
in Brazil in June of 1992.

GEDEX CD-ROM Disk Set Available at International Space Year Conference

The second of four major conferences in celebration of the ISY was held in
Munich, Germany at the Gasteig Convention Center the week of March 30th,
1992, with registered participants numbering close to 1500. Members of the
Commission of the European Communities (CEC), the European Space Agency
(ESA), and the German Space Agency (DARA) served as joint organizers.
"Space in the Service of the Changing Earth" was the overall theme of the
Conference.  Concurrent symposia attracted outstanding participation in
both a Central Symposium and the four Satellite Symposia.

It was within the Central Symposium, designated the "Environment Observing
and Climate Modeling through International Space Projects" that NASA's
Contribution to the International Space Year was presented. A paper was
presented entitled, "The Greenhouse Effect Detection Experiment (GEDEX)
CD-ROM, A Collection of Data Sets for Global Change Research".  Also, an
exhibit in the conference area allowed interested participants to view the
contents of the disks.  A limited number of disks were available for
distribution at the conference.  Disks are being mailed to others
requesting them.

Thousands of additional interested observers were drawn to the Gasteig area
of Munich by the "International Space Show, Planet Earth,"  held
concurrently where four halls of space-related exhibits and a festival of
space films organized by the European Association of Students of
Aeronautics and Astronautics capitivated attendees.