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OBTAINING EARTH OBSERVATION DATA FROM 
U.S. AND INTERNATIONAL DATA AND INFORMATION SYSTEMS 
James R. Thieman 
NASA / Goddard Space Flight Center, National Space Science Data Center, 
Code 633.2, Greenbelt, MD 20771. USA. 
Lola Olsen 
NASA / Goddard Space Flight Center, Global Change Data Center, 
Code 902, Greenbelt, MD 20771, USA. 
ABSTRACT 
Multiple archives of remote sensing data now exist, and the number is expected to increase in the years to come. It is 
becoming a more challenging task to determine which archives hold the data of interest, as well as to locate the relevant 
in-situ or correlative data and information. This accentuates the need for high-level directories and other information 
systems to aid in the search. Two organizations have been active in setting up systems to help users in locating data and 
information. First is the U.S. Interagency Working Group on Data Management for Global Change (IWGDMGC) 
composed of many federal agencies having data or information useful for the study of global change problems. This 
organization has created a computer-accessible Global Change Data and Information System (GCDIS) which is intended 
to aid users interested in the causes and effects of global change. The GCDIS includes many interconnected information 
systems which are useful for this purpose, such as the Earth Observing System Data and Information System (EOSDIS). 
Secondly, international information system activities are also ongoing through the auspices of the Committee on Earth 
Observation Satellites (CEOS). An International Directory Network (IDN) sponsored by CEOS has provided users in 
many nations with quick access to data information for the last several years. The IDN, in turn, leads to other network- 
accessible information systems which have detailed information about à wide variety of data. Examples of data 
information access within GCDIS, IDN, and related systems will be given. 
KEY WORDS: Directory, Archives, Data location, Information systems 
1. INTRODUCTION 
The use of computer networks to locate and access data 
of interest is increasing rapidly. Online services are 
being offered by a variety of data archives and the trend 
is to make as many data products as possible directly 
accessible over the network. Remote locations 
throughout the world are now being effectively connected 
to the networks, and other locations that have network 
connections are depending more on it as their bandwidth 
increases, allowing larger files to be transferred 
efficiently. Some of the latest network search 
technologies, such as World Wide Web, Mosaic, WAIS, 
etc. can be characterized as experiencing explosive 
growth. The amount of information available through the 
network is overwhelming. It is often difficult to find 
information on a particular topic unless one knows 
exactly where to go. This does not help if one is 
searching for information on a particular subject but have 
no idea what location stores that information. Within the 
Earth observation/remote sensing community the 
locations of major data archives are well known, but there 
are a number of observing sites, archives, and data 
analysis locations around the world which may offer 
potentially valuable data as well. Several aids are now 
available which may help the user locate and use needed 
data. This paper will discuss the Global Change Data and 
Information System (GCDIS), the International Directory 
Network (IDN), and other tools which can be used to 
access Earth observation data. 
2. THE GLOBAL CHANGE DATA AND 
INFORMATION SYSTEM 
For many years now the U.S. federal agencies have been 
working togetfier to support the data needs of the 
community in addressing the problems associated with 
global environmental change. The organization created 
to do this is called the Interagency Working Group on 
Data Management for Global Change (IWGDMOGC). 
Most of the U.S. federal agencies which hold data 
relevant for the study of global change are a part of this 
group (Department of Agriculture, Department of 
Commerce, Department of Defense, Department of 
Energy. Department of Interior, Environmental Protection 
Agency, National Aeronautics and Space Administration, 
and the National Science Foundation. Together they have 
created the Global Change Data and Information System 
as a tool to aid the community in obtaining data and 
information relevant to global change. Detailed 
information about GCDIS can be found in the GCDIS 
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