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Through these objectives the project aims at improving
significantly the most important source of uncertainty in our
understanding of the role of the biota in the global carbon
cycle. At the same time, the project will contribute
significantly to improving the database for several
international policy initiatives including the Framework
Convention on Climate Change, the activities of the
Intergovernmental Panel on Climate Change, national
emission inventories and many others which focus on the role
of tropical forests. It is our aim that the results of this project
will simultaneously fulfill the needs of the global change
research community, the international policy community, and
national-level forest resources and economic development
programs. The project will focus on the three regions where
most of the tropical deforestation in the world has occurred:
(1) the Amazon Basin, (2) Central Africa, and (3) Southeast
Asia. Mapping deforestation in these three regions will
account for the majority of deforestation activities in closed
tropical forests worldwide and will account for approximately
75-80% of the current net biotic flux of carbon.
As part of NASA's Pathfinder Program we had a two very
specific goals:
l. "To utilize large amounts of existing satellite
technologies and data in new ways to address important
global change research questions in advance of, and
leading toward, the launch of the Earth Observing System
(EOS)".
2. "'To develop a foundation of experience for managing
large amounts of satellite data for global change research
prior to the launch of the Earth Observing System,
thereby testing and proving the technologies and
approaches for information management which will be
needed by the community at large with the launch of the
Earth Observing System. In other words, we are
Pathfinding”. |
3. OVERVIEW OF APPROACH
Our approach to Pathfinder was straightforward. The first step
was the identification and acquisition of a pan-tropical, wall-
to-wall LANDSAT digital data set from the national archive at
the EROS Data Center and the archives of the foreign ground
receiving stations with coverage of the study areas (e.g.
Brazil, Thailand, and Australia). A three-date data set was
selected based on data availability. The three dates, or epochs,
selected were the early-1970s (i.e. 1972-1974), mid-1980s
(ie.. 1984-1986), and early 1990s (i.e. 1989-1994). This
parsing of data analysis over three year wide epochs enables
better coverage due to persistent cloud cover found in the
tropics. LANDSAT MSS data were used for the two earliest
epochs. LANDSAT TM data were used for the 1990s epoch.
MSS was the only sensor in the 1970's and the most
| International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998
data set.
commonly ordered and archived in the mid-1980's. Once
acquired, the digital data was then analyzed to create a science
product data set: a digital map database, in a geographic
information system, of the rate and extent of deforestation.
The development of a project Information Management
System (IMS) was an essential element of the project and in
keeping with the overall goals of the NASA Pathfinder
Program. The IMS has three functions: Data query and archive
metadata retrieval; Data management and lineage tracking for
the project; and Archive management and data dissemination.
The Pathfinder project used ARC/INFO, a vector-based GIS, for
spatial data analysis and as the basis for the IMS development.
The entire data set and all analyses can either be referenced by
geographic location, or a tiling system based on the
LANDSAT World Reference System path/row footprint. The
tile system provides an organized' foundation for data
acquisition, cataloging, processing and overall data
management. The GIS permits re-sorting, grouping, or
subsetting across the tile system or any other map projection,
thus it greatly enhanced our flexibility in analysis of the data.
From the derived data set, several science end-uses can be
envisioned. Some, such as carbon emissions, are derived
directly from the product data set when it is used in
conjunction with numerical models. Others, such as wetlands
and hydrography mapping, can be derived from the original
Landsat image data using different methodologies. Timber
inventories, resource and environmental planning,
management and assessment can also make good use of this
There are many other users in wide-ranging
disciplines including the social sciences, and others, that can
apply these data to a myriad of uses once they are widely
distributed.
3.1 Provision of Landsat Data to Project
The EROS Data Center (EDC) provides data pre-processing
support to the Pathfinder. EDC also provides technical support
and data brokerage services for foreign acquisitions. The MSS
data archive at the EROS Data Center was tapped to acquire
digital MSS data whenever possible. In addition, data from the
ground stations in Thailand, Indonesia, Australia, Brazil,
Ecuador, and, Gabon, Kenya, and South Africa are also used
when EDC archive coverage was poor. A program of new
acquisitions for early-1990s was developed under the NASA /
EOSAT data grant and the NASA Landsat Data Buy, as well as
through collaborative efforts with other agencies such as EPA
and the World Bank.
Digital data selected from the national or foreign archives and
from new acquisitions were sent to EDC for specially designed
Pathfinder preprocessing. This includes conversion to a
common format (CCT-P) from other formats (e.g. CCT-X,
CCT-A, and others) and the addition of map coordinates. Each
scene was registered to a Universal Transverse Mercator (UTM)
map projection using satellite navigation data (includes only
system corrections), and the digital image was imbedded with
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