NEW 5' x 5' DIGITAL GRA VITY AND TERRAIN
MODELS OF THE EARTH
ABSTRACT
Christopher M. Green and J. Derek Fairhead
GETECH, Department of Earth Sciences,
University of Leeds, Leeds LS2 9JT, UK
Since 1986, GETECH has, through a series of oil industry funded projects, compiled 5' x
5' digital gravity and digital terrain models for all land areas of the Earth excluding North
America and Antarctica. This has been achieved with the support of various international
organisations and a very large number of national groups.
The GETECH gravity model covers about 90 per cent of the Earth's surface. The model
has been compiled from public domain data, a wealth of archived oil industry data for
Africa, South America, Europe and South East Asia and major national data sets of the
Former Soviet Union, China and Australasia. Some of the largest remaining gaps are in
central Brazil and are currently being filled with ground data by GETECH in
collaboration with EPUSP.
The digital terrain model was originally required to apply topographic corrections to the
archive data in the construction of coherent gravity anomaly compilations. It uses the
extensive database of gravity station heights and bathymetry, existing DTM's and
digitised topographic maps to provide the most up to date global DTM product.
INTRODUCTION
By the mid 1980s gravity surveying had been ongoing for over 40 years and huge
quantities of data had been acquired by academic, government and commercial groups.
These surveys, which range in scale from a few kilometres to virtually worldwide
transects had been used in a local context, but not brought together into a coherent
database. Many of the data that existed were available only in contour map form and in
many organisations, staff changes and restructuring meant that knowledge of what gravity
data existed in the archives was slowly being lost.
227
MODELS OF THE EARTH
ABSTRACT
Christopher M. Green and J. Derek Fairhead
GETECH, Department of Earth Sciences,
University of Leeds, Leeds LS2 9JT, UK
Since 1986, GETECH has, through a series of oil industry funded projects, compiled 5' x
5' digital gravity and digital terrain models for all land areas of the Earth excluding North
America and Antarctica. This has been achieved with the support of various international
organisations and a very large number of national groups.
The GETECH gravity model covers about 90 per cent of the Earth's surface. The model
has been compiled from public domain data, a wealth of archived oil industry data for
Africa, South America, Europe and South East Asia and major national data sets of the
Former Soviet Union, China and Australasia. Some of the largest remaining gaps are in
central Brazil and are currently being filled with ground data by GETECH in
collaboration with EPUSP.
The digital terrain model was originally required to apply topographic corrections to the
archive data in the construction of coherent gravity anomaly compilations. It uses the
extensive database of gravity station heights and bathymetry, existing DTM's and
digitised topographic maps to provide the most up to date global DTM product.
INTRODUCTION
By the mid 1980s gravity surveying had been ongoing for over 40 years and huge
quantities of data had been acquired by academic, government and commercial groups.
These surveys, which range in scale from a few kilometres to virtually worldwide
transects had been used in a local context, but not brought together into a coherent
database. Many of the data that existed were available only in contour map form and in
many organisations, staff changes and restructuring meant that knowledge of what gravity
data existed in the archives was slowly being lost.
227