| The Land and Marine Gravity 1999 Edition 2-volume CD-ROM set contains observed and
derived land and marine gravity data contributed by many national and international
organizations, from both the academic and government sectors. Approximately 70 percent
of the data are observed values--regional station data collections (separated primarily
by contributors) and absolute gravity measurements. Grids and other derived summary
data sets represent another 30 percent of the data. In general, data record parameters
include Latitude, Longitude, Observed Gravity and Elevation, Bouguer Gravity Anomaly
(land), and Free- air Anomaly (ocean). In all cases, each data set contains associated
documentation, including source contributor. Data are in binary format with ancillary
files for conversion of the data to ASCII. On the Land Gravity CD- ROM, data sets
are grouped into directories based on type: Absolute, Grids, Regional, Global, and
Correlative (Geoids). The Marine Gravity CD-ROM has gravity data from 1,555 ocean
surveys grouped by regional location of the survey. Directories exist for the Gulf
of Mexico and Caribbean Sea, Indian Ocean, Mediterranean and Black Seas, North Pacific,
South Pacific, North Atlantic and South Atlantic. Surveys which cross ocean areas
are included in both regional directories. The marine gravity data were collected
from ships operated between the years 1961 and 1996. The Marine gravity surveys are
provided in a modified MGD77 format containing survey location, observed gravity and
free air-anomaly. The 1999 Edition of Gravity Data is Year 2000 compliant. All date
values are full 4-digit years. The GeoVu geophysical data browse and visualization
software is also Year 2000 compliant. The compliance is inherent because there are
no built-in date manipulation routines. However, GeoVu is written to run on specific
platforms and operating systems. There is no guarantee that GeoVu will operate on
platforms other than those indicated in the Software documentation. |