Surface Gravity Prediction

Surface Gravity Prediction

Surface gravity is predicted by interpolation based on observed values. Observed gravity data in the National Geodetic Survey's Integrated Data Base are referenced to the International Gravity Standardization Net 1971, which is an absolute gravity datum.

ENTER: Latitude, Longitude and height above Mean Sea Level

The entry of mean sea level (topographic) height is NOT mandatory - the prediction of surface gravity value is still possible (frequently with diminished accuracy).

[may enter latitude and longitude in three formats:
1. degrees, minutes and seconds ( xxx xx xx.xxx)
2. degrees and minutes ( xxx xx.xxx)
3. degrees ( xxx.xxxxx)
may enter height in meters or feet:
1. in meters: xxxx.xxx
2. in feet : xxxx.xxx FT ( MUST include FT or ft for feet !)

Note: decimals can be keyed commensurate with the entry's precision, but are not required;

MUST include one or more blanks between entry fields]

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ENTER Latitude : '

ENTER Longitude: (positive WEST)

ENTER Sea level height:

When the site's sea level height is unknown DO NOT ENTER ZERO, but leave the entry field BLANK !

Be patient after clicking on "Let's go", data base access and computations may take a few seconds.

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It is possible that the surface gravity prediction may not succeed; there could be numerous reasons for this, including position and height entry errors. In such case an error code is returned; questions concerning the gravity prediction process may be mailed to NGS