VCR/LTER GPS Network

Version 2.01, 10 September 1994


The Virginia Coast Reserve Long-term Ecological Research project, in
association with the Virginia Marine Resources Commission, conducted
an intensive GPS survey during February 1992.  A second GPS survey was
conducted in August 1994 to add supplemental GPS monuments.  All data 
were processed by the VCR/LTER.  Several caveats must be applied to use
of this survey network:

1. These are preliminary results and are subject to change as the
network is revised.

2. This network is designed for research purposes only, the data are
not suitable for legal uses of survey data.

3.  The network includes several US Government benchmarks, but except
for the VCR1 monument recently resurveyed and "fixed" by the National
Geodetic Survey (see below), the coordinates for those benchmarks have
not been adjusted to agree with “blue-book” values for those
benchmarks.

4. Elevations are based on mean sea-level for a single point (VCR1).
No geoid corrections have been applied to any other point.

Data Processing

1. Data were processed using TRIMVEC+ software.

2. Baselines were computed using “widelane” fixed solutions whenever
possible. If a quality ratio <3 could not be obtained, a float
solution was used instead.

3. A network made up of only the highest quality baselines (fixed)
solutions was created and fixed based on the geographical coordinates
and elevation of the VCR1 monument.

4. A network comprised of all points was compiled. As before, the
coordinates for VCR1 (VCR LTER 1) were fixed in 3 dimensions. The
stations BROWNSVILLE, FARL and SHUG were fixed to their horizontal
coordinates in the high-quality-only network. Network adjustments were
then performed on all other points.

NGS location of VCR1 (VCR LTER 1) monument

5/3/94 - National Geodetic Survey fixes the VCR1 monument at
37-deg, 17-min, 42.15663-seconds North Latitude and 75-deg, 55-min,
59.49256-sec. West Longitude, with an ellipsoidal height of -28.261 m.
Geoid height is modeled to be 8.7 m. Horizontal datum is NAD 83 and
vertical datum is NAVD 88 (for NGVD 29, add 0.2 m).

Any questions regarding the data processing should be directed to John
Porter (Internet: JHP7E@VIRGINIA.EDU) at the University of Virginia
Department of Environmental Sciences.