In the CWEX11 S directory at EOL is a file of Splus code, latlonalt.q, for computing averages of the GPS values of latitude, longitude and altitude.
I ran it on 6 days of data from Jul 9 11:15 to Jul 15 16:00 (arbitrary period), and it returned the following:
stn | Lat(deg) | Lat stddev(deg) | Lon(deg) | Lon stddev(deg) | Alt(m) | Alt stdev(m) |
|---|---|---|---|---|---|---|
1 | 42.06605 | 1.101896e-05 | -93.28521 | 9.501855e-06 | 339.0 | 1.8 |
2 | 42.06977 | 1.317406e-05 | -93.28515 | 1.091214e-05 | 340.4 | 1.8 |
3 | 42.07344 | 1.417124e-05 | -93.28522 | 1.358779e-05 | 340.0 | 2.0 |
4 | 42.07679 | 1.39572e-05 | -93.28523 | 1.211881e-05 | 341.6 | 2.0 |
Note that the GPS does not provide a highly accurate estimate for altitude, the std deviations are about 2 meters.
Here's a kml file viewable in GoogleEarth, cwex_ncar.kml, with the above positions.