There are three different kinds of plots you can look at:
Is there natural variability in the data? Because the GPS data and the geostationary data do not exactly overlap, it seems right to consider the natural spread in the data. If, for example, the GPS was 25 kilometers from the nominal center of the retrieved GOES estimated precipitable water, what kind of spread could be thought of as normal. This topic is addressed here.
When wet delays are processed with the temperature and pressure at the surface, GPS can produce precipitable water measurements. Here is where the comparisons between GOES Sounder-derived precipitable water and GPS-derived precipitable water are presented. I got the GPS precipitable water from Yoaz Bar-Sever at JPL and the GOES Sounder data from CIMSS.
Wayne Feltz of SSEC provided AERI data (click here for more information on AERI data) at the CART site in Oklahoma (station ARM1) that can be compared to the computed precipitable water from GPS and GOES Sounder data. Click here.
In addition to the AERI data, Wayne also kindly provided, GaMIT-processed GPS precipitable water at nearby Lamont, OK, which can be compared to the GPS-processed precipitable water there. Alas it is for but 4 days, but the time series comparison is here.
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Click here for more information on GOES precipitable water and things to keep in mind about it.
Click here for more information on GPS precipitable water and things to keep in mind about it.