DRAFT DOCUMENT

README.txt for MGAUS soundings from XPIA/CABL, BAO, March 2015
Julie Lundquist, Julie.Lundquist@colorado.edu

List of soundings:

Caveats:
Data are completely raw and unprocessed; with caaution,
preferably with sounding software like ASPEN
(https://www.eol.ucar.edu/software/aspen).

Although the "A00" line in the sounding should give the 
GPS altitude of 1588 m, it was initially incorrectly set to 1607m.

GPS altitude should not be used; more info below from Kate Young, NCAR:
"For fixed sites, to obtain accurate heights I use
Google Earth Pro to determine the surface geometric height and then use the
equation below to compute a starting point for the geopotential height.
Running the soundings through ASPEN will produce a hydrostatically computed
geopotential altitude for the profile.  This is the altitude that should be
used for evaluating sounding data, not the GPS altitude.  The vertical
accuracy of the GPS is typically +/- 25 m and there is no quality control
performed (in ASPEN) on GPS height.

Geometric Height = 1582.52 m

pi  <-  3.14159265359
latrad <-  as.numeric(lau.lat[1]) / 360 * 2 * pi                       #lat in
radians
g <- 9.80616 * (1.0 - cos(2.0 * latrad) * .0026373)      #gravity constant
corrected for lat
dem <- 3.085462e-06 + 2.27e-09 * cos(2.0 * latrad) - 2.0e-12 * cos(4.0 *
latrad)
R <- 2.0 * g / dem
geoalt[1] <- (g * R * geometric[k]) / (9.8 * (R + geometric[k]))
#Geopotential altitude