[The following is exerpted from a letter to Allen Meece.]
[Updated 4 September 2002]
I have compiled a graph of the upper level temperatures we can
expect during the year. The data used is all SOCA station temperature vs.
altitude data from November 1, 2000 to October 31, 2001. The spreadsheet
program I use isn't capable of handling that much data, but I was able to whip
up a simple qbasic program to draw the graph for me.
The temperature decreases roughly linearly until 16500m.
Up until this point, the temperature range over the entire year is
only about 10C. Above 17000m, the temperature begins increasing
roughly linearly and the yearly variation increases to nearly 20C. The
points along the 190K line between 23000m and 29000m represent a single day's
measurement.
This discontinuity in temperature at 16500m probably
marks the tropopause, with the region of temperature increase being the
stratosphere.
Upper level wind speeds are less predictable over the
course of an entire year.
The winds at each altitude vary more or less stochastically,
although their range does vary with altitude. A peak in wind velocity
occurs between 15000m and 16500m, just before the stratosphere. After the
tropopause, the wind drops down to surface speeds again, creating a region
of low wind force from 16500m to 20000m, then increases more rapidly with
altitude. This region of low wind force is the best place to station the
VBP platform.
Winds of up to 160 knots were recorded at varying
altitudes. However, these gusts were measured on only three days
out of the year.
The regularly spaced vertical lines at 11000m, 14000m, 16000m,
etc., are an artifact caused by the fact that the sounding balloon always
automatically returns data upon reaching these altitudes regardless of
time or conditions. Data at these altitudes exists for every day of the
year that a sounding balloon attained them, so the data at these altitudes
appears denser.
It's important to note that all data does not exist for all
altitudes on all days of the year. Instrument failures appear common with
these soundings.
