These comments are very preliminary, but they are a starting point.
From the tethersonde data it appears that the cold layer
that develops as the sun sets is very shallow (less than 20mb
or 200m, and usually less than this) with an increase of about
7°C between about 2m above the surface (lowest level of the
radiosonde approximately) and 100m above the ground level.
During the afternoon the boundary layer appears to be at least 70mb
thick (the dry adiabatic - well mixed layer) but this seems to be variable.
The tethersonde data appear "noisy" because each up- and down-sounding
took perhaps 15 minues and cariations over this period add variability to
each sounding. The data can be averaged to obtain smoother profiles. Very
noisy data sometimes occurred when the battery voltage became very low.
The best solution to battery voltage was to build a battery pack with 10 "AA"
Alkaline Duracell batteries. These ran at least 15 hours.
Pilot balloon time-height sections
The time-height sections show that the data is fairly good, with only small
changes in the profiles over the experiment. Diurnal variations are not easily
apparent from these plots, since the winds were fairly strong at upper-levels
(above 8 km). Most daytime balloons could be tracked to 12 km, whereas the
nighttime soundings extended to about 4-6 km. Although the CORRIGE
program was used to process the winds and correct errors, some errors are still
present, such as at Pampa de Majes (next to last sounding, near 4.5 km). It
should be noted that time-height sections are an effective means of detecting
errors in wind soundings, provided that there are frequent observations.
The maps show a number of features:
1) The average winds are smoothly varying - at higher levels (above 8km) all three
stations show similar mean winds from the NW.
2) La Joya shows the strongest SE winds in the lower troposphere, as expected.
3) On average, the winds below 3500 mASL are westerly at La Pampilla
(City of Arequipa) while the winds at Pampa de Majes and La Joya are easterly.
This implies that the airflow between the surface and 3500 m approaches Arequipa
from the S, then SW, and finally W (in the mean). The air appars to be flowing around
the higher terrain (near Cerro Verde) south of the city and approaching the city
from the west. This westward flow is most obvious in the afternoon (PM means) and
between 2500 and 300 mASL.
4) The difference winds (PM minus AM means) show that there is an upslope
flow in the afternoon, but that it is very shallow. The winds at 1750m are clearly
towards the higher terrain at Pampa Majes and La Joya but by 2250 they are from the
mountins - this is the retur flow of the afternoon upslope (valley) breeze. A second
maximum in upslope winds can be seen in the 3000-4000 m layer. Between 6000 and 8000m
there s a clear flow from the higher terrain towards the ocean (difference winds from
the NE). Above this level the data are fewer, with no nighttime winds.
5) The mean afternoon meridional wind profiles all show a similar feature - the maximum
in southerly flow between 3000 and 4000m. This flow towards the higher terrain may be a
result of the afternoon heating of the Pacific slopes of the altiplano.