2011 - Cooperative Institute for Research in Environmental Sciences ...

Ben Balsley
Fine-Scale In Situ Measurements to Study
Atmospheric Dynamics (0-10 km)
We are currently involved
in examining the
fine-scale details of atmospheric
dynamic processes
from the surface
to upper-tropospheric
heights. Understanding
these processes, which
occur on scales of meters
and seconds, is turning
out to be critical for gaining
a better understanding
of energy-cascading
processes throughout
this region.
The vehicle used in
these measurements,
called the CUMAV
(University of Colorado
Micro Autonomous
Vehicle), was developed by Professor Dale Lawrence of
CU’s Aerospace Engineering Department. The CUMAV
is a small, low-cost, programmable, reusable, autonomous,
GPS-controlled, battery-powered aircraft. Total cost
per unit is in the vicinity of $1,000. CIRES has equipped
it with fast-response sensors to measure temperature,
humidity, wind speed, wind direction and ‘temperature’
turbulence (CT2). Data are both telemetered to the ground
as well as archived aboard for later downloading and
analysis.
For upper-tropospheric measurements, the CUMAV
will be carried aloft beneath a conventional meteorological
balloon. After release, it will fly to a specific location,
spiral downward and then land at a predetermined site.
Typical spiral diameter is 100 to 200 m. Vertical resolution
is in the range of 1 to 2 m.
An example of our initial measurements appears in
Figure 1. This figure plots temperature (expressed here
in volts) versus time. These data were obtained while
the CUMAV was flying a series of 12 circles at a constant
height of 56 m over central Kansas. Although the
full range of temperatures shown here is very small
(1.11–1.17°C), a clear indication of mean heating can be
seen by the upward trend in the dotted line. The sharp
‘spikes’ on top of this mean curve appear to be manifestations
of early convective activity that increases with time
as the atmosphere warms. The horizontal width of the
smaller spikes can be less than 15 m or so.
We anticipate that this technique will serve as an impetus
for developing a unique, new and powerful technology
for studying fine-scale dynamic processes throughout
the first 10 km of the atmosphere.
PHOTOS BY DAVID OONK/CIRES
In one of three possible launch modes, the CUMAV is launched using a bungee
cord. In this case, the actual release is triggered by a computer command.
Dale Lawrence, Professor Aerospace Engineering Sciences, prepares to
launch the CUMAV by hand.
To launch from a higher altitude, the CUMAV is raised into the air via balloon,
released and then controlled remotely. Landing the CUMAV in all situations
is autonomous, with the landing site programmed prior to launch.
Because of its relative ruggedness (Styrofoam fuselage, pusher propeller
and embedded sensors), the aircraft can land safely virtually anywhere.
Figure 1
CIRES Annual Report 2011 25