AIRCRAFT MEASUREMENTS
Intensive
aircraft field measurements over the two sides of the bunny fence will
be conducted during the NCAR GLASS radiosonde measurement period at
no cost to the project. This experiment
will be similar to the buFex (Bunny Fence Experiments) intensive
field campaigns which were conducted in the 1990’s (e.g.,
Lyons et al, 1993).
The aircraft will be instrumented with sensors capable of measuring
all of the components of surface energy budget (Hacker and Schwerdtfeder,
1988). These measurements will be supplemented with simultaneous
continuous surface observations of turbulent fluxes as well as
standard meteorological parameters and infrared thermometry. Results
from previous expeditions are archived at the Western Australian
Remote Sensing Application Centre. Relationships derived
from the aircraft transects and field measurements then are used
to characterize the large-scale variation in surface temperature,
albedo and surface roughness and their variability throughout the
day. This will be accomplished by repeated overpasses across
the bunny fence in transects between the two Bowen Ratio sites
and on long traverses on either side of the fence. These
data in turn will be combined with local meteorological data to
estimate the latent and sensible heat fluxes between native and
agricultural vegetation.
As reported by
Ray et al (2003), aircraft measurements for the time period of 1000-1100
LST were compared to satellite-derived values taken at approximately
1030 LST. In general, comparisons of
latent heat values for the satellite and aircraft measurements were
found to be in good agreement, but with discrepancies in sensible
heat fluxes. The combination of simultaneous aircraft, satellite,
radiosonde, and Bowen Ratio station observations will allow us to
compare the various approaches and to validate them with surface
measurements. |
