PALS flights over Iowa Validation Site.
Cooperation between Iowa State University, the University of Iowa, the
USDA ARS National Soil Tilth Lab, and the NASA Jet Propulsion Lab.
Overview of experiment that occurred 9/23 to 9/25/2008.
Brian Hornbuckle, Iowa State University, bkh@iastate.edu.
Brian with the Twin Otter on 9/25/2008.
Tracy Rowlandson (ISU graduate student)
measuring dew on 9/25/2008.
Hypotheses to be tested:
a: Dew and/or intercepted precipitation effects the radar backscatter
and brightness temperature.
b: Brightness temperature is a smooth function of soil and
vegetation temperatures, such that observed brightness temperature
variations can be related to observed variations in soil and
vegetation properties as soil and vegetation temperatures change.
c: Existing theory can be used to relate brightness temperature at
different scales.
d: Observed variation in brightness temperature along a transect
can be quantitatively related to observed variations in soil and
vegetation properties.
Target sequence:
a. Fly from 1A to 1B and 1B to 1A over corn fields @ 3000 ft AGL.
b. Fly from 2A to 2B and 2B to 2A over IVS @ 3000 ft AGL.
c. Fly from 3A to 3B, 3B to 3A, 4A to 4B, 4B to 4A,
5A to 5B, 5B to 5A, 6A to 6B, and 6B to 6A @ 1000 ft AGL.
d. Fly from 7A to 7B, 7B to 7A, 8A to 8B, 8B to 8A, 9A to 9B,
and 9B to 9A @ 500 ft AGL.
e. Repeat lines 1 and 2 until flight hours for that day expire.
Timing: PALS begins at 1A at 7:45am CDT each day in order to catch
maximum dew (30 to 60 minutes after sunrise at 7:00am) and to
observe dew dryoff and changes in soil and vegetation temperatures.
Calibration: Fly over Saylorville Reservoir for calibration
on route from DSM to Iowa Validation site,
and on route from Site to DSM.
Note: PALS at 1A at 7:45am. Fly lines 1 through 9.
Then repeat lines 1 and 2 as often as flight hours allow.
N
Zumwalt Station Road
State Ave
South Dakota
IVS = Iowa Validation Site
2 through 9. Flights over IVS.
2A
NSTL corn flux
1B
510th Ave
X Ave
Y Ave
260th St
520th Ave
2B
IVS
1A
approximate footprint size @ 3000 ft AGL
270th St
1. Flight over corn fields south of IVS.
Iowa Validation Site
radar/radiometer 3000 ft AGL 560 x 420 m
radar/radiometer 1000 ft AGL 190 x 140 m
radiometer 500 ft AGL 95 x 70 m
3B
3A
7B
4B and 8B
7A
4A and 8A
2A and 9A
5A
2B and 9B
5B
975 m
6A
N
Lines 2 through 9 over IVS.
792 m
6B
Description of lines.
Line 1. PALS at 3000 ft AGL, both radiometer and radar are functional.
South of Iowa Validation Site over private fields and near USDA ARS
NSTL instruments. Landcover is almost entirely corn. Line length of
about 5000 m.
Line 2. PALS at 3000 ft AGL, both radiometer and radar are functional.
Over Iowa Validation Site. Landcover at site is soybean. Line length of
about 2000 m.
Lines 3 through 6. PALS at 1000 ft AGL, radiometer functional, radar
might be functional. Over Iowa Validation Site. Landcover at site is
soybean. Line lengths of about 2000 m.
Lines 7 through 9. PALS at 500 ft AGL, radiometer functional, radar not
likely functional. Over Iowa Validation Site. Landcover at site is
soybean. Line lengths of about 2000 m.
Notes from experiment.
Tuesday 9/23: cloudy night (little or no dew present), mostly clear
morning. Excellent weather for control day to test hypothesis a and b.
PALS sees vegetation with no dew and changes in Tb and backscatter
as soil and vegetation warm. Significant v-pol RFI present. PALS
measures lines 1 through 9, then repeatedly measures 1 and 2.
Wednesday 9/24: significant rain during the night, significant change in
soil moisture. Cloudy morning so Twin Otter must remain at 3000 ft
AGL and PALS measures lines 1 and 2 repeatedly. PALS sees
vegetation with some intercepted precipitation and increased soil
moisture. Some of intercepted precipitation dries during morning. No
apparent RFI present according to Dinardo.
Thursday 9/25: mostly clear skies during the night, large dew event.
Twin Otter about an hour late but in time for high amounts of dew on
both corn and soybean. Perfect weather to test hypothesis a. No
apparent RFI present according to Dinardo. PALS measures lines 1
through 9, then repeatedly measures 1 and 2.