polynya John Cassano and Shelley Knuth Department of Atmospheric and Oceanic Sciences Cooperative Institute for Research in Environmental Sciences University of Colorado Project Overview Use Aerosonde ID: 515513
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Slide1
UAV observations of the wintertime boundary layer over the Terra Nova Bay polynya
John Cassano and Shelley Knuth
Department of Atmospheric and Oceanic Sciences
Cooperative Institute for Research in Environmental Sciences
University of ColoradoSlide2
Project OverviewUse
Aerosonde
unmanned aerial vehicles (
UAVs
) to make meteorological measurements in the vicinity of Terra Nova Bay
Why Terra Nova Bay?
Location of recurring
polynya
Region of strong
katabatic
winds
Source region for Antarctic bottom water
Prior to this project there were no in-situ atmospheric measurements of the wintertime atmosphere over the Terra Nova Bay
polynyaSlide3
MODIS-Terra 04-Oct 2005Slide4
Science Questions
What atmospheric processes control the size of the Terra Nova Bay
polynya
?
Winds?
Surface energy budget?
How do changes in the atmospheric state alter the amount of heat and moisture removed from the ocean in the
polynya
?
What impact does this have on the development of Antarctic bottom water?
How does the presence of the
polynya
modify the
katabatic
airstream as it passes over the
polynya
?Slide5
Aerosonde
UAVSlide6
Wingspan
3 meters
Weight
15 kg
Payload Capacity
2-5 kg
Endurance
12-17+ hrs
Range
1000+ kmAltitude100-6000 m
Communications via 900 MHz radio and IridiumFlies in fully autonomous mode with user-controlled capability
Aerosonde
UAVSlide7
Wind Speed/Direction
Pitot
with GPS
RH/Temp/Pressure
Standard
Radiosonde
Met Sensors
Ocean /Ice Skin Temperature
Infrared Thermometer
Ocean/Ice Visible ImageryStill Digital CameraNet Shortwave RadiationPyranometerNet Longwave RadiationPyrgeometer
RH/T/P/wind profiles
Dropsondes
Altitude and Surface WavesLaser Altimeter
Aerosonde
MeasurementsSlide8
The ChallengesCold temperatures
Impacted:
Engine
Parts failure
Communication failures
Wind
Take-off / landing
In flight winds
Aircraft icingSlide9
Aerosonde LaunchPegasus Runway (14 Sept 2009)Slide10
Aerosonde RecoveryPegasus Runway (7 Sept 2009)Slide11
16 flights8 science flights to TNB11000 km (7000 miles)130 flight hoursSlide12
14 September 2009
First successful TNB flight
15 hour flight
1230 km (750 miles)
Max wind speed
29.1
m/s
(65 mph)Slide13Slide14
Aerial Photos
Local test flight 9 Sept 2009
Aerial survey of Pegasus runway
Flown at 1000
m
altitudeSlide15
Pegasus Runway
Mosaic courtesy of Jim
MaslanikSlide16Slide17Slide18
Aerial Photos of TNB Polynya22 September 2009Slide19
Complex rafting and finger rafting: Produces accumulation of ice mass within thin-ice locations
Image width: 70m
Photo location shown in MODIS satellite image
Courtesy of Jim
MaslanikSlide20
Nilas ice forming in area of relatively calm winds. Sea smoke is also present.
Frazil ice in location of strong winds, including waves with white caps.
Courtesy of Jim
MaslanikSlide21
Frazil and pancake ice accumulating to form a band of thicker ice
Courtesy of Jim
MaslanikSlide22
Pancake ice, with largest floes averaging about 2m diameter
Courtesy of Jim
MaslanikSlide23
Ridging within consolidated pack ice. Ridging indicates thicker ice compared to locations with rafted ice.
Courtesy of Jim
MaslanikSlide24
TNB Air Mass Modification
24 September 2009
Two plane mission to Terra Nova Bay
Determine modification of
katabatic
air stream as it passes over
polynyaSlide25
Cross-wind Leg: Wind SpeedSlide26Slide27
Temperature
100-600
m
layer: ~2 K warming
SHF Profile 1-2:
~
608
W/m
2 (10.6 km)SHF Profile 2-3: ~580 W/m2 (11.8 km)SHF Profile 3-4: ~83 W/m2 (24.1 km)SHF Profile 1-4: ~327 W/m2 (46.5 km)Slide28
Relative Humidity
100-600
m
layer:
125% inc. in specific humidity
LHF Profile 1-2:
~
63
W/m2 (10.6 km)LHF Profile 2-3: ~161 W/m2 (11.8 km)LHF Profile 3-4: ~86 W/m2 (24.1 km)LHF Profile 1-4: ~101 W/m2 (46.5 km)Slide29
Wind SpeedSlide30
Future Work
Estimate surface turbulent sensible and latent heat fluxes
Bulk method
Compare to fluxes estimated from air mass modification (profiles)
Estimate turbulent momentum flux to surface
What are the dynamics responsible for the downwind modification of the
katabatic
jet?
Is
polynya opening / closing driven by winds or changes in the surface energy budget?Repeat UAV observations when high vertical resolution mooring is present in TNBSlide31
Questions?