HR: 11:50h
AN: C42A-07    [Abstracts]
TI: Using Digital Imagery from a Small Unmanned Aerial Vehicle (UAV) to Estimate Arctic Melt Pond Coverage on Sea Ice
AU: * Mulac, B L
EM: b.mulac@aerosonde.com
AF: Aerosonde North America INC, NASA GSFC WFF Bldg N159, Rm W158, Wallops Island, VA 23337 United States
AU: Tschudi, M A
EM: tschudi@ucar.edu
AF: NCAR Atmospheric Technology Division, 10802 Airport Court, Broomfield, CO 80021 United States
AU: Maslanik, J A
EM: james.maslanik@colorado.edu
AF: University of Colorado Dept Aerospace Engeering Sciences, CCAR, UCB 431, Boulder, CO 80309 United States
AU: Holland, G J
EM: g.holland@aerosonde.com
AF: Aerosonde North America INC, NASA GSFC WFF Bldg N159, Rm W158, Wallops Island, VA 23337 United States
AB: Photo mapping of melt pond coverage on sea ice was undertaken in the Arctic during the summer of 2004 using an Aerosonde. Aerosondes are small, long endurance UAV designed to undertake a wide range of operations in a highly flexible and inexpensive mode. The Aerosonde conducts a defined mission in a completely autonomous mode. All flights are under the command of a ground controller who can change missions and respond to air traffic control requests, etc. An NSF-funded effort (Office of Polar Programs' Long Term Observations [LTO]) is now underway to deploy Aerosondes for routine mapping and atmospheric sounding missions in the Arctic. Aerosondes were deployed at Barrow, AK, during June, 2004 as part of the LTO effort. During this deployment, several flights were dedicated to examining the fractional coverage of melt ponds over sea ice in the Beaufort and Chukchi Seas, as part of a study funded by NASA. Melt ponds have been identified as a key feature in determining the amount of solar insulation absorbed by sea ice, and hence is a primary controller of the melt rate of the ice through the summer. Sea ice models have, to date, crudely parameterized ponds, due in part to a lack of large-scale observations of their temporal and spatial evolution. The NASA-funded study uses observations from the EOS sensor MODIS to estimate pond fraction over a large portion of the Beaufort and Chukchi, by examining several spectral (visible and near-infrared) MODIS bands and deducing melt pond coverage from the known spectral properties of ponds. The Aerosonde flights dedicated to the melt pond study were necessary to test the validity of the pond coverage estimated using the MODIS data. A downward-looking Olympus C-3030 digital camera was mounted within the Aerosonde to photograph the sea ice. The digital photos are analyzed to classify each photo according to the percentage cover of melt ponds, unponded ice, and open water. These estimates are compared to the values retrieved using MODIS for the same area of coverage. To enhance these comparisons, missions were flown with 10 km x 10 km grid patterns, with overlapping (along-track and cross-track) digital photos, which allow for comparison with 400 MODIS pixels (500 m resolution). Additional missions were designed to examine the evolution of pond coverage over sea ice off the coast of Point Barrow, Alaska. The sea ice in this area of interest was fast ice (i.e. not drifting ice) and served as an area where melt ponds can be observed during formation and their evolution through the summer. The Aerosonde team flew several flights paralleling Point Barrow and overlapping in a pattern that provided contiguous digital camera images of the fast ice from shore to a few km off the coast. These flights were repeated several times during June, providing imagery that will assist investigators in determining how pond fraction changes over this period. The technique and results of pond coverage estimation from airborne digital photography will be presented, as will comparisons to estimates retrieved using MODIS.
DE: 3349 Polar meteorology
DE: 4207 Arctic and Antarctic oceanography
DE: 1894 Instruments and techniques
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting