Meltpond Experiment (MP) 2000

Figure 1. PSR/C imagery of ice floes within Baffin Bay, July 7, 2000. Observations were made at an altitude of 21,000 feet at 6.925 GHz, horizontal polarization, annd at an incident angle of 55°. Open water areas are distinguished by cold brightness temperatures.

As part of NASA's Earth Observing System AQUA sea ice validation program for the Advanced Microwave Scanning Radiometer (AMSR-E), a series of aircraft flights using the PSR over melting arctic ice were performed. The campaign, Meltpond 2000, occurred during June-July 2000 with the objective of quantifying the errors incurred in proposed AMSR-E sea ice algorithms resulting from the presence of melting ponds on the surface of dissipating pack ice. Melt ponds are currently the largest source of error in the determination of Arctic sea ice concentrations using satellite passive microwave sensors. A secondary objective of Meltpond 2000 was to develop a microwave capability to discriminate between melt ponds and open sea water.

The campaign focused on the use of the PSR for high-resolution polarimetric surface imaging, and involved the efforts of the Navy and personnel at the NASA Goddard Space Flight Center. A Navy P-3 aircraft made a series of five 8-hour flights over Baffin Bay (Figure 1), Viscount Melville Sound, and a Canadian ice camp near Resolute, Canada. The P-3 flew out of Thule Air Base, Greenland. The aircraft was outfitted with one of two PSR scanheads operating at two key sets of radiometric bands. The PSR/A scanhead covered the bands of 10.7, 18.7, 21.5, 37, and 89 GHz, and the PSR/C scanhead covered four bands from 6.0 to 7.5 GHz. These two scanheads were used on alternate days, thus demonstrating the ability to swap PSR scanheads for different experiments under field conditions. The aircraft also carried the NOAA/NOS Scanning Low Frequency Microwave Radiometer (SLFMR), operating at a frequency of 1.4 GHz. The complement of instruments provided a unique sensing package in terms of spectral coverage, polarization capability, and imaging spatial resolution. Satellite imagery provided additional information on surface conditions during the overflights.

The aircraft radiometer measurements elucidated the microwave spectral and polarimetric characteristics of the Arctic ice cover during the summer melt period. Final data processing is nearing completion, and the first paper stemming from this campaign was presented at the fall 2000 Oceans from Space Meeting. Collaborators on the project included NOAA ETL scientists A.J. Gasiewski, M. Klein, A. Yevgrafov, and T. Uttal, NASA scientists D. Cavalieri, T. Markus, and E. Kim, and Lt. Miles Ervin of the Naval Air Warfare Center at Patuxent River NAS. Besides fabricating and operating the radiometer equipment, NOAA ETL engineers were heavily involved in the modification of the P-3, the installation of the radiometer equipment, and flight planning and operations.