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Proceedings Paper

Spaceborne microwave remote sensing of seasonal freeze-thaw processes in the terrestrial high latitudes: relationships with land-atmosphere CO2 exchange
Author(s): Kyle C. McDonald; John S. Kimball; Maosheng Zhao; Eni Njoku; Reiner Zimmermann; Steven W. Running
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Paper Abstract

Landscape transitions between seasonally frozen and thawed conditions occur each year over roughly 50 million square kilometers of Earth's Northern Hemisphere. These realtively abrupt transitions represent the closest analog to a biospheric and hydrologic on/off switch existing in nature, affecting surface meteorological conditions, ecological trace gas dynamics, energy exchange and hydrologic activity profoundly. We utilize time series satellite-borne microwave remote sensing measurements from the Special Sensor Microwave Imager (SSM/I) to examine spatial and temporal variability in seasonal freeze/thaw cycles for the pan-Arctic basin and Alaska. Regional measurements of spring thaw timing are derived using daily brightness temperature measurements from the 19 GHz, horizontally polarized channel, spearately for overpasses with 6 AM and 6 PM equatorial crossing times. Spatial and temporal patterns in regional freeze/thaw dynamics show distinct differences between North Americ and Eurasia, and boreal forest and Arctic tundra biomes. Annual anomalies in the timing of thawing in spring also correspond closely to seasonal atmospheric CO2 concentration anomalies derived from NOAA CMDL arctic and subarctic monitoring stations. Classification differences between AM and PM overpass data average approximately 5 days for the region, through both appear to be effective surrogates for monitoring annual growing seasons at high latitudes.

Paper Details

Date Published: 22 December 2004
PDF: 12 pages
Proc. SPIE 5654, Microwave Remote Sensing of the Atmosphere and Environment IV, (22 December 2004); doi: 10.1117/12.578906
Show Author Affiliations
Kyle C. McDonald, Jet Propulsion Lab. (United States)
John S. Kimball, Univ. of Montana (United States)
Maosheng Zhao, Univ. of Montana (United States)
Eni Njoku, Jet Propulsion Lab. (United States)
Reiner Zimmermann, Max-Planck-Institute fuer Biogeochemie (Germany)
Steven W. Running, Univ. of Montana (United States)

Published in SPIE Proceedings Vol. 5654:
Microwave Remote Sensing of the Atmosphere and Environment IV
Gail Skofronick Jackson; Seiho Uratsuka, Editor(s)

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