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Spaceborne microwave remote sensing of seasonal freeze-thaw processes in theterrestrial high l atitudes : relationships with land-atmosphere CO2 exchangeLandscape transitions between seasonally frozen and thawed conditions occur each year over roughly 50 million square kilometers of Earth's Northern Hemisphere. These relatively 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, separately 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 America 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, though both appear to be effective surrogates for monitoring annual growing seasons at high latitudes.
Document ID
20060043971
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
External Source(s)
Authors
McDonald, Kyle C.
Kimball, John S.
Zhao, Maosheng
Njoku, Eni
Zimmermann, Reiner
Running, Steven W.
Date Acquired
August 23, 2013
Publication Date
November 8, 2004
Subject Category
Earth Resources And Remote Sensing
Meeting Information
Meeting: International Society for Optical Engineering (SPIE) International Asia Pacific Environmental Remote Sensing Symposium
Location: Honolulu, HI
Country: United States
Start Date: November 8, 2004
Distribution Limits
Public
Copyright
Other
Keywords
Sensor Microwave Imager (SSM/I)carbon cycle
remote sensingborealarcticgrowing seasonfreeze-thawnet primary productsSpecial

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