www.elsevier.com/locate/sna Application of the NASA Scatterometer (NSCAT) for Determining the Daily Frozen

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.470.4324; http://secure.ntsg.umt.edu/publications/2001/KMKFR01/rse75_01.pdf

The seasonal transition of the land surface between fro- spring were also generally consistent with seasonal in-zen and nonfrozen conditions affects a number of terres- creases in river discharge for five major Alaska basins. trial processes that cycle between wintertime dormant The NSCAT sensor appears to be responsive to changes and summertime active states. The relatively short (2.14 in dielectric properties associated with surface freeze/ cm) Ku-band of the space-borne NASA scatterometer thaw transitions over broad boreal and arctic landscapes. (NSCAT) is sensitive to changes in dielectric properties, Further study involving longer time-series information, associated with large-scale shifts in the relative abun- alternative radar wavelengths, and finer spatial scales is dance and phase (frozen or thawed) of canopy and sur- needed, however, to resolve the various components (i.e., face water. We used a temporal change detection analysis soil, vegetation, snow) of the regional radar freeze/thaw of NSCAT daily radar backscatter measurements to clas- signature for improved monitoring of the circumpolar sify surface freeze/thaw state across a 1.4 million km2 re- high latitudes. Ó Elsevier Science Inc., 2001 gion of Alaska from January to June 1997. In the spring, radar backscatter measurements showed pronounced de-conditions, which corresponded with sustained maximum