Seasat, ERS-1/2 and NSCAT scatterometer observed changes on the large ice sheets

Abstract

-Satellite-borne wind scatterometers are effective tools for monitoing ice sheets and microwave imaging techniques enable comparison of historic and contemporary scatterometer data in climate change studies. We document scattering characteristics of the Greenland ice sheet using data from the NSCAT, ERS-112 and Seasat SASS instruments. C-and Ku-band data enable characterization of frequencydependent scattering characteristics and regional melting delineation. SASS-NSCAT differences show 18 year changes in dry-snow zone extent and indicate the decadal reponse to changes in the spatial patterns of accumulation and ablation.

Observation and characterization of radar backscatter over Greenland

“…Variations in the average backscatter have been used to estimate accumulation [3], [4], monitor melt and ablation [2], [6] and study long-term climate change [27], [28]. Using our model with the CGS assumption enables lower variance estimates of and increased temporal resolution compared with the methods used in these studies.…”

Greenland snow accumulation estimates from satellite radar scatterometer data

“…Enhanced resolution images from the 13.6 GHz (Ku band) Seasat A scatterometer system (SASS) [Long and Drinkwater, 1994], the 5.3 GHz (C band) ERS-1 and ERS-2 scatterometer [Drinkwater and Long, 1998], and the 13.6 GHz (Ku band) NASA scatterometer (NSCAT) [Long and Drinkwater, 1999] Long and Drinkwater, 1994]. Enhancing the resolution tends to increase the noise.…”

Large-scale inverse Ku-band backscatter modeling of sea ice

“…Assuming that the surface can be modeled as an ensemble of reflective facets with Gaussian slope distributions, a geometric optics solution can be used [27], [29] so that (4) where is the surface power reflection coefficient at nadir and is the rms surface slope.The geometric optics solution is derived under the assumption that the wavelength is significantly smaller than the typical roughness dimensions. At 14 GHz, the corresponding wavelength is approximately 2.1 cm.…”

“…Though the SASS mission was short, SASS data illustrated that Ku-band measurements are sensitive to the presence of sea ice and show valuable variations within the ice pack that relate to surface features [3]- [6]. Later, the Active Microwave Instrumentation (AMI) scatterometers aboard the European Remote Sensing 1 and 2 (ERS-1 and ERS-2) satellites demonstrated the value of C-band active scatterometer data in monitoring sea and glacial ice regions [4], [7], [8]. The National Aeronautics and Space Administration (NASA) Scatterometer (NSCAT) flew aboard the Advanced Earth Observation Satellite (ADEOS) platform from approximately August 1996 through June 1997.…”

“…The National Aeronautics and Space Administration (NASA) Scatterometer (NSCAT) flew aboard the Advanced Earth Observation Satellite (ADEOS) platform from approximately August 1996 through June 1997. Ku-band NSCAT data have been used in a number of cryosphere studies [4], [9]- [11]. When the NSCAT mission was prematurely terminated due to a solar panel failure, the NASA-built SeaWinds instrument aboard QuikSCAT filled the gap of active Ku-band data in mid-1999.…”