Hydrology and Earth System Sciences
www.hydrol-earth-syst-sci.net
1027-5606
1607-7938
11
4
2007
10.5194/hess-11-1353-2007
http://www.hydrol-earth-syst-sci.net/11/1353/2007/
http://www.hydrol-earth-syst-sci.net/11/1353/2007/hess-11-1353-2007.html
http://www.hydrol-earth-syst-sci.net/11/1353/2007/hess-11-1353-2007.pdf
1353
1360
2007-05-22
Commentary on comparison of MODIS snow cover and albedo products with ground observations over the mountainous terrain of Turkey
A. Ü. Şorman
sorman@metu.edu.tr
Z. Akyürek
A. Şensoy
A. A. Şorman
A. E. Tekeli
Department of Civil Engineering, Middle East Technical University, Ankara, Turkey
Department of Civil Engineering, Anadolu University, Eskisehir, Turkey
Remote Sensing Division, Turkish State Meteorological Service, Ankara, Turkey
The MODerate-resolution Imaging Spectroradiometer (MODIS) snow cover product
was evaluated by Parajka and Blösch (2006) over the territory of
Austria. The spatial and temporal variability of the MODIS snow product
classes are analyzed, the accuracy of the MODIS snow product against
numerous in situ snow depth data are examined and the main factors that may
influence the MODIS classification accuracy are identified in their studies.
The authors of this paper would like to provide more discussion to the
scientific community on the "Validation of MODIS snow cover images" when
similar methodology is applied to mountainous regions covered with abundant
snow but with limited number of ground survey and automated stations.
<br><br>
Daily snow cover maps obtained from MODIS images are compared with ground
observations in mountainous terrain of Turkey for the winter season of
2002–2003 and 2003–2004 during the accumulation and ablation periods of
snow. Snow depth and density values are recorded to determine snow water
equivalent (SWE) values at 19 points in and around the study area in Turkey.
Comparison of snow maps with in situ data show good agreement with overall
accuracies in between 62 to 82 percent considering a 2-day shift during
cloudy days. Studies show that the snow cover extent can be used for
forecasting of runoff hydrographs resulting mostly from snowmelt for a mountainous basin in Turkey.
<br><br>
MODIS-Terra snow albedo products are also compared with ground based
measurements over the ablation stage of 2004 using the automated weather
operating stations (AWOS) records at fixed locations as well as from the
temporally assessed measuring sites during the passage of the satellite.
Temporarily assessed 20 ground measurement sites are randomly distributed
around one of the AWOS stations and both MODIS and ground data were
aggregated in GIS for analysis. Reduction in albedo is noticed as snow depth
decreased and SWE values increased.
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