 |
| Titel |
Validation of MODIS snow cover images over Austria |
| VerfasserIn |
J. Parajka, G. Blöschl |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 10, no. 5 ; Nr. 10, no. 5 (2006-09-27), S.679-689 |
| Datensatznummer |
250008193
|
| Publikation (Nr.) |
 copernicus.org/hess-10-679-2006.pdf |
|
|
|
|
|
| Zusammenfassung |
| This study evaluates the Moderate Resolution Imaging Spectroradiometer
(MODIS) snow cover product over the territory of Austria. The aims are (a)
to analyse the spatial and temporal variability of the MODIS snow product
classes, (b) to examine the accuracy of the MODIS snow product against in
situ snow depth data, and (c) to identify the main factors that may influence
the MODIS classification accuracy. We use daily MODIS grid maps (version 4)
and daily snow depth measurements at 754 climate stations in the period from
February 2000 to December 2005. The results indicate that, on average,
clouds obscured 63% of Austria, which may significantly restrict the
applicability of the MODIS snow cover images to hydrological modelling. On
cloud-free days, however, the classification accuracy is very good with an
average of 95%. There is no consistent relationship between the
classification errors and dominant land cover type and local topographical
variability but there are clear seasonal patterns to the errors. In December
and January the errors are around 15% while in summer they are less than
1%. This seasonal pattern is related to the overall percentage of snow
cover in Austria, although in spring, when there is a well developed snow
pack, errors tend to be smaller than they are in early winter for the same
overall percent snow cover. Overestimation and underestimation errors
balance during most of the year which indicates little bias. In November and
December, however, there appears to exist a tendency for overestimation.
Part of the errors may be related to the temporal shift between the in situ snow
depth measurements (07:00 a.m.) and the MODIS acquisition time (early
afternoon). The comparison of daily air temperature maps with MODIS snow
cover images indicates that almost all MODIS overestimation errors are
caused by the misclassification of cirrus clouds as snow. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|