Validation of MODIS snow cover images over Austria
Open Access
- 27 September 2006
- journal article
- Published by Copernicus GmbH in Hydrology and Earth System Sciences
- Vol. 10 (5), 679-689
- https://doi.org/10.5194/hess-10-679-2006
Abstract
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.Keywords
This publication has 15 references indexed in Scilit:
- Updating a Land Surface Model with MODIS-Derived Snow CoverJournal of Hydrometeorology, 2004
- Validation of daily MODIS snow cover maps of the Upper Rio Grande River Basin for the 2000–2001 snow yearRemote Sensing of Environment, 2003
- Advances in the use of observed spatial patterns of catchment hydrological responseAdvances in Water Resources, 2002
- Evaluation of the snow‐covered area data product from MODISHydrological Processes, 2002
- An assessment of the differences between three satellite snow cover mapping techniquesHydrological Processes, 2002
- Satellite-derived snow cover maps for north America: Accuracy assessmentAdvances in Space Research, 2002
- MODIS snow-cover productsRemote Sensing of Environment, 2002
- Assessment of Snow-Cover Mapping Accuracy in a Variety of Vegetation-Cover Densities in Central AlaskaRemote Sensing of Environment, 1998
- Prelaunch characteristics of the Moderate Resolution Imaging Spectroradiometer (MODIS) on EOS-AM1IEEE Transactions on Geoscience and Remote Sensing, 1998
- Distributed Snowmelt Simulations in an Alpine Catchment: 1. Model Evaluation on the Basis of Snow Cover PatternsWater Resources Research, 1991