Abstrakt
This study evaluates MODIS snow cover characteristics for large number of snowmelt runoff events in 145 catchments from 9 countries in Europe. The analysis is based on open discharge daily time series from the Global Runoff Data Center database and daily MODIS snow cover data.
Runoff events are identified by a base flow separation approach. The MODIS snow cover characteristics are derived from Terra 500m observations (MOD10A1 dataset, V005) in the period 2000-2015 and include snow cover area, cloud coverage, regional snowline elevation (RSLE) and its changes during the snowmelt runoff events.
The snowmelt events are identified by using estimated RSLE changes during a runoff event. The results indicate that in the majority of catchments there are between 3 and 6 snowmelt runoff events per year.
The proportion of snowmelt events in all runoff events tends to increase with the maximum elevation of catchments and the mean duration between the beginning and peak of snowmelt runoff events is about 3 days. Clouds limit the estimation of snow cover area and RSLE, particularly for dates of runoff peaks.
In most of the catchments, the median of cloud coverage during runoff peaks is larger than 80%. The evaluation of RSLE changes shows that the mean minimum snow cover elevation is situated approximately in the mean catchment elevation.
It means that snowmelt events do not start only during maximum snow cover conditions, but also after this maximum. The mean RSLE during snowmelt peaks is on average 170m lower than at the start of the snowmelt events, but the change differs regionally.