Satellite derived products vs Webcam derived data

In these comparisons, FSC (SCE) and binary snow cover values from satellite derived snow products are compared with FSC values derived from webcam images, which are available in the operational monitoring processing chains. Webcam derived data is fetched from the FMIPROT Download data API. "Snow cover fraction" parameter is calculated are included in the comparison. Temporal extent and the data producing algorithm can be selected using the dialog below.

If the satellite product already provides binary snow cover information, class values are converted to 0 and 100 before the categorization, i.e. there are always only two categories for those products.

If the webcam derived data contains ROI Geolocation information, ROI is used for the selection of satellite product pixels. If ROI is not provided, camera location is used. For the "Point" type ROIs and camera locations, single pixel which corresponds to that point is used for each webcam derived data point. For the "Polygon" type ROIs, all the pixels whom their cell area intersects with the ROI are used, for each webcam derived data point.

After collecting all data pairs, their median value for each day and camera location (all the points in ROI together) are calculated. Invalid values (nan, cloud, dark etc.) are discarded. "N points" in the plots corresponds to the number of data pairs for those each location for each day. "N days" in maps correspond to the number of days which has valid data for each location.

RMSE Maps show RMSE values calculated from all the (daily median) data pairs for each location. RMSE from 0 to 100 is colored from green to red. Scatter Plots show daily value (median) pairs for each location. Different locations are colored differently.

Maps and plots will only be visible if there is any valid data in comparison. For example, there may be no valid data in winter days due to the camera data corresponds to the low sun zenith angle (polar night) pixels.

From the listed products, "EUMETSAT HSAF H34" and "EUMETSAT HSAF H43" are binary snow cover products, i.e. only 0% and 100% values are presented in the comparison. Please consider that when choosing comparison options.

After the RMSE map is drawn, scatter plot for a location can be drawn by clicking on it on the map.

Comparison options

Satellite product:	Copernicus HRSI Pan-EU 20m Copernicus HRSI Pan-EU Gap-Filled 60m Copernicus SCE NH 1km Copernicus SCE Pan-EU 500m EUMETSAT HSAF H12 EUMETSAT HSAF H34 EUMETSAT HSAF H35 EUMETSAT HSAF H43
Webcam algorithm:	All
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Contingency matrix cat.:	2 3 4 5 6 7 8 9 10
Category ranges:	Min. (incl.) Max. (excl.)
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> Link to the product's official web page

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