There is almost no snow in the High Atlas mountains now.

Image captured on 2020-Mar-04 by Terra/MODIS (corrected reflectance in false color composite: Red = Band 7, Green = Band 2, Blue = Band 1). The snow appears in light blue.

Even in the Toubkal massif which culminates at 4167 m above sea level is almost clear of snow.

2020-02-26, Sentinel-2A L1C, True color

However, the snow cover area is known to be highly variable in the High Atlas (Marchane et al. 2015; Baba et al. 2018). How does it compare to previous years?

The MODIS archive provides daily images since 2000. I selected one image with low cloud cover in early March for each year.

Time series of Terra/MODIS images. All images were acquired between 03 and 09 March.

Then I extracted the normalized snow difference index (NDSI) from the corresponding MOD10A1 product to compute the snow cover extent over this region (pixels where NDSI>0.2).

Time series of Terra/MODIS NDSI for the same dates (snow cover area in parenthesis)

This analysis shows that the snow cover area in early March 2020 (113 km²) is significantly lower than the previous worst year on record (325 km² in 2000).

 

This low snowpack is very bad news for the people in the Haouz region where lakes and rivers are already dry due to the low precipitation in the past two years. In normal years, snow melt runoff sustains the river discharge and replenish the reservoirs in spring.

References

  • Marchane A., Jarlan L., Hanich L., Boudhar A., Gascoin S., Tavernier A., Filali N., Le Page M., Hagolle O., Berjamy B., (2015) Assessment of daily MODIS snow cover products to monitor snow cover dynamics over the Moroccan Atlas Mountain range, Remote Sensing of the Environment, 160, 72-86, doi:10.1016/j.rse.2015.01.002
  • Baba, M. W., S. Gascoin, L. Jarlan, V. Simonneaux, L. Hanich (2018), Variations of the snow water equivalent in the Ourika catchment (Morocco) over 2000-2018 using downscaled MERRA-2 data, Water, 10(9), 1120, doi:10.3390/w10091120.

High Atlas Snow Monitor

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