Towards an enhanced method to map snow cover areas and derive snow-water equivalent in Lebanon

- Combination of Terra and Aqua MODIS to generate a cloud free product named TAC.
- Calculation of snow days per year from the snow covers dataset in Lebanon.
- Identification of spatial and temporal variability of snow in Lebanon.
- Combination of TAC and AMSR-E product in order to downscale the SWE derived from AMSR-E to sub-pixel resolution of 500 m.
- Identification of SWE values across Lebanon between 2002 and 2011.

SummarySnow cover contributes to the definition of the hydrologic system of most River Basins in Lebanon. Despite its importance little is known about the proper quantification of snow cover extent and snow water equivalent (SWE), as well as the snow contribution to the hydrologic budget at the national scale. By taking advantage of the moderate-resolution optical sensors (MODIS) from both Terra and Aqua satellites it was possible to generate enhanced, eight-days, Terra-Aqua Combined (TAC) product set at a spatial resolution of 500 m. An innovative method that combines the AMSR-E SWE data (∼25 km spatial resolution) and the enhanced TAC dataset was developed to derive a SWE product at a sub-pixel spatial resolution of 500 m. Both the enhanced TAC and the downscaled SWE were developed for the entire Lebanon. The enhanced TAC dataset was found to reduce cloud cover area by ∼13% when compared to the original MOD10A2 dataset. Snow cover area was validated against ETM+ data and the SWE was assessed against in situ measurements; the overall accuracy of the snow cover maps was ∼85%, whereas, the comparison between ground points measured and remotely sensed derived SWE indicates a poor correlation. This study concluded that while the use of TAC is well suited for the assessment of snow cover extent nationwide, the derived SWE from AMSR-E is not fully deployable in Lebanon. Meanwhile, a snow melt method that takes advantage from the remotely sensed SWE is needed to better achieve results suitable for hydrologic studies.