Characterization of the time dynamics of monthly satellite snow cover data on Mountain Chains in Lebanon

• Main Authors: Telesca, L., Shaban, A., Gascoin, S., Darwich, T., Drapeau, Laurent, El Hage, M., Faour, G.
• Format: Text
• Language: English
• Published: 2014
• Subjects: Snowpack; Satellite image; SSA; Periodogram; Lebanon; North Atlantic; North Atlantic oscillation
• Online Access: http://www.documentation.ird.fr/hor/fdi:010063690

In this study, the time dynamics of the monthly means of the snow cover have been on Lebanese Mountain Chains from 2000 to 2012, derived from the MODIS Aqua/Terra satellite snow products was analyzed. This represents the longest satellite-based snow cover time series produced for Lebanon so far. Field survey was also carried out over the last three years in order to measure the in-situ snow/water equivalent and depth in different localities. Analyzing the regime of the snow cover in Mount-Lebanon (Western Mountain Chains) region, it was found that: (i) snowmelt accounts for about 31% of the rivers and springs discharge in Lebanon; (ii) consecutive peaks in the snow cover time series, representing the change-point between accumulation phase and ablation phase are present in three different patterns (edged, non-edged and double peaked); (iii) the areal snow coverage has big diversity between different years; (iv) the annual periodicity represents the most statistically significant and predominant frequency of the series contributing for about the 40% of the total variance of the snow cover series; (v) the longterm trend, totally hidden by the more powerful yearly component and detected by using the singular spectrum analysis (SSA), accounts for about the 33% of the total variance of the series; (vi) the long-term trend shows an apparent cyclic behavior with an estimated period (interval between the two minima) of about nine years; (vii) the comparison of the long-term trend with the North Atlantic Oscillation (NAO) monthly index reveals that the minima in 2009-2010 of the SSA long-term component coincides with a persistent negative phase in the NAO Index.