Snow Lapse Rate Changes in the Atlas Mountain in Morocco Based on MODIS Time Series during the Period 2000–2016

Ahmed Marchane,Lahoucine Hanich,Abdelghani Chehbouni,Mohammed Wassim Baba,Abdelghani Boudhar

doi:10.3390/rs13173370

Abstract

The spatio-temporal distribution of snow cover metrics in a mountainous area is mainly related to the climatic conditions as well as to the prevailing morphological conditions. The present study aimed to investigate the altitudinal sensitivity of snow cover metrics using the MODIS Terra snow cover product (MOD10A1 v5). Annual snow metrics, including start of snow season (SOSS), end of snow season (EOSS), and snow cover duration (SCD) were extracted from snow-covered area (SCA) maps, which had been pre-processed using a cloud removal algorithm; the maps were of the Atlas Mountains, taken from the period of 2001–2016. In addition, a linear regression was applied to derive an annual altitudinal gradient for each snow metric in relation to various spatial scales in order to analyze the interdependency between snow and topography, and especially to assess the potential temporal trend of the snow gradient. Results indicated that elevation was the principal regulator of snow presence where snow was mostly accumulated above 2500 m. The annual altitudinal gradients for EOSS and SCD showed a marked negative trend beginning in 2007. However, the SOSS altitudinal gradient was marked by a positive trend. The mean SCD gradient for the entire Atlas Mountains decreased from 6 days/100 m to 3 days/100 m. This is a new and important finding since it may indicate the impact of climate change on the dynamics of snow metrics and provides guidance for water managers to better manage the snowmelt water with different terrain features.

Highlights

Introduction published maps and institutional affilMeltwater issued from a snow-covered area is a significant component of the water balance in many of the world’s catchments [1]
The maximum snow cover is registered during the winter months (December, January, and February)
The evolution of fractional snow-covered area (fSCA) is Generally, snow season effectively at theis beginning of November and in elevation-dependent

Summary

Introduction

Meltwater issued from a snow-covered area is a significant component of the water balance in many of the world’s catchments [1]. Snow accumulation during the cold season presents a major source of fresh water during the melt period, in a mountainous region. It provides water for irrigation, aquifer recharges, and contributes to fill dams, which are important for agriculture and hydropower generation [2–4]. The runoff regime in the high-elevation catchments is highly dependent on snow cover, and snowmelt contribution is roughly estimated to be between 15% and 50% of the total annual discharge in the Tensift river sub-basins [5]. The runoff regime in the high-elevation catchments is highly dependent on snow cover, and snowmelt contribution is roughly estimated to be between 15% and 50% of the total annual discharge in the Tensift river sub-basins [5]. iations.

Objectives

Results

Conclusion