Spatiotemporal variations and comparative analysis of snow cover at typical mid to high latitudes mountain ranges in the Northern Hemisphere from 2002 to 2021
Snow cover is an essential component of the cryosphere,and it has low thermal conductivity,high re-flectivity,and large latent heat of melting,playing an important role in the energy balance process of the Earth.There are significant spatial differences in the response of snow cover to climate change.Snow cover is widely distributed in mid to high latitudes mountainous areas in the Northern Hemisphere,and spatiotemporal variations in mountainous snow cover have important implications for human life,the economy,and ecosystems.The Al-tai,the Alps and the Cascade Mountains are respectively one of the most important mountains in Asia,Europe and North America.The three mountains are located in the mid to high latitudes of the Northern Hemisphere,with rich snow resources.The three mountains are the only three typical mountain ranges in the mid to high lati-tudes of the Northern Hemisphere that can be horizontally compared.Based on daily snow cover products from MODIS,four snow cover parameters of the Altai,the Alps and the Cascade Mountains after cloud removal pro-cessing were obtained,including snow cover fraction(SCF),snow cover duration(SCD),snow onset day(SOD),and snow end day(SED).A comparative analysis was conducted on the spatiotemporal distribution and trend of snow cover parameters in three mountain ranges from 2002 to 2021,and the impact of climate fac-tors on snow cover parameters was studied using satellite and reanalysis data.The results indicate that:(1)The spatial distribution differences in snow parameters among the three mountain ranges are evident and closely relat-ed to elevation.The Altai Mountains exhibit the maximum snow cover fraction,the longest snow cover dura-tion,the earliest snow onset day and the latest snow end day,which are 38.00%,141 days,66 days,and 207 days respectively.The Alps has intermediate values for snow cover parameters.The snow cover fraction,snow cover duration,snow onset day and snow end day in the Alps are 21.68%,79 days,97 days,and 194 days re-spectively.The Cascade Mountains show the minimum snow cover fraction,the shortest snow cover duration,the latest snow onset day and the earliest snow end day,which are 15.18%,56 days,103 days,and 183 days re-spectively.(2)In terms of trends,snow cover fraction increases in the Altai Mountains,with earlier snow onset and later snowmelt leading to an increase in snow cover duration.Conversely,the Alps experience a reduction in snow cover fraction due to earlier snowmelt,resulting in a decrease in snow cover duration.The Cascade Mountains exhibit an increase in snow cover fraction,with later snowmelt contributing to an increase in snow cover duration.(3)The land surface temperature and precipitation in the three mountain ranges are increasing.The land surface temperature and precipitation have a greater impact on snow cover fraction and snow cover dura-tion of the three mountains.The correlation coefficient between land surface temperature and snow onset day,and the correlation coefficient between precipitation and snow onset day and snow end day are relatively smaller.Temperature has a greater impact on snow cover parameters in the three mountain ranges compared to precipita-tion.
snow coverAltai MountainsAlps MountainsCascade MountainsMODISspatiotemporal vari-ationsanalysis of trends
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