Bedrock outcropping in the accumulation zone of the largest glacier in Mexico(Glaciar Norte of Citlaltépetl),as evidence of a possible accelerated extinction  

作　　者：SOTO Víctor 

机构地区：[1]Colegio de Geografía,Facultad de Economía,Universidad Veracruzana,Av.Xalapa s/n,Obrero Campesina,91020,Xalapa,Ver.,México

出　　处：《Journal of Mountain Science》2023年第2期338-354,共17页山地科学学报（英文）

摘　　要：The highest volcano in Mexico,at the same time the third largest mountain in North America(Citlaltépetl,5610 m a.s.l.),is home to the largest glacier in the country.Because of the extinction of the Popocatépetl glacier(5500 m a.s.l.)caused by eruptive activity,and the almost disappearance of the Iztaccíhuatl glaciers(5220 m a.s.l.)due to the lower elevation of the mountain,the Glaciar Norte of Citlatépetl has been the only glacier that has shown a certain degree of stability as a response to the altitude in which it is located.However,as occurs in almost all glaciers on the planet,the retreat of its glacier terminus has been continuous.Furthermore,during the last years the thickness of its upper part began to decrease rapidly until its bedrock was exposed for the first time in 2019.Due to its ecosystem importance and because it is the main glacier in Mexico,as well as the only one in the world located at latitude 19°N,in this work its current dimensions are updated,as well as the local climatology that governs the current state of the glacier is pointed out.The study was based on the analysis of high-resolution Sentinel-2 optical images,as well as through Sentinel-1 SAR images,with the support of climatological information from the study area.Therefore,the outcropping of the bedrock in the accumulation zone and the consequent horizontal retreat of the upper part of the glacier are documented;at the same time,the decrease in the thickness of the ice along it is noted.The rocky outcrop in the accumulation zone suggests that the flow dynamics of the ice towards the ablation zone will be considerably less,accelerating the retreat of the glacier terminus.Finally,the ascent of the glacial front to 5102 m a.s.l.and the modelled altitude of the equilibrium line to 5276 m a.s.l.are reported as a warning signal in terms of snow catchment and mass balance;likewise,the decrease of 23%of its surface is also indicated regarding the surface reduction monitoring that has been done until 2017.These findings may indicate that

关 键 词：Bedrock outcrop Citlaltépetl glacier Glacial accumulation zone Glacier retreat Glacial thickness 

分 类 号：P343.6[天文地球—水文科学]