Observations of Winter Ablation on Glaciers in the Mount Everest Region in 2020–2021

Mauri Pelto,Jon Maurer,L Baker Perry,Tom Matthews,Prajjwal Panday

doi:10.3390/rs13142692

Mauri Pelto, Jon Maurer + Show 3 more

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https://doi.org/10.3390/rs13142692

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Abstract

Recent observations of rising snow lines and reduced snow-covered areas on glaciers during the October 2020–January 2021 period in the Nepal–China region of Mount Everest in Landsat and Sentinel imagery highlight observations that significant ablation has occurred in recent years on many Himalayan glaciers in the post-monsoon and early winter periods. For the first time, we now have weather stations providing real-time data in the Mount Everest region that may sufficiently transect the post-monsoon snow line elevation region. These sensors have been placed by the Rolex National Geographic Perpetual Planet expedition. Combining in situ weather records and remote sensing data provides a unique opportunity to examine the impact of the warm and dry conditions during the 2020 post-monsoon period through to the 2020/2021 winter on glaciers in the Mount Everest region. The ablation season extended through January 2021. Winter (DJF) ERA5 reanalysis temperature reconstructions for Everest Base Camp (5315 m) for the 1950–February 2021 period indicate that six days in the January 10–15 period in 2021 fell in the top 1% of all winter days since 1950, with January 13, January 14, and January 12, being the first, second, and third warmest winter days in the 72-year period. This has also led to the highest freezing levels in winter for the 1950–2021 period, with the January 12–14 period being the only period in winter with a freezing level above 6000 m.

Highlights

A six-decade-long mass record of glaciers in the Mount Everest region compiled by [1]found increasingly negative balances each decade, with thinning evident at an elevation up to 6000 m
The mass balance loss has been driven by increased summer ablation and rising freezing levels during the summer monsoon [2,3]
A prolonged period of warm dry weather extended from the post-monsoon season of 2020 into late January of 2021 in regions of Mount Everest

Summary

Introduction

A six-decade-long mass record of glaciers in the Mount Everest region compiled by [1]found increasingly negative balances each decade, with thinning evident at an elevation up to 6000 m. A six-decade-long mass record of glaciers in the Mount Everest region compiled by [1]. The mass balance loss has been driven by increased summer ablation and rising freezing levels during the summer monsoon [2,3]. The higher freezing line during the summer monsoon identifies that the elevation where frozen precipitation predominates in the area has risen to 5400 m [4]. The summer monsoon period is the period with the highest melt rates at lower elevations on the glaciers. October has been considered the end of the melt season in the region, with little precipitation in the post-monsoon and early winter season (October–December), averaging ~3% of the total annual precipitation [4]. Ablation was observed in winter on the Mera Glacier at all elevations due to wind erosion and sublimation [5]

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