Three-decade spatial patterns in surface mass balance of the Nivlisen Ice Shelf, central Dronning Maud Land, East Antarctica

Bhanu Pratap,Meloth Thamban,Katrin Lindbäck,Kenichi Matsuoka,Geir Moholdt,Rahul Dey,C M Laluraj,Vikram Goel

doi:10.1017/jog.2021.93

Bhanu Pratap, Meloth Thamban + Show 6 more

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https://doi.org/10.1017/jog.2021.93

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Abstract

AbstractThe coastal Droning Maud Land in East Antarctica is characterized by small ice shelves with numbers of promontories and locally grounded isles, both called ice rises. These ice rises are typically dome-shaped and surface elevations are hundreds of meters above the surrounding ice shelves, which cause strong orographic effects on surface mass balance (SMB). We conducted shallow ice-penetrating radar sounding to visualize firn stratigraphy in the top 35 m over ~400 km of profiles across the Nivlisen Ice Shelf, and in a grid pattern over two adjacent ice rises (Djupranen and Leningradkollen). We tracked six reflectors (isochrones) and dated them using two ice cores taken at the ice rise summits, from which SMB over six periods in the past three decades was retrieved. The overall SMB pattern across the ice shelf remained similar for all periods; however, the eastwest contrast in SMB varies by a factor of 1.5–2 between the Leningradkollen and Djupranen grounding lines. The SMB patterns over the ice rises are more varied owing to complex interactions between topography, snowfall and wind. We use our results to evaluate the regional climate model RACMO2.3p2 in terms of the spatial SMB distribution and temporal changes over the ice shelf and ice rises at regional scale.

Highlights

Antarctic mass balance is challenging to measure and predict, which directly impacts current estimates of sea-level rise and future projections (Fürst and others, 2016; IMBIE team, 2018; Lenaerts and others, 2019)
We carried out ground-penetrating radar (GPR) and Global Navigation Satellite System (GNSS) surveys to measure spatial variations in surface mass balance (SMB) over the last three decades and ice topography of the Nivlisen Ice Shelf and the adjacent two ice rises
We found that the surface was smooth on the eastern windward side, whereas it was rough on the western leeward side

Summary

Introduction

Antarctic mass balance is challenging to measure and predict, which directly impacts current estimates of sea-level rise and future projections (Fürst and others, 2016; IMBIE team, 2018; Lenaerts and others, 2019). In the Antarctic coastal regions, ice–ocean interactions, surface mass balance (SMB) and buttressing from locally grounded ice rises and rumples all affect ice shelf mass balance, which has a major control on mass discharge from the ice sheet through the grounding line (Matsuoka and others, 2015). SMB is often estimated using regional climate models or satellite observations of passive microwave, which have a spatial resolution of tens of kilometers in most cases (Lenaerts and others, 2017; van Wessem and others, 2018). This is not sufficient to capture the finer scale topography of ice rises and rumples which induce considerable local variations in SMB (Lenaerts and others, 2014; Wang and others, 2016; Kausch and others, 2020). Detailed observational constraints are necessary in order to evaluate and improve regional climate models

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