Surface mass balance and energy balance of the 79N Glacier (Nioghalvfjerdsfjorden, NE Greenland) modeled by linking COSIPY and Polar WRF

M T Blau,J V Turton,T Mölg,T Sauter

doi:10.1017/jog.2021.56

Abstract

AbstractTo get a better overview of atmosphere-driven mass changes at the 79N Glacier (Nioghalvfjerdsfjorden Glacier), the largest outlet glacier of the northeast Greenland ice stream, the surface mass balance (SMB) is modeled by linking the COupled Snowpack and Ice surface energy and mass-balance model in PYthon (COSIPY) with the output of a regional atmospheric model (Polar WRF) for the years 2014–2018. After a manual model optimization, the model produces reliable results when compared to observations in the region and to values from the literature. High spatial resolution (1 km) simulations reveal strong interannual variability of the SMB. Stronger surface melting increased the ablation and runoff in years with high mass loss (2016 and 2017) whereas in other years (2015 and 2018) melting and refreezing inside the snowpack dominated the mass balance (MB). A cooler regional climate with higher snowfall-driven accumulation, higher albedo and reduced surface melt in the ablation period of 2018 resulted in a positive SMB in 2018, however, the annual total MB remained negative. The results suggest a promising new dataset for gaining more insights into mass-balance processes and their contribution to the acceleration of glacier retreat in northeast Greenland.

Highlights

The northeast Greenland ice stream (NEGIS) covers an area of ∼200 000 km2 of the Greenland ice sheet (GrIS) and drains through three marine-terminating outlet glaciers (Fig. 1)
The inland extent of the glacier is difficult to outline, as it joins with Zachariae Isstrøm (ZI) and Storstrømmen Glaciers to become the NEGIS
COSIPY-weather research and forecasting (WRF) simulates the observed conditions at both automatic weather stations (AWSs) well in the optimization period

Summary

Introduction

The northeast Greenland ice stream (NEGIS) covers an area of ∼200 000 km of the Greenland ice sheet (GrIS) and drains through three marine-terminating outlet glaciers (Fig. 1). Together, those drain ∼12% of the GrIS (Fig. 1a; Mayer and others, 2018). The floating tongue of the 79N Glacier directly connects the GrIS to the Atlantic Ocean (Schaffer and others, 2017). It is ∼8 km wide at the grounding line and extends ∼80 km long into the Nioghalvfjerds fjord. The glacier outlines can be approximately determined by the high ice velocity compared to the surrounding ice sheet (Fig. 1b; Krieger and others, 2020)

Objectives

Results

Conclusion