Basal melting of Antarctics ice shelves in Amundsen and Bellingshausen seas

Abstract

West Antarctic ice shelves in the Amundsen and Bellingshausen seas are losing mass from basal melting. This is caused by the intrusion of circumpolar deep water underneath the ice shelves. The mechanisms driving circumpolar deep water towards the Western Antarctic ice shelves are still not fully understood. I will present time series (for the years from 2003 to 2023) of basal melt rate for the ice shelves in Amundsen and Bellingshausen seas along with time series for the upper end of Antarctic bottom water layer from underneath ice shelves. From these two data sets, we want to quantify the mass loss from the ice shelves and see how the freshwater flux that results from it will affect the volume of Antarctic bottom water. Our work requires estimating ice shelf height change from 2003 to 2023 in two different reference frames: Lagrangian and Eulerian from differential equations of height change where we can incorporate satellite observations of ice elevation. From the differential equation of Lagrangian reference frame, we determine the characteristics of ice flow of the ice shelf. This will help us to highlight the contribution of basal melt rate to the ice shelf height change. The height change from Eulerian reference frame will be used in a formula that produces a time series of basal melt rate. This time series will show the differences between the basal melt rate in the Eulerian reference frame and the steady state in the Lagrangian frame. For the Lagrangian ice shelf height where the ice shelf height is equal to ice elevation data from satellite altimetry minus ocean height data, we will create a unique data set of ocean surface height containing data produced by Southern Ocean State Estimate (SOSE) general circulation model where the data shows the distribution of water properties to a high depth.  This can be used to evaluate the ocean heat content. With this dataset, we aim to determine how many times the circumpolar deep water travels from the Antarctic circumpolar current to the ice shelves in the Amundsen and Bellingshausen seas (in the years between 2003 and 2023). We also want to ascertain whether changes in the distribution of water layers beneath the ice shelves contribute to propelling the circumpolar deep water closer to the surface. This could potentially aid in the improvement of ice shelf models by incorporating a function that represents the effect of ocean thermal forcing on ice shelves.