Global Climate Anomalies and its Influence on the Mass Balance of the Antarctic Ice Sheet

Abstract:

Nominal mass change patterns in the Antarctic Ice Sheet (AIS) are altered by climate anomalies such as those associated with El Niño Southern Oscillation (ENSO) locally with time to time. Alternating ENSO warm and ENSO cold conditions alter moisture transport and precipitation in and around AIS. Southern Oscillation Index (SOI) being a robust representation of the ENSO phenomenon is used to evaluate its characteristics. A combined analysis of surface mass and elevation changes using data from the GRACE and Envisat satellite missions signal between 08/2002 and 10/2010 shows a considerable delay in the occurrence of anomaly associated with ENSO between Dronning Maud Land (DML) and Pine Island Glacier (PIG) region. Further analysis reveals a sub 4-year periodic signal that accounts for almost 15 – 30% of the time variability in the filtered and detrended surface mass and elevation data. Processing the surface mass data up to 07/2016 represents anomalies with a periodicity of about 4 – 6 years is found to circle the AIS in about 8 – 10 years. These findings are in coherence with the properties of anomalies associated with the Antarctic Circumpolar Wave (ACW) which is known to affect several key climate variables, including precipitation, surface pressure, sea surface temperature, etc. It suggests that variability in the surface mass balance (SMB) of the AIS may also be modulated by the ACW. Elevation changes time series from the firn compaction (FC) model using inputs from the regional climate model (RACMO2.3p2) too support our findings. Long term analysis of these time series will give key insights into the interdecadal changes associated with ACW and its characteristics. Proper understanding of the ACW and its interconnections with ENSO will help us make future estimates of mass change due to global climate anomalies.