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The West Antarctic Ice Sheet (WAIS) contains an ice-volumetric equivalent of roughly 4.3 m. To understand its role in sea-level rise projections, we must understand the climate mechanisms that influence its surface mass balance (SMB). Previous work highlights temperature-related trends and the roles of the El Niño Southern Oscillation (ENSO) and the Southern Annular Mode. Recent studies have also emphasized changes in ice sheet mass due to precipitation variability. Thus, we turn our focus to interannual variability of precipitation associated with tropical Rossby waves originating in the central Pacific and Indian Oceans. Using SMB measurements from 39 WAIS ice cores from 1851-2010, a k-means clustering algorithm with k = 2 separated cores along a topographic ridgeline into East and West sectors. Each sector had oppositely signed mean SMB trends, which were then removed to focus on year-to-year variations. Each sector featured three high SMB months that were identified by correlating NOAA-CIRES-DOE Twentieth Century Reanalysis Version 3 data with core SMB. Analyzing composite convection, geopotential height, and wave activity flux revealed tropical Rossby wave source regions that produced anomalous WAIS SMB. The primary drivers of West SMB were ENSO and the nonuniformity in the phase distribution of the Madden-Julian Oscillation (MJO). East SMB drivers were shifted further west and featured dipole convection patterns flanking the Maritime Continent and eastern Indian Ocean. Analysis of the role of cyclones and an offshore ridge pattern corresponding to high SMB is presented. Preliminary results are presented from related boundary forcing experiments based on observational results.
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This content will become publicly available on May 28, 2027
Tropical Controls on West Antarctic Ice Sheet Surface Mass Balance Interannual Variability in the Twentieth Century
Abstract The West Antarctic Ice Sheet (WAIS) contains an ice volumetric equivalent of 5.3 m of global mean sea‐level rise. Understanding the climate mechanisms that influence WAIS surface mass balance (SMB) can help reduce uncertainties in sea‐level rise projections. Previous work has focused on trends related to temperature and the roles of well‐known climate phenomena in the Pacific sector, including the El Niño Southern Oscillation (ENSO) and the Southern Annular Mode. Here, the focus is on interannual variability of precipitation associated with Rossby wave trains emanating from tropical convection regions in the Indian Ocean and the central tropical Pacific. Objective clustering of SMB measurements from 25 WAIS ice and firn cores from 1900 through 1999 indicated oppositely signed mean SMB trends in the East and West sectors of WAIS, and these trends were removed to focus on year‐to‐year variations. Climatically important months for each sector were identified by correlating reanalysis precipitation with ice core SMB. Tropical Rossby wave source regions that produced anomalous WAIS SMB were identified by analyzing composite convection, geopotential height, and wave activity flux. East WAIS SMB variability was controlled by anomalously low geopotential height over the Ross and Amundsen Seas. West WAIS SMB variability was driven by ENSO and non‐uniformity in the phase distribution of the Madden‐Julian Oscillation. These results provide a deeper understanding of the drivers of WAIS SMB variability and may improve projections of future sea‐level rise.
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- Award ID(s):
- 2337486
- PAR ID:
- 10691626
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 131
- Issue:
- 11
- ISSN:
- 2169-897X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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