Tuesday, 30 April 2013
North/West Room (Renaissance Seattle Hotel)
Recent studies have noted an asymmetrical climate change across Antarctica, with significant warming in West Antarctica and the Antarctica Peninsula, and primarily insignificant trends in East Antarctica. Due to its proximity, variations in the position and intensity of the Amundsen-Bellingshausen Seas Low (ABSL) are a suspected atmospheric mechanism. The ABSL has a known climatological seasonal cycle in its location, being further north and east during austral summer and farther south and west, towards the Ross Sea, in austral winter. Here, multiple National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM) 3.0 Atmospheric Model Intercomparsion Project (AMIP) simulations are compared against reanalysis data in order to understand how well the ABSL is depicted. Specifically, the mean characteristics of the model's pressure variability in the South Pacific are compared to reanalysis data to investigate if the same seasonal cycles in pressure and location of the ABSL are observed. The primary focus is on the sensitivity of the model resolution (both T45 and T85) and the initial and boundary conditions (through multiple ensemble simulations and/or different sea surface temperature conditions) in representing the climatological ABSL features, as well as their interannual variability and overall range. Analyzing these sensitivities helps to provide a more clear understanding of the relative roles of local topographic forcing vs. remote forcing from the tropics on the ABSL climatological and interannual variations.
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