An examination of the precipitation delivery mechanisms for Dolleman Island, eastern Antarctic Peninsula

Russell, Andrew; McGregor, Glenn R.; Marshall, Gareth J. ORCID: 2004 An examination of the precipitation delivery mechanisms for Dolleman Island, eastern Antarctic Peninsula. Tellus, 56A, No.5. 501-513.

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The variability of size and source of significant precipitation events were studied at an Antarctic ice core drilling site: Dolleman Island (DI). located on the eastern coast of the Antarctic Peninsula. Significant precipitation events that occur at DI were temporally located in the European Centre for Medium-Range Weather Forecasting (ECMWF) reanalysis data set, ERA-40. The annual and summer precipitation totals from ERA-40 at DI both show significant increases over the reanalysis period. Three-dimensional backwards air parcel trajectories were then run for 5 d using the ECMWF ERA-15 wind fields. Cluster analyses were performed on two sets of these backwards trajectories: all days in the range 1979-1992 (the climatological time-scale) and a subset of days when a significant precipitation event occurred. The principal air mass sources and delivery mechanisms were found to be the Weddell Sea via lee cyclogenesis, the South Atlantic when there was a weak circumpolar trough (CPT) and the South Pacific when the CPT was deep. The occurrence of precipitation bearing air masses arriving via a strong CPT was found to have a significant correlation with the southern annular mode (SAM); however, the arrival of air masses from the same region over the climatological time-scale showed no such correlation. Despite the dominance in both groups of back trajectories of the westerly circulation around Antarctica, some other key patterns were identified. Most notably there was a higher frequency Of lee cyclogenesis events in the significant precipitation trajectories compared to the climatological time-scale. There was also a tendency for precipitation trajectories to come from more northerly latitudes, mostly from 50-70degreesS. The El Nino Southern Oscillation (ENSO) was found to have a strong influence on the mechanism by which the precipitation was delivered: the frequency of occurrence of precipitation from the east (west) of DI increased during El Nino (La Nina) events.

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Antarctic Climate Processes
ISSN: 0280-6495
NORA Subject Terms: Meteorology and Climatology
Date made live: 25 Jan 2012 11:43 +0 (UTC)

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