The Impact of Madden-Julian Oscillation on the Antarctic Atmosphere

The Impact of Madden-Julian Oscillation on the Antarctic Atmosphere

Authors: A. N. Lois¹, G. R. Henderson¹

¹Oceanography Dept., U.S. Naval Academy, Annapolis MD 21402

Intraseasonal tropical climate variability poses important implications on mid-latitude climate, and has been shown to contribute to various extreme events in the United States, including Arctic air outbreaks during the winter months across the central and eastern portions of the country. Recent studies have shown a strong relationship between the leading mode of tropical intraseasonal variability, the Madden-Julian Oscillation (MJO), and variability in the Arctic atmosphere. In such studies, the Northern Hemisphere extratropics have tended to lag the tropical MJO convection by approximately 7 days. Little is known, however, about the relationship and lag between the MJO and the Antarctic atmosphere. The goal of this paper is to consider how the MJO projects itself on the Antarctic mid-troposphere and subsequently surface state variables. Data used included the Wheeler and Hendon MJO Index, NASA MERRA 2 reanalysis data from 1982, and ERA Interim reanalysis data from 1979. Composite analysis of 500-hPa geopotential height fields was used to examine anomalies on an intraseasonal timescale. Preliminary results for the months of June and December for 500-hPa geopotential height fields, sea level pressure, and surface winds do show evidence of lagged intraseasonal modulation of the Antarctic atmosphere and will be discussed.