J12.4
The Influence of the Madden-Julian Oscillation (MJO) on Northern Hemisphere High Latitude Wintertime Surface Air Temperatures
Gabriel A. Vecchi, JISAO/Univ. of Washington, Seattl, WA; and N. Bond
The Madden-Julian Oscillation (MJO) is the primary mode of large-scale intraseasonal variability in the tropics. Previous work has explored remote influences of the MJO on atmospheric circulation anomalies over the North Pacific, and precipitation in California, among other effects. The present study focuses on the relationship between the MJO and wintertime surface air temperatures in the northern hemisphere high latitudes. The MJO is diagnosed using principal component analysis based on 850 mb zonal winds from the NCEP/NCAR Reanalysis for 1979 through 2002. Station data of varying lengths are used for surface air temperature in Alaska, Canada, the former USSR, Greenland and Iceland. The results indicate that the phase of the MJO has a substantial systematic and spatially coherent effect on intraseasonal variability in wintertime surface air temperature through the northern hemisphere high latitudes. Composites of geopotential height and specific humidity suggest that both radiative and advective effects are important in the observed connections. These statistical connections may be useful for wintertime temperature forecasts. The mechanisms connecting eastward propagating tropical variability with polar and sub-polar variability bear examination. .
Joint Session 12, Subseasonal forecasting (Joint with 15th Symp. on Global Change and Climate Variations and the Symp on Forecasting the Weathe and Climate of the Atmosphere and Ocean; Room 6C)
Tuesday, 13 January 2004, 8:30 AM-5:30 PM, Room 6C
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