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GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 13, 1704, doi:10.1029/2003GL017280, 2003

Impact of the wintertime North Atlantic Oscillation (NAO) on the summertime atmospheric circulation

Masayo Ogi

Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan


Yoshihiro Tachibana

International Arctic Research Center, Frontier Research System for Global Change, Tokyo, Japan
Liberal Arts Education Center, Tokai University, Hiratsuka, Japan


Koji Yamazaki

Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan
International Arctic Research Center, Frontier Research System for Global Change, Tokyo, Japan


Abstract

Using the NCEP/NCAR reanalysis dataset and other observations, we show that the summer high-latitude climate in the Northern Hemisphere is influenced by the NAO of the previous winter. We find this influence in the summertime surface air temperature, the geopotential height, the sea surface temperature (SST), sea-ice/continental snow cover extent fields as well as in the zonal mean geopotential height and zonal wind fields. This summertime NAO signal is annular but its meridional scale is much smaller than the winter annular mode. Distinct summer anomalies are located at the nodal latitudes of the winter anomalies. We suggest that the sea-ice, SST and snow cover anomalies provide the memory allowing the winter NAO to affect the summer climate.

Received 10 March 2003; accepted 11 June 2003; published 10 July 2003.

Index Terms: 1620 Global Change: Climate dynamics (3309); 1863 Hydrology: Snow and ice (1827); 3309 Meteorology and Atmospheric Dynamics: Climatology (1620); 3322 Meteorology and Atmospheric Dynamics: Land/atmosphere interactions.

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Citation: Ogi, M., Y. Tachibana, and K. Yamazaki (2003), Impact of the wintertime North Atlantic Oscillation (NAO) on the summertime atmospheric circulation, Geophys. Res. Lett., 30(13), 1704, doi:10.1029/2003GL017280.