Superposed epoch analysis of meteorological reanalysis data is used to demonstrate a significant connection between intraseasonal solar variability and temperatures in the stratosphere. Decreasing solar flux leads to a cooling of the tropical upper stratosphere above 7 hPa, while increasing solar flux leads to a warming of the tropical upper stratosphere above 7 hPa, after a lag of approximately 6-10 days. Late winter (February-March) Arctic stratospheric temperatures also change in response to changing incoming solar flux in a manner consistent with that seen on the 11 year timescale: 10-30 days after the start of decreasing solar flux, the polar cap warms during the easterly phase of the quasi-biennial oscillation. In contrast, cooling is present after decreasing solar flux during the westerly phase of the quasi-biennial oscillation (though it is less robust than the warming during the easterly phase). The estimated composite mean changes in Northern Hemisphere upper stratospheric (~ 5 hPa) polar temperatures exceed 8 K and are potentially a source of intraseasonal predictability for the surface. These changes in polar temperature are consistent with the changes in wave driving entering the stratosphere.
Bibliographical noteFunding Information:
C.I.G. was supported by a start-up grant from Hebrew University of Jerusalem and by the Israel Science Foundation(grant 1558/14). V.S. and N.H. were supported by the German-Israeli Foundationgrant 1151/2011. The authors thank Dann M. Mitchell and the other two anonymous reviewers for their constructive feedback. The solar flux values we used are available at ftp://ftp.geolab.nrcan.gc.ca/data/ solar_flux/daily_flux_values/, ftp://ftp. geolab.nrcan.gc.ca/data/solar_flux/ daily_flux_values/fluxtable.txt, and http://lasp.colorado.edu/lisird/ nrlssi/ts.html.
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