Lagged response of tropical tropospheric temperature to solar ultraviolet variations on intraseasonal time scales

Abstract

Correlative and regression analyses of daily ERA-Interim reanalysis data for three separate solar maximum periods confirm the existence of a temperature response to short-term (mainly similar to 27 day) solar ultraviolet variations at tropical latitudes in both the lower stratosphere and troposphere. The response, which occurs at a phase lag of 6-10 days after the solar forcing peak, consists of a warming in the lower stratosphere, consistent with relative downwelling and a slowing of the mean meridional (Brewer-Dobson) circulation, and a cooling in the troposphere. The midtropospheric cooling response is most significant in the tropical Pacific, especially under positive El Nino-Southern Oscillation conditions and may be related to a reduction in the number of Madden-Julian oscillation events that propagate eastward into the central Pacific following peaks in short-term solar forcing.