Stratospheric response to intraseasonal changes in incoming solar radiation

Abstract

AbstractSuperposed 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.