11‐Year Solar Cycle Signature in the Summer Stratospheric Temperature Over the Pacific

Abstract

Although previous studies have identified a quasi‐11‐year solar cycle signal in sea surface temperature and tropopause temperature over the Pacific, the existence of a solar cycle signal in the Pacific stratosphere remains underexplored. This study analyses temperature data from various levels of the Pacific stratosphere during June, July and August (JJA) from 1980 to 2022. Through regional averaging, vertical integration and power spectrum analysis, we identify a significant influence of solar activity on EOF2 of JJA‐mean 50 hPa temperature over the Pacific. This response is characterized by a meridional tripolar distribution, with cold anomalies over the equator and warm anomalies in the subtropics. Mechanism analysis shows that during high solar activity years (HSY), enhanced radiative heating in the subtropical stratosphere over the Pacific reduces the meridional temperature gradient, which weakens zonal winds according to the thermal wind principle, thus facilitating planetary wave propagation. This leads to increased wave activity, which strengthens the Brewer‐Dobson (BD) circulation. More ozone is transported from the equator to the subtropics, raising ozone concentrations, absorbing more solar ultraviolet (UV) radiation and causing warming in the subtropics. In contrast, the equatorial region experiences cooling, resulting in a meridional tripolar structure in the JJA‐mean 50 hPa temperature over the Pacific. Using the CMIP6 hist‐sol experiment, we analyse the key physical processes under the influence of solar activity and reveal how solar activity impacts ozone distribution through planetary waves and the BD circulation, ultimately affecting temperature.

Bibliographic Information