Abstract

The effect of solar variability upon the atmosphere remains poorly understood. This study explored the impact of 27-day rotation of sunspots on the equatorial upper and middle equatorial atmospheric photochemistry from Whole Atmosphere Community Climate Model 3 (WACCM3) output. WACCM3 was driven ... Show moreThe effect of solar variability upon the atmosphere remains poorly understood. This study explored the impact of 27-day rotation of sunspots on the equatorial upper and middle equatorial atmospheric photochemistry from Whole Atmosphere Community Climate Model 3 (WACCM3) output. WACCM3 was driven with observed solar and greenhouse gas forcing for a period during the last solar maximum which included 1999, 2000, and 2001. Specifically, Fourier and wavelet analysis is applied to determine the magnitude and phase responses to the solar induced forcing on ozone (O3), temperature, hydroxyl (OH), molecular oxygen (O (3P)), hydroperoxyl radical (HO2), water vapor (H2O), hydrogen, and shortwave heating. Wavelet analysis demonstrated that the response of these atmospheric constituents to the 27-day forcing is intermittent and depends largely on the magnitude of solar forcing. Fourier and phase analysis demonstrated that the largest responses of ozone occurred around 80 and 40km. The former is attributed to increased production of odd hydrogen (HOX) from photolysis of water vapor at Lyman-Îą while the latter is attributed to increased O3 production in the stratopause from increased UV. The analysis also demonstrated that the largest responses of temperature occurred around 70 km and 40km. They are attributed to increased UV at those altitudes. The amplitude of these responses compared well with data from models and observations. Phase difference, on the other hand, did not. This may be as a result of internal modes of variability with periods close to 27-days contributing to the phase difference in addition to the fact that the model was run with observed greenhouse gas and solar forcing. Show less