Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

Abstract

The impact of NO<sub>x</sub> and HO<sub>x</sub> production by three types of energetic particle precipitation (EPP), aurora, solar proton events and galactic cosmic rays is examined using a chemistry climate model. Ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions were conducted for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10% in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4% more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing

What is the solar influence on climate? Overview of activities during CAWSES-II

“…Codrescu et al 1997;Semeniuk et al 2011) or from semiempirical geomagnetic activity-based parameterisations for NO x production (Baumgaertner et al 2009;Rozanov et al 2012), although the latter responds strongly not just to NO x produced by EPP in the upper mesosphere, but also to NO x produced by EPP in the thermosphere and transported downwards Holt et al 2012;Funke et al 2014). The use of the POES observations also has problems as highlighted by Rodger et al (2010): During geomagnetically disturbed times, i.e.…”

“…The results suggested that a major future event of similar scale could potentially impact the total ozone levels in polar regions with reductions of up to 20 DU. Further work with two different CCMs was done to evaluate the wider effects from CR (also including EPP) (Rozanov et al 2012;Semeniuk et al 2011;Calisto et al 2011). A review by Rozanov et al (2012) examining the potential impacts on both atmospheric chemistry and some climate variables concluded that at least in the model (CCM SOCOL), the combined effects of GCR, SPEs and EEP can potentially affect not just the chemical composition but atmospheric dynamics as well.…”

“…For comparison, on annual scales, stratospheric ozone changes were predicted to be of the order of 2% to 6%, while those arising from solar UV variation are of the order of 2% to 4%, with the combined GCR + SPE + EEP ozone losses peaking at high latitudes. While the same GCR ionisation calculation was used in all studies, Semeniuk et al (2011) examined the atmospheric response from the different particle forcing sources (EEP, SPE, GCR) separately as well as together to estimate their relative roles. The results suggested that the frequently observed deficit of lower stratospheric NO y in CCMs could partially be explained by the missing GCR source of NO y (Semeniuk et al 2011).…”

“…While the same GCR ionisation calculation was used in all studies, Semeniuk et al (2011) examined the atmospheric response from the different particle forcing sources (EEP, SPE, GCR) separately as well as together to estimate their relative roles. The results suggested that the frequently observed deficit of lower stratospheric NO y in CCMs could partially be explained by the missing GCR source of NO y (Semeniuk et al 2011).…”

Response of the Middle Atmosphere in the Southern Hemisphere to Energetic Particle Precipitation in the Latest Reanalysis Data

“…This captures some of the EPP indirect effect but not all. Increases in NOy transported into the lower stratosphere could survive from the previous winter to the following summer and fall (Orsolini 2001;Orsolini et al 2003) and contribute to the ozone loss in early winter because of a long lifetime of NOy there (Semeniuk et al 2011). This process may have an impact on polar vortex formation during its early stage in late fall and early winter.…”