Atmospheric response to NO_y source due to energetic electron precipitation

Abstract

[1] We have introduced additional NO y sources caused by energetic electron precipitation (EEP) during 1987 into a Chemistry-Climate model. Comparison of two model runs with and without EEP reveals increase of reactive nitrogen by about 2 ppbv in the middle stratosphere over the tropical and middle latitudes. In the upper stratosphere over the polar winter regions the simulated NO y enhancement reaches 10 ppbv. Decreases of the ozone mixing ratio in the stratosphere by up to 5% over midlatitudes and up to 30% over southern high-latitudes are calculated. A $0.5 K cooling in the middle stratosphere over the tropics and up to 2 K over southern high-latitudes is calculated with detectable changes in the surface air temperatures. These results confirm that the magnitude of the atmospheric response to EEP events can potentially exceed the effects from solar UV fluxes. These mechanisms work in phase outside polar latitudes, but can compensate each other within polar latitudes. Citation: Rozanov, E., L. Callis, M. Schlesinger, F. Yang, N. Andronova, and V. Zubov (2005), Atmospheric response to NO y source due to energetic electron precipitation, Geophys. Res. Lett., 32, L14811,

Geomagnetic activity signatures in wintertime stratosphere wind, temperature, and wave response

“…These results provide a significant step in understanding the chemicaldynamical coupling mechanisms connecting geomagnetic activity/EPP and tropospheric variations found in previous studies [Rozanov et al, 2005;Seppälä et al, 2009]. While our analysis is based on the longest available re-analysis data set ( 50 years), the limited amount of data available will always leave some level of uncertainty on the statistical results.…”

“…[3] Rozanov et al [2005] and Baumgaertner et al [2011] investigated the top-down link from mesospheric NO x production with independent climate models, but while their individual model results predicted significant perturbations in stratospheric and tropospheric temperatures during polar winter, their analysis did not conclusively determine the underlying cause that led to the downward descent of the signals. Rozanov et al [2005] included a low intensity, continuous electron precipitation forcing in their model, providing a source for NO x (energetic particle precipitation produced NO x , EPP-NO x ) in the middle atmosphere.…”

“…In the study of Baumgaertner et al [2011], the model experiment included an A p indexdriven EPP-NO x source at the mesospheric upper boundary (0.01 hPa). They then used a chemistry general circulation model to simulate surface temperature response to geomagnetic activity variations by realistically varying the A p index to further explore the mechanisms leading to the temperature responses reported earlier by Rozanov et al [2005]. The A p -driven NO x parameterization that they used in their model had previously proved to be realistic and in a good agreement with observations [Baumgaertner et al, 2009], concurring well with earlier observations of the relationship between polar middle atmosphere NO x concentrations and the variation in geomagnetic activity and particle precipitation [Siskind et al, 2000;Randall et al, 2007;Seppälä et al, 2007;Sinnhuber et al, 2011].…”

“…Rozanov et al [2005] included a low intensity, continuous electron precipitation forcing in their model, providing a source for NO x (energetic particle precipitation produced NO x , EPP-NO x ) in the middle atmosphere. The predicted EPP-NO x enhancements led to up to 30% annual decrease in polar stratospheric ozone, accompanied by significant polar stratospheric temperature reductions.…”

N2O production by high energy auroral electron precipitation

“…In the winter time, during the long polar night and under suitable dynamical conditions significant amounts of NO x may be transported down to the lower mesosphere and upper stratosphere [e.g., Solomon et al, 1982;Randall et al, 2005;Hauchecorne et al, 2007]. If the latter occurs then the auroral NO x can impact the ozone budget in the stratosphere [e.g., Rozanov et al, 2005]. However, there is uncertainty about the source region of the NO x .…”