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I. G. Usoskin - One of the best experts on this subject based on the ideXlab platform.
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Middle atmosphere response to the solar cycle in irradiance and ionizing Particle Precipitation
Atmospheric Chemistry and Physics, 2011Co-Authors: K. Semeniuk, V. I. Fomichev, J. C. Mcconnell, S. M. L. Melo, I. G. UsoskinAbstract:Abstract. The impact of NO x and HO x production by three types of energetic Particle Precipitation (EPP), auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions 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.
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Middle atmosphere response to the solar cycle in irradiance and ionizing Particle Precipitation
Atmospheric Chemistry and Physics Discussions, 2010Co-Authors: K. Semeniuk, V. I. Fomichev, J. C. Mcconnell, S. M. L. Melo, I. G. UsoskinAbstract:Abstract. The impact of NOx and HOx 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.
N. Wieters - One of the best experts on this subject based on the ideXlab platform.
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The Impact of Energetic Particle Precipitation on the Chemical Composition of the Middle Atmosphere: Measurements and Model Predictions
Climate and Weather of the Sun-Earth System (CAWSES), 2013Co-Authors: M. Sinnhuber, N. Wieters, Holger WinklerAbstract:We investigate the impact of energetic Particle Precipitation on the chemical composition of the middle atmosphere by developing models, and combining model results with observations of the chemical response to Particle Precipitation events. We show that in the upper stratosphere and lower mesosphere, negative ion chemistry plays a role in addition to the well-known NOx and HOx production due to positive ion chemistry, releasing chlorine from its reservoir, and re-partitioning NOy. Model results also show a large direct impact of energetic electron Precipitation on the chemical composition of the upper stratosphere and mesosphere, both during large solar events and during and after geomagnetic storms. Observations show that the indirect impact of energetic electron Precipitation events on the middle atmosphere composition can be much larger than the impact of even large solar Particle events. However, observations have not shown clear evidence for a direct impact of energetic electron Precipitation at altitudes below 80 km so far; if there is a direct impact of energetic electron Precipitation on the lower mesosphere and upper stratosphere as suggested by the model results, then it is small compared to the direct contribution of large solar events, or to the indirect impact of energetic electron Precipitation due to downward propagation of mesospheric or thermospheric air during polar winter.
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energetic Particle Precipitation and the chemistry of the mesosphere lower thermosphere
Surveys in Geophysics, 2012Co-Authors: M. Sinnhuber, H. Nieder, N. WietersAbstract:Precipitation of energetic Particles into the atmosphere greatly disturbs the chemical composition from the upper stratosphere to the lower thermosphere. Most important are changes to the budget of atmospheric nitric oxides (NOx = N, NO, NO2) and to atmospheric reactive hydrogen oxides (HOx = H, OH, HO2), which both contribute to ozone loss in the stratosphere and mesosphere. The impact of energetic Particle Precipitation on the chemical composition of the atmosphere has been studied since the 1960s, and there are a number of observations as well as model studies concerning especially the auroral impact and large solar Particle events. Changes to the NOx budget due to energetic Particle Precipitation can be quite long-lived during polar winter and can then be transported down into the lower mesosphere and stratosphere, where NOx is one of the main participants in catalytic ozone destruction. Energetic Particle Precipitation can also affect temperatures and dynamics of the atmosphere from the source region down to the stratosphere and possibly even down to the surface, due to a coupling of chemical composition changes affecting atmospheric heating and cooling rates, the mean circulation, and wave propagation and breaking. Thus, energetic Particle Precipitation impacts have been implemented in chemistry-climate models reaching from the surface up to the mesosphere or lower thermosphere. However, there are still a number of open questions in the theoretical description of the energetic Particle Precipitation impact; the most important are uncertainties in the formation rate of different NOx species due to energetic Particle Precipitation, and the complex coupling between chemical changes, atmospheric heating and cooling rates, and atmospheric dynamics.
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Energetic Particle Precipitation and the Chemistry of the Mesosphere/Lower Thermosphere
Surveys in Geophysics, 2012Co-Authors: M. Sinnhuber, H. Nieder, N. WietersAbstract:Precipitation of energetic Particles into the atmosphere greatly disturbs the chemical composition from the upper stratosphere to the lower thermosphere. Most important are changes to the budget of atmospheric nitric oxides (NOx = N, NO, NO_2) and to atmospheric reactive hydrogen oxides (HOx = H, OH, HO_2), which both contribute to ozone loss in the stratosphere and mesosphere. The impact of energetic Particle Precipitation on the chemical composition of the atmosphere has been studied since the 1960s, and there are a number of observations as well as model studies concerning especially the auroral impact and large solar Particle events. Changes to the NOx budget due to energetic Particle Precipitation can be quite long-lived during polar winter and can then be transported down into the lower mesosphere and stratosphere, where NOx is one of the main participants in catalytic ozone destruction. Energetic Particle Precipitation can also affect temperatures and dynamics of the atmosphere from the source region down to the stratosphere and possibly even down to the surface, due to a coupling of chemical composition changes affecting atmospheric heating and cooling rates, the mean circulation, and wave propagation and breaking. Thus, energetic Particle Precipitation impacts have been implemented in chemistry-climate models reaching from the surface up to the mesosphere or lower thermosphere. However, there are still a number of open questions in the theoretical description of the energetic Particle Precipitation impact; the most important are uncertainties in the formation rate of different NOx species due to energetic Particle Precipitation, and the complex coupling between chemical changes, atmospheric heating and cooling rates, and atmospheric dynamics.
Cora E. Randall - One of the best experts on this subject based on the ideXlab platform.
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Arctic and Antarctic polar winter NOx and energetic Particle Precipitation in 2002–2006
Geophysical Research Letters, 2007Co-Authors: Annika Seppälä, Mark A. Clilverd, Cora E. Randall, Pekka T. Verronen, Johanna Tamminen, Viktoria Sofieva, Leif Backman, Erkki KyröläAbstract:Received 19 February 2007; revised 8 May 2007; accepted 16 May 2007; published 26 June 2007. [1] We report GOMOS nighttime observations of middle atmosphere NO2 and O3 profiles during eight recent polar winters in the Arctic and Antarctic. The NO2 measurements are used to study the effects of energetic Particle Precipitation and further downward transport of polar NOx. During seven of the eight observed winters NOx enhancements occur in goodcorrelation withlevelsofenhancedhigh-energyParticle Precipitation and/or geomagnetic activity as indicated by the Ap index. We find a nearly linear relationship between the average winter time Ap index and upper stratospheric polar winterNO2columndensityinbothhemispheres.IntheArctic winter 2005–2006 the NOx enhancement is higher than expected from the geomagnetic conditions, indicating the importance of changing meteorological conditions.
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Energetic Particle Precipitation effects on the Southern Hemisphere stratosphere in 1992–2005
Journal of Geophysical Research, 2007Co-Authors: Cora E. Randall, Mihail Codrescu, V. L. Harvey, C. S. Singleton, Scott M. Bailey, Peter F. Bernath, Hideaki Nakajima, James M. RussellAbstract:[1] Measurements from several different satellite instruments are used to estimate effects of energetic Particle Precipitation (EPP) on NOx (NO + NO2) in the Southern Hemisphere stratosphere from 1992 to 2005. The focus is the EPP Indirect Effect (IE), whereby NOx produced in the mesosphere or thermosphere via EPP (EPP-NOx) descends to the stratosphere during the polar winter, where it can participate in catalytic ozone destruction. EPP-NOx entering the stratosphere is found to vary in magnitude from 0.1 to 2.6 gigamoles per year, with maximum values occurring in 1994 and 2003. The interannual variation correlates strongly with several measures of EPP activity, including auroral and medium energy electron hemispheric power, and satellite measurements of thermospheric NO. This represents the first estimation of EPP-NOx contributions to the stratospheric odd nitrogen budget using observations over an entire solar cycle. The results will be useful for evaluating and constraining global models to investigate coupling of the upper and lower atmosphere by the EPP IE, including any influences this might have on ozone trends and possibly on climate.
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stratospheric effects of energetic Particle Precipitation in 2003 2004
Geophysical Research Letters, 2005Co-Authors: Cora E. Randall, V. L. Harvey, Gloria L. Manney, Yvan J. Orsolini, Christopher E. Sioris, Samuel Brohede, Craig S. Haley, M Codrescu, Larry L. GordleyAbstract:Upper stratospheric enhancements in NOx (NO and NO2) were observed at high northern latitudes from March through at least July of 2004. Multi-satellite data analysis is used to examine the temporal evolution of the enhancements, to place them in historical context, and to investigate their origin. The enhancements were a factor of 4 higher than nominal at some locations, and are unprecedented in the northern hemisphere since at least 1985. They were accompanied by reductions in O-3 of more than 60% in some cases. The analysis suggests that energetic Particle Precipitation led to substantial NOx production in the upper atmosphere beginning with the remarkable solar storms in late October 2003 and possibly persisting through January. Downward transport of the excess NOx, facilitated by unique meteorological conditions in 2004 that led to an unusually strong upper stratospheric vortex from late January through March, caused the enhancements.
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Stratospheric effects of energetic Particle Precipitation in 2003–2004
Geophysical Research Letters, 2005Co-Authors: Cora E. Randall, Mihail Codrescu, V. L. Harvey, Gloria L. Manney, Yvan J. Orsolini, Christopher E. Sioris, Samuel Brohede, Craig S. Haley, Larry L. Gordley, Joseph M. ZawodnyAbstract:Upper stratospheric enhancements in NOx (NO and NO2) were observed at high northern latitudes from March through at least July of 2004. Multi-satellite data analysis is used to examine the temporal evolution of the enhancements, to place them in historical context, and to investigate their origin. The enhancements were a factor of 4 higher than nominal at some locations, and are unprecedented in the northern hemisphere since at least 1985. They were accompanied by reductions in O-3 of more than 60% in some cases. The analysis suggests that energetic Particle Precipitation led to substantial NOx production in the upper atmosphere beginning with the remarkable solar storms in late October 2003 and possibly persisting through January. Downward transport of the excess NOx, facilitated by unique meteorological conditions in 2004 that led to an unusually strong upper stratospheric vortex from late January through March, caused the enhancements.
K. Semeniuk - One of the best experts on this subject based on the ideXlab platform.
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Middle atmosphere response to the solar cycle in irradiance and ionizing Particle Precipitation
Atmospheric Chemistry and Physics, 2011Co-Authors: K. Semeniuk, V. I. Fomichev, J. C. Mcconnell, S. M. L. Melo, I. G. UsoskinAbstract:Abstract. The impact of NO x and HO x production by three types of energetic Particle Precipitation (EPP), auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions 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.
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Middle atmosphere response to the solar cycle in irradiance and ionizing Particle Precipitation
Atmospheric Chemistry and Physics Discussions, 2010Co-Authors: K. Semeniuk, V. I. Fomichev, J. C. Mcconnell, S. M. L. Melo, I. G. UsoskinAbstract:Abstract. The impact of NOx and HOx 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.
V. L. Harvey - One of the best experts on this subject based on the ideXlab platform.
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simulation of energetic Particle Precipitation effects during the 2003 2004 arctic winter
Journal of Geophysical Research, 2015Co-Authors: C E Randall, B Funke, V. L. Harvey, Laura Holt, Daniel R Marsh, Douglas E Kinnison, P F BernathAbstract:Energetic Particle Precipitation (EPP) during the 2003–2004 Arctic winter led to the production and subsequent transport of reactive odd nitrogen (NOx = NO + NO2) from the mesosphere and lower thermosphere (MLT) into the stratosphere. This caused NOx enhancements in the polar upper stratosphere in April 2004 that were unprecedented in the satellite record. Simulations of the 2003–2004 Arctic winter with the Whole Atmosphere Community Climate Model using Specified Dynamics (SD-WACCM) are compared to satellite measurements to assess our understanding of the observed NOx enhancements. The comparisons show that SD-WACCM clearly displays the descent of NOx produced by EPP but underestimates the enhancements by at least a factor of four. Comparisons with NO measurements in January and February indicate that SD-WACCM most likely underestimates EPP-induced NO production locally in the mesosphere because it does not include Precipitation of high energy electrons. Comparisons with temperature measurements suggest that SD-WACCM does not properly simulate recovery from a sudden stratospheric warming in early January, resulting in insufficient transport from the MLT into the stratosphere. Both of these factors probably contribute to the inability of SD-WACCM to simulate the stratospheric NOx enhancements, although their relative importance is unclear. The work highlights the importance of considering the full spectrum of precipitating electrons in order to fully understand the impact of EPP on the atmosphere. It also suggests a need for high-quality meteorological data and measurements of NOx throughout the polar winter MLT.
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energetic Particle Precipitation effects on the southern hemisphere stratosphere in 1992 2005
Journal of Geophysical Research, 2007Co-Authors: C E Randall, V. L. Harvey, M Codrescu, C. S. Singleton, Scott M. Bailey, Peter F. Bernath, Hideaki Nakajima, James M. RussellAbstract:[1] Measurements from several different satellite instruments are used to estimate effects of energetic Particle Precipitation (EPP) on NOx (NO + NO2) in the Southern Hemisphere stratosphere from 1992 to 2005. The focus is the EPP Indirect Effect (IE), whereby NOx produced in the mesosphere or thermosphere via EPP (EPP-NOx) descends to the stratosphere during the polar winter, where it can participate in catalytic ozone destruction. EPP-NOx entering the stratosphere is found to vary in magnitude from 0.1 to 2.6 gigamoles per year, with maximum values occurring in 1994 and 2003. The interannual variation correlates strongly with several measures of EPP activity, including auroral and medium energy electron hemispheric power, and satellite measurements of thermospheric NO. This represents the first estimation of EPP-NOx contributions to the stratospheric odd nitrogen budget using observations over an entire solar cycle. The results will be useful for evaluating and constraining global models to investigate coupling of the upper and lower atmosphere by the EPP IE, including any influences this might have on ozone trends and possibly on climate.
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Energetic Particle Precipitation effects on the Southern Hemisphere stratosphere in 1992–2005
Journal of Geophysical Research, 2007Co-Authors: Cora E. Randall, Mihail Codrescu, V. L. Harvey, C. S. Singleton, Scott M. Bailey, Peter F. Bernath, Hideaki Nakajima, James M. RussellAbstract:[1] Measurements from several different satellite instruments are used to estimate effects of energetic Particle Precipitation (EPP) on NOx (NO + NO2) in the Southern Hemisphere stratosphere from 1992 to 2005. The focus is the EPP Indirect Effect (IE), whereby NOx produced in the mesosphere or thermosphere via EPP (EPP-NOx) descends to the stratosphere during the polar winter, where it can participate in catalytic ozone destruction. EPP-NOx entering the stratosphere is found to vary in magnitude from 0.1 to 2.6 gigamoles per year, with maximum values occurring in 1994 and 2003. The interannual variation correlates strongly with several measures of EPP activity, including auroral and medium energy electron hemispheric power, and satellite measurements of thermospheric NO. This represents the first estimation of EPP-NOx contributions to the stratospheric odd nitrogen budget using observations over an entire solar cycle. The results will be useful for evaluating and constraining global models to investigate coupling of the upper and lower atmosphere by the EPP IE, including any influences this might have on ozone trends and possibly on climate.
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stratospheric effects of energetic Particle Precipitation in 2003 2004
Geophysical Research Letters, 2005Co-Authors: Cora E. Randall, V. L. Harvey, Gloria L. Manney, Yvan J. Orsolini, Christopher E. Sioris, Samuel Brohede, Craig S. Haley, M Codrescu, Larry L. GordleyAbstract:Upper stratospheric enhancements in NOx (NO and NO2) were observed at high northern latitudes from March through at least July of 2004. Multi-satellite data analysis is used to examine the temporal evolution of the enhancements, to place them in historical context, and to investigate their origin. The enhancements were a factor of 4 higher than nominal at some locations, and are unprecedented in the northern hemisphere since at least 1985. They were accompanied by reductions in O-3 of more than 60% in some cases. The analysis suggests that energetic Particle Precipitation led to substantial NOx production in the upper atmosphere beginning with the remarkable solar storms in late October 2003 and possibly persisting through January. Downward transport of the excess NOx, facilitated by unique meteorological conditions in 2004 that led to an unusually strong upper stratospheric vortex from late January through March, caused the enhancements.
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Stratospheric effects of energetic Particle Precipitation in 2003–2004
Geophysical Research Letters, 2005Co-Authors: Cora E. Randall, Mihail Codrescu, V. L. Harvey, Gloria L. Manney, Yvan J. Orsolini, Christopher E. Sioris, Samuel Brohede, Craig S. Haley, Larry L. Gordley, Joseph M. ZawodnyAbstract:Upper stratospheric enhancements in NOx (NO and NO2) were observed at high northern latitudes from March through at least July of 2004. Multi-satellite data analysis is used to examine the temporal evolution of the enhancements, to place them in historical context, and to investigate their origin. The enhancements were a factor of 4 higher than nominal at some locations, and are unprecedented in the northern hemisphere since at least 1985. They were accompanied by reductions in O-3 of more than 60% in some cases. The analysis suggests that energetic Particle Precipitation led to substantial NOx production in the upper atmosphere beginning with the remarkable solar storms in late October 2003 and possibly persisting through January. Downward transport of the excess NOx, facilitated by unique meteorological conditions in 2004 that led to an unusually strong upper stratospheric vortex from late January through March, caused the enhancements.