scholarly journals Direct and indirect electron precipitation effect on nitric oxide in the polar middle atmosphere, using a full-range energy spectrum

2017 ◽  
Vol 122 (8) ◽  
pp. 8679-8693 ◽  
Author(s):  
Christine Smith-Johnsen ◽  
Hilde Nesse Tyssøy ◽  
Koen Hendrickx ◽  
Yvan Orsolini ◽  
Grandhi Kishore Kumar ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Energy Spectrum ◽  
Middle Atmosphere ◽  
Full Range ◽  
Electron Precipitation ◽  
Precipitation Effect

scholarly journals Direct observations of nitric oxide produced by energetic electron precipitation into the Antarctic middle atmosphere

2011 ◽  
Vol 38 (20) ◽  
pp. n/a-n/a ◽  
Author(s):  
David A. Newnham ◽  
Patrick J. Espy ◽  
Mark A. Clilverd ◽  
Craig J. Rodger ◽  
Annika Seppälä ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Middle Atmosphere ◽  
Energetic Electron ◽  
Electron Precipitation ◽  
Direct Observations ◽  
The Antarctic

scholarly journals 3-D GCM modelling of thermospheric nitric oxide during the 2003 Halloween storm

2006 ◽  
Vol 24 (9) ◽  
pp. 2403-2412 ◽  
Author(s):  
A. L. Dobbin ◽  
E. M. Griffin ◽  
A. D. Aylward ◽  
G. H. Millward
Keyword(s):  
Nitric Oxide ◽  
Geomagnetic Activity ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
No Production ◽  
Auroral Activity ◽  
Modelling Studies ◽  
University College London ◽  
The University

Abstract. Numerical modelling of thermospheric temperature changes associated with periods of high geomagnetic activity are often inaccurate due to unrealistic representation of nitric oxide (NO) densities and associated 5.3-μm radiative cooling. In previous modelling studies, simplistic parameterisations of NO density and variability have often been implemented in order to constrain thermospheric temperature predictions and post storm recovery timescales during and following periods of high auroral activity. In this paper we use the University College London (UCL) 3-D Coupled Thermosphere and Middle Atmosphere (CMAT) General Circulation Model to simulate the 11-day period from 23 October to 3 November 2003, during which the Earth experienced some of the largest geomagnetic activity ever recorded; the so called "Halloween storm". This model has recently been updated to include a detailed self consistent calculation of NO production and transport. Temperatures predicted by the model compare well with those observed by the UCL Fabry Perot Interferometer at Kiruna, northern Sweden, when changes in solar and auroral activity are taken into account in the calculation of NO densities. The spatial distribution of predicted temperatures at approximately 250-km altitude is also discussed. Simulated NO densities at approximately 110 km are presented. Large quantities of NO are found to be present at to the equator, one to two days after the most intense period of geomagnetic activity. This is the first 3-D GCM simulation of NO production and transport over the 2003 Halloween storm period.

scholarly journals Simultaneous measurements of X-rays and electrons during a pulsating aurora

1998 ◽  
Vol 16 (2) ◽  
pp. 148-160 ◽  
Author(s):  
N. Østgaard ◽  
J. Stadsnes ◽  
K. Aarsnes ◽  
F. Søraas ◽  
K. Måseide ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Energy Range ◽  
Energetic Particle ◽  
Good Method ◽  
Electron Energy Spectrum ◽  
Electron Precipitation ◽  
X Rays ◽  
X Ray ◽  
Electron Spectra ◽  
Simultaneous Measurements

Abstract. The PULSAUR II rocket was launched from Andøya Rocket Range at 23.43 UT on 9 February 1994 into a pulsating aurora. In this paper we focus on the observations of precipitating electrons and auroral X-rays. By using models it is possible to deduce the electron energy spectrum from X-ray measurements. Comparisons are made between the deduced electron fluxes and the directly measured electron fluxes on the rocket. We found the shape of the observed and the deduced electron spectra to fit very well, with almost identical e-folding energies in the energy range from 10 ke V to ~60–80 ke V. For the integrated fluxes from 10.8 to 250 ke V, we found a discrepancy of 30% . By combining two models, we have found a good method of deducing the electron precipitation from X-ray measurements. The discrepancies between calculations and measurements are in the range of the uncertainties in the measurements.Key words. Ionospheric particle precipitation · Magnetospheric physics · Annual phenomena · Energetic particle

scholarly journals Unusually strong nitric oxide descent in the Arctic middle atmosphere in early 2013 as observed by Odin/SMR

2014 ◽  
Vol 14 (3) ◽  
pp. 3563-3581
Author(s):  
K. Pérot ◽  
J. Urban ◽  
D. P. Murtagh
Keyword(s):  
Nitric Oxide ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Polar Vortex ◽  
Meteorological Conditions ◽  
Atmospheric Composition ◽  
The Arctic ◽  
The Reformation ◽  
Polar Stratosphere ◽  
Energetic Particle Precipitation

Abstract. The middle atmosphere has been affected by an exceptionally strong midwinter stratospheric sudden warming (SSW) during the Arctic winter 2012/2013. These unusual meteorological conditions led to a breakdown of the polar vortex, followed by the reformation of a strong upper stratospheric vortex associated with particularly efficient descent of air. Measurements by the Sub-Millimetre Radiometer (SMR), on board the Odin satellite, show that very large amounts of nitric oxide (NO), produced by Energetic Particle Precipitation (EPP) in the mesosphere/lower thermosphere (MLT), could thus enter the polar stratosphere in early 2013. The mechanism referring to the downward transport of EPP generated-NOx during winter is generally called the EPP indirect effect. SMR observed up to 20 times more NO in the upper stratosphere than the average NO measured at the same latitude, pressure and time during three previous winters where no mixing between mesospheric and stratospheric air was noticeable. This event turned out to be an unprecedently strong case of this effect. Our study is based on a comparison with the Arctic winter 2008/2009, when a similar situation was observed and which was so far considered as a record-breaking winter for this kind of events. This outstanding situation is the result of the combination between a relatively high geomagnetic activity and an unusually high dynamical activity, which makes this case a prime example to study the EPP impacts on the atmospheric composition.

Solar wind structures and their effects on energetic electron precipitation

2021 ◽  
Author(s):  
Josephine Alessandra Salice ◽  
Hilde Nesse Tyssøy ◽  
Christine Smith-Johnsen ◽  
Eldho Midhun Babu
Keyword(s):  
Solar Wind ◽  
Ozone Concentration ◽  
High Speed ◽  
Climate Models ◽  
Middle Atmosphere ◽  
Energetic Electron ◽  
Accurate Estimate ◽  
Electron Precipitation ◽  
Loss Cone ◽  
Speed Solar Wind

<p>Energetic electron precipitation (EEP) into the Earth's atmosphere can collide with gases and deposit their energy there. The collisions between electrons and atmospheric gasses initiate several chemical reactions which can reduce the ozone concentration. Ozone is critically important in the middle atmosphere energy budget as changes in the ozone concentration impact temperature and winds. EEP is not fully understood in terms of how much energy is being deposited and what the associated drivers are. An accurate quantification of EEP has limitations due to instrumental challenges and therefore imposes limitations of the associated EEP parameterization into climate models. A solution to this problem is a better understanding of the driver processes of energetic electron acceleration and precipitation, alongside optimized data handling. In this study the bounce loss cone fluxes are inferred from EEP measurements by the Medium Energy Proton and Electron Detector (MEPED) on board the Polar Orbiting Environmental Satellite (POES) and the Meteorological Operational Satellite Program of Europe (METOP) at tens of keV to relativistic energies. It investigates EEP in contexts of different solar wind structures: high-speed solar wind streams (HSSs) and coronal mass ejections (CMEs), during an eleven-year period from 2004 – 2014. While today's chemistry climate models only provide snapshots of EEP, independent of context, this study aims to understand the context EEP is created in, which will allow a more accurate estimate of the EEP to be applied in atmospheric climate models.</p>

Observational evidence of polar mesospheric ozone loss following substorm events

2021 ◽  
Author(s):  
Keeta Chapman-Smith ◽  
Annika Seppälä ◽  
Craig Rodger ◽  
Aaron Hendry
Keyword(s):  
Middle Atmosphere ◽  
Energetic Particles ◽  
Observational Evidence ◽  
Electron Precipitation ◽  
Data Sets ◽  
Ozone Loss ◽  
Mesospheric Ozone ◽  
Ozone Monitoring ◽  
The Impact

<p>Ozone in the polar middle atmosphere is known to be affected by charged energetic particles precipitating into the atmosphere from the magnetosphere. In recent years there has been increased interest in the sources and consequences of electron precipitation into the atmosphere. Substorms are an important source of electron precipitation. They occur hundreds of times a year and drive processes which cause electrons to be lost into our atmosphere. The electrons ionise neutrals in the atmosphere resulting in the production of HO<sub>x</sub> and NO<sub>x</sub>, which catalytically destroy ozone. Simulations have examined substorm driven ozone loss and shown it is likely to be significant. However, this has not previously been verified from observations. Here we use polar mesospheric ozone observations from the Global Ozone Monitoring by Occultation of Stars (GOMOS) and Microwave Limb Sounder (MLS) instruments to investigate the impact of substorms. Using the superposed epoch technique we find consistent 10-20% reduction in mesospheric ozone in both data sets. This provides the first observational evidence that substorms are important to the ozone balance within the atmosphere.<span> </span></p>

scholarly journals Ionization and NO production in the polar mesosphere during high-speed solar wind streams: model validation and comparison with NO enhancements observed by Odin-SMR

2015 ◽  
Vol 33 (5) ◽  
pp. 561-572 ◽  
Author(s):  
S. Kirkwood ◽  
A. Osepian ◽  
E. Belova ◽  
J. Urban ◽  
K. Pérot ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Solar Wind ◽  
Seasonal Variation ◽  
High Speed ◽  
Middle Atmosphere ◽  
Satellite Observations ◽  
Ion Chemistry ◽  
Direct Production ◽  
Order Of Magnitude ◽  
Odd Nitrogen

Abstract. Precipitation of high-energy electrons (EEP) into the polar middle atmosphere is a potential source of significant production of odd nitrogen, which may play a role in stratospheric ozone destruction and in perturbing large-scale atmospheric circulation patterns. High-speed streams of solar wind (HSS) are a major source of energization and precipitation of electrons from the Earth's radiation belts, but it remains to be determined whether these electrons make a significant contribution to the odd-nitrogen budget in the middle atmosphere when compared to production by solar protons or by lower-energy (auroral) electrons at higher altitudes, with subsequent downward transport. Satellite observations of EEP are available, but their accuracy is not well established. Studies of the ionization of the atmosphere in response to EEP, in terms of cosmic-noise absorption (CNA), have indicated an unexplained seasonal variation in HSS-related effects and have suggested possible order-of-magnitude underestimates of the EEP fluxes by the satellite observations in some circumstances. Here we use a model of ionization by EEP coupled with an ion chemistry model to show that published average EEP fluxes, during HSS events, from satellite measurements (Meredith et al., 2011), are fully consistent with the published average CNA response (Kavanagh et al., 2012). The seasonal variation of CNA response can be explained by ion chemistry with no need for any seasonal variation in EEP. Average EEP fluxes are used to estimate production rate profiles of nitric oxide between 60 and 100 km heights over Antarctica for a series of unusually well separated HSS events in austral winter 2010. These are compared to observations of changes in nitric oxide during the events, made by the sub-millimetre microwave radiometer on the Odin spacecraft. The observations show strong increases of nitric oxide amounts between 75 and 90 km heights, at all latitudes poleward of 60° S, about 10 days after the arrival of the HSS. These are of the same order of magnitude but generally larger than would be expected from direct production by HSS-associated EEP, indicating that downward transport likely contributes in addition to direct production.

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