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

Smith‐Johnsen, Christine; Tyssøy, Hilde Nesse; Hendrickx, Koen; Orsolini, Yvan; Kumar, G. Kishore; Ødegaard, Linn-Kristine Glesnes; Sandanger, Marit Irene; Stordal, Frøde; Megner, Linda

doi:10.1002/2017ja024364

Cited by 25 publications

(38 citation statements)

References 46 publications

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“…The geomagnetic storm period of April 2010 was driven by a combination of both co-rotating interaction regions associated with high-speed solar wind streams and of coronal mass ejections associated with dense transient solar wind flows. This period is also described in more detail in Smith-Johnsen et al (2017). We use the Disturbance Storm Time (Dst) index to characterize the storm onset and evolution.…”

Section: The Waccm-d Simulations and Ancillary Datamentioning

confidence: 99%

Mesospheric Nitric Acid Enhancements During Energetic Electron Precipitation Events Simulated by WACCM‐D

et al. 2018

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While observed mesospheric polar nitric acid enhancements have been attributed to energetic particle precipitation through ion cluster chemistry in the past, this phenomenon is not reproduced in current whole-atmosphere chemistry-climate models. We investigate such nitric acid enhancements resulting from energetic electron precipitation events using a recently developed variant of the Whole Atmosphere Community Climate Model (WACCM) that includes a sophisticated ion chemistry tailored for the D-layer of the ionosphere (50-90 km), namely, WACCM-D. Using the specified dynamics mode, that is, nudging dynamics in the troposphere and stratosphere to meteorological reanalyses, we perform a 1-year-long simulation (July 2009-June 2010) and contrast WACCM-D with the standard WACCM. Both WACCM and WACCM-D simulations are performed with and without forcing from medium-to-high energy electron precipitation, allowing a better representation of the energetic electrons penetrating into the mesosphere. We demonstrate the effects of the strong particle precipitation events which occurred during April and May 2010 on nitric acid and on key ion cluster species, as well as other relevant species of the nitrogen family. The 1-year-long simulation allows the event-related changes in neutral and ionic species to be placed in the context of their annual cycle. We especially highlight the role played by medium-to-high energy electrons in triggering ion cluster chemistry and ion-ion recombinations in the mesosphere and lower thermosphere during the precipitation event, leading to enhanced production of nitric acid and raising its abundance by 2 orders of magnitude from 10 À4 to a few 10 À2 ppb.Both SPEs and energetic electron precipitation (EEP) lead first to the formation of primary ions such as O + , O + 2 , N + 2 , and N + through dissociation and dissociative ionization. These ions are then involved in fast ionchemistry reactions, ultimately producing NO x and hydrogen oxides (HO x ; e.g., see Sinnhuber et al., 2012 for a review). The chemistry of ion clusters plays a key role in the production of the neutral nitrogen species. Ion clusters are groups of m molecules tied to a positive or negative ion. For example, m water molecules can form the hydrated water cluster H + (H 2 O) m , or else other water clusters like NO 3 À (H 2 O) m or NO + (H 2 O) m . The

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Section: The Waccm-d Simulations and Ancillary Datamentioning

confidence: 99%

Mesospheric Nitric Acid Enhancements During Energetic Electron Precipitation Events Simulated by WACCM‐D

et al. 2018

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“…In the mesosphere‐lower‐thermosphere (MLT), descent or mixing in the vortex (Fisher et al, ) is required to transport nitrogen oxides (NO x = NO + NO 2 ) produced by energetic particle precipitation (EPP) from the thermosphere to the stratosphere (Meraner & Schmidt, ; Randall et al, , and references therein). This process, known as the EPP Indirect Effect (EPP IE, Randall et al, ), has been extensively observed (e.g., Bailey et al, ; Callis et al, ; Hendrickx et al, ; Natarajan et al, ; Randall et al, , , ; Rinsland et al, ; Russell et al, ; Siskind et al, , ; Smith‐Johnsen et al, , and references therein). The polar vortex plays a key role in this process in that it confines the EPP‐NO x to high latitudes in polar night conditions where the chemical lifetime is long and descent to the stratosphere is possible.…”

Section: Introductionmentioning

confidence: 99%

On the Upward Extension of the Polar Vortices Into the Mesosphere

et al. 2018

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The polar vortices play a central role in vertically coupling the atmosphere from the ground to geospace by shaping the background wind field through which atmospheric waves propagate. This work extends the vertical range of previous polar vortex climatologies into the upper mesosphere. The mesospheric polar vortices are defined using the CO gradient method with Microwave Limb Sounder satellite data; the stratospheric polar vortices are defined using a stream function‐based algorithm with data from meteorological reanalyses. Strengths and weaknesses of the two vortex definitions are given, as well as recommendations for when, where, and why to use each definition. Midwinter mean vortex geometry in the mesosphere is funnel shaped in the Arctic, with a wide top and narrow bottom. The Antarctic mesospheric vortex tapers with height in early winter and broadens with height in late winter. The seasonal evolution of mesospheric vortex frequency of occurrence, size, and zonal symmetry in both hemispheres is presented. Unexpected behavior above 60 km includes late season vortex broadening in both hemispheres, especially following winters without sudden stratospheric warmings. Following extreme stratospheric disturbances the polar night jet in the mesosphere strengthens and shifts poleward, resulting in a mesospheric vortex that contracts. Overall, the mesospheric polar vortices are more similar between the two hemispheres than their stratospheric counterparts. The vortex climatology presented here serves as an observational benchmark to which the mesospheric polar vortices in high‐top climate models can be evaluated.

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“…Still, with few exceptions, the MEPED 0°detector is used as quantitative measurement of the MEE precipitation (e.g., Arsenovic et al, 2016;Codrescu & Fuller-Rowell, 1997;Smith-Johnsen et al, 2017). These studies provide a useful first approximation for the minimum impact of MEE upon the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Intercomparison of the POES/MEPED Loss Cone Electron Fluxes With the CMIP6 Parametrization

et al. 2019

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Quantitative measurements of medium energy electron (MEE) precipitation (>40 keV) are a key to understand the total effect of particle precipitation on the atmosphere. The Medium Energy Proton and Electron Detector (MEPED) instrument on board the NOAA/Polar Orbiting Environmental Satellites (POES) has two sets of electron telescopes pointing ~0° and ~90° to the local vertical. Pitch angle anisotropy, which varies with particle energy, location, and geomagnetic activity, makes the 0° detector measurements a lower estimate of the flux of precipitating electrons. In the solar forcing recommended for Coupled Model Intercomparison Project (CMIP) 6 (v3.2) MEE precipitation is parameterized by Ap based on 0° detector measurements hence providing a general underestimate of the flux level. In order to assess the accuracy of the Ap model, we compare the modeled electron fluxes with estimates of the loss cone fluxes using both detectors in combination with electron pitch angle distributions from theory of wave‐particle interactions. The Ap model falls short in respect to reproducing the flux level and variability associated with strong geomagnetic storms (Ap > 40) as well as the duration of corotating interaction region storms causing a systematic bias within a solar cycle. As the Ap‐parameterized fluxes reach a plateau for Ap > 40, the model's ability to reflect the flux level of previous solar cycles associated with generally higher Ap values is questioned. The objective of this comparison is to understand the potential uncertainty in the energetic particle precipitation applying the CMIP6 particle energy input in order to assess its subsequent impact on the atmosphere.

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

Cited by 25 publications

References 46 publications

Mesospheric Nitric Acid Enhancements During Energetic Electron Precipitation Events Simulated by WACCM‐D

Mesospheric Nitric Acid Enhancements During Energetic Electron Precipitation Events Simulated by WACCM‐D

On the Upward Extension of the Polar Vortices Into the Mesosphere

Intercomparison of the POES/MEPED Loss Cone Electron Fluxes With the CMIP6 Parametrization

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