MAVEN observations of the solar cycle 24 space weather conditions at Mars

Lee, Christina O.; Hara, Takuya; Halekas, J. S.; Thiemann, E.; Chamberlin, Phillip C.; Eparvier, F.; Lillis, R. J.; Larson, D. E.; Dunn, P.; Espley, J. R.; Gruesbeck, J.; Curry, S.; Luhmann, J. G.; Jakosky, B. M.

doi:10.1002/2016ja023495

Cited by 98 publications

(155 citation statements)

References 74 publications

Supporting

Mentioning

143

Contrasting

Order By: Relevance

“…Moreover, the largest nightside densities recorded by MAVEN have been observed at high northern altitudes during this time period coincidently with a major solar energetic particle event (Lee et al, 2017). First period: electron depletions have equally been observed on the duskside and on the dawnside.…”

Section: Detail Of Each Time Periodmentioning

confidence: 70%

Dawn/Dusk Asymmetry of the Martian UltraViolet Terminator Observed Through Suprathermal Electron Depletions

et al. 2019

Self Cite

View full text Add to dashboard Cite

Suprathermal electron depletions are structures of the nightside ionosphere of Mars resulting from an equilibrium between electron loss and creation processes. Photoionization of oxygen and carbon dioxide by UV and EUV photons is the main ionization process of the Martian atmosphere. The observation of suprathermal electron depletions is strongly unexpected in the portion of the Martian environment where photoionization can occur. This region is delimited by the UltraViolet (UV) terminator, behind which no UV ionizing photons are detected. In this study suprathermal electron depletions are used to determine the position of the UV terminator thanks to MAVEN observations. The MAVEN spacecraft is now in its fourth year of data recording and has already covered more than one Martian year, a large range of latitude, local time, and solar zenith angle in the nightside down to 110‐km altitude. This coverage enables us to determine the approximate position of the UV terminator over one Martian year. We then investigate the variation of its position on the dawnside and duskside and depending on seasons. Our results are compared with models of the Martian atmosphere and in situ data of the atmospheric composition which all highlight an asymmetry between the duskside and the dawnside at equinox. However, models show an inversion in the position of the dusk and the dawn UV terminator at perihelion and aphelion, which cannot yet be confirmed or disproved by the data.

show abstract

Section: Detail Of Each Time Periodmentioning

confidence: 70%

Dawn/Dusk Asymmetry of the Martian UltraViolet Terminator Observed Through Suprathermal Electron Depletions

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…The CIR associated with the coronal hole triggered a moderate geomagnetic storm on 7 June 2015, and a minor geomagnetic storm on 4 July 2015 at Earth . Lee et al (2017) observed that the IMF configuration fluctuated between Parker spiral configuration and radial configuration, upon crossing the heliospheric current sheet associated with the HSS. In this study, we present the observations only for the June 2015 event.…”

Section: Observationsmentioning

confidence: 99%

“…The images of coronal hole in May, June, and July are shown in Figure 7 of Lee et al (2017). The images of coronal hole in May, June, and July are shown in Figure 7 of Lee et al (2017).…”

Section: Observationsmentioning

confidence: 99%

On the response of Martian Ionosphere to the Passage of a Corotating Interaction Region: MAVEN Observations

2019

View full text Add to dashboard Cite

The response of Martian ionosphere to the passage of corotating interaction region (CIR) of June 2015 is studied using observations from several instruments aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. An intense CIR arrived at Mars on 22 June 2015, during which the upstream solar wind and interplanetary magnetic field conditions were monitored by the Solar Wind Ion Analyzer (SWIA), Solar Wind Electron Analyzer (SWEA), Solar Energetic Particle (SEP), and Magnetometer (MAG) instruments aboard MAVEN. The CIR event was characterized by enhancements in solar wind density, velocity, and dynamic pressure, and increased and fluctuating interplanetary magnetic field and was associated with enhanced fluxes of Solar Energetic Particles. The Langmuir Probe and Waves (LPW) instrument onboard MAVEN provided the ionospheric observations such as electron density and electron temperature during this period. The dayside ionosphere is significantly compressed only near the peak of solar wind dynamic pressure enhancement (∼14 nPa). In contrast, on the nightside, the electron density remains depleted for a longer period of time. The electron temperatures are also enhanced during the period of electron depletion on the nightside. The Suprathermal and Thermal Ion Composition (STATIC) measurements show enhanced fluxes of suprathermal heavy ions in the Martian exosphere during CIR period, and evidences for enhanced tailward flow of these pickup ions. The analysis suggests that the nightside ionosphere is primarily controlled by the precipitating Solar Energetic Particles and pickup ions transported across the Martian terminator and depletes significantly when the heavy ion flux in the exosphere enhances.

show abstract

“…Throughout this period the EUV irradiance at Mars changed by a factor of about 2, primarily owing to the varying Mars‐Sun distance rather than solar cycle variability. The EUV irradiance was highest during the beginning of the mission, when Mars was near perihelion [ Bougher et al , ; Lee et al , ].…”

Section: Ngims Data Descriptionmentioning

confidence: 99%

“…Alternatively, a more plausible explanation may be that the larger nightside densities were the result of a period of enhanced particle precipitation. The first period of observations covered the full month of December 2014, during which the MAVEN Solar Energetic Particle (SEP) instrument [ Larson et al , ] detected an extended event of energetic electron fluxes [ Lee et al , ]. These energetic electrons are expected to produce significant ionization at these altitudes [e.g., Sheel et al , ] and MARSIS observations show that nightside densities are enhanced during SEP events [ Němec et al , ].…”

Section: Variabilitymentioning

confidence: 99%

Nightside ionosphere of Mars: Composition, vertical structure, and variability

et al. 2017

Self Cite

View full text Add to dashboard Cite

We provide an overview of the composition, vertical structure, and variability of the nightside ionosphere of Mars as observed by Mars Atmosphere and Volatile EvolutioN (MAVEN)'s Neutral Gas and Ion Mass Spectrometer (NGIMS) through 19 months of the MAVEN mission. We show that O 2+ is the most abundant ion down to ∼130 km at all nightside solar zenith angles (SZA). However, below 130 km NO+ is the most abundant ion, and NO+ densities increase with decreasing altitude down to at least 120 km. We also show how the densities of the major ions decrease with SZA across the terminator. At lower altitudes the O 2+ and CO 2+ densities decrease more rapidly with SZA than the NO+ and HCO+ densities, which changes the composition of the ionosphere from being primarily O 2+ on the dayside to being a mixture of O 2+, NO+, and HCO+ on the nightside. These variations are in accord with the expected ion‐neutral chemistry, because both NO+ and HCO+ have long chemical lifetimes. Additionally, we present median ion density profiles from three different nightside SZA ranges, including deep on the nightside at SZAs greater than 150° and discuss how they compare to particle precipitation models. Finally, we show that nightside ion densities can vary by nearly an order of magnitude over monthlong timescales. The largest nightside densities were observed at high northern latitudes during winter and coincided with a major solar energetic particle event.

show abstract

MAVEN observations of the solar cycle 24 space weather conditions at Mars

Cited by 98 publications

References 74 publications

Dawn/Dusk Asymmetry of the Martian UltraViolet Terminator Observed Through Suprathermal Electron Depletions

Dawn/Dusk Asymmetry of the Martian UltraViolet Terminator Observed Through Suprathermal Electron Depletions

On the response of Martian Ionosphere to the Passage of a Corotating Interaction Region: MAVEN Observations

Nightside ionosphere of Mars: Composition, vertical structure, and variability

Contact Info

Product

Resources

About