The Total Electron Content of the Martian Ionosphere From MRO/SHARAD Observations

Mendillo, M.; Narvaez, C.; Campbell, B. A.

doi:10.1002/2017je005391

Cited by 11 publications

(12 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Total electron content is the integral of electron density with respect to altitude. Here we adopt an integration range of 80 to 270 km for consistency with recent studies using Mars Reconnaissance Orbiter (MRO) Shallow Radar (SHARAD) observations (Mendillo et al, ). The uncertainty in total electron content was found using the same Monte Carlo approach as for peak altitude.…”

Section: Validation Of Datasetmentioning

confidence: 99%

First Ionospheric Results From the MAVEN Radio Occultation Science Experiment (ROSE)

et al. 2018

Self Cite

View full text Add to dashboard Cite

Radio occultation observations of the ionosphere of Mars can span the full vertical extent of the ionosphere, in contrast to in situ measurements that rarely sample the main region of the ionosphere. However, most existing radio occultation electron density profiles from Mars were acquired without clear context for the solar forcing or magnetospheric conditions, which presents challenges for the interpretation of these profiles. Here we present 48 ionospheric electron density profiles acquired by the Mars Atmosphere and Volatile EvolutioN mission (MAVEN) Radio Occultation Science Experiment (ROSE) from 5 July 2016 to 27 June 2017 at solar zenith angles of 54 ∘ to 101 ∘ . Latitude coverage is excellent, and comprehensive context for the interpretation of these profiles is provided by other MAVEN instruments. The profiles show a 9-km increase in ionospheric peak altitude in January 2017 that is associated with a lower atmospheric dust storm, variations in electron densities in the M1 layer that cannot be explained by variations in the solar soft X-ray flux, and topside electron densities that are larger in strongly magnetized regions than in weakly magnetized regions. MAVEN Radio Occultation Science Experiment electron density profiles are publicly available on the NASA Planetary Data System.

show abstract

Section: Validation Of Datasetmentioning

confidence: 99%

First Ionospheric Results From the MAVEN Radio Occultation Science Experiment (ROSE)

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…The Martian total electron content (TEC) has been the topic of several studies in recent times because of its potential to monitor the Martian ionospheric behavior (e.g., Cartacci et al, , ; Lillis et al, ; Mendillo et al, , ; Mendillo, Narvaez, & Campbell, ; Mendillo, Narvaez, et al, ; Morel et al, ; Safaeinili et al, ; Sánchez‐Cano et al, ; Sánchez‐Cano, Morgan, et al, ). The TEC represents the number of free electrons that are contained along the path between a radio transmitter and receiver.…”

Section: Overviewmentioning

confidence: 99%

Spatial, Seasonal, and Solar Cycle Variations of the Martian Total Electron Content (TEC): Is the TEC a Good Tracer for Atmospheric Cycles?

et al. 2018

View full text Add to dashboard Cite

We analyze 10 years of Mars Express total electron content (TEC) data from the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument. We describe the spatial, seasonal, and solar cycle behavior of the Martian TEC. Due to orbit evolution, data come mainly from the evening, dusk terminator and postdusk nightside. The annual TEC profile shows a peak at Ls = 25–75° which is not related to the solar irradiance variation but instead coincides with an increase in the thermospheric density, possibly linked with variations in the surface pressure produced by atmospheric cycles such as the CO2 or water cycles. With the help of numerical modeling, we explore the contribution of the ion species to the TEC and the coupling between the thermosphere and ionosphere. These are the first observations which show that the TEC is a useful parameter, routinely measured by Mars Express, of the dynamics of the lower‐upper atmospheric coupling and can be used as tracer for the behavior of the thermosphere.

show abstract

“…These are not complete TEC values since they do not include the portions of the ionosphere below ~150 km (including the peak electron density). For solar zenith angles in the range 65°–85° during average solar flux conditions of September 2017, the Mars Initial Reference Ionosphere model (http://sirius.bu.edu/miri/) gives full TEC values in the range 2.5 to 4.5 TECU, as derived using observations from the SHARAD radar on the MRO spacecraft (Mendillo, Narvaez, Campbell ). No evidence for TEC enhancements at late times can be drawn from these observations.…”

Section: What Did Maven Observe?mentioning

confidence: 99%

Flares at Earth and Mars: An Ionospheric Escape Mechanism?

et al. 2018

Self Cite

View full text Add to dashboard Cite

Solar flares are nature's active experiment upon a planet's upper atmosphere and ionosphere.Observed effects at Earth are consistent with a "second sunrise" scenario that produces changes in electron density, electron temperature, and plasma dynamics. A solar active region in September 2017 provoked ionospheric disturbances due to solar flares observed at Earth (6 September) and later at Mars (10 and 17 September). Incoherent scatter radar observations from the Millstone Hill Observatory showed a burst of upward diffusion due to electron temperature enhancements. We explore the companion possibility of flares causing upward drifts and plasma escape at Mars. Solar observations made by the EUV Monitor instrument on the Mars Atmosphere and Volatile EvolutioN (MAVEN) satellite are used to portray the time histories of irradiance changes to determine the "early" (onset to peak emission) and "late" (decay to background) time scales for these flares. During the initial phase of a flare (when photons ionize an atmosphere unmodified by flare heating), MAVEN was well above the ionosphere and thus no in situ data are available to asses this period of possible plasma escape. Estimates made using a simple terrestrial model for plasma drifts in the topside ionosphere suggest that escape rates can be enhanced at Mars at "early" times. The "late time" effects observed below 400 km 2 hr after the flare onset times did not reveal conclusive remnants of the proposed mechanism. No model of the Martian thermosphere-ionosphere system has produced a self-consistent simulation of solar flare effects upon Mars' upper atmosphere and ionosphere.A very brief summary of prior work on the ionized component of escape at Mars begins with results from the Russian Phobus-2 mission (Lundin et al., 1989), followed by the many studies using the European Space Agency', and references therein). The global escape rates for electrons and ions found in all of these prior studies consistently fell within the range of~10 24 to~10 25 per second. National Aeronautics and Space Administration (NASA) MAVEN mission strives to quantify the current escape processes for neutral and ionized gases at Mars and to use them to estimate long-term atmospheric loss (Jakosky, 2015). Plasma escape rates found using MAVEN observations are also in~10 24 to~10 25 /s range. Brain et al. (2015) estimated a lower bound value of 3 × 10 24 /s for ions with energies >25 eV observed MENDILLO ET AL. Key Points: • Observations and models for Earth show that flare-induced ionospheric enhancements of N e and T e lead quickly to plasma escape • September 2017 flares confirm terrestrial pattern at early times (~10 min), but observations at Mars only available after~2 hr • For Mars, analytical 1-D model predicts upward plasma drift capable of escape; new observations for "early time" flare effects needed Supporting Information: • Supporting Information S1

show abstract

The Total Electron Content of the Martian Ionosphere From MRO/SHARAD Observations

Cited by 11 publications

References 43 publications

First Ionospheric Results From the MAVEN Radio Occultation Science Experiment (ROSE)

First Ionospheric Results From the MAVEN Radio Occultation Science Experiment (ROSE)

Spatial, Seasonal, and Solar Cycle Variations of the Martian Total Electron Content (TEC): Is the TEC a Good Tracer for Atmospheric Cycles?

Flares at Earth and Mars: An Ionospheric Escape Mechanism?

Contact Info

Product

Resources

About