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Mars does not currently have a global dipole magnetic field, and consequently, the atmosphere of the red planet is in direct contact with the incoming solar wind. However, there is a large presence of remnant crustal magnetic fields, of variable strength and direction, in the southern hemisphere and equatorial regions. Their subsequent, complex interactions with the solar wind as they themselves rotate with the planet produces a “hybrid magnetosphere”. The influence of these interactions is seen as complex dynamics that occur in the ionosphere. Thus, in this study, we use nearly 17 years of observations from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board Mars Express to characterise the variability of the topside electron density profiles over the strong anomalies in the Southern hemisphere. The effect of numerous parameters, such as the solar zenith angle (and hence, local time), solar activity, Mars’ season, crustal magnetic field inclination, and solar wind dynamic pressure are investigated. We also compare these observations with the empirical model NeMars to evaluate the degree of variability, as well as with profiles far from these crustal field regions.

During perihelion, Mars enters a dust season which sees the onset of numerous dust storms travelling over different regions of the planet. Occasionally these storms can grow and merge into a global storm system covering the entire planet. The last of these events occurred in 2018, 2007 and 2001. Dust storms on Mars can increase hydrogen loss by up to 10 times, and cause atmospheric heating of 40 K. This study focuses on the 2007 event, and using data from Mars Express looks to see if the influence that the dust storm has on the atmosphere and ionosphere can be seen above at two plasma boundaries - the induced magnetospheric boundary and the bow shock. Using data from the ASPERA-3 and MARIS instruments we compare crossings of each boundary to MHD models to look for signatures of the dust event in boundary location.

Multispacecraft and multiwavelength observations of solar eruptions such as flares and coronal mass ejections are essential to understand the complex processes behind these events. The study of solar burst events in the radio-frequency spectrum has relied almost exclusively on data from ground-based radiotelescopes and dedicated heliophysics missions such as STEREO or Wind. Reanalysing existing data from the Mars Reconnaissance Orbiter (MRO) Shallow Radar (SHARAD) instrument, a Martian planetary radar sounder, we have detected 38 solar radio burst events with a correlated observation by at least one dedicated solar mission. The very high resolution of the instrument, both in temporal and frequency directions, its bandwidth, and its position in the solar system enable SHARAD to make significant contributions to heliophysics; it could inform on plasma processes on the site of the burst generation and also along the propagation path of associated fast electron beams. In this letter, we characterise the sensitivity of the instrument to type-III solar radio bursts through a statistical analysis of correlated observations, using STEREO and Wind as references. We establish the conditions under which SHARAD can observe solar bursts in terms of acquisition geometry, laying the foundation for its use as a solar radio-observatory. We also present the first analysis of type-III characteristic times at high resolution beyond 1 AU. The scaling laws are also comparable to results found on Earth, except for the fall time; a clearer distinction between fundamental and harmonic components of the bursts may be needed to resolve the discrepancy., Comment: 15 pages, 5 figures, 2 tables

The Hunga Tonga-Hunga Ha‘apai volcano eruption was a unique event that caused many atmospheric phenomena around the globe. In this study, we investigate the atmospheric gravity waves in the mesosphere/lower thermosphere (MLT) launched by the volcanic explosion in the Pacific leveraging multistatic meteor radar observations from the Chilean Observation Network De Meteor Radars (CONDOR) and the Nordic Meteor Radar Cluster in Fennoscandia. MLT winds are computed using a recently developed 3DVAR+DIV algorithm. We found an eastward and a westward traveling gravity wave in the CONDOR zonal and meridional wind measurements, which arrived 12 hours and 48 hours after the eruption, and one in Nordic Meteor Radar Cluster that arrived 27.5 hours after the volcanic detonation. We obtained observed phase speeds for the eastward great circle path at both locations of about 250 m/s and 170–150 m/s for the opposite propagation direction. The intrinsic phase speed was estimated to be 200–212 m/s. Furthermore, we identified a potential lamb wave signature in the MLT winds using 5 minute resolved 3DVAR+DIV retrievals.

Several studies (Banerjee et al. (2020) and before that Sun et al. (2014)) found a trend reversal between winter and summer circulation in the southern hemisphere around 2000 in the middle atmosphere. One may argue that the negative trend after 2000 is due to the CO2-induced change in stratospheric dynamics. However, Ramesh et al. (2020), using the newest WACCM6 simulation and a multiple linear regression model, confirmed that the negative trend in the stratosphere after 2000 can be attributed to ozone recovery. Here we investigate how stratospheric trends relate to trends in the mesosphere and lower thermosphere (MLT) dynamics. Using the adaptive spectral filtering (ASF) method (Stober et al., 2021), we study long-term changes in mesospheric wind and planetary and gravity wave estimates of meteor radar stations in the northern (NH: Collm, Kiruna, Sodankyla, CMOR) and southern (SH: Rio Grande, Davis, Rothera) hemisphere, respectively, for the altitude range of 80–100 km. Linear trends have been estimated (from monthly means calculated from the preprocessed original data using ASF) by the Theil–Sen estimator (Theil, 1950; Sen, 1968). The robustness of our fitting method is assessed in terms of spurious trends due to, e.g., high autocorrelation of relatively short time series. The long-term changes are validated in two whole-atmosphere models, namely, GAIA and WACCMX-SD (both nudged in the stratosphere). While both models reveal issues reproducing basic climatology in the mesosphere, GAIA fairly reproduces the trends captured by the meteor radars. Finally, we conclude that the ozone recovery effects in the SH stratosphere influence the dynamics in MLT via gravity wave coupling.

Figshare 'Share' poster from Cardiff Met.Made with Adobe Spark.Licence = CC BY 4.0

Figshare 'Archive' poster from Cardiff Met.Made with Adobe Spark.Licence = CC BY 4.0

Historical overview of mid-latitude SuperDARN. (PDF 212â kb)

A presentation given at Gregynog 2019 - a colloquium organised for IT and library staff to discuss recent development and exchange experiences.#gregynog2019

Presentation/talk given at figshare fest 2019."Engagement with figshare……​(A story of how I stopped worrying and just got on with it)"#figsharefest #FigshareFest

Since the internally-generated magnetic field of Mars is weak, strong coupling is ex- pected between the solar wind, planetary magnetosphere, and planetary ionosphere. However, few previous observational studies of this coupling incorporated data that extended from the solar wind to deep into the ionosphere. Here we use solar wind, magnetosphere, and ionosphere data obtained by the Mars Express spacecraft dur- ing March/April 2010 to investigate this coupling. We focus on three case studies, each centered on a pair of ionospheric electron density profiles measured by radio occultations, where the two profiles in each pair were obtained from the same lo- cation at an interval of only a few days. We find that high dynamic pressures in the solar wind are associated with compression of the magnetosphere, heating of the magnetosheath, reduction in the vertical extent of the ionosphere, and abrupt changes in electron density at the top of the ionosphere. The first three of these associations are analogous to the behavior of the plasma environment of Venus, but the final one is not. These results reinforce the notion that changes in solar forc- ing influence the behaviors of all of the tightly coupled regions within the Martian plasma environment.

The Super Dual Auroral Radar Network (SuperDARN) is a network of HF coherent scatter radars. At the end of 2012there were 31 operational radars of which 22 were in the northern hemisphere and 9 in the southern hemisphere. The radars areoperated by 17 different research groups from 11 different countries. In this paper we give an overview of the network and its development over the last twenty years, concentrating on the nature of the collaboration. We describe the data parameters that areavailable, radar operational modes, and the structure of the SuperDARN collaboration. A brief, “light touch” review is also given of the science achieved with the network. Finally we give a brief look to future science directions.

Solar cycle variations in solar radiation create notable changes in the Martian ionosphere, which have been analysed with Mars Express plasma datasets in this paper. In general, lower densities and temperatures of the ionosphere are found during the low solar activity phase, while higher densities and temperatures are found during the high solar activity phase. In this paper, we assess the degree of influence of the long term solar flux variations in the ionosphere of Mars.