Martian upper atmosphere warming reflects the energy-materials interactions from the lower atmosphere layers. In this paper, we show a new phenomenon that enhances Mars upper atmosphere density in the equatorial region during the winter periods. First, both accelerometer-derived density and NGIMS-measured species from MAVEN show that the winter equatorial region has a secondary warming peak compared with that of the high-latitude polar warming area. Second, the major neutrals (CO2, Ar, CO, N2, and O) indicate that the phenomenon extends at least up to 240 km during both day and night sides. Furthermore, the topographic-related longitudinal structure emerged in the equatorial sector indicates that the variations are more dynamical than we expected. The warming found in this study suggest to be dust-related and influenced by the evolution of the seasonal solar insolation. Both local factors, upward small-scale gravity waves and CO2 IR-thermal effect transfer, may play key roles in shaping the warming structure.

Tracking the onset of inelastic (permanent) deformation is critical to quantifying the stress experienced by an aquifer system so that the effects of current groundwater extraction practices are put in the context of the sedimentary and geological histories of a region. However, the pre-consolidation stress is rarely known due to the lack of multi-decadal ground-based data. In this paper, we propose a new approach to track the onset and spatial evolution of inelastic deformation based on a 2003-2020 multi-sensor Interferometric Synthetic Aperture Radar time series analysis. Our study reveals that in central Iran, many locations that used to experience elastic (recoverable) deformation just a few years ago, are now deforming inelastically, leading to irreversible lowering of the ground surface and irreversible loss of aquifer storage. Lithologic data reveals that the total thickness of the drained clay layers controls the extent and timing of the observed inelastic deformation, while groundwater data confirms that the multi-decadal lowering of groundwater levels is driving the long-term compaction. These results highlight that we are now at or near a tipping point in time between sustainability and permanent damage to our underground water resources, emphasizing the fact that current decisions have the potential to change the natural resources landscape permanently.

Groundwater extraction at rates exceeding recharge is occurring throughout Iran for agricultural and industrial activities, resulting in land subsidence in many areas, particularly the Yazd-Ardakan Plain (YAP) in the dry and desert regions of central Iran. In this study, Interferometric Synthetic Aperture Radar (InSAR) time series analysis and statistical models are used to characterize the controls on land subsidence in the YAP, from 2003 to 2020. Our results reveal the existence of a northwest-southeast elongated area of 363 experiencing subsidence at rates up to 15 cm/yr. In the YAP, the international Airport, railway, transit road, and several industrial and historical sites are threatened by the differential subsidence. Well data confirm that groundwater levels have decreased by 18 meters between 1974 and 2018, driving the compaction of sediments within the underlying aquifer system. Our statistical analysis shows that the thickness of a shallow, clay-rich aquitard layer controls the extent of the observed subsidence and an Independent Component Analysis of the InSAR time series shows that inelastic compaction dominates. This work reveals that in central Iran, current groundwater extraction practices are not sustainable and result in permanent subsidence, ground fractures with impact on infrastructures, and a permanent decrease in water storage capacity.

Thermospheric mass density (TMD) measurements are invaluable to accurately estimate and predict the position and velocity of orbiting objects in Low Earth Orbit (LEO). Existing observational methods and empirical models fail to describe and predict, with enough accuracy and resolution, the actual air-drag variations required for practical applications. With the increasing number of LEO satellites equipped with high-precision Global Navigation Satellite System (GNSS) receivers, precise orbit technology can be used to obtain non-gravitational accelerations, and therefore estimate accurate TMD variations. In this work, TMD is estimated from CASSIOPE precise orbits, and data from the February 2014 geomagnetic storm can be investigated to high accuracy and resolution. Using this method, a more accurate description than previous methods and empirical models, that are unable to describe short-term TMD variations, during geomagnetic storm conditions is given.

Earthquakes often occur and may induce the ionospheric disturbance. In order to understand the generation and process of the earthquake, the seismic ionospheric disturbance (SID) may provide insights on earthquakes. In this paper, the seismic ionospheric disturbances following the Mw 7.7 Jamaica earthquake on 28 January 2020 are detected after 12min of the main shock by the dual-frequency GPS measurements. Two disturbances in different azimuths are significantly found by satellite PRN26 and PRN03. The one is located at the southwest area in the range of 700-800km away from the epicenter while the other is located at the southeast area in the range of 200-450km. The propagation speeds of the two disturbances are 2.53km/s and 2.57km/s respectively. Furthermore, we estimated the detailed characteristics of SID (primarily the amplitude, elevation and azimuth angle, waveform and frequency) and discussed the generation and motion process of the ionospheric disturbance with seismograph, focal mechanism and magnetic field. The relation among SID, Rayleigh wave and focal mechanism are interpreted. Furthermore, the azimuthal asymmetry of SID amplitude and the appearance of the inverted N-shape waveform observed by satellite PRN26 are the main distinctions in the two disturbances as a result. Finally, the up propagating secondary acoustic wave triggered by the seismic Rayleigh wave from the strike-slip earthquake is the main source of the two disturbances.