The Southern Ocean is chronically under-sampled due to its remoteness, harsh environment and sea-ice cover. Ocean circulation models yield significant insight into key processes and to some extent obviate the dearth of data, however they often underestimate surface mixed layer depth (MLD), with consequences for water-column properties. In this study, a coupled circulation and sea-ice model was implemented for the region adjacent to the West Antarctic Peninsula (WAP), a climatically sensitive region which has exhibited decadal trends toward higher temperatures, a shorter sea-ice season and increasing glacial freshwater input, overlain by strong interannual variability. Hindcast simulations were conducted with different air-ice drag coefficients and Langmuir-circulation parameterizations to determine the impact of these factors on MLD. Including Langmuir circulation deepened the surface mixed layer, with the deepening being more pronounced in the shelf and slope regions. Optimal selection of an air-ice drag coefficient also increased the modeled MLD by similar amounts, and had a larger impact in improving the reliability of the simulated MLD interannual variability. This study highlights the importance of sea ice volume and redistribution to correctly reproduce the physics of the underlying ocean, and the potential of appropriately parameterizing Langmuir circulation to help correct for a bias towards shallow MLD in the Southern Ocean. The model also reproduces observed freshwater patterns in the WAP during late summer and suggests that areas of intense summertime sea-ice melt can still show net annual freezing due to high sea-ice formation during the winter.

Wheat is one of the most widely grown crops and it plays an important role in food production. Currently there is considerable interest in identifying traits that contribute to high yields. Trait selection has mainly focused on the above-ground part of the plant neglecting below-ground processes. Climate change and the greater uncertainty in weather conditions challenge our current food system and create the need to select more varieties with grater resilience against the effects of climate variation. The root system of the plant plays a key part in this resilience, but it is difficult to study at the field-scale which is essential for the effective selection of breeding lines. Geophysical tools such as electromagnetic induction (EMI) and electrical resistivity tomography (ERT) offer the possibility to study the below-ground phenotype of the plant in a non-destructive and high-throughput manner. In this study, changes in soil moisture induced by root water uptake are monitored using time-lapse ERT/EMI surveys. These methods were applied at two scales: (a) at a high-spatial resolution where hundreds of wheat varieties were monitored monthly using EMI in a wheat breeding field trial and (b) at high-temporal resolution where hourly ERT measurements were collected along with above-ground phenotyping traits on a few plots with a field facility (Field Scanalyzer). Coupling these geophysically-based below-ground data with above-ground canopy measurements can increase our understanding of the crop response to its environment. Good correlation was found between leaf area index (LAI) and soil drying inferred from EMI measurements for the high-spatial experiment (a). The ERT monitoring experiment (b) accurately showed the dynamics of two different nitrogen treatments, their interactions with weather conditions and their correlation with above-ground crop growth. Coupling geophysically-based below-ground measurements with above-ground data allows the increased understanding of the whole plant phenotype. This might help to identify useful traits to select for increased crop yield and resilience.

Accurate forecasting of the arrival time and arrival speed of coronal mass ejections (CMEs) is a unsolved problem in space weather research. In this study, a comparison of the predicted arrival times and speeds for each CME based, independently, on the inputs from the two STEREO vantage points is carried out. We perform hindcasts using ELlipse Evolution model based on Heliospheric Imager observations (ELEvoHI) ensemble modelling. An estimate of the ambient solar wind conditions is obtained by the Wang-Sheeley-Arge/Heliospheric Upwind eXtrapolation (WSA/HUX) model combination that serves as input to ELEvoHI. We carefully select 12 CMEs between February 2010 and July 2012 that show clear signatures in both STEREO-A and STEREO-B HI time-elongation maps, that propagate close to the ecliptic plane, and that have corresponding in situ signatures at Earth. We find a mean arrival time difference of 6.5 hrs between predictions from the two different viewpoints, which can reach up to 9.5 hrs for individual CMEs, while the mean arrival speed difference is 63 km s$^{-1}$. An ambient solar wind with a large speed variance leads to larger differences in the STEREO-A and STEREO-B CME arrival time predictions ($cc = 0.92$). Additionally, we compare the predicted arrivals, from both spacecraft, to the actual in situ arrivals at Earth and find a mean absolute error of 7.5 $\pm$ 9.5 hrs for the arrival time and 87 $\pm$ 111 km s$^{-1}$ for the arrival speed. There is no tendency for one spacecraft to provide more accurate arrival predictions than the other.

The Lattice Boltzmann Method (LBM) is an elegant method to simulate fluid dynamics based on modelling distributions of particles moving and colliding on a lattice. We present examples of two phase flow using the Rothman and Keller (RK) colour gradient Lattice Boltzmann model to study phenomena associated with two phase immiscible fluid flow relevant to water being injected into an oil saturated sandstone. The model involves streaming and colliding two distribution functions (red and blue) representing the number densities of two fluids, where the collision step involves two terms which represents how particle distributions change in each time step due to collision while encouraging colour segregation. We conducted 2D numerical experiments to study the effect of wetting angle on the morphology of flow of a lower viscosity fluid being injected at the left of a simplified model rock matrix that was filled with a higher viscosity fluid. The cases studied involved the injected fluid being non-wetting (wetting angle = 180 degrees), neutral wetting (wetting angle = 90 degrees) and wetting (wetting angle = 0 degrees). These three cases show viscous fingering behaviour with different morphologies for the different wetting angles. For the case of the non-wetting fluid injection, a series of narrow fingers are observed. For the case of neutral wetting, broader and rounded fingers are observed. And for the case of injecting a wetting fluid, a broad but distorted front is observed approaching stable displacement. The results show the importance of the wetting angle on the morphology of viscous fingering. This study demonstrates that the multiphase Lattice Boltzmann Method can simulate phenomenology relevant to studies of enhanced oil recovery such as water injection, and hence, may lead to improved estimates of oil recovery factors.

While not specifically designed as a planetary mission, NASA’s Parker Solar Probe (PSP) mission uses a series of Venus gravity assists (VGAs) in order to reduce its perihelion distance. These orbital maneuvers provide the opportunity for direct measurements of the Venus plasma environment at high cadence. We present first observations of kinetic scale turbulence in the Venus magnetosheath from the first two VGAs. In VGA1, PSP observed a quasi-parallel shock, $\beta\sim1$ magnetosheath plasma, and a kinetic range scaling of $k^{-2.9}$. VGA2 was characterised by a quasi-perpendicular shock with $\beta\sim 10$, and a steep $k^{-3.4}$ spectral scaling. Temperature anisotropy measurements from VGA2 suggest an active mirror mode instability. Significant coherent waves are present in both encounters at sub-ion and electron scales. Using conditioning techniques to exclude these electromagnetic wave events suggests the presence of developed sub-ion kinetic turbulence in both magnetosheath encounters.

Persistent dry and wet spells can arise from stationary weather situations or recurrent flow patterns and result in significant socio-economic impacts. Here, we study the effects of recurrent synoptic-scale transient Rossby wave packets (RRWPs) on the persistence of dry and wet spells using the ERA-Interim reanalysis data. RRWPs significantly alter (decrease and increase) dry and wet spell persistence across the globe. Spatial patterns of statistically significant links between RRWPs and spell durations arise from the superposition of a zonally symmetric component and a wave-like component that is modulated by local factors such as orography and the position relative to major moisture sources. The zonally symmetric component is apparent during the Northern Hemisphere winter and dominates the Southern Hemisphere signal in winter and summer. The wave-like component appears primarily in the Northern Hemisphere, changes its wavenumber with the season and is thus, conceivably related to stationary wave dynamics.

Xenoliths of plutonic rocks sporadically torn off by erupting magmas are known to carry valuable information about volcano plumbing systems and the lithosphere in which they emplace. One of the main steps to interpret such information is to quantify the pressure and temperature conditions at which the xenolith mineral assemblages last equilibrated. This chapter discusses some aspects of geothermobarometry of mafic and ultramafic rocks using the xenolith populations of Hualalai and Mauna Kea volcanoes, Hawaii, as case studies. Multiple- reaction geobarometry, recently revisited for olivine + clinopyroxene + plagioclase  spinel assemblages, provides the most precise pressure estimates (uncertainties as low as 1.0 kbar). An example is shown that integrates these estimates with calculated seismic velocities of the xenoliths and the available data from seismic tomography. The results allow to better constrain some km-scale horizontal and vertical heterogeneities in the magmatic system beneath Hawaii. Ultramafic xenoliths at Hualalai are the residuals of magma crystallization at 16–21 km depth, below the pre-Hawaiian oceanic crust. Few available gabbronorites and diorites record instead lower pressures and likely represent conduits or small magma reservoir crystallized at 0–8 km depth. At Mauna Kea, on the other hand, a significant portion of the xenolith record is composed by olivine-gabbros, which crystallized almost over the entire crustal thickness (3– 18 km). Ultramafic xenoliths are less abundant and might represent the bottom of the same magma reservoirs that crystallized in the deeper portion of the magmatic systems (11–18 km). Some unresolved issues remain in geothermometry of mafic and ultramafic rocks representing portions of magma reservoirs that cooled and recrystallized under subsolidus conditions. This suggests that further experimental and theoretical work is needed to better constrain the thermodynamics and kinetics of peridotitic and basaltic systems at low (< 1000 ̵̊C) temperatures.

To support the data analysis for the MErcury Radiometer and Thermal Infrared Imaging Spectrometer (MERTIS) instrument on the ESA-JAXA BepiColombo mission, we have measured the thermal infrared emissivity of finely grained silicates (<25 μm grain size) at different temperatures under vacuum to simulate the daytime conditions on the surface of Mercury. The silicates were selected to represent the mineralogy of Mercury as closely as possible (Helbert et al., 2007; Namur and Charlier, 2017; Vander Kaaden et al., 2017). The set includes one olivine (a Mg-rich forsterite), three pyroxenes (diopside, enstatite, and hypersthene), five feldspars (plagioclase group; anorthite, labradorite, andesine, oligoclase, and K-feldspar; microcline) and a feldspathoid (nepheline). The emissivity measurements for each mineral was carried out within the MERTIS spectral range of 7-14 μm with temperatures increasing from 100 C up to 500 C under vacuum (~0.1 mbar). The relationships between the spectral parameters such as the Christiansen Feature (CF) position, first Reststrahlen band (RB1) position, RB1 emissivity, and RB spectral contrast and temperature were investigated for all silicates. The study shows that the RB1 position shifts to longer wavelengths, RB1 emissivity decreases, and RB spectral contrast increases with increasing temperatures for all silicates studied. We apply the plot of CF vs RB1 as a tool to discriminate the major silicate groups such as feldspars, pyroxenes, and olivine, regardless of the temperatures at which they were measured. The CF vs RB1 plot can facilitate the first order discrimination of the mineralogy of Mercury’s surface with MERTIS. Moreover, this approach can be more widely used to map the igneous surface mineralogy of silicate targets such as the Moon, Mars, and S-type asteroids in the 7-14 μm spectral region with remote sensing from orbit and ground-based telescope observations.

Global mapping of the nature and distribution of volatiles such as sulfides on Mercury’s surface is essential for understanding the thermal evolution of the planet. The surface exposure of these sulfides over extreme day-night temperature cycles (176 days; 450 degC to -170 degC) on Mercury leads to thermal weathering of these sulfide compounds. It has been seen that among the proposed sulfides on Mercury (MgS, FeS, CaS, CrS, TiS, NaS, and MnS), CaS showed relatively stable and distinctive spectral features in the thermal infrared region (TIR; 7-14 μm) when studied under the simulated Mercury day conditions for temperatures ranging from 100 degC up to 500 degC under vacuum (0.1 mbar) (Varatharajan et al., 2019). In this study, we re-investigated the stability of CaS and its spectral emissivity spectral behavior. We exposed the sample for four consecutive Earth days simulating Mercury day cycles and measured the TIR spectra of CaS for temperatures up to 500 degC (with steps of 100 degC) every day. This time the spectral analysis is coupled and supported by XRD diffraction on the fresh and temperature-processed sample, showing the mineralogical evolution with temperature. We confirm that CaS is a stable compound and therefore it would remain stable on Mercury’s surface regardless of investigated peak surface temperatures. This study further implies that, for the hollows dominated by the sublimation of sulfides on Mercury (Blewett et al., 2013; Helbert et al., 2013a; Vilas et al., 2016), CaS could be the last of the sulfides that could be mapped on Mercury as other sulfides were lost by thermal decomposition, leaving behind hollows. This could make CaS an important tracer for other sulfides, which might be lost in the hollow-forming process and supports the detection of CaS within hollows by MESSENGER (Vilas et al., 2016). The emissivity spectra reported here are significant for the detection and mapping of CaS associated with hollows and pyroclastics using the Mercury Radiometer and Thermal Imaging Spectrometer (MERTIS) datasets.

WWLLN (World Wide Lightning Location Network) data on global lightning are used to investigate the increase of total lightning strokes at Arctic latitudes. We focus on the summertime data from June, July and August, which average >200,000 strokes each year above 65o North latitude, for each of the years from 2010 – 2020. The influence of WWLLN network detection efficiency increases is minimized by normalizing to the total global strokes for each northern summer. The ratio of strokes occurring above 65o increases with latitude, showing that the Arctic is becoming much more influenced by lightning. We compare the increasing fraction of strokes with the global temperature anomaly for those months, and find that the fraction of strokes above 65o to total global strokes for these months increases linearly with the temperature anomaly and grows by a factor of 3 as the anomaly increases from 0.65 to 0.95 degrees C.

Mountain snow is a fundamental freshwater supply in the arid regions. Climate warming alters the timing of snowmelt and shortens the snow cover duration, which profoundly influences the regional climate and water management. However, a reliable estimation of snow mass in the Tianshan Mountains (TS) is still unclear due to the scarcity of extensive continuous surface observations and a complex spatial heterogeneity. Therefore, a long-time series of snow simulation was performed in the WRF/Noah-MP from 1982 until 2018 to quantify the snow mass in the TS, forced by the ERA5 reanalysis data and real-time updated leaf area index and green vegetation fraction. Meanwhile, March snow mass (close to the annual peak snow mass), snow cover fraction (SCF), and trends were investigated in the TS. The results indicated a good accuracy of the estimated snow water equivalent (root mean square error (RMSE): 7.82 mm/day) with a slight overestimation (2.84 mm/day). Compared with the ERA5 dataset, the RMSE and mean bias (MB) of the daily snow depth from the WRF/Noah-MP were significantly reduced by 95.74% and 93.02%, respectively. The climatological March snow mass measured 97.85 (±16.60) gigatonnes in the TS and exhibited a negligible tendency. The total precipitation during the cold season controlled the variations of the March snow mass. The increased precipitation in the high-altitude regions contributed to an extensive snow mass, which could offset the loss in the TS lowland. In contrast, rapidly rising air temperature caused a significant reduction of the March SCF, particularly in the Southern TS.

The upper atmosphere of Mars is directly affected by solar activity and the resulting solar irradiance impinging upon it. Variations in solar forcing can affect the rate at which atmospheric species escape from the planetary system. Remotely sensed observations of the upper atmosphere of Mars have been made during solar activity extrema of Solar Cycles 22 and 24. These observations were made of D and H Lyman-a emissions using the Mars Atmosphere and Volatile Evolution (MAVEN) mission and the Hubble Space Telescope (HST) high resolution spectrographs. Data obtained from the two missions are analyzed and used to derive densities and escape rates of D and H from the martian upper atmosphere. The results show that the properties of these two water-spawned atoms vary with solar cycle, and display significant inter-annual variability, mainly due to variations in atmospheric temperature. The findings suggest that cooler atmospheric temperatures due to reduced solar EUV flux may enhance the abundance of H atoms in the upper atmosphere of Mars, yet this does not increase their escape rates.

A submesoscale-permitting global ocean model is used to study the upper ocean turbulence. Submesoscale processes peak in winter and, consequently, geostrophic kinetic energy (KE) spectra tend to be relatively shallow in winter (∼k-2) with steeper spectra in summer (∼k-3). This seasonal transition from steep to shallow power-law in the KE spectra indicates a transition from quasi-geostrophic (QG) turbulence in summer to pronounced surface-QG-like turbulence in winter. It is shown that this transition in KE spectral scaling has two phases. In the first phase (late autumn), KE spectra show a presence of two spectral regimes: ∼k-3 scaling in mesoscales (100-300 km) and ∼k-2 scaling in submesoscales (<50 km), indicating the coexistence of QG, surface-QG, and frontal dynamics. In the second phase (late winter), mixed-layer instabilities convert available potential energy into KE, which cascades upscale leading to flattening of the KE spectra at larger scales, and k-2 power-law develops in mesoscales too.

Simultaneous measurements of cloud electric field and raindrop size at the surface have been analysed to investigate an anticipated relation between the two cloud parameters. A significant positive correlation is observed between the magnitude of the surface electric field and raindrop size supported by a theoretical framework advanced here. It is shown that in the presence of an electric field, raindrops increase their sizes through electrically-induced collision and coalescence processes near the Earth's surface. This study also demonstrates that the presence of an electric field inside the cloud can enhance the rain intensity by influencing the growth rate of raindrops. This new insight may be useful for a proper understanding of the rain microphysics and for developing better numerical weather models for simulation and forecasting of heavy rainfall events associated with stronger in-cloud electrical environments.

Probably the founding father of Geology, Sir James Hutton was raised as a doctor but his passions for the nature surrounding his farm led him to rocks, then specimens, then fossils. The result was what we might call a comparative physician – the first paleontologist, in fact. His upbringing in medicine had given him the classical knowledge of his time, from Latin to mathematics, and from biology to drawing. Not only did the lack of a specific scientific discipline bring Sir Hutton to devise a novel field of study of his own – it also molded strands of his formal learning into a synthesis of intellectual tools. These days, hyper specialization has brought upon novel discoveries of paramount importance and marvel, from graphene to vaccines. It also is a means of necessity in applying for academic positions and to publish in ever nascent journals. This architecture, however, reflects a system of parallel disciplinarity, with scientific fields somehow on their own course. On the other hand, complexities at stake require solutions that may well evade any given single field, at times astray from usual avenues. Such approach not only entails multi-disciplinarity (diverse teams – yesterday), but it also requires cross-disciplinarity (across specific disciplines – today) and, especially, trans-disciplinarity (beyond firm disciplines – today and tomorrow). For their very nature, geosciences are bound to glean lessons learned from the past to provide insight into the future. Geoscientists were once thought to study ancient rocks, fiddle with very slow-moving tectonic plates, and bantering about invisible earth’s features, too large, or too deep, or too far away to even imagine for us earthlings. But the geosciences are more than ever side by side with some of the most pressing issues surrounding contemporary societies – after having been at the heart of a couple of global energy revolutions. From a series of examples, this work thus tries to put into perspective: Hazards stemming from multiple, at times unpredictable sources; The precious role of geosciences to decipher them – and to forecast them; The complexity of natural hazards, the (need of) flexibility in human planning; Modern issues challenging societies and economies – today, tomorrow, and thereafter.

Ideally, the response of the Advanced Topographic Laser Altimeter System (ATLAS) instrument on the Ice, Cloud, and land Elevation Satellite–2 (ICESat-2) observatory to returns from a flat target at a fixed distance would be a single peak. However, ICESat-2 profiles from very flat surfaces display extra features below the presumed Earth surface. This paper identifies the multiple reflections within the ATLAS receiver that create those extra pulses. We describe their sources, compare their measured position to optical ray trace predictions, and discuss their relative amplitude. We then explore the possibility of using afterpulses to extract surface elevation information from highly saturated returns, in which the first return pulse is distorted and displaced by nonlinear effects in the detector.

The formation of layers at mid-latitudes has been related to neutral winds activity at altitudes below 130km in the Mesosphere and Lower Thermosphere (MLT). Recent SAMI3 simulations by Krall et al. (2020) of ionospheric metallic layers at Arecibo suggest that forces induced by the meridional winds cause low altitude layers near 100 km. However, the classic mechanism, originally proposed by Whitehead (1961), correctly states that zonal wind shear has a bigger effect than meridional wind shear in the lower E region. Haldoupis and Shalimov (2021), referring to observations of ionosonde-based sporadic E statistics and radio occultation sporadic E measurements using low Earth orbiting satellites, support the idea that zonal winds dominate layer formation at these altitudes, apparently disputing the findings of Krall et al. (2020). Perhaps the latest technique to continuously measure mid-latitude MLT daytime neutral winds was developed by Hysell et al. (2014). That technique used a unique configuration of the Arecibo radar dual-beam. Unfortunately, since Arecibo lost the capability of the dual-beam in 2017 (when one antenna was destroyed by Hurricane Maria), there are only few valuable data sets that can help elucidate the origin of the lower altitude layers at Arecibo. We present Arecibo neutral wind data correlated with lower altitude layers. While not disputing current theory, we find that, near 100 km, meridional neutral wind shear can be much stronger than zonal wind shear when a layer is present, with the meridional shear correctly positioned to support the layer. We also present a complete analysis of the vertical ion drift, including declination, where the meridional winds become more important and with a reversed mechanism for altitudes below 115km for Arecibo conditions. References: Haldoupis et al. (2021), https://doi.org/10.1016/j.jastp.2021.105537 Hysell et al. (2014), http://doi.org/10.1002/2013JA019621 Krall et al. (2020), https://doi.org/10.1029/2019JA027297

During the forthcoming decade and beyond there will be a plethora of global space-based active and passive measurements of cirrus and ice cloud. These measurements will be across the electromagnetic spectrum, from the ultra-violet to the far-infrared, through to the sub-millimeter, where there are no current radiance observations in the latter spectral regions. To take advantage of these unprecedented high-resolution and spectral-like measurements, ice crystal models are required that are physically consistent throughout the electromagnetic spectrum, and which are consistent with microphysics assumptions in weather and climate models. Achieving such physical consistency between ice crystal models, remote-sensing, and large-scale models to meet the challenges posed by the forthcoming measurements over the next decade or so is problematic. However, it is necessary to overcome this difficulty to improve the predictive quality of weather and climate models to address extreme weather events and climate change, respectively. However, cirrus and ice cloud types consist of ice crystals that vary considerably both in shape and size between the cloud top and bottom. Not surprisingly, with such variability in the shapes and sizes, obtaining models that are coherent across the spectrum while at the same time being consistent with microphysics assumptions in weather and climate models is difficult. In this talk, to address the above issues, an approach using an ensemble model of cirrus ice crystals to predict consistently the observed radiative properties of cirrus from the ultra-violet to the far-infrared will be discussed using aircraft and satellite-based high-resolution radiance measurements. In this analysis, different shapes of the particle size distribution are utilized that are consistent with a weather and climate model, remote-sensing, and with an in-situ mass power law. Here, the need for improved simultaneous in-situ and aircraft remote-sensing spectral characterization of cirrus across the electromagnetic spectrum will be emphasized. Moreover, an example of the development of a new ice crystal model that follows in-situ ice crystal mass and area power laws, which are consistent with a weather and climate model is described, with some preliminary results, to help address the radiative issues.