Using x-ray tomography in coreflooding experiments allows to characterize the sub-core, mm-scale, multiphase flow properties such as permeability, porosity, relative permeability and capillary pressure. This has been studied previously for CO2-brine drainage experiments and a procedure has been developed for sub-core property estimation, showing that their implementation in numerical models leads to accurate predictions of experimental measurements, such as core saturation distribution. Much less work has been conducted regarding CO2-brine imbibition modeling. In this work we characterize hysteretic sub-core properties using experimental data of CO2-brine imbibition coreflooding conducted on two core samples. We adopt the approach of [1] for sub-core capillary pressure modeling and that of [2] for relative permeability modeling, however, we find that these are not sufficient for accurate modeling of saturation distribution within the core. We improve the models by considering a unique turning point and Land trapping coefficient for each mm-scale grid block in our model and also by calculating new imbibition characteristic relative permeability curves based on a procedure developed in [3]. Results show improvements in matching experimental data. [1] R. Pini, and S.M. Benson. “Capillary pressure heterogeneity and hysteresis for the supercritical CO2/water system in a sandstone.” Advances in Water Resources 108 (2017): 277-292. [2] O. Dury, U. Fischer, and R. Schulin. “A comparison of relative nonwetting‐phase permeability models.” Water Resources Research 35.5 (1999): 1481-1493. [3] E. Anto-Darkwah, S.M. Benson, and A. Rabinovich. “An improved procedure for sub-core property characterization using data from multiple coreflooding experiments.” International Journal of Greenhouse Gas Control 105 (2021): 103226.

Due to the advancement in satellite and remote sensing technologies, a number of satellite precipitation products (SPPs) are easily accessible online at free of cost. These precipitation products have a huge potential for hydro-meteorological applications in data-scare catchments. However, the use of such products is still limited owing to their lack of accuracy in capturing the ground truth. To improve the accuracy of these products, we have developed a quantile based Bayesian model averaging (QBMA) approach to merge the satellite precipitation products. QBMA is a probabilistic approach to assign optimal weights to the SPPs depending on their relative performances. The QBMA approach is compared with simple model averaging and one outlier removed. TRMM, PERSIANN-CDR, CMORPH products were experimented for QBMA merging during the monsoon season over India’s coastal Vamsadhara river basin. QBMA optimal weights were trained using 2001 to 2013 daily monsoon rainfall data and validated for 2014 to 2018. Results indicated that QBMA approach with bias corrected precipitation inputs outperformed the other merging methods. On monthly evaluation, it is observed that all the products perform better during July and September than that in June and August. The QBMA approaches do not have any significant improvement over the SMA approach in terms of POD. However, the bias-corrected QBMA products have lower FAR. The developed QBMA approach with bias-corrected inputs outperforms the IMERG product in terms of RMSE.

InSAR time-series (InSAR-TS) analysis enables us to obtain the displacement time-series by using a number of SAR images repeatedly acquired on the area. Among the factors affecting the accuracy of the InSAR-TS analysis, this study focuses on three factors that may severely affect the signal detection limit: 1) the selection of the reference point (determining the offset in each interferogram), 2) ramp-type artifact that originate from inaccuracy in the orbit data or ionospheric disturbance, and 3) altitude-correlated tropospheric noise. Fukushima et al. (2019, Earth, Planets and Space) proposed an InSAR-TS analysis method to simultaneously solve for the displacement time-series and the error terms mentioned above as well as the error in the digital elevation model. In the proposed method, the unwrapped phase in interferograms is assumed to be composed of a linear combination of the LOS displacement, offset, planar ramp, altitude-correlated phase, and error in the used digital elevation model. A set of unwrapped small-baseline interferograms is then inverted to simultaneously obtain the displacement time-series and the parameters describing the error terms under the minimum norm condition on the displacement time-series. In this study, I applied the above-mentioned method after some updates such as introduction of the temporal constraint adopted by the NSBAS algorithm (Doin et al., 2011) and data masking, on the ALOS-2 data acquired around the Arima-Takatsuki fault zone in western Honshu, Japan. Data of four different Paths (20 and 21 from descending orbit, 127 and 128 from ascending orbit) obtained between August 2014 and March 2021 were analyzed. Some of the original interferograms contained severe noise such as a phase ramp equivalent to approximately 25 cm of LOS displacements. The average velocity field obtained by applying the method captured a relative range decrease of a few mm/year on the southern side of the fault, consistent with the results obtained from Sentinel-1 data analysis. Given the fact that the Sentinel-1 dataset had much favorable conditions (much larger number of data and much smaller ionospheric noise), the consistency in the average velocity field suggests the effectiveness of the proposed approach.

The Early Cretaceous was dominated by greenhouse conditions coupled with increased ocean crust production rate, which led to critical climate, geographic and oceanographic changes and abrupt shifts in redox conditions in the oceans. Regarding Earth’s magnetic field, the Aptian time interval recorded a high rate of polarity reversals. However, after 121.4 Ma, a long period of polarity stability, known as the Cretaceous Normal Polarity Superchron (CNPS), was established for ~38 Myr. Although, there is debate on the causes and consequences of this extreme event, the exact behavior of the geomagnetic field during the Aptian–Albian is still poorly understood, and data from volcanic and sedimentary rocks are usually conflicting. Here we integrate paleomagnetic and biostratigraphic data across the Aptian–Albian transition in the Sergipe-Alagoas Basin (Brazil). Studies suggesting the correlation between magnetostratigraphic and biostratigraphic data for this interval in the Brazilian sedimentary basins are rare, as well as for the South Atlantic marginal basins. Additionally correlations with the Tethyan realm are still unclear. Magnetic parameters, such as magnetic susceptibility, with a resolution of 25 cm, and anhysteretic remanent magnetization (ARM), with a resolution of 2.1 m, were collected over the ~200 m-long succession of Core SER-03 in the Sergipe-Alagoas Basin. ARM acquisition curves were separated into discrete coercivity components and they were interpreted as related to detrital magnetite and/or eolian dust inputs. The entire section spans 6 Myr, including the Aptian–Albian boundary. Our interpretation of environmental magnetism parameter, therefore, allow us to trace shifts between wet and dry climate conditions. Therefore, these data will aid to develop an age model framework in order to assist this uncovered region and future comparisons with Tethyan sections (e.g., Vocontian Basin - France and Poggio Le Guaine - Italy).

Two rock magnetic methods can be used to determine the emplacement temperature of pyroclastic deposits. The first is by looking at the unblocking temperature spectra of the thermoremanent magnetization (TRM) and the second is through the repeatability of thermomagnetic behavior. Chachimbiro volcanic complex is an andesitic-dacitic stratovolcano located at the northern zone of the Ecuadorian volcanic arc. The lateral blast eruption that occurred at 3640-3510 BC originated from a ∼650 m wide and ∼225 m high rhyodacite dome. This satellite lava dome, located ∼6 km to the east of the main vent, erupted, resulting in a large pyroclastic density current (PDC). PDCs are hot mixtures of lithic fragments, gas and pumice, varying in size from fine ash up to metric blocks that descend the flanks of a volcano at great speeds, being the primary cause of death during explosive eruptions. The resulting PDC from this violent laterally directed explosion covered an area of 62 km^2, with the thickest parts of the deposit displaying as much as 15 m. We collected ~63 oriented block samples from 6 locations; their distances varying between 1.8 km to 6.7 km away from the source. Here we present the emplacement temperatures of the Chachimbiro pyroclastic deposits and the potential factors controlling them. Our rock-magnetic results indicate low titanium Ti-magnetite as the main magnetization carrier; maghemite being present in trace amounts. We have recognized that, based on the unblocking analysis of the TRM, the overall temperatures vary from 250 °C to 450 °C depending on the clast size and type. In general, our results suggest a minimum temperature of ~250 °C, with a large portion of the juvenile clasts having temperatures up to about ~450 °C. Furthermore, the analysis and the comparison of the Curie temperature executed in ~30 samples, against the emplacement temperatures obtained through the typical paleomagnetic studies will be presented. This work highlights the usefulness of paleomagnetism and rock magnetism to evaluate the emplacement temperatures of PDCs, thereby allowing to better assess the associated risk.

Ice shelves control the stability of ice sheets and regulate ice sheet contribution to sea level rise by buttressing ice �ow. Most of Greenland’s ice shelves have already been lost, and many ice shelves around Antarctica are thinning and retreating. Ice shelves are increasingly vulnerable to thinning and destabilization due to surface and basal melting, and these processes may be exacerbated by the presence of basal channels, which are deep grooves that entrain meltwater at the base of ice shelves. Basal channels have been observed alongside spatial and temporal changes in grounding line geometry, strain rates and stress transfer, and the incidence and advection of other surface and basal features. The relationships between these processes, and their implications for ice shelf stability, remain largely unknown due to the lack of observations of su�ciently high spatial and temporal resolution. Our methodology employs high temporal and spatial resolution digital elevation models (DEMs) from REMA and ArcticDEM, laser altimetry from ICESat-2, radar sounding and laser altimetry from Operation IceBridge, and velocity data derived from interferometry, enabling us to constrain the morphology and evolution of channels and other ice shelf features at the fringes of both ice sheets. We intend to investigate how the relationships between channels, grounding line processes, and rifts and crevasses impact the persistence of ice shelf area necessary to maintain a “safety band”, or su�cient buttressing force, against grounded ice. Where time-evolving grounding line position data are sparse, we use the DEMs to track the boundary of hydrostatic equilibrium, which we use as a proxy for changes in grounding line position in order to investigate changes in ice shelf geometry. We have completed analysis of three ice shelves and plan to observe at least twelve more in order to develop an inventory of at- risk ice shelves. Based on our preliminary results, we hypothesize that rapidly evolving basal channels are associated with high rates of change in the grounding zone. This work is integral to assessing past and future ice shelf stability, and it will help the glacier dynamics community more accurately account for small-scale ice shelf processes in computational models which predict ice sheet contribution to sea level rise.

The window remove-restore technique, suggested by Abd-Elmotaal and Kühtreiber (2003) to get rid of the double consideration of the topographic-isostatic masses within the data window, is implemented for the African gravity field recovery in the framework of the activities of the IAG Sub-Commission on the gravity and geoid in Africa. Within the course of the window technique, one needs to compute the effect of the topographic-isostatic masses (terrain correction) for the full data window. Since the African data window is fairly large (-42º ≤ φ ≤ 44º; -22º ≤ λ ≤ 62º), the computation of the effect of the topographic-isostatic masses of the full data window consumes very long CPU time using the common TC-program (Forsberg, 1984). This investigation proposes an optimal terrain correction software for the window remove-restore technique. It uses three radii around the computational point. The first radius is used for the innermost zone utilizing the finest DTM for a relatively short radius (around 2 km). The second radius is used for the inner zone up to a short radius (10-15 km). Here a reasonably fine DTM is sufficient. The third radius is used for the rest of the full data window utilizing a coarse DTM. A thorough comparison between the developed software and the TC-program is performed to assess the quality of the developed technique and to compare the needed CPU time to perform the terrain correction for Africa.

Experts in the area of educational research have documented that students can simultaneously possess alternate knowledge frameworks. Furthermore, the development and use of such knowledge frameworks are context dependent. John Heron, of University of Surrey provides guidelines to transform attitudes towards learning in educational institutions and society at large. Inspired by John Heron’s Research, the author has generated DISCUSS to cultivate inspiration in the college experience. In this presentation, the author presents an analysis of the data he has collected and tries to draw conclusions as to how to improve classroom teaching techniques. Directional: By providing direct guidance and steering them in the appropriate direction. Informative: By giving instruction and documenting necessary knowledge and information. Supporting: By affirming the worth and value of student’s beliefs, actions and qualities. Catalytic: By motivating and encouraging them to learn and to move towards self-discovery. Uplifting: By enabling the student to ease tension and to react to powerful emotions. Steering: By means of creative feedback to challenging the student to rise to the occasion. Stimulating: By asking the student to develop interesting problem-solving methodologies. In this presentation, the author tries to present a model analysis. Here, he tries to apply qualitative research to establish and interpret a quantitative data representation. References Gardner, Howard. Intelligence Reframed: Multiple Intelligences for the 21st Century. New York: Basic, 2000. Barr, R. B., & Tagg, J. (1995, November/December). From teaching to learning: A new paradigm for undergraduate education. Change: The Magazine of Higher Education, 13-24. Saxe, S. (1990, June). Peer influence and learning. Training and Development Journal, 42 (6), 50-53. Senge, P. M. (1990). The fifth discipline: The art and practice of the learning organization. New York: Currency Doubleday. Sims, R. R. (1992, Fall). Developing the learning climate in public sector training programs. Public Personnel Management, 21 (3), 335-346.

Non-polarized electrodes are used to measure the potential differences between two points of ionic conductors. They have been widely used in geoelectric measurements,e.g., magnetotelluric (MT), induced polarization (IP), and spontaneous potential (SP). In practical applications, non-polarized electrodes have the following shortcomings: (1) Regular maintenance is required, and the electrodes must be placed in a special solution after use. (2)The working life is limited due to improper maintenance (3)The electrode is large and generally weighs more than 0.5kg. (4) The electrode temperature coefficient is usually 0.1~1mv/℃ which is required to be buried deep (>1m) for long-term observation. We have developed a maintenance-free solid Pb-PbCl2 non-polarized electrode. The electrode has the following advantages. (1) No maintenance is required, the bottom of the electrode is sealed with a rubber sheath. (2)The potential of electrodes is stable, with a monthly drift of less than 50 μV. (3)The temperature coefficient is 10-20 μV/℃. (4) For 100m electrode distance, the signal-to-noise ratio relative to the natural induced electric field is >20 dB at periods of 10,000 s and 10 dB at periods of 100,000 s, comparing 10 dB and -10 dB for PMS 9000 electrodes, respectively. We developed five types of electrodes for different measurements. The smallest diameter is 2.5cm and 10cm in height, and the weight is 0.1 kg which can be also used in the lab. All types of electrodes are waterproof and can be used for the measurement of the electric field in waters, e.g., lake bottom. The field test shows that our electrode can significantly improve the data quality at dead-band (0.1-10 s) and low-frequency for MT measurement, e.g., one can obtain smooth MT impedance with a period of more than 50,000 s for a month acquisition.

The Bayesian Observationally Constrained Statistical–Physical Scheme (BOSS) is a bulk microphysics framework that calculates process rates using generalized power laws of the moments of the droplet size distribution. Formula parameters are inferred with Monte Carlo methods, evaluating a proposed set of parameter values by comparing model outputs to observations. In this study, we produce a set of 2- and 3-moment BOSS schemes that effectively emulate the behavior of a bin microphysics model, using an idealized 1D driver for various forcing conditions that produce either non-precipitating or drizzling cloud. In this driver, BOSS is fully responsible for collision-coalescence, condensation/evaporation, and calculation of hydrometeor fall speeds, with only dynamical forcing and droplet activation handled externally. Comparing BOSS schemes with different terms and different numbers of prognostic cloud moments allows us to evaluate whether the model benefits from the added complexity of these changes. BOSS also has an advantage over black-box machine-learning methods in that the process rate formulas are “human-readable”, allowing us to analytically identify potential sources of instability.

Accentuating Student Performance in a Hydrology Class The author has successfully used student centered performance pedagogy to enhance student learning in a Fluid Mechanics and Hydrology Class. In this particular research activity, he has used Socratic Inquisition Techniques to enhance student learning. He presents detailed analysis of the data he has collected to examine and determine how student performance can be accentuated and improved. Socratic Inquisition is based on Critical thinking and Critical thinking is the objective analysis of facts to form a judgment. The subject is complex, and several different definitions exist. However, one can generally view it as “unbiased analysis or expressive evaluation of factual evidence.” Scholars agree that Critical thinking must be self-directed, self-disciplined, self-monitored, and self-corrective procedure. This helps the students to become independent learners and be enthusiastic to expand their knowledge base. Fluid Mechanics and Hydrology is a junior level course that is based on providing a mathematical base for building the needed knowledge for a variety of subsequent engineering courses. The main objective has been to instill effective communication skills among students and to enhance problem-solving abilities. The author is satisfied with the results gathered, however he sees lots of areas for improvement of student learning. Based on the research data collected, the author has concluded that the method of Critical Thinking actually motivates the students to take ownership of learning. This is definitely a useful path for Accentuating Student Performance in a Fluid Mechanics and Hydrology Class. References 1. Gardner, Howard (2000). Intelligence Reframed: Multiple Intelligences for the 21st Century. New York: Basic. 2. Keefe, J. W. (1991). Learning style: Cognitive and thinking skills. Reston, VA: National Association of Secondary School Principals. 3. Lage, M. J.,Platt, G. J. & Treglia, M. (2000). Inverting the classroom: A gateway to creating an inclusive learning environment. Journal of Economic Education.

Mangrove ecosystems are an essential component of tropical and subtropical urban coastal regions where they provide critical ecosystem services and ensures climate mitigation while playing a pivotal role in the livelihoods of coastal communities. However, growing anthropogenic pressures from rampant urbanization and infrastructural demands are leading to an unparalleled loss and degradation of mangrove cover especially in coastal cities of the global south. Addressing the immediate need for monitoring, protection and restoration of the ecologically stressed mangroves, this study uses earth observations, machine learning and cloud computing methods for advancing timely and accurate spatiotemporal mangrove mapping and change detection. Image classification through four different models i.e. Classification and Regression Trees (CART), Random Forest (RF), Gradient Tree Boost (GTB) and Support Vector Machine (SVM) was performed using Google Earth Engine to classify mangrove extent along the coastal regions of Mumbai, India. Spatially explicit temporal trend in mangrove extent was studied and used to estimate the rate of change of mangrove extent over a period of 30 years. Accuracy assessment was conducted to validate the robustness of trained classifier models alongside their comparative performance. Classification accuracies on the order of 95% were achieved through the machine learning-based classifier models in distinguishing mangrove areas from other land cover types. The time-series analysis combined with image classification reveals the pattern and causes of spatiotemporal changes in mangrove cover and highlights the hotspots of mangrove loss and gain. This approach can aid stakeholders in the management and restoration of mangrove ecosystems through periodic and cost-effective monitoring of mangrove cover particularly in data deficient coastal cities. The outcomes of the study will contribute towards efficient decision-making in achieving the localization of Sustainable Development Goals 6 and 11 of the United Nations.

Dryland play a major role in the global carbon cycle. The US Southwest is experiencing fewer, larger precipitation events and longer dry intervals between rainfalls. These longer droughts are likely driving physiological, phenological, morphological, and community-level responses of dryland vegetation with unknown feedbacks to atmospheric CO2. It remains unclear how seasonal drought intensity and duration affect the magnitude, duration, and direction of dryland vegetation carbon cycling and atmospheric feedbacks. To address this question, we integrated the measurements of soil hydrology, plant community, and carbon fluxes from a new rainfall manipulation experiment site (RainManSR) in the Santa Rita Experimental Range of Southeast Arizona, US into the Community Land Model (CLM5). This field experiment imposed four precipitation treatments (S1–S4), each with the same summer growing season total rainfall (205 mm) but packaged into a range of many/small to few/large rainfall events. This experiment enabled a comprehensive evaluation and parameterization of drought tolerance of semiarid grassland plant functional types (i.e. deep-rooted perennials and shallow-rooted annuals) and their effects on climate extreme-carbon cycles feedbacks. The ability of the improved CLM model to capture dryland productivity and carbon fluxes was then validated at larger scales with observed carbon fluxes from closeby AmeriFlux sites in the US Southwest, such as the semi-arid Kendall grassland site (US-WKG). Applying this model in the Arizona grassland sites indicated that high tolerances of dryland plants to relatively low soil water potential maintains the growing season length of the dryland ecosystem under drought conditions, whereas the acclimation of carbon assimilation and root dynamics to drought mitigate drought effects on vegetation productivity and interannual variability of carbon exchange.

Defense Meteorological Satellite Program-Operational Line scan System (DMSP-OLS) and Suomi National Polar-orbiting Partnership-Visible Infrared Imaging Radiometer Suite (NPP-VIIRS) night-time light (NTL) datasets portraying nocturnal lit pixels have been widely applied to effectively monitor anthropogenic activities, temporal variation in urbanization, and assessment of the dynamics of socio-economic activities and development. Among the various challenges in conventional NTL remote sensing studies, one has been the development of a consistent and long-term NTL time series dataset, indispensable for extended duration analysis. Lack of onboard-calibration, low spatial and radiometric resolution causing saturation for dense urban built up and blooming effect exaggerating the urban extent; pose challenges in the efficient use of DMSP-OLS (2.7 km) data for urban development studies despite its availability since 1992. Therefore, this study attempts to generate high resolution enhanced DMSP-OLS dataset which could generate long-term and consistent NTL time series (1992-2021), intercalibrating with NPP-VIIRS (500 m) products considering invariant pixels. Considering NPP-VIIRS data as base, enhanced DMSP-OLS data are simulated for the period 2012-2013 (common to both retrieved datasets). Calibration of remaining DMSP-OLS datasets is performed utilizing the simulated products (for 2012, 2013) and taking advantage of neighborhood layers. Consequently, a consistent and more accurate NPP-VIIRS like NTL time series is achieved for the entire period overcoming the issue of saturation and blooming effects for DMSP-OLS products. The developed NTL time series is then used to study the urbanization patterns for major Indian metropolitan cities of Delhi, Mumbai, Chennai, and Kolkata. A significant increase in urbanization has been observed with decadal growth rate ranging from 20 to about 40 percent in the 30-year study period, depicting maximum growth proportion during the second decade, for majority of the cities. Further, adopting machine learning approach, Landsat 5 and 8 images have been classified to extract urban extent for the designated period and validate the intensity of urban development derived through NTL products. Keywords: Night-time lights, DMSP-OLS, NPP-VIIRS, urban growth

Traveling Ionospheric Disturbances (TIDs) are propagating variations in ionospheric electron densities that affect radio communications and can help with understanding energy transport throughout the coupled magnetosphere-ionosphere-neutral atmosphere system. Large scale TIDs (LSTIDs) have periods T ≈30-180 min, horizontal phase velocities vH≈‍100-‍250 m/s, and horizontal wavelengths H>1000 km and are believed to be generated either by geomagnetic activity or lower atmospheric sources. TIDs create concavities in the ionospheric electron density profile that move horizontally with the TID and cause skip-distance focusing effects for high frequency (HF, 3-30 MHz) radio signals propagating through the ionosphere. The signature of this phenomena is manifest as quasi-periodic variations in contact ranges in HF amateur radio communication reports recorded by automated monitoring systems such as the Weak Signal Propagation Reporting Network (WSPRNet) and the Reverse Beacon Network (RBN). In this study, members of the Ham Radio Science Citizen Investigation (HamSCI) present a climatology of LSTID activity using RBN and WSPRNet observations on the 1.8, 3.5, 7, 14, 21, and 28 MHz amateur radio bands from 2017. Results will be organized as a function observation frequency, longitudinal sector (North America and Europe), season, and geomagnetic activity level. Connections to geospace are explored via SYM-H and Auroral Electrojet indexes, while neutral atmospheric sources are explored using NASA’s Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2).

Permafrost is permanently frozen ground that covers over 10% of the Earth’s surface. Many northern regions have extensive infrastructure built on this hard, frozen ground. When permafrost thaws, the ground becomes a softer mix of soil and water, which can cause degradation and damage to critical infrastructure. Permafrost thaw has substantial economic, strategic, and environmental implications. While thawing permafrost due to climate change will affect energy infrastructure in many countries, this work focuses on Russia’s current and planned arctic energy infrastructure. To quantify Russian energy infrastructure locations on permafrost, geospatial data was collected and mapped. Specifically, our analysis focuses on Russian gas and oil terminals and power plants. First, we determined the types of permafrost extents (e.g., continuous, discontinuous, sporadic, and isolated) on which each energy facility lies. Next, to evaluate the infrastructure hazard potential of permafrost thaw, we leveraged an existing analysis by [Karjalainen et al., 2019] in which data on ground conditions were weighted and aggregated to generate low, medium, or high hazard classifications under various greenhouse gas trajectories. For the time frame 2041-2060 and assuming greenhouse gas trajectories consistent with RCP 4.5, most facilities were found to be located in moderate and high hazard zones. A similar analysis was conducted for the years 2060-2081 under various climate conditions. Next, we generated supplemental analysis to define similar hazard classifications under current climatic conditions. The future climate scenario findings are compared with current conditions to identify potential variations in hazard zones, which could heighten infrastructure destabilization. Findings are applied to a targeted case study of the Yamal Peninsula to assess implications for Russia in the areas of energy capacity, foreign investment and supply chains, and future infrastructure construction projects. Citation: Karjalainen, O., Aalto, J., Luoto, M. et al. Circumpolar permafrost maps and geohazard indices for near-future infrastructure risk assessments. Sci Data 6, 190037 (2019). https://doi.org/10.1038/sdata.2019.37

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.

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.