For the past 5 years, NASA’s Oceans Melting Greenland (OMG) mission has been motivated by the question: “to what extent are the oceans melting Greenland’s ice from below?” Three out of the mission’s four observational components employed aircraft to collect data on and around the ice sheet: (i) airborne gravity above the continental shelf to infer seafloor geometry, (ii) airborne radar (GLISTIN-A) to measure year-to-year glacier elevation changes, and (iii) airborne-deployed oceanographic instruments (AXCTDs, ALAMO and APEX floats, XBTs, and drifters) to measure year-to-year ocean temperature and salinity changes. After highlighting the mission’s operational parameters and key scientific findings, we will detail our rationale for designing the mission to include extensive aircraft-based measurements. Now that OMG has completed its final observational campaign, we will summarize our experience with using aircraft in polar environments and suggest ways in which aircraft could be used to efficiently extend the ocean climate data record started by OMG and the potential for using aircraft in future missions to make similar oceanographic measurements around Antarctica.

The surface of Ganymede is characterized by dark and light terrains. Light terrain, covering two thirds of the surface, is retained to be younger and resulted from resurfacing events, likely correlated to a global expansion of Ganymede [1]. It is typically characterized by several sets of subparallel troughs and ridges, called grooves. They highly modify the dark terrain and the other pre-existing features. Since these areas display two different superposed spacing scales, grooves have been interpreted as the product of extensional tectonism [2] and two different faulting styles have been recognized (horst-graben and domino) [3]. Nevertheless, the stratigraphical relationship, the required conditions to the grooves’ origin and the tectonic mechanisms are still objects of debate. In preparation of the ESA Juice Mission, we are producing DEMs of extended areas of the surface of Ganymede, using both Galileo and Voyager imagery. We use the open-source suite of tools NASA Ames Stereo Pipeline (ASP) [4], by using the photoclinometry-based “shape-from-shading” (SfS) tool. Since SfS needs an input DEM generated preferably with stereo images, and we do not have such data in this area of Ganymede, we used the methodology proposed by Lesage et al. 2021 [5]. Figure 1 shows an example of Digital Elevation Model using a Galileo image (EDR 2878r, with a resolution of 151 m/px) of Anshar Sulcus (167.40° E, 11.50° N). The DEM clearly shows the height variations of the ridge and trough systems included in the study area. These novel Digital Elevation Models can provide new insights on the geological processes of Ganymede. Acknowledgments GM acknowledges support from the Italian Space Agency (contract ASI/2018-25-HH.0). References [1] Pappalardo R.T., et al., 2004. Jupiter: The Planet, Satellites and Magnetosphere, 2:363. [2] Prockter L.M. et al.,2010. Space Sci Rev 153:63-111 [3] Pizzi A. et al., 2017. Icarus 288: 148-159 [4] Beyer, R. A. et al., (2018), Science, 5. [5] Lesage E. et al. (2021), Icarus, 114373.

Terrestrial hot springs have existed throughout Earth’s history and house some of the most ancient evidence of life on our planet. These settings are known for their high habitability and preservation potential, and are extensively studied as analog environments since hot spring deposits are thought to exist on the surface of Mars. Hot spring water commonly precipitates silica that coats microbial life dwelling in the hot spring outflow streams. This process can entomb microorganisms and preserve microbial remains over long timescales and with high morphological fidelity. Here we present research carried out on modern and sub-recent remains of microbial filaments from amorphous (unaltered) silica deposits in Yellowstone National Park. This work suggests that various elements sequestered by hot spring-dwelling organisms during life are preserved in microbial remains and persist over > 10,000 years. We also present findings from microfossils preserved in mid-Paleozoic terrestrial hot spring deposits which also show sequestrations of select elements in microfossil remains, suggesting that certain elements may persist even after several hundred million years and substantial host rock alteration. These elemental concentrations may be indicative of metabolic functioning during life and have application as biosignatures. Recent developments in analytical instrumentation now allow for even extremely low trace elemental abundances to be detected and mapped, regardless of sample complexity. This work is especially relevant to the search for life on Mars, as evidence of impact-induced hydrothermal activity may exist near the rim of Jezero Crater and may be sampled by the Perseverance rover. As a primary objective of the Mars 2020 mission is to search for evidence of past life on Mars, we suggest the application of this analytical technique to be valuable for potential samples returned to Earth by future Mars Sample Return missions. Distribution Statement A. Approved for public release: distribution unlimited.

Introduction The complex geomorphology of Triton reflects its geological history [1]. The morphological heterogeneity on small scale has led to discerning three main complexes: cantaloupe terrains, equatorial plains, and south polar cap terrains. We analyse an area located in the east equatorial zone of Triton called Monad Regio (centred at 37°N, 2°E), characterized by the presence of walled plains. We produced a new geological map and a DEM (Digital Elevation Model) to recognize the main terrains and features in the study area. We used Voyager 2 imagery named c1139533 (600 m/px) [2], properly calibrated, filtered, and georeferenced using the Integrated Software for Imagers and Spectrometers (ISIS4) [3]. Results and conclusions We mapped the different geological units and main features according to differences in surface morphology (Fig.1). Terraced terrain covers most of the studied area. It shows a chaotic pattern characterized by several terraces, some of which lay in a parallel arrangement around some of the large depressions. These basins have areas ranging from 1300 to 2050 km2, and their degree of alteration is variable, with the features inferred to be more recent showing an inner minor basin within the main one. The most altered basins appear smoother, featureless, and shallower. Sizes and excavation depths estimated using DEM data of the observed basin features appear to be relatively homogeneous, which leads us to exclude an impact related origin. We argue that the origin of these depressions is linked to processes analogue to those described in the formation of terrestrial maar craters and possible explosion craters discussed on Titan [4]. Alternatively, diapirism may also explain the origin of such features. Further analysis could help to understand the nature and related processes that originated these basins. Acknowledgements G.M., C.C. and D.S. acknowledge support from the Italian Space Agency (2020-13-HH.0). References [1] Basilevsky A.T. et al.,1992. Adv. Space Res.,12(11), 123-132. [2] Smith, B. A., et al. (1989), Science, 246 (4936), 1422-1449. [3] Houck J.C. and DeNicola L.A. (2000) Astronomical Data Analysis Software and Systems IX, ASP Conference Series,216. [4] Mitri G., et al. (2019), Nature Geoscience, 12, 791,796.

Passage zones are stratigraphic surfaces found in littoral settings separating deposits diagnostic of subaqueous environments from overlying sequences of subaerial deposits. In glaciovolcanic settings, passage zone surfaces are unequivocal records of the heights and depths of paleo-englacial lakes at a specific point in time and space thereby informing on the presence and nature of the enclosing ice sheet. Kima Kho, a Pleistocene glaciovolcano (i.e. tuya) features multiple and diverse passage zones. The basaltic volcano comprises 4 main stratigraphic packages: i) subaqueously and subaerially deposited lapilli tuffs forming a central tephra cone and representing an explosive onset to the eruption, ii) subaqueously deposited, steeply-inclined beds of tuff breccia dominated by pillow lava fragments, iii) stacked sheets of subaerial lavas , and iv) dykes and sills (I) intruding all units. Stratigraphic and geochemical relationships suggest that Kima Kho volcanism was continuous and 40Ar/39Ar geochronometry on 3 samples yields a mean age of 1949 ±63 ka. Three temporally distinct passage zones record the interplay between growth of the volcanic edifice, syn-volcanic melting of the enclosing ice sheet, and fluctuations in the depth of the englacial lake. The earliest passage zone is expressed in two different ways indicating a transition to effusive eruption: (i) within pyroclastic deposits of the tephra cone (< 1800 masl), and (ii) by pillow lava tuff breccia deposits overlain by subaerial lavas. Together they record a peak, sustained lake depth of 320-340 m that constrains the enclosing ice sheet to a minimum thickness of ~400 m and a minimum radial extent >7 km relative to Kima Kho. Two subsequent passage zones, also defined by sequences of subaerial lavas resting on dipping beds of pillow lava tuff breccias, occur at lower elevations: 1690-1640 masl and 1740-1720 masl, respectively. The latter two passage zones indicate a major draining of the englacial lake followed by refilling to depths of 230-180 m and 260-280 m, respectively. The substantial decline in lake level between passage zones suggests a massive, catastrophic deluge (i.e. jökulhlaup) of 1-2 km3. Lastly, the reconstructed evolution of Kima Kho demands the presence of a regionally extensive, cold-based ice sheet on the Kawdy plateau at ~1.9 Ma.

The groundwater is relatively a pure natural resource as compared to the surface water, but anthropogenic activities pose a threat to its purity and suitability for drinking purpose. Thus, monitoring of spatial and temporal variation of groundwater quality is very important for its management and protection. Geographical Information System (GIS) and statistics can be useful to monitor and evaluate the groundwater quality. For London, there is no comprehensive work in the last two decades for studying the spatio-temporal variation for monitoring groundwater quality and its parameters. We have used data samples from over 500 wells in London basin and the data is provided in free open access domain by Environment Agency. The Trilinear-Piper plot highlighted overall groundwater as dominant magnesium bicarbonate type. To study spatio-temporal variation in London’s groundwater quality, several water quality parameters were considered, for example, nitrates, nitrites, hardness, sodium, Dissolved Oxygen (DO) and others. The concentration of nitrates and nitrites in groundwater were less than 10 mg/l and 0.02 mg/l respectively, at all times (except outliers), during our observation period i.e between the years 2000 and 2020. The groundwater hardness, sodium and DO varied between 50 mg/l to 2363 mg/l, 11 to 308 mg/l and 0 to 10.7 mg/l respectively. The spatial variation maps showed that there are localised patches of groundwater above acceptable Drinking Water Inspectorate (DWI) limits, but overall London’s groundwater is of potable status. The variations in the range of each constituent were attributed to variation in geology of the London palaeogene aquifers and anthropogenic activities. The Pearson correlation coefficients showed that hardness and sodium are negatively corelated and, DO and sodium are also negatively correlated. The study can act as a guide for decision making and to flag contaminate of concern. It can be helpful to outline the suitability of groundwater for its intended purpose, identifying pollution inputs and assessing any spatio-temporal changes.

It is typically assumed that dinitrogen (N2) fixation and denitrification are mutually exclusive processes in riverine ecosystems because N2 fixation is favored in high light, low nitrogen (N) environments but denitrification is favored under anoxic, high N conditions. Yet recent work in marine and lake ecosystems has demonstrated that N2 fixation can happen under high N conditions and in sediments, challenging this assumption. We conducted a cross-ecoregion study to test the hypothesis that N2 fixation and denitrification would co-occur in streams and rivers across a range of reactive N concentrations. Between 2017 and 2019, we sampled 30 streams in 13 ecoregions, using chambers to quantify N2 flux using membrane inlet mass spectrometry, N2 fixation using acetylene reduction, denitrification using acetylene block, and microbial diversity using 16S gene sequencing. 25 of the study streams were part of the National Ecological Observatory Network or the StreamPULSE network, which provided data on water temperature, light, nutrients, discharge and metabolism. We found that N2 fixation rates were detectable in half of the streams surveyed, and were most frequently detected on rock, wood, and/or macrophyte substrates. Denitrification potential was detected in all streams, with rates 1-2 orders of magnitude higher than N2 fixation rates and the highest rates measured in sediments. Substrate heterogeneity, and associated variation in environmental conditions, appeared to facilitate the coexistence of N2 fixation and denitrification in the study streams. Rates of denitrification were significantly positively related to streamwater nitrate concentrations (r2 = 0.35), but N2 fixation rates were not, despite the common simplifying assumption that denitrification dominates the N2 flux in streams under high N and N2 fixation only occurs under low N conditions. Additional analyses are exploring reach to watershed characteristics, and metabolic regimes as drivers of cross-ecoregion patterns in processes.

The UK Polar Data Centre (PDC, https://www.bas.ac.uk/data/uk-pdc/) is the focal point for Antarctic environmental data management in the UK. Part of the Natural Environmental Research Council’s (NERC) network of environmental data centres and based at the British Antarctic Survey (BAS), the PDC coordinates the management of polar data from UK-funded research. In the last two years, the geophysics team at the PDC has made significant progress to improve the management of BAS aerogeophysics data, a challenging task considering that the British Antarctic Survey is one of the largest acquisitors of airborne geophysics data over Antarctica. In 2020, we published bedrock elevation data for fourteen airborne radar surveys over the continent, and more than thirty airborne gravity and magnetics datasets. This year, we will release large swaths of processed airborne radar data collected by BAS since the early 2000s, including extensive surveys over Pine Island (2004-05) and Thwaites (2018-20) glaciers, as well as the large surveys covering the Wilkes subglacial basin (2005-06) and the South Pole (2015-16), amongst others. Considerable effort has been made to curate these datasets to make them up-to-date and comply with the FAIR (Findable, Accessible, Interoperable and Re-usable) principles. In doing so, we believe that these datasets will be a valuable asset to future geophysical and glaciological studies over the Antarctic. Our aim here is to show our progress in re-processing and publishing these datasets and, for the first time, showcase our new Polar Aerogeophysics Data Portal which will serve as a user-friendly interface to discover and download the newly-published aerogeophysics data deposited on BAS’s data catalogue.

In this era of open data and reproducible science, graduate students need to learn where and how to publish their data and to be conversant with the challenges inherent when re-using someone else’s data. The Environmental Data Initiative partnered with UNM Libraries and Florida Coastal Everglades LTER to organize a 1-credit, semester-long distributed graduate seminar to learn if this approach could be an effective mechanism for transmitting such information. Each week during the Spring 2021 semester, an informatics specialist spoke remotely to students at University of New Mexico, Florida International University, and University of Wisconsin-Madison on topics ranging from FAIR principles to data security, team science to data provenance. Students prepared for the lecture with one or more readings, and in-class exercises reinforced the material covered. Student assignments included writing quality metadata for their own data and archiving their data in the EDI Repository. The capstone writing assignment, a data management plan for their own research project, allowed the students to integrate much of what they had learned. Student response to this class was positive, and students indicated that they learned a lot of immediately useful information without the course being a significant time-sink. The low registration numbers at UNM and FIU (6 and 7 students, respectively), however, where the seminar was not required, suggest a need to better inform both students and their advisors of the opportunity and the value provided by the training. Instructors also learned that it would be easier to create a cohesive flow to the course, without repetition, if the group of instructors took turns lecturing, rather than bringing in specialists on each subject. It was also apparent from student comments that many felt this information should be integrated, at an introductory level, into undergraduate classes or classes for new graduate students.

The equatorial ionosopheric anomalies (EIA) at night are the slowly recombining remnants of the dayside ionosphere, and charged particle densities slowly decay during the course of the night. Thus the electron density in ionosphere in the early morning (0300-0400 Local time) is usually very low and the ionospheric UV 135.6 nm O+ recombination emission is rarely detectable from current UV remote sensing instruments. However, there are times when the EIA have unusually high density even during these morning times and are observable by the DMSP/SSUSI and TIMED/GUVI instruments. By using other UV ‘colors’ - 130.4 nm (from monatomic Oxygen) and N2 Lyman Birge Hopfield bands - we can establish that this emission is definitely from the ionosphere recombination emission. We will show examples of this phenomenon, and correlate these occurrences to geomagnetic storm events. We estimate the electron density in the early morning EIA and compare with other ionosphere observations and climatological models. In the figure below, we show the 135.6 nm radiance seen by DMSP F16 SSUSI as it crosses the equator around 210 degrees longitude (over the Pacific Ocean) at 03:45 local time. The equatorial anomaly peaks are clearly visible in the SSUSI data. These radiances are background subtracted, which is not perfect and introduces a small (-1 Rayleigh) bias to the resulting radiances. DMSP = Defense Meteorological Satellite Program, SSUSI = Special Sensor Ultraviolet Spectrographic Imager; TIMED = Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics, GUVI = Global UltraViolet Imager

Nutrient enrichment is a major issue to many inland and coastal waterbodies worldwide, including Chesapeake Bay. River water quality integrates the spatial and temporal changes of watersheds and forms the foundation for disentangling the effects of anthropogenic inputs. However, many water-quality studies are focused on limited portions of the watershed or a subset of potential drivers. We demonstrate with the Chesapeake Bay Nontidal Monitoring Network (84 stations) that advanced machine learning approaches – i.e., hierarchical clustering and random forest – can be combined to better understand the regional patterns and drivers of total nitrogen (TN) trends in large monitoring networks. Cluster analysis revealed the regional patterns of short-term TN trends (2007-2018) and categorized the stations to three distinct clusters, namely, V-shape (n = 25), monotonic decline (n = 35), and monotonic increase (n = 26). Random forest models were developed to predict the clusters using watershed characteristics and major N sources, which provided information on regional drivers of TN trends. We show encouraging evidence that improved nutrient management has resulted in declines in agricultural nonpoint sources, which in turn contributed to water quality improvement. Additionally, water-quality improvements are more likely in watersheds underlain by carbonate rocks, reflecting the relatively quick groundwater transport of this terrain. However, TN trends are degrading in forested watersheds, suggesting new sources of N in forests. Finally, TN trends were predicted for the entire Chesapeake Bay watershed at the scale of 979 river segments, providing fine-level information that can facilitate targeted watershed management, especially in unmonitored areas. More generally, this combined use of clustering and classification approaches can be applied to other monitoring networks to address similar questions.

Oceanic Transform Faults (TF) comprise first order discontinuities bounded between mid-ocean ridge spreading centres. TF mainly accommodate strike slip motion, separating lithospheric plates of different age and thermal structure. Oceanic TF are intriguing in that they do not produce earthquakes as large as might be expected given their long length, with seismic slip corresponding only to a small fraction of the total tectonic slip. The relative geologic simplicity of oceanic TF means that they are an important analogue for more hazardous continental TF, with high potential for improving insights into the earthquake cycle. We investigate the earthquake properties along Chain, a ~300 km long TF in the equatorial MAR by combining both microseismic and teleseismic data. We use the ~1-year microseismicity data (total of 812 events) gathered during the PI-LAB (Passive Imaging of the Lithosphere-Asthenosphere Boundary) experiment and EURO-LAB (Experiment to Unearth the Rheological Lithosphere-Asthenosphere Boundary). We perform cluster analysis in multi-dimensional phase space, consisting of various seismic (epicentral coordinates, magnitude) and geophysical (gravity anomalies, bathymetry, tidal height) parameters. We investigate potential triggering mechanisms, including tidal, static and dynamic stresses. We extend our analysis back in time by considering stronger earthquakes (MW>~5.0) from Global Centroid Moment Tensor (GCMT) since 1976. We find three unique, 50-100 km long clusters or segments from our analysis going from east to west, separated by seismic gaps. Microseismic activity is highest at the eastern segment of Chain where there is the largest positive flower structure, negative rMBA gravity anomaly but very few M>5.5 events. The western segment has reduced seismicity rates relative to the eastern, and is associated with a positive rMBA and a few small flower structures. The central segment is bounded between two seismic gaps and demonstrates relatively high activity rates in the middle. Our result suggests that trans-pression of highly altered mantle/crust and/or high pore pressure due to hydrothermal fluid circulation in the eastern flower structure enhances seismic activity. Overall, we find the existence of consecutive locking and creeping segments, with some of the patches exhibiting hybrid behaviour, potentially causing their sporadic activation/reactivation.

The orbital history of Triton, coupled to its thermal evolution, and the role played from obliquity tides [1, 2], together with the ongoing geological activity [3] suggest a differentiated interior, with an outer ice shell, a possible sub-surface ocean, and a deep-rocky interior. Triton’s deep interior could be hydrated, as suggested for other icy satellites, such as Titan [4, 5]. Antigorite (density: 2.5-2.6 g/cm3) is the most evocated mineral to explain the low estimated average density of the deep interior of icy moons [5]. Nevertheless, a model of a hydrated deep interior must consider the chemical environment, the lithostatic pressure, and the internal temperature, which define by their own the resulting mineral assemblages. Methods We adopt the algorithm Perple_X [6] to produce a pseudosection (Fig.1), modelling the stability fields of several mineral phases at thermodynamical equilibrium, in the function of pressure (P) and temperature (T). We select as the initial bulk composition of a proto-Triton a chondritic material. Results Figure 1 shows an Orgueil-like bulk composition simulating the rocky deep interior composition in a hydrated scenario. In addition to antigorite, we found that the mineralogy of hydrated deep interior should be characterized by the primary phases: amphibole, chlorite, antigorite, and talc, for the expected temperature and pressure of Triton’s deep interior and at a temperature lower than 980 K. For higher temperature we found that hydrated phases dehydrate in olivine and pyroxenes, as main phases. We plan to investigate the role of volatiles and ices in modelling the mineralogy of the deep interior. Acknowledgments G.M. and C.C., acknowledge support from the Italian Space Agency (2020-13-HH.0). References [1] McKinnon, W. B. (1984). Nature, 311(5984), 355-358. [2] Nimmo, F., & Spencer, J. R. (2015). Icarus, 246, 2-10. [3] Hansen C.J., & Kirk R. (2015), 46th LPSC, 2423. [4] Fortes, A. D., et al. (2007). Icarus, 188(1), 139-153. [5] Castillo-Rogez J.C., Lunine J.I. (2010). Geophys. Res. Lett.37(20). [6] Connolly, J. A. D. (2005). Earth Planet Sci Lett, 236.1-2:524-541.

The new dual-frequency radar satellite ASAR-ISRO provide simultaneously and for the first time a wide wavelength spectrum which is critical to discriminate surface roughness based on different backscattering characteristics. Here we use such dual L-band and S-band airborne SAR system to characterize and map various volcanic areas in the Northern Cascades through their backscattering properties. Mapping volcanic flows (lava flows, pyroclastic currents, lahars) is vastly improved by using backscattering as a metric of surface roughness. Various types of volcanic flow deposits and surface textures are distinguished by their roughness measured with radar systems. The ability of radar systems to distinguish volcanic flow textures, represented by roughness, is a key factor in understanding the processes and timescales of flow emplacement. For instance, transition from pahoehoe to aa lava flows is associated with change in flux and steepness of topographic gradient. Therefore, lava textures are essential data for calibrating and improving lava flow emplacement codes. Similarly, the textures of high velocity, and more deadly, pyroclastic currents and lahars change along their flow paths, also revealing critical data about the mechanisms of flow emplacement. As with lava flows, we use the ASAR-ISRO L+S SAR system to characterize the run-out distances of pyroclastic currents and lahars where large numbers of blocks accumulate in such deposits (places where flow momentum was lost, whether due to friction or break-in-slope and vast quantities of blocks accumulate in a relatively small area compared to the total area inundated by the flow). Mapping volcanic flow textures in a variety of volcanic terrains will provide clues about modes and rates of emplacement, and change in these through time, in a way that is simply unavailable by traditional geologic mapping. The next generation of volcanic flow maps, used for hazard assessment, will rely on radar data to delineate these textures.

Oceanic lithosphere created at mid-ocean ridges (MOR) is shaped by a complex interplay of magmatic, tectonic and hydrothermal processes. Where melt budget decreases at (ultra)slow spreading rates, the tectonic mode changes from normal to detachment faulting. We investigate an endmember type of detachment faulting, the so-called “flip-flop” detachment mode, observed exclusively at almost amagmatic sections of ultraslow-spreading MORs (e.g. Southwest Indian Ridge 62°E to 65°E): Active detachments migrate across the ridge axis towards the hanging wall side until they are superseded by a new on-axis fault of opposite polarity. Using a steady-state temperature field, numerical experiments by Bickert et al. (EPSL, 2020, 10.1016/j.epsl.2019.116048) show that an axial temperature maximum is essential to trigger flip-flop faults by focusing flexural strain in the footwall of the active fault. However, ridge segments without a significant melt budget are more likely to be in a transient thermal state controlled, at least in part, by the faulting dynamics themselves. In our study we investigate (1) which processes have first order control on the thermal structure of the lithosphere, (2) their respective feedbacks on the mechanical evolution of the lithosphere, and (3) how they facilitate flip-flop detachment faulting. We present results of 2-D thermo-mechanical numerical modelling including serpentinization reactions and dynamic grain size evolution. The model features a novel form of parametrized hydrothermal cooling along fault zones as well as the thermal and rheological effects of periodic sill intrusions. We find that both hydrothermal cooling of the active fault zone and periodic sill intrusions in the footwall are essential for entering the flip-flop detachment mode. Hydrothermal cooling of the fault zone pushes the temperature maximum into the footwall, while intrusions near the temperature maximum further weaken the rock and facilitate the opening of new faults with opposite polarity. We conclude that this interplay of hydrothermal cooling and magmatic intrusions is required to produce the observed flip-flop faulting. Our model allows us to put constraints on the magnitude of both processes, and we obtain reasonable melt budgets and hydrothermal heat fluxes only if both are considered.

Origins of the interdecadal fluctuations of the ENSO-Indian summer monsoon (ISM) teleconnection strength measured by running window correlation coefficients have been much debated. The main question is whether it’s due mostly (i) to sampling errors, or, (ii) under internal variability decadal time scale drivers modulate it, and/or, (iii) it has undergone some forced change recently. A new statistical test does not detect any of (ii-iii) in observations. However, it does not mean that there could not be such effects, just that the data is insufficient. Large ensemble data sets are well suited to investigate these questions. Previously, (iii) was found to be small (even if possibly important) in the MPI-GE data set, and the situation is similar in the new CESM2-LE data set. This time we investigate (ii), too, and find that the decadal variability of e.g. the Dipole Mode Index (DMI*, decorrelated from Nino3) of the Indian Ocean “explains” 4% of the apparent variability of the ENSO-ISM teleconnection. If the CESM2-LE were faithful to reality, then this signal would take two millenia to have a 50% chance to detect. We also find that this apparent DMI* influence is due to heteroscedasticity, namely, to the apparent DMI* influence on ENSO variance. However, we also find that this influence is mostly apparent, indeed, as it is the ENSO variance that dominantly influences the DMI*.

The SuperCam instrument [1,2] onboard Mars2020 disposes of a variety of active and passive techniques, including passive spectroscopy in the 0.40-0.85 (VIS) and 1.3 to 2.6 microns (IR, [3,4]) wavelength ranges. Since the landing on Mars of Perseverance in February 2021, Supercam has acquired numerous observations of its near and distant environment, exploring the geological and mineralogical context of Jezero crater. In addition, several measurements were devoted to probing the atmosphere surrounding the Perseverance rover. The technique of using sky spectra in passive mode, known as “passive sky”, has already been demonstrated with ChemCam on the Mars Science Laboratory (MSL) rover [4]. SuperCam provides a superset of the ChemCam capabilities used in [4], and in particular adds a near-infrared component that includes absorption and scattering characteristics of key gases and aerosols/clouds. “Passive sky” measurements have typically been performed every other week to allow a consistent monitoring of the seasonal evolution of the main quantities (CO2, O2, H2O, CO, aerosols/clouds). Particular attention was given to joint measurements of O2 and CO, as they appear as key components of the Martian chemical cycle and have never been measured together at the same time on the surface of Mars. As the 2 μm wavelength region is used for the first time at the surface of Mars, it enables the detection of CO (around 2.35 μm). CO possesses a small absorption that has made it difficult to identify in SuperCam spectra so far. An overview of SuperCam’s progress to date in its attempt to characterize the Martian atmosphere at Jezero will be presented. References : [1] Wiens, R.C., et al. , 2021. Space Sci Rev 217, 4, [2] Maurice, S., et al., 2021. Space Sci Rev 217, 47, [3] Royer, C., et al.., 2020. Review of Scientific Instruments 91, 063105, [4] Fouchet, T., et al., 2021, Icarus, submitted. [5] McConnochie T. H et al., 2018. Icarus 307, 294

Terrestrial vegetation is known to be an important sink for carbon dioxide (CO2). However, fluxes to and from vegetation are often not accounted for when studying anthropogenic CO2 emissions in urban areas. This project seeks to quantify urban biogenic fluxes in the Greater Toronto and Hamilton Area located in Southern Ontario, Canada. Toronto is Canada’s most populated city but also has a large amount of green-space, covering approximately 13 % of the city. In addition, vegetation is not evenly distributed throughout the region. We therefore expect biogenic fluxes to play an important role in the spatial patterns of CO2 concentrations and the overall local carbon budget. In order to fully understand biogenic fluxes they can be partitioned into the amount of CO2 sequestered via photosynthesis, gross primary productivity (GPP), and the amount respired by vegetation, ecosystem respiration (Reco). Solar induced chlorophyll fluorescence (SIF) measured from space has been shown to be a valuable proxy for photosynthesis and thus can be used to estimate GPP. Vegetation models, including the Urban Vegetation Photosynthesis and Respiration Model (UrbanVPRM) and the SIF for Modelling Urban biogenic Fluxes (SMUrF) model, have also been used to estimate both GPP and Reco In this study we compare modelled and SIF-derived biogenic CO2 fluxes at a 500 m by 500 m resolution, to ground-based flux tower measurements in Southern Ontario to determine how well these methods estimate biogenic CO2 fluxes. This study works towards determining the importance of biogenic fluxes in the Greater Toronto and Hamilton Area. Furthermore, the results of this work may inform policy makers and city planners on how urban vegetation affects CO2 concentrations and patterns within cities.