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This study proposes a first conceptual model for the hydrogeological functioning of the Tindouf Aquifer System (TAS) building upon geomorphological, geological and hydrological remotely sensed and ground observations. Exploratory sketches of the piezometric contours for the main aquifers of the TAS identified (i) recharge areas on the Anti-Atlas relief and the Hamada plateau, (ii) and discharge areas mainly located in the southeastern region where countless salt pans associated with groundwater evaporation were observed. The latter confirms a chiefly endorheic functioning of the TAS. A basin-scale groundwater balance based on gravity data from the Gravity Recovery And Climate Experiment (GRACE) was established to estimate values of the different terms of the hydrogeological water budget of the TAS. A recharge at $0.8\pm 0.2$ mm${\cdot }$yr$^{-1}$, an evaporation at $0.9\pm 0.2$ mm${\cdot }$yr$^{-1}$ and GRACE-derived groundwater depletion at $-0.7\pm 0.1$ mm${\cdot }$yr$^{-1}$ due to pumping and evaporation in excess of lateral groundwater flow are obtained.

The Djeffara plain, extending over Tunisia and Libya $(\mbox {48,000}~\mathrm{km}^{2})$, experiences unsustainable exploitation of groundwater, the severity of which needs to be determined. Here, we used data from Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) to assess the groundwater storage variation $(\Delta \mathrm{GWS})$ for the period 2002–2016. $\Delta \mathrm{GWS}$ values, downscaled over a $0.5\text{°}\times 0.5\text{°}$ grid using pumping wells spatial distribution and rates, were introduced in a discrete set of groundwater and salt budget equations to ascertain the recharge and the coastal fluxes. An average recharge of $4.3\pm 2.7~\mathrm{mm}{\cdot }\mathrm{yr}^{-1}$ representing $2.2\pm 1.4\%$ of the domain-averaged annual rainfall was obtained. A saline intrusion of $147.3\times 10^6$ and $46.9\times 10^6~\mathrm{m}^{3}{\cdot }\mathrm{yr}^{-1}$ was calculated for the Tripoli (Libya) and Djerba (Tunisia) areas, respectively. The overall Submarine Groundwater Discharge (SGD) of freshwater along the 450 km long Djeffara coast represents about $339.6\times 10^6~\mathrm{m}^{3}{\cdot }\mathrm{yr}^{-1}$ for the 2002–2016 period.

The Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission will carry into space the Ocean Color Instrument (OCI), a spectrometer measuring at 5nm spectral resolution in the ultraviolet (UV) to near infrared (NIR) with additional spectral bands in the shortwave infrared (SWIR), and two multi-angle polarimeters that will overlap the OCI spectral range and spatial coverage, i. e., the Spectrometer for Planetary Exploration (SPEXone) and the Hyper-Angular Rainbow Polarimeter (HARP2). These instruments, especially when used in synergy, have great potential for improving estimates of water reflectance in the post Earth Observing System (EOS) era. Extending the top-of-atmosphere (TOA) observations to the UV, where aerosol absorption is effective, adding spectral bands in the SWIR, where even the most turbid waters are black and sensitivity to the aerosol coarse mode is higher than at shorter wavelengths, and measuring in the oxygen A-band to estimate aerosol altitude will enable greater accuracy in atmospheric correction for ocean color science. The multi-angular and polarized measurements, sensitive to aerosol properties (e.g., size distribution, index of refraction), can further help to identify or constrain the aerosol model, or to retrieve directly water reflectance. Algorithms that exploit the new capabilities are presented, and their ability to improve accuracy is discussed. They embrace a modern, adapted heritage two-step algorithm and alternative schemes (deterministic, statistical) that aim at inverting the TOA signal in a single step. These schemes, by the nature of their construction, their robustness, their generalization properties, and their ability to associate uncertainties, are expected to become the new standard in the future. A strategy for atmospheric correction is presented that ensures continuity and consistency with past and present ocean-color missions while enabling full exploitation of the new dimensions and possibilities. Despite the major improvements anticipated with the PACE instruments, gaps/issues remain to be filled/tackled. They include dealing properly with whitecaps, taking into account Earth-curvature effects, correcting for adjacency effects, accounting for the coupling between scattering and absorption, modeling accurately water reflectance, and acquiring a sufficiently representative dataset of water reflectance in the UV to SWIR. Dedicated efforts, experimental and theoretical, are in order to gather the necessary information and rectify inadequacies. Ideas and solutions are put forward to address the unresolved issues. Thanks to its design and characteristics, the PACE mission will mark the beginning of a new era of unprecedented accuracy in ocean-color radiometry from space.

On glacial‐interglacial time scales, changes in the Earth's orbital configuration control climate seasonality and mean conditions. Tropical coral skeletons can be sampled at a sufficient resolution to reconstruct past seasonality. Here, last deglacial Porites skeletons from Integrated Ocean Drilling Program Expedition 310 to Tahiti are investigated and, supported by a modern calibration, monthly resolved time series in geochemical proxies (Sr/Ca, δ18O, δ13C) are constructed. For most of the deglaciation, Sr/Ca seasonality was similar to modern (0.139 ± 0.010 mmol mol−1; 2.8 ± 0.2°C) reflecting the small change in insolation seasonality. However, during the Younger Dryas, high values in Sr/Ca seasonality (0.171 ± 0.017 mmol mol−1; 3.4 ± 0.3°C) suggest a reduced mixed layer depth and enhanced influence of the South Pacific Subtropical Gyre due to South Pacific Convergence Zone (SPCZ) inactivity. Furthermore, high amplitudes in Younger Dryas skeletal δ18O (0.40 ± 0.22 ‰) and δ13C (0.86 ± 0.22 ‰) seasonality compared to modern (δ18O = 0.29 ± 0.08 ‰; δ13C = 0.27 ± 0.08 ‰) point to elevated winter‐summer discrepancies in rainfall and runoff. Mean coral Sr/Ca variability suggests an influence of Northern Hemisphere climate events, such as the Younger Dryas cooling (+0.134 ± 0.012 mmol mol−1;−2.6 ± 0.2°C), or the Bølling–Allerød warming (+0.032 ± 0.040 mmol mol−1; −0.6 ± 0.4°C). Deglacial mean coral Δδ18O (δ18Oseawater contribution to skeletal δ18O), corrected for the ice volume effect, was elevated pointing to more saline, thus dryer conditions, likely due to a northward migration of the SPCZ. Seasonal cycles in coral δ13C were likely caused by variations in linear extension rates that were reduced during the last deglaciation (1.00 ± 0.6 cm year−1) compared to today (1.6 ± 0.3 cm year−1). Plain Language Summary: Changes in the Earth's movement around the sun are the primary cause of changes in the annual cycle and annual mean of environmental conditions during the last glacial‐interglacial periods. Distinct from most climate archives, the annual bands of coral skeletons can be sampled at a monthly resolution that allows for reconstructions of past seasonal cycles. In this study, the chemical composition of coral skeletons from the genus Porites that grew during the last deglaciation at Tahiti (∼15,000–9,000 years ago) was analyzed to infer seasonal variations and mean conditions in past sea surface temperature and salinity. Prior to application, the methods were successfully calibrated using modern coral skeletons from Tahiti. Results showed that sea surface temperature seasonality was similar to today during most of the deglaciation. However, for the Younger Dryas, a particular cold interval, a marked increase in sea surface temperature seasonality suggests that Tahiti was at that time located outside the South Pacific Convergence Zone, a rain band extending across the tropical Southwest Pacific. Furthermore, coral reconstructions revealed that, although distant, North Atlantic last deglacial climate events influenced mean climate conditions at Tahiti. In addition, we show that last‐deglacial coral growth rates were reduced compared to today. Key Points: Last deglacial changes in Tahiti coral Sr/Ca suggest an influence of Northern‐Hemisphere climate events on the tropical South PacificVariations in last deglacial Tahitian climate were modulated by meridional migrations of the South Pacific Convergence ZoneLast deglacial Porites corals revealed reduced linear extension rates (1.0 ± 0.6 cm year−1) compared to today (1.6 ± 0.3 cm year−1) [ABSTRACT FROM AUTHOR]

Background: Internationally, there is a growing interest in the potential benefits of psilocybin-assisted therapy to treat existential distress at the end of life. However, the social acceptability of this therapy is not yet well known. Aim: This study assesses the social acceptability of the medical use of psilocybin to treat existential distress at the end of life. Design: An online survey was conducted in Canada between November 23 and December 4, 2022. The questionnaire included items pertaining to perceptions, attitudes and concerns towards psilocybin-assisted therapy to treat existential distress at the end of life. Participants: The sample (n = 2800) was stratified by province, age and sex. Participants were adults from four provinces of Canada: Québec, Ontario, Alberta and British Columbia. Results: Overall, 79.3% considered psilocybin-assisted therapy a reasonable medical choice for a patient suffering from existential distress at the end of life, 84.8% agreed that the public health system should cover the costs of the intervention and 63.3% would welcome the legalisation of psilocybin for medical purposes. Previous psilocybin use (p < 0.0001, for all dependent variables), exposure to palliative care (p < 0.05, for all dependent variables) and a progressive political orientation (p < 0.05, for all dependent variables) were associated with more favourable attitudes towards psilocybin-assisted therapy at the end of life. Conclusion: The social acceptability of psilocybin-assisted therapy for existential distress at the end of life is rather high in Canada. These findings may contribute to efforts to mobilise resources and improve access to this emerging therapy in palliative and end of life care settings. [ABSTRACT FROM AUTHOR]