Bottom-water hypoxia in the Paracas Bay (Peru, 13.8°S) associated with seasonal and synoptic time scale variability of winds and water stratification

International audienceCoastal hypoxia can occur naturally in inshore areas of the Eastern Boundary Upwelling Systems, influenced by the nutrient-rich and low-oxygen upwelling waters. This study aims to explore the influence of water stratification and winds on bottom-water hypoxia of the Paracas Bay, an area subjected to the most intense alongshore winds and active coastal upwelling in the Peruvian coast. Monitoring data of the Pisco-Paracas water properties (dissolved oxygen, temperature, salinity and estimated stratification), the Pisco River flow, and the intensities of surface winds of the outside upwelling area, and of the local area, were analysed for the period 2006 to 2015. Bottom waters deeper than 8 m in the bay were shown undergoing a hypoxic regime (oxygen <1.4 mL L−1) that becomes more frequent towards austral summer and less frequent towards winter. This seasonal difference was associated with changes in the oxygen content of incoming upwelling waters and changes in the intensity of both local and upwelling winds that drive the hydrodynamics of the bay. High frequency data analysis revealed that synoptic time-scale fluctuations of the upwelling-favourable and local winds modulate the intra-seasonal variability of hypoxia. Fluctuations of the former drive the inshore expansion of mixed and less hypoxic upwelling waters during June–September, whereas fluctuations of the latter during December–April drive the entrance and circulation of more hypoxic upwelling waters, and the development of stratification events that contribute to the persistence of bottom hypoxia

ARES VI: Are 1D retrieval models accurate enough to characterize exo-atmospheres with transmission spectroscopy in the era of JWST and Ariel?

International audienceThe observed exoplanets transit spectra are usually retrieved using one-dimensional models to determine atmospheric composition. However, planetary atmospheres are three-dimensional. With the new state-of-the-art James Webb Space Telescope (JWST) and future space telescopes such as Ariel (Atmospheric Remote-sensing Infrared Exoplanet Large-survey), we will be able to obtain increasingly accurate transit spectra. The 3D effects on the spectra will be visible, and we can expect biases in the 1D extractions. In order to elucidate these biases, we have built theoretical observations of transit spectra, from 3D atmospheric modeling through transit modeling to instrument modeling. For that purpose, we used a Global Climate Model (GCM) to simulate the atmosphere, a 3D-radiative transfer model to calculate theoretical transmission spectra, and adapted instrument software from JWST and Ariel to reproduce telescope noise. Next, we used a 1D-radiative transfer inversion model to retrieve the known input atmosphere and disentangle any biases that might be observed. The study has been done from warm planets to ultra-hot planets to assess biases as a function of average planet temperature. Three-dimensional effects are observed to be strongly non-linear from the coldest to the hottest planets. These effects also depend on the planet's metallicity and gravity. Considering equilibrium chemistry, 3D effects are observed through very strong variations for certain features of the molecule, or very small variations over the whole spectrum. We conclude that we cannot rely on the uncertainty of retrievals at all pressures, and that we must be cautious about the results of retrievals at the top of the atmosphere. However the results are still fairly close to the truth at mid altitudes (those probed). We also need to be careful about the chemical models used for planetary atmosphere. If the chemistry of one molecule is not correctly described, this will bias all the others, as well as the retrieved temperature. Finally, although fitting a wider wavelength range and higher resolution has been shown to increase retrievals accuracy, we show that this could depend on the wavelength range chosen, due to the accuracy on modeling the different features. In any case, 1D retrievals are still correct for the detection of molecules, even in the event of an erroneous abundance retrieval

Association between transportation noise exposure ans hypertension risk in the french E3N cohort

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Evapotranspiration partitioning based on underlying conductance in a complex tree-grass orchard ecosystem in the humid area of southern China

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Determination of the X-Auger electron spectroscopy evolution of indium in InSb by linear and nonlinear least squares approaches

International audienceX-ray photoelectron spectroscopy is a major and valuable chemical analysis technique that can bring a wide range of information if one takes time to carefully interpret the spectra. In particular, many metrological developments deal with the modeling of photoelectron peaks while X-Auger transitions still remain hardly exploited. Here, an innovative approach examining these spectral features in a complementary way is presented and illustrated on a concrete case dealing with chemical changes of indium in the InSb semiconductor during its air aging. Indium contains an extensive range of photopeaks along the energy scale, meaning electrons emitted from different escape depths are present on the same widescan spectrum, and, thus, information from different depths is accessible. Specifically, this study focuses on indium’s X-Auger electron spectroscopy (X-AES) transitions and decomposition to track the outer surface chemistry evolution of the InSb semiconductor. To this end, we compared linear and nonlinear least-squares approaches to decompose In M4,5N4,5N4,5 X-AES transition and demonstrate oxide growth progression. For both approaches, we applied the vectorial method (also known as the informed amorphous sample model) to retrieve the different chemical environments present during air aging. Linear and nonlinear least-squares approaches were both found to yield comparable results, with a comparative error of less than 10%. Over time, a progressive growth of the oxide layer was demonstrated, ranging from 0.3 ± 0.2 to 2.9 ± 0.2 nm using the X-AES transitions. Additionally, decomposition of the In 3d and In 4d photoelectron peaks showed a lower thickness of oxide with time due to the lesser surface sensitivity of these peaks

Le travail des gens de théâtre

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Calibration of omnidirectional wave height spectra by SWIM through an BU-Net

International audienceSWIM can provide global wave spectra, but under small sea conditions, the presence of parasitic peaks at low wavenumber, surfboard effects, and residual speckle noise lead to performance degradation of SWIM wave height spectrum products. To reduce the impacts of the factors above on SWIM wave height spectrum, in this paper, a convolution neural network (CNN) method based on BU-Net is proposed for calibrating SWIM omnidirectional wave height spectra with buoy measurements under sea states (wind wave mainly/swell mainly) and sea surface conditions (wind speed from 9m/s to 19m/s, significant wave height from 0.8m to 3.4m∼4.2m). The calibration results show that the impact of the factors above on SWIM omnidirectional wave height spectrum can be corrected. The correlation coefficients between the corrected SWIM beams 6°, 8°, 10 °and the buoy mean omnidirectional wave height spectrum are all greater than 0.90, and the relative error of the peak wave number is within 10%. The relative error of the integrated energy is mostly less than 20%. In addition, the performance of spectral integration parameters (effective wave height Hs, energy wave period Tm-10) of each spectral beam of SWIM has been verified using MFWAM reanalysis data. The validation results show that RMSE of the Hs and Tm-10, for the corrected SWIM beam 6 °(8 °, 10 °) under wind wave sea conditions are 0.31m (0.32m, 0.25m) and 0.50s (0.51s, 0.49s) respectively; those for swell cases are 0.16m (0.16m, 0.13m) and 0.87s (0.77s, 0.72s), respectively

Stop in the Name of the Law: The Legal Regulation of Police Stops in Europe

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Changing Climate Threatens Irrigation Benefits of Maize Gross Primary Productivity in China

International audienceChina has the largest area of irrigated maize and the second-largest irrigated area in the world (Food and Agriculture Organization of the United Nations, 2021). Almost 50% of the arable land (up to 70 million ha) is fully equipped with irrigation infrastructure, and contributes 75% of the national grain production (China Statistical Yearbook, 2021). Maize is one of the most important staple crops in China, providing plentiful food and animal feed, and accounting for over 30% of the national grain production (Liu et al., 2012; Luo et al., 2023). One-third (∼14 million ha) of the maize planting area is located in the more productive irrigation districts, that is, the majo