Seamount Observatory and SAMOC Overturning, Cruise No. MSM60, January 04 - February 01, 2017, Cape Town (South Africa) - Montevideo (Uruguay)

The scientific program of the MARIA S. MERIAN MSM60 expedition was the first basin-wide section across the South Atlantic following the SAMBA/SAMOC line at 34°30'S. The scientific program consisted of full water depth sampling (up to 5300m) using the CTD/O2/lADCP rosette system. The water samples have been analysed on board for oxygen, dissolved inorganic carbon, alkalinity, salinity, CFC12, and SF6. In addition samples have been taken for later analysis of nutrients, chlorophyll structure (HPLC), POC, and nitrogen isotope analysis. The sampling and measurements where performed against highest standards defined in the GO-SHIP cruise recommendations (http://www.go-ship.org/). An Underwater Vision Profiler (UVP) was mounted on the CTD for full depth particle photography. Underway measurements included hull mounted ADCPs (75kHz and 38kHz) and high resolution (11nm) XBT probes. The data will be analysed for multiple purposes including calculation of the meridional volume, heat, and freshwater transport across the SAMBA/SAMOC line. The biogeochemical data will be compared to historical data acquired at neighbouring sections, e.g. along the WOCE/GO-SHIP A10 section (30°S) occupied by RV Meteor in 1993 as part of the WOCE program. The MSM60 expedition is a contribution to the EU H-2020 AtlantOS project

Cross sections for vibrational excitation of H2(X 1Σ +g, ν" = 0) via electronically excited singlet states populated by low energy electron impact

Absolute cross sections are calculated for excitation of hydrogen, H 2(X 1Σ+g, v" = 0), on its different vibrational levels, by radiative decay from the B, B', C, and D electronic singlet states first populated by low energy electron collisions. The cross sections present a maximum around 50 electron-volts, but about 20 to 40 % higher than those reported by Hiskes considering the same excitation process only through the B and C electronic singlet states.Les sections efficaces d'excitation vibrationnelle de H2(X 1Σ+g , v" = 0) après passage sur les niveaux électroniques singulets B, B', C et D et retombée radiative sur les différents niveaux vibrationnels de l'état fondamental sont calculées en fonction de l'énergie des électrons (0-150 eV) pouvant créer cette excitation indirecte. Des maxima apparaissent vers 50 eV et sont environ 20 à 40 % plus élevés que ceux obtenus par Hiskes en ne tenant compte que de l'excitation électronique des niveaux B et C

Étude numérique et expérimentale de la structure de l'écoulement autour d'une sphère placée dans un écoulement raréfié

International audienc

Monoenergetic seeded nozzle beams up to 35 eV

SIGLEAvailable from CEN Saclay, Service de Documentation, 91191 Gif-sur-Yvette Cedex (France) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Rovibrational state population distributions calculated from spontaneous fluorescence measurements for CO (v<4, J<10) in highly heated supersonic free jets of CO in N and Ar

SIGLEAvailable from CEN Saclay, Service de Documentation, 91191 - Gif-sur-Yvette Cedex (France) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Reconciling Observation and Model Trends in North Atlantic Surface CO2

The North Atlantic Ocean is a region of intense uptake of atmospheric CO2. To assess how this CO2 sink has evolved over recent decades, various approaches have been used to estimate basin-wide uptake from the irregularly sampled in situ CO2 observations. Until now, the lack of robust uncertainties associated with observation-based gap-filling methods required to produce these estimates has limited the capacity to validate climate model simulated surface ocean CO2 concentrations. After robustly quantifying basin-wide and annually varying interpolation uncertainties using both observational and model data, we show that the North Atlantic surface ocean fugacity of CO2 (fCO(2-ocean)) increased at a significantly slower rate than that simulated by the latest generation of Earth System Models during the period 1992-2014. We further show, with initialized model simulations, that the inability of these models to capture the observed trend in surface fCO(2-ocean) is primarily due to biases in the models' ocean biogeochemistry. Our results imply that current projections may underestimate the contribution of the North Atlantic to mitigating increasing future atmospheric CO2 concentrations