A numerical model of mesoscale frontal instabilities and plankton dynamics - I. Model formulation and initial experiments

Previous observational and modelling studies of open ocean frontal regions have found large vertical velocities associated with instabilities on the frontal jet. A combined physical/ecosystem numerical model is used to investigate the impact of jet instability and the associated vertical motions on the local ecosystem. The evolution of the instability of a mesoscale frontal jet gives rise to vertical transport of nutrients into the euphotic zone and subduction of biota out of the euphotic zone. The upwelling of nutrients stimulates increases in primary production, with resulting increases in phytoplankton stocks. The reaction of the ecosystem is found to be dependent on the physical characteristics of the front, but the increase in primary production can be locally of the order of 100%, and of the order of 10% when averaged over the frontal region. The action of upwelling and subduction introduces spatial heterogeneity in primary production and plankton biomass. The heterogeneity is at a variety of length scales, from the order of a few kilometres for thin filaments and up to 50 km for coherent features. With increases in new production occurring over several degrees of latitude, frontal dynamics may make a significant contribution to the strength of the biological pump

Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model

The continued increase in the atmospheric concentration of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. About half of the current emissions are being absorbed by the ocean and by land ecosystems, but this absorption is sensitive to climate as well as to atmospheric carbon dioxide concentrations, creating a feedback loop. General circulation models have generally excluded the feedback between climate and the biosphere, using static vegetation distributions and CO2 concentrations from simple carbon-cycle models that do not include climate change. Here we present results from a fully coupled, three-dimensional carbon–climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a 'business as usual' scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt C yr-1 is balanced by the terrestrial carbon source, and atmospheric CO2 concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon models, resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback

Search for new resonances decaying to a WW or ZZ boson and a Higgs boson in the ℓ+ℓ−bbˉ\ell^+ \ell^- b\bar b, ℓνbbˉ\ell \nu b\bar b, and ννˉbbˉ\nu\bar{\nu} b\bar b channels with pppp collisions at s=13\sqrt s = 13 TeV with the ATLAS detector

See paper for full list of authors, 18 pages (plus author list + cover pages: 36 pages total), 13 figures, 1 table. Submitted to PLB. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2015-18/International audienceA search is presented for new resonances decaying to a $W$ or $Z$ boson and a Higgs boson in the $\ell^+ \ell^- b\bar b$, $\ell\nu b\bar b$, and $\nu\bar{\nu} b\bar b$ channels in $pp$ collisions at $\sqrt s = 13$ TeV with the ATLAS detector at the Large Hadron Collider using a total integrated luminosity of 3.2 fb$^{-1}$. The search is conducted by looking for a localized excess in the $WH$/$ZH$ invariant or transverse mass distribution. No significant excess is observed, and the results are interpreted in terms of constraints on a simplified model based on a phenomenological Lagrangian of heavy vector triplets