Modeling ice shelf cavities in a z coordinate ocean general circulation model

Abstract. Processes at the ice shelf-ocean interface and in particular in ice shelf cavities around Antarctica have an observable effect on the solutions of basin scale to global coupled ice-ocean models. Despite this, these processes are not routinely represented in global ocean and cli-mate models. It is shown that a new ice shelf cavity model for z-coordinate models can re-produce results from an intercomparison project of earlier approaches with vertical σ- or isopy-cnic coordinates. As a proof of concept, ice shelves are incorporated in a 100 year global in-tegration of a z-coordinate model. In this simulation, glacial melt water can be traced as far as north as 15 ◦ S. The observed effects of processes in the ice shelf cavities agree with pre-vious results from a σ-coordinate model, notably the increase in sea ice thickness. However, melt rates are overestimated probably because the parameterization of basal melting does not suit the low resolution of this configuration. 1

Potential Contribution of Payments for Ecological Goods and Services to Farm Income

Agri-environmental payments are part of a re-instrumentation of farm support in some developed countries. In general, they are meant to contribute to the cost of meeting regulations, compensate for income lost by adopting certain practices, and reward farmers for providing environmental services. In this context, agri-environmental payments are seen as a vehicle which could potentially contribute to meet the double objectives of providing environmental benefits to society while supporting farm income. Such agri-environmental payments are gaining importance in the policy portfolio of certain countries in response to higher social expectations with respect to the environmental performance of the agricultural sector as well as in response to international agreements constraining the use of trade-distorting support measures. The present study sheds some light on limited international experience by assessing the contribution that payments for ecological goods and services make to farm income in Switzerland, France and the Walloon region of Belgium. Results show that the contribution from agri-environmental payments to farm income differs from country to country, is modest and commensurate with the additional costs incurred by agricultural producers.Agricultural and Food Policy, Environmental Economics and Policy,

Advances in planetary sustainability.

In the 21st century, existing human societies and biodiversity on the Earth are under threat because human resource consumption is exceeding or projected to exceed some of the physical and chemical boundaries of our planet (Rockström et al., 2009). Space research and space exploration are an integral part of a sustainable development that mitigates these threats: Space science and exploration allow us to monitor environmental threats and they open up access to global communication and participation for all human societies. In addition, space exploration also promises to expand the existing limitations and planetary boundaries imposed on human development. On the other hand space exploration can also cause additional environmental problems. The best known example for the latter is the anthropogenic space debris orbiting Earth, but similar problems are likely to occur in other places, for instance on the Moon, due to scientific and commercial space exploration in the near future. Planetary sustainability is a helpful concept to address the promises and challenges posed by space exploration with respect to sustainability. This concept can be understood as a sustainable development that considers the Earth as a planet in its space environment and considers the space environment as an integral part of sustainable development, with scientific, ethical, economic, and legal ramifications. In this article we review the recent advancements in planetary sustainability. This includes the proposal that the space environment of Earth should be added as an independent goal to the existing 17 Sustainable Development Goals defined by the United Nations, considerations of the planned return of humans to the Moon in 2024, and the implications of the increase of commercial satellite networks in low Earth orbit

Combining Stationary Ocean Models and Mean Dynamic Topography Data

In this study, a new estimate for the Mean Dynamic Topography (MDT) and its error description is analysed in terms of its impact on the performance of ocean models. For the first time, a full MDT error covariance matrix is available whose inverse can readily be used as weighting matrix in the optimization. Two different steady-state inverse ocean models are analysed in terms of their response to the new MDT data set. The output of each of these ocean models in turn provides a combined satellite-ocean model MDT. This study investigates whether the inverse ocean models benefit from the new MDT data set and its error covariance. It is examined whether oceanographic features such as the ocean current structure, the overturning circulation and heat transports are improved by the assimilated MDT data set. Special focus is given to the MDT error covariance estimate as it is crucial in the optimization

Optical signatures of a fully dark exciton condensate

We propose optical means to reveal the presence of a dark exciton condensate that does not yield any photoluminescence at all. We show that (i) the dark exciton density can be obtained from the blueshift of the excitonic absorption line induced by dark excitons; (ii) the polarization of the dark condensate can be deduced from the blueshift dependence on probe photon polarization and also from Faraday effect, linearly polarized dark excitons leaving unaffected the polarization plane of an unabsorbed photon beam. These effects result from carrier exchanges between dark and bright excitons.Comment: 5 pages, 4 figure

Soft-tissue specimens from pre-European extinct birds of New Zealand

We provide the first complete review of soft tissue remains from New Zealand birds that became extinct prior to European settlement (c. AD 1800). These rare specimens allow insights into the anatomy and appearance of the birds that are not attainable from bones. Our review includes previously unpublished records of ‘lost’ specimens, and descriptions of recently discovered specimens such as the first evidence of soft tissues from the South Island goose (Cnemiornis calcitrans). Overall, the soft tissue remains are dominated by moa (with specimens from each of the six genera), but also include specimens from Finsch's duck (Chenonetta finschi) and the New Zealand owlet-nightjar (Aegotheles novaezealandiae). All desiccated soft tissue specimens that have radiocarbon or stratigraphic dates are late Holocene in age, and most have been found in the semi-arid region of Central Otago