Similarity scaling of jet noise sources for low-order jet noise modelling based on the Goldstein generalised acoustic analogy

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors are grateful to the UK Government for supporting the SILOET program during which the model-scale data were acquired in the QinetiQ NTF and Dr Paul Strange (Rolls-Royce Plc) for facilitating access to these data. The work has been partially supported by the UK Engineering and Physical Sciences Research Council (EP/I017747/1) and partially by Aero Acoustics Research Consortium (AARC)

Airfoil flow and noise computation using monotonically integrated large eddy simulation and acoustic analogy: Effect of the grid resolution.

A new scalable Monotonically Integrated Large Eddy Simulation (MILES) method based on the Compact Accurately Boundary-Adjusting high-REsolution Technique (CABARET) has been applied for the simulation of unsteady flow around NACA0012 airfoil at Re = 400,000 and M = 0.058. The flow solution is coupled with the Ffowcs Williams-Hawkings formulation for far-field noise prediction. The computational modeling results are presented for several computational grid resolutions: 8, 16, and 32 million grid cells and compared with the experimental data available

North Siberian lakes: A methane source fueled by pleistocene carbon

The sizes of major sources and sinks of atmospheric methane (CH4), an important greenhouse gas, are poorly known. CH4 from north Siberian lakes contributes ~1.5 teragrams CH4 year+1 to observed winter increases in atmospheric CH4 concentration at high northern latitudes. CH4 emitted from these lakes in winter had a radiocarbon age of 27,200 years and was derived largely from Pleistocene-aged carbon

North Siberian lakes: A methane source fueled by pleistocene carbon

The sizes of major sources and sinks of atmospheric methane (CH ), an important greenhouse gas, are poorly known. CH from north Siberian lakes contributes ~1.5 teragrams CH year to observed winter increases in atmospheric CH concentration at high northern latitudes. CH emitted from these lakes in winter had a radiocarbon age of 27,200 years and was derived largely from Pleistocene-aged carbon. 4 4 4 4 4 +

Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia

The future trajectory of greenhouse gas concentrations depends on interactions between climate and the biogeosphere. Thawing of Arctic permafrost could release significant amounts of carbon into the atmosphere in this century. Ancient Ice Complex deposits outcropping along the ĝ̂1/47,000- kilometre-long coastline of the East Siberian Arctic Shelf (ESAS), and associated shallow subsea permafrost, are two large pools of permafrost carbon, yet their vulnerabilities towards thawing and decomposition are largely unknown. Recent Arctic warming is stronger than has been predicted by several degrees, and is particularly pronounced over the coastal ESAS region. There is thus a pressing need to improve our understanding of the links between permafrost carbon and climate in this relatively inaccessible region. Here we show that extensive release of carbon from these Ice Complex deposits dominates (57ĝ€‰ ±ĝ€‰2 per cent) the sedimentary carbon budget of the ESAS, the worldĝ€™s largest continental shelf, overwhelming the marine and topsoil terrestrial components. Inverse modelling of the dual-carbon isotope composition of organic carbon accumulating in ESAS surface sediments, using Monte Carlo simulations to account for uncertainties, suggests that 44ĝ€‰ ±ĝ€ ‰10 teragrams of old carbon is activated annually from Ice Complex permafrost, an order of magnitude more than has been suggested by previous studies. We estimate that about two-thirds (66ĝ€‰ ±ĝ€‰16 per cent) of this old carbon escapes to the atmosphere as carbon dioxide, with the remainder being re-buried in shelf sediments. Thermal collapse and erosion of these carbon-rich Pleistocene coastline and seafloor deposits may accelerate with Arctic amplification of climate warming