Turbulent Aeroheating Measurements on a 7-deg Half-Angle Sphere-Cone in a High-Enthalpy CO2 Expansion Tunnel

A database of heating and pressure measurements on a 7-deg half-angle cone in a highenthalpy expansion tunnel in CO2 has been generated to support development and validation of computational models to be employed in the design of future Mars missions. Laminar, transitional, and turbulent simulations were performed at the test conditions for comparisons with the data. Close agreement was obtained for both fully-laminar and fully turbulent conditions. For the remaining transitional/turbulent conditions, agreement to within, or slightly more than, the estimated experimental uncertainty was demonstrated. The influence of transition intermittency and transition length models on predicted heating levels was demonstrated, as were differences in turbulent heating predictions generated using various algebraic, one-equation, and two-equation turbulence models. These comparisons provide some measure of confidence in turbulent simulation capabilities; however, because the data were not obtained on a relevant entry vehicle geometry, it is not possible to fully quantify computational uncertainties for the definition of Mars mission aerothermodynamic environments at this tim

Winter-to-summer transition of Arctic sea ice breakup and floe size distribution in the Beaufort Sea

Breakup of the near-continuous winter sea ice into discrete summer ice floes is an important transition that dictates the evolution and fate of the marginal ice zone (MIZ) of the Arctic Ocean. During the winter of 2014, more than 50 autonomous drifting buoys were deployed in four separate clusters on the sea ice in the Beaufort Sea, as part of the Office of Naval Research MIZ program. These systems measured the ocean-ice-atmosphere properties at their location whilst the sea ice parameters in the surrounding area of these buoy clusters were continuously monitored by satellite TerraSAR-X Synthetic Aperture Radar. This approach provided a unique Lagrangian view of the winter-to-summer transition of sea ice breakup and floe size distribution at each cluster between March and August. The results show the critical timings of a) temporary breakup of winter sea ice coinciding with strong wind events and b) spring breakup (during surface melt, melt ponding and drainage) leading to distinctive summer ice floes. Importantly our results suggest that summer sea ice floe distribution is potentially affected by the state of winter sea ice, including the composition and fracturing (caused by deformation events) of winter sea ice, and that substantial mid-summer breakup of sea ice floes is likely linked to the timing of thermodynamic melt of sea ice in the area. As the rate of deformation and thermodynamic melt of sea ice has been increasing in the MIZ in the Beaufort Sea, our results suggest that these elevated factors would promote faster and more enhanced breakup of sea ice, leading to a higher melt rate of sea ice and thus a more rapid advance of the summer MIZ

Potential climatic transitions with profound impact on Europe

We discuss potential transitions of six climatic subsystems with large-scale impact on Europe, sometimes denoted as tipping elements. These are the ice sheets on Greenland and West Antarctica, the Atlantic thermohaline circulation, Arctic sea ice, Alpine glaciers and northern hemisphere stratospheric ozone. Each system is represented by co-authors actively publishing in the corresponding field. For each subsystem we summarize the mechanism of a potential transition in a warmer climate along with its impact on Europe and assess the likelihood for such a transition based on published scientific literature. As a summary, the ‘tipping’ potential for each system is provided as a function of global mean temperature increase which required some subjective interpretation of scientific facts by the authors and should be considered as a snapshot of our current understanding. <br/

Exploring the Sea Urchin Neuropeptide Landscape by Mass Spectrometry

Neuropeptides are essential cell-to-cell signaling messengers and serve important regulatory roles in animals. Although remarkable progress has been made in peptide identification across the Metazoa, for some phyla such as Echinodermata, limited neuropeptides are known and even fewer have been verified on the protein level. We employed peptidomic approaches using bioinformatics and mass spectrometry (MS) to experimentally confirm 23 prohormones and to characterize a new prohormone in nervous system tissue from Strongylocentrotus purpuratus, the purple sea urchin. Ninety-three distinct peptides from known and novel prohormones were detected with MS from extracts of the radial nerves, many of which are reported or experimentally confirmed here for the first time, representing a large-scale study of neuropeptides from the phylum Echinodermata. Many of the identified peptides and their precursor proteins have low homology to known prohormones from other species/phyla and are unique to the sea urchin. By pairing bioinformatics with MS, the capacity to characterize novel peptides and annotate prohormone genes is enhanced. Graphical Abstract.status: publishe

Experiments in numerical studies of low density and real gas effects on regions of shock wave/boundary layer interaction in hypervelocity flows /

Experiments with extensive numerical simulations were conducted examining effects of low density flows and real gas effects on aerothermal characteristics of flows in hypervelocity facilities and in simple and complex flowfields in hypervelocity flows. These studies demonstrated that in the absence of real gas effects the DSMC and Navier-Stokes solutions accounting for slip effects were in excellent agreement with measurements. An extensive series of calibration and validation studies were done defining the free stream flows in the LENS I and X tunnels for low density and high enthalpy flows at velocities up to 16,000 ft/s. Measurements on double cone configuration showed that above 13,000 ft/s the interaction regions differed significantly in nitrogen and air flows; while the computations agreed with the measurements in nitrogen, they differed significantly in the size and properties of interaction regions in air. With the shuttle configuration, we demonstrated that real gas effects decrease the size of a separated interaction region over the flap, reduce the pressure over the adjacent curved surfaces, and reduce Reynolds number for onset of boundary layer transition.Photocopy."June 30, 2006.""Final Report : April 2003 -- October 2006."Includes bibliographic refereces (pages 66-67).Experiments with extensive numerical simulations were conducted examining effects of low density flows and real gas effects on aerothermal characteristics of flows in hypervelocity facilities and in simple and complex flowfields in hypervelocity flows. These studies demonstrated that in the absence of real gas effects the DSMC and Navier-Stokes solutions accounting for slip effects were in excellent agreement with measurements. An extensive series of calibration and validation studies were done defining the free stream flows in the LENS I and X tunnels for low density and high enthalpy flows at velocities up to 16,000 ft/s. Measurements on double cone configuration showed that above 13,000 ft/s the interaction regions differed significantly in nitrogen and air flows; while the computations agreed with the measurements in nitrogen, they differed significantly in the size and properties of interaction regions in air. With the shuttle configuration, we demonstrated that real gas effects decrease the size of a separated interaction region over the flap, reduce the pressure over the adjacent curved surfaces, and reduce Reynolds number for onset of boundary layer transition.Report prepared by CUBRC, Buffalo, New York, under contract no.Mode of access: Internet