A global low order spectral model designed for climate sensitivity studies

A two level, global, spectral model using pressure as a vertical coordinate is developed. The system of equations describing the model is nonlinear and quasi-geostrophic. A moisture budget is calculated in the lower layer only with moist convective adjustment between the two layers. The mechanical forcing of topography is introduced as a lower boundary vertical velocity. Solar forcing is specified assuming a daily mean zenith angle. On land and sea ice surfaces a steady state thermal energy equation is solved to calculate the surface temperature. Over the oceans the sea surface temperatures are prescribed from the climatological average of January. The model is integrated to simulate the January climate

The effect of pre-exposure on family resemblance categorization for stimuli of varying levels of perceptual difficulty

This study investigated the effect that pre-exposure to a set of stimuli has on the prevalence of family resemblance categorization. 64 participants were tested to examine the effect that pre-exposure type (same-stimuli vs unrelated-stimuli) and the perceptual difficulty of the stimuli (perceptually similar vs perceptually different) has on categorization strategy. There was a significant effect of perceptual difficulty, indicating that perceptually different stimuli evoked a higher level of family resemblance sorting than perceptually similar stimuli. There was no significant main effect of pre-exposure type; however, there was a significant interaction between pre-exposure type and level of perceptual difficulty. Post-hoc tests revealed that this interaction was the result of an increase in family resemblance sorting for the perceptually different stimuli under relevant preexposure but no such effect for perceptually similar stimuli. The theoretical implications of these findings are discussed

Interaction of large, high power systems with operational orbit charged particle environments

A potentially hazardous spacecraft environment interaction is discussed. The interaction of large high voltage systems with low energy (less than 50 eV) plasmas which can result in loss of power and/or arching was examined. The impact of this class of interactions where the ambient operation is most severe at low orbits where the ambient plasmas are densest. Results of experimental work and predictions of simple analytical models were presented and their implications for design of space systems were reviewed

Environmental charging of spacecraft surfaces: Tests of thermal control materials for use on the global positioning system flight space vehicle. Part 1: Specimens 1 to 5

The NASA/USAF program on Environmental Charging of Spacecraft Surfaces consists of experimental efforts directed toward evaluating the response of materials to the environmental charged particle flux. Samples of thermal blankets and second surface mirrors of the type to be used on the Global Positioning System Flight Space Vehicle were tested to determine their response to electron flux. The primary result observed was that the ground connection of the metal layers of the blanket, as made by the baseline grounding technique using serrated washers and grommets, deteriorated with time at test. The discharges observed on the blankets were the glow type, not the 'lightning' strike observed on past specimens. Testing was performed at ambient laboratory temperatures

Environmental charging of spacecraft-tests of thermal control materials for use on the global positioning system flight space vehicle. Part 2: Specimen 6 to 9

The NASA/USAF program on the Environmental Charging of Spacecraft Surfaces consists, in part, of experimental efforts directed toward evaluating the response of materials to the environmental charged particle flux. Samples of thermal blankets of the type to be used on the Global Positioning System Flight Space Vehicles were tested to determine their response to electron flux. The primary result observed was that no discharges were obtained with the quartz-fiber-fabric-covered multilayer insulation specimen. The taped aluminized polyester grounding system used on all specimens did not appear to grossly deteriorate with time; however, the specimens require specific external pressure to maintain constant grounding system resistance

The Lewis Research Center geomagnetic substorm simulation facility

A simulation facility was established to determine the response of typical spacecraft materials to the geomagnetic substorm environment and to evaluate instrumentation that will be used to monitor spacecraft system response to this environment. Space environment conditions simulated include the thermal-vacuum conditions of space, solar simulation, geomagnetic substorm electron fluxes and energies, and the low energy plasma environment. Measurements for spacecraft material tests include sample currents, sample surface potentials, and the cumulative number of discharges. Discharge transients are measured by means of current probes and oscilloscopes and are verified by a photomultiplier. Details of this facility and typical operating procedures are presented

Development of environmental charging effect monitors for operational satellites

Design details and design goals are given of an instrumentation package to monitor the effects of the environmental charging of spacecraft surfaces on the systems of operational spacecraft

Environmental charging tests of spacecraft thermal control louvers

The environmental charging of spacecraft surfaces program consists, in part, of experimental evaluation of material response to the environmental charged particle flux. A flight type spacecraft thermal control louver assembly has been tested in an electron flux. The louver blade surface potential, the louver assembly currents, and the relatively high number of discharges observed in the electron environment are self-consistent results. The unexpected result of this testing was the flutter observed when the louvers were closed. The flutter is about 1 to 2 Hz in frequency and is probably electrostatically induced

A detailed X-ray investigation of zeta Puppis IV. Further characterization of the variability

Previously, the X-ray emission of zeta Puppis was found to be variable with light curves harbouring "trends" with a typical timescale longer than the exposure length. The origin of these changes was proposed to be linked to large-scale structures in the wind, but further characterization of the variability at high energies was needed. Since then, a number of new X-ray observations have become available. Furthermore, a cyclic behaviour with a 1.78d period was identified in long optical photometric runs, which is thought to be associated with the launching mechanism of large-scale wind structures. We analysed these new X-ray data, revisited the old data, and compared X-ray with optical data, including when simultaneous. We found that the behaviour in X-rays cannot be explained in terms of a perfect clock because the amplitude and shape of its variations change with time. For example, zeta Puppis was much more strongly variable between 2007 and 2011 than before and after this interval. Comparing the X-ray spectra of the star at maximum and minimum brightness yields no compelling difference beyond the overall flux change: the temperatures, absorptions, and line shapes seem to remain constant, well within errors. The only common feature between X-ray datasets is that the variation amplitudes appear maximum in the medium (0.6-1.2keV) energy band. Finally, no clear and coherent correlation can be found between simultaneous X-ray and optical data. Only a subgroup of observations may be combined coherently with the optical period of 1.78d, although the simultaneous optical behaviour is unknown. The currently available data do not reveal any obvious, permanent, and direct correlation between X-ray and optical variations. The origin of the X-ray variability therefore still needs to be ascertained, highlighting the need for long-term monitoring in multiwavelengths, i.e. X-ray, UV, and optical.Comment: accepted for publication by A&

A 1200-micron MAMBO survey of ELAISN2 and the Lockman Hole - I. Maps, sources and number counts

The definitive version is available at www.blackwell-synergy.com '.--Copyright Blackwell Publishing. DOI : 10.1111/j.1365-2966.2004.08235.xWe present a deep, new 1200μm survey of the ELAISN2 and Lockman Hole fields using the Max Planck Millimeter Bolometer array (MAMBO). The areas surveyed are 160 arcmin2 in ELAISN2 and 197 arcmin2 in the Lockman Hole, covering the entire SCUBA ‘8mJy Survey’. In total, 27 (44) sources have been detected at a significance 4.0 ( 3.5 ). The primary goals of the survey were to investigate the reliability of (sub)millimetre galaxy (SMG) samples, to analyse SMGs using flux ratios sensitive to redshift at z > 3, and to search for ‘SCUBA drop-outs’, i.e. galaxies at z >> 3. We present the 1200μm number counts and find evidence of a fall at bright flux levels. Employing parametric models for the evolution of the local 60μm IRAS luminosity function (LF), we are able to account simultaneously for the 1200 and 850μm counts, suggesting that the MAMBO and SCUBA sources trace the same underlying population of high-redshift, dust-enshrouded galaxies. From a nearest-neighbour clustering analysis we find tentative evidence that themost significantMAMBO sources come in pairs, typically separated by 23′′. Our MAMBO observations unambiguously confirm around half of the SCUBA sources. In a robust sub-sample of 13 SMGs detected by both MAMBO and SCUBA at a significance 3.5 , only one has no radio counterpart. Furthermore, the distribution of 850/1200μmflux density ratios for this sub-sample is consistent with the spectroscopic redshift distribution of radio-detected SMGs (Chapman et al. 2003). Finally, we have searched for evidence of a high-redshift tail of SMGs amongst the 18 MAMBO sources which are not detected by SCUBA. While we cannot rule out that some of them are SCUBA drop-outs at z >> 3, their overall 850-to-1200μm flux distribution is statistically indistinguishable from that of the 13 SMGS which were robustly identified by both MAMBO and SCUBA.Peer reviewe