The impact of precipitation on speed–flow relationships along a UK motorway corridor

Although the fundamental traffic diagram provides the characteristics of a typical road traffic speed–flow relationship, little consideration has been given to the impact of adverse weather conditions on the relationship and the subsequent impact on local speed–flow. For the first time, this study uses precipitation radar along with a state-of-the art traffic information system to ascertain the relationship between speed–flow and precipitation on a UK transport corridor at the local (junction to junction) scale. It is evident that precipitation causes a significant reduction in speed and maximum flow on many links of the corridor as well as a downward reduction in the overall speed-flow relationship. With increased instances of heavy precipitation predicted in the UK as a result of climate change, these findings highlight the subsequent impact on journey travel times and associated economic costs.     

Canada-France-Hawaii Telescope's “redeye” infrared camera system: Array performance

The Canada-France-Hawaii Telescope (CFHT) has recently commissioned two facility infrared cameras for astronomical observations in the 1.0 to 2.5 micron region. These cameras use NICMOS3 256×256 pixel arrays fabricated from Hg:Cd:Te. We report here on array performance and discuss two unique features of these arrays, namely corner glow and residual images. We have developed techniques for reducing corner glow and a method of clearing residual image charge. We discuss our techniques and their side effects.     

Estimation of ocean-bottom properties by matched-field inversion ofacoustic field data

A method for estimating properties of the ocean bottom such as bathymetry and geoacoustic parameters such as sound speed, density and attenuation, using matched-field inversion is considered. The inversion can be formulated as an optimization problem by assuming a discrete model of unknown parameters and a bounded search space for each parameter. The optimization then involves finding the set of parameter values which minimizes the mismatch between the measured acoustic field and modeled replica fields. Since the number of possible models can be extremely large, the method of simulated annealing, which provides an efficient optimization that avoids becoming trapped in suboptimal solutions, has been used. The matching fields are computed using a normal mode model. In inversions for range-dependent parameters, the adiabatic approximation is employed. This allows mode values to be precomputed for a grid of parameter values and stored in look-up tables for fast reference, which greatly improves computational efficiency. Synthetic inversion examples are presented for realistic range-independent and range-dependent environments     

The Growth of Facular Area Surrounding Large, Decaying Sunspots

In a previous paper, we investigated the facular area around 31 decaying sunspots of varied size. The growth of facular area as a function of spot decay was marginally significant (r ² = 0.1255, p = 0.05). Using new data, this paper examines the change in facular area surrounding large decaying sunspots some of which grew very rapidly. The data are from full-disk photometric images taken with CFDT2 (2.5″ pixels). For 10 sunspots, we find a statistically significant increase in facular area as a function of the spot decay rate with a regression coefficient, squared, of r ² = 0.611 (p < 0.02).     

The Chinese comet observation in AD 773 January

The strong ¹⁴C increase in the year AD 774/5 detected in one German and two Japanese trees was recently suggested to have been caused by an impact of a comet onto Earth and a deposition of large amounts of ¹⁴C into the atmosphere (Liu et al. 2014). The authors supported their claim using a report of a historic Chinese observation of a comet ostensibly colliding with Earth's atmosphere in AD 773 January. We show here that the Chinese text presented by those authors is not an original historic text, but that it is comprised of several different sources. Moreover, the translation presented in Liu et al. is misleading and inaccurate. We give the exact Chinese wordings and our English translations. According to the original sources, the Chinese observed a comet in mid January 773, but they report neither a collision nor a large coma, just a long tail. Also, there is no report in any of the source texts about “dust rain in the daytime” as claimed by Liu et al. (2014), but simply a normal dust storm. Ho (1962) reports sightings of this comet in China on AD 773 Jan 15 and/or 17 and in Japan on AD 773 Jan 20 (Ho 1962). At the relevant historic time, the Chinese held that comets were produced within the Earth's atmosphere, so that it would have been impossible for them to report a “collision” of a comet with Earth's atmosphere. The translation and conclusions made by Liu et al. (2014) are not supported by the historical record. Therefore, postulating a sudden increase in ¹⁴C in corals off the Chinese coast precisely in mid January 773 (Liu et al. 2014) is not justified given just the ²³⁰Th dating for AD 783 ± 14. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The effect of lensing on the identification of SCUBA galaxies

Spectroscopic surveys of submillimetre(submm)-selected sources have uncovered optically bright galaxies at   z ≲ 1  close to the positions of several submm sources. Naive statistical analyses suggest that these galaxies are associated with the submm emission. However, in some cases, it is difficult to understand this association given the relatively modest redshifts and unprepossessing spectral characteristics of the galaxies. These are in stark contrast to those expected from the massive dust-enshrouded starbursts and AGN thought to power the bulk of the bright submm population. We present new observations of optically bright counterparts to two luminous submm sources, along with a compilation of previously proposed optically bright counterparts with   z ≲ 1  . We suggest that the majority of these associations between bright galaxies and submm sources may be as a result of the action of the foreground galaxies as gravitational lenses on the much fainter and more distant submm sources. We discuss the implications of this conclusion for our understanding of the SCUBA population.     

Combining borehole temperature and meteorologic data to constrain past climate change

Geothermal observations from a suite of boreholes in western Utah, USA, combined with meteorologic data at nearby weather stations are used to test the hypothesis that temperatures in the earths subsurface contain an accurate record of recent climate change. The change in air temperature over the last hundred years successfully predicts detailed subsurface temperature profiles to better than ±0.05°C, indicating that ground temperatures tract air temperatures over long periods and that climate change signals are conducted into, and recorded in, the solid earth by the process of heat conduction. We combine borehole temperature data with meteorologic data from the nearest weather station to determine the time averaged difference between surface ground temperature and surface air temperature for borehole-weather station pairs and to infer the long term mean air temperature prior to the observational record. For our western Utah sites the preobservational mean temperature is close to the average surface air temperature for this century suggesting that up to 0.5°C of warming deduced from the last 100 years of weather station data may be attributed to recovery from a cool period at the turn of the century.