Contiguous US summer maximum temperature and heat stress trends in CRU and NOAA Climate Division data plus comparisons to reanalyses.

Warming is a major climate change concern, but the impact of high maximum temperatures depends upon the air's moisture content. Trends in maximum summertime temperature, moisture, and heat index are tracked over three time periods: 1900-2011, 1950-2011, and 1979-2011; these trends differ notably from annual temperature trends. Trends are emphasized from two CRU datasets (CRUTS3.25 and CRUTS4.01) and two reanalyses (ERA-20C and 20CRv2). Maximum temperature trends tend towards warming that is stronger over the Great Lakes, the interior western and the northeastern contiguous United States. A warming hole in the Midwest generally decreases in size and magnitude when heat stress trends are calculated because the region has increasing moisture. CRU and nearly all reanalyses find cooling in the northern high plains that is not found in NOAA Climate Division trends. These NOAA trends are captured better by CRUTS401. Moistening in the northeast amplifies the heat stress there. Elsewhere the moisture trends are less clear. Drying over northern Texas (after 1996) in CRUTS401 translates into decreasing heat stress there (less so in CRUTS325). Though other reanalyses are not intended for long-term trends, MERRA-2 and ERA-Interim match observed trends better than other reanalyses

The Cluster Soft Excess: new faces of an old enigma

Until the advent of XMM-Newton, the cluster soft excess (CSE) was the subject of some controversy due to both data analysis issues and uncertainties with the soft excess emission mechanism. XMM-Newton observations have finally laid to rest any doubts as to the existence of the CSE and have also given tantalising clues as to the nature of its emission mechanism. Here we report on the analysis of XMM-Newton observations of a number of CSE clusters in an attempt to improve the analysis and understanding of the CSE. Included as part of the study is an analysis of the effects of background subtraction, which calls to question the integrity of the claimed O VII line discovery, though not the soft excess itself. We also give details of both thermal and non-thermal fits to the CSE cluster Abell 3112.Comment: Paper presented at the Plenary session of the International Dark Matter Meeting, Edinburgh, Sept. 2004 (to appear in the Proceedings

Calibration of a general optical equation for remote sensing of suspended sediments in a moderately turbid estuary

Abstract A general algorithm for determining suspended sediment concentrations in the surface waters of estuaries has been developed for use with satellite data. The algorithm uses a three-parameter general optical equation to relate suspended sediment concentrations to water reflectances that have been corrected for sun angle effects, atmospheric path radiance, and tidal excursion. Using data collected by the advanced very high resolution radiometer on five different dates, reflectances were determined using two different methods, one providing maximum correction for haze and the other providing minimum sensitivity to pigments. For both methods, in situ and remotely sensed samples from Delaware Bay acquired within 3.5 hours of each other agreed to within 60% at the 95% confidence level. Pixel and subpixel scale spatial variations and variability associated with in situ measurements produced about 50% of the differences. Chlorophyll concentrations of \u3e50 μg/L produced a discrepancy in the reflectance method that provided the best haze correction. The parameter values may be adjusted to allow for variations in sediment size and pigment variations, allowing application of the calibration to estuaries having optically different suspended sediments

Remote estimation of the diffuse attenuation coefficient in a moderately turbid estuary

Abstract Solutions of the radiative transfer equation are used to derive relationships of water reflectance to the diffuse attenuation coefficient (K) in moderately turbid water (K \u3e 0.5 m−1). Data sets collected from the NOAA AVHRR and in situ observations from five different dates confirm the appropriateness of these relationships, in particular the logistic equation. Values of K calculated from the reflectance data agree to within 60% of the observed values, although the reflectance derived using a more comprehensive aerosol correction is sensitive to chlorophyll concentrations greater than 50 μg L−1. Agreement between in situ and remote observations improves as the time interval between samples is narrowed

A Rational Model of the Closed-End Fund Discount

The discount on closed-end funds is widely accepted as proof of investor irrationality. We show,however, that a parsimonious rational model can generate a discount that exhibits many of the characteristics observed in practice. The only required features of the model are that managers have (imperfectly observable) ability to generate excess returns; they sign long-term contracts guaranteeing them a fee each year equal to a fixed fraction of assets under management; and they can leave to earn more money elsewhere if they turn out to be good. With these assumptions, time-varying discounts are not an anomaly in a rational world with competitive investors -- they are required.