40 research outputs found
Testing E-OBS European high-resolution gridded data set of daily precipitation and surface temperature
No full textGridded data sets derived through interpolation of station data have a number of potential inaccuracies and errors. These errors can be introduced either by the propagation of errors in the station data into derived gridded data or by limitations in the ability of the interpolation method to estimate grid values from the underlying station network. Recently, Haylock et al. (2008) reported on the development of a new high-resolution gridded data set of daily climate over Europe (termed E-OBS). E-OBS is based on the largest available pan-European data set, and the interpolation methods used were chosen after careful evaluation of a number of alternatives, yet the data set will inevitably have errors and uncertainties. In this paper we assess the E-OBS data set with respect to: (1) homogeneity of the gridded data; (2) evaluation of inaccuracies arising from available network density, through comparison with existing data sets that have been developed with much denser station networks; and (3) the accuracy of the estimates of interpolation uncertainty that are provided as part of E-OBS. We find many inhomogeneities in the gridded data that are primarily caused by inhomogeneities in the underlying station data. In the comparison of existing data with E-OBS, we find that while correlations overall are high, relative differences in precipitation are large, and usually biased toward lower values in E-OBS. From the analysis of the interpolation uncertainties provided as part of E-OBS, we conclude that the interpolation standard deviation provided with the data significantly underestimates the true interpolation error when cross validated using station data, and therefore will similarly underestimate the interpolation error in the gridded E-OBS data. While E-OBS represents a valuable new resource for climate research in Europe, users of the data need to be aware of the limitations in the data set and use the data appropriately
Interannual variability of mean and extreme rainfall and relationship with large-scale circulation
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No full textWe present a European daily high-resolution gridded dataset for precipitation and minimum, maximum and mean surface temperature for the period 1950-2006. This dataset improves on previous products in its spatial resolution and extent, time period, number of contributing stations and attention to finding the most appropriate method for spatial interpolation of daily climate observations. The data is delivered on four spatial resolutions to match the grids used in previous products as well as many of the rotatedpole regional climate models currently in use. The dataset has been designed to provide the best estimate of grid box averages rather than point values, to enable direct comparison with regional climate models. We examine the effect that interpolation has on the magnitude of the extremes in the observations by calculating areal reduction factors for daily maximum temperature and precipitation events with return periods up to ten years. Interpolation uncertainty is quantified by the provision of daily 95 % confidence limits at every grid point. The daily uncertainty averaged across the entire region is shown to be largely dependent on the season and number of contributing observations
Cravath by the Sea: Recruitment in the Large Halifax Law Firm, 1900-1955
No full textThe traditional view is that regularized, meritocratic hiring in Canadian law firms had to wait until the 1960s, with the rise in importance of Ontario university law schools. There was, however, more regional variation than this view allows. After an overview of the rise of large firms in the U.S. and Canada, and of the modern hiring strategies (the Cravath system ) that developed in New York in the early twentieth century, the author considers whether Halifax firms were employing these strategies between 1900 and 1955. Nepotistic hiring continued unabated; however, the three large firms of the period recruited young students with good academic records with increasing regularity,in the New York manner. The article concludes by proposing that the difference between firms\u27 hiring in Toronto and Halifax might be explained by the enthusiasm with which the bar in each of these cities adopted modern professional views on legal education
The National Class as Extraterritorial Legislation
No full textThis article argues that provincially constituted multijurisdictional class actions violate the constitutional law of extraterritoriality. It begins with a brief overview of the lawof adjudicativejurisdiction, then provides a longer overviewof the separate body of law that imposes extraterritorial limits on substantive provincial legislation. The author then demonstrates the substantive characterof classaction legislation, which necessarily entails the applicability of the law ofextraterritoriality However, much of the relevant jurisprudence, as well as some of the relevant academic literature, has ignored this important issue.Application ofthe lawofextraterritoriality does, indeed, raise serious constitutional concerns, as the article\u27s central section demonstrates. The desirable efficiencies of national classes may, however, be largely preserved through the use of co-ordinated parallel provincial classes. These have already worked in practice, and the flexibility of existing class action legislation can easily accommodate them
The Predictability of Interdecadal Changes in ENSO Activity and ENSO Teleconnections
No full textEl Niño-Southern Oscillation (ENSO) in a century-long integration of a Bureau of Meteorology Research Centre (BMRC) coupled general circulation model (CGCM) drives rainfall and temperature changes over Australia that are generally consistent with documented observational changes: dry/hot conditions occur more frequently during El Niño years and wet/mild conditions occur more frequently during La Niña years. The relationship between ENSO [as measured by Niño-4 or the Southern Oscillation index (SOI), say] and all-Australia rainfall and temperature is found to be nonlinear in the observations and in the CGCM during June-December: a large La Niña sea surface temperature (SST) anomaly is closely linked to a large Australian response (i.e., Australia usually becomes much wetter), whereas the magnitude of an El Niño SST anomaly is a poorer guide to how dry Australia will actually become. Australia tends to dry out during El Niño events, but the degree of drying is not as tightly linked to the magnitude of the El Niño SST anomaly. Nonlinear or asymmetric teleconnections are also evident in the western United States/northern Mexico. The implications of asymmetric teleconnections for prediction services are discussed. The relationship between ENSO and Australian climate in both the model and the observations is strong in some decades, but weak in others. A series of decadal-long perturbation experiments are used to show that if these interdecadal changes are predictable, then the level of predictability is low. The model's Interdecadal Pacific Oscillation (IPO), which represents interdecadal ENSO-like SST variability, is statistically linked to interdecadal changes in ENSO's impact on Australia during June-December when ENSO's impact on Australia is generally greatest. A simple stochastic model that incorporates the nonlinearity above is used to show that the IPO [or the closely related Pacific Decadal Oscillation (PDO)] can appear to modulate ENSO teleconnections even if the IPO-PDO largely reflect unpredictable random changes in, for example, the relative frequency of El Niño and La Niña events in a given interdecadal period. Note, however, that predictability in ENSO-related variability on decadal time scales might be either underestimated by the CGCM, or be too small to be detected by the modest number of perturbation experiments conducted. If there is a small amount of predictability in ENSO indices on decadal time scales, and there may be, then the nonlinearity described above provides a mechanism via which ENSO teleconnections could be modulated on decadal time scales in a partially predictable fashion. © 2006 American Meteorological Society
Evaluating geostatistical methods of blending satellite and gauge data to estimate near real-time daily rainfall for Australia
No full textRain gauges provide valuable information about the amount and frequency of rainfall. In Australia, the majority of rain gauges are located in populated, wet coastal regions. Approximately 2000 gauges reporting within 24 h of a target day were used to make near real-time (NRT) estimates of daily precipitation. The remaining approximate to 4000 gauges for the same target day were used to evaluate bias and estimation performance using several traditional statistics. There is considerable potential to improve the estimation of rainfall in Australia using related ancillary data, particularly in sparsely gauged areas. The Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA-RT) near real-time product (3B42RT) provided images (0.25 degrees resolution) of precipitation across Australia. Daily precipitation was estimated in 2009110 approximately every 5 km across Australia. This study evaluated selected geostatistical methods for estimating daily rainfall maps across Australia. It tackled the change of support problem and spatial intermittency of daily rainfall data in blending satellite and gauge data. Dissension occurred amongst traditional global statistical measures of performance which were compounded by extremes of gauge density. Overall, our assessment is that blending the 3B42RT satellite and rain gauge data was not worthwhile. However, the blending considerably reduced the estimation variance indicating that uncertainty of the map estimates was a neglected property necessary to detect change and difference in patterns. (C) 2013 Elsevier B.V. All rights reserved.II
