The June 2013 Alberta catastrophic flooding event – part 2: fine‐scale precipitation and associated features

Data obtained from a variety of sources including the Canadian Lightning Detection Network, weather radars, weather stations and operational numerical weather model analyses were used to address the evolution of precipitation during the June 2013 southern Alberta flood. The event was linked to a mid‐level closed low pressure system to the west of the region and a surface low pressure region initially to its south. This configuration brought warm, moist unstable air into the region that led to dramatic, organized convection with an abundance of lightning and some hail. Such conditions occurred in the southern parts of the region whereas the northern parts were devoid of lightning. Initially, precipitation rates were high (extreme 15‐min rainfall rates up to 102 mm h^?1 were measured) but decreased to lower values as the precipitation shifted to long‐lived stratiform conditions. Both the convective and stratiform precipitation components were affected by the topography. Similar flooding events, such as June 2002, have occurred over this region although the 2002 event was colder and precipitation was not associated with substantial convection over southwest Alberta. Copyright © 2016 Her Majesty the Queen in Right of Canada. Hydrological Processes. © John Wiley & Sons, Ltd.     

WMO PROJECT ON INTERCOMPARISON OF CONCEPTUAL MODELS USED IN HYDROLOGICAL FORECASTING

Abstract

The paper describes the development of a method which enables formulation of reservoir operation rules in a multi-reservoir water resources system. The method consists of three major steps: (1) development of a mathematical model of a multivariate (time and space) river flow process and generation of a synthetic input to the system, (2) development of a mathematical model of a water resources system and the simulation of its operation over the whole period of synthetic inflows (simulation coupled with one of the mathematical programming techniques), and (3) statistical analysis of the results of the simulation-optimization computations. Consecutive implementation of all steps leads to the formulation of the operation rules for all the reservoirs in the system.     

Crustal structure beneath exposed accreted terranes of Southern Alaska

Summary. The crustal structure beneath the exposed terranes of southern Alaska has been explored using coincident seismic refraction and reflection profiling. A wide-angle reflector at 8–9 km depth, at the base of an inferred low-velocity zone, underlies the Peninsular and Chugach terranes, appears to truncate their boundary, and may represent a horizontal decollement beneath the terranes. The crust beneath the Chugach terrane is characterized by a series of north-dipping paired layers having low and high velocities that may represent subducted slices of oceanic crust and mantle. This layered series may continue northward under the Peninsular terrane. Earthquake locations in the Wrangell Benioff zone indicate that at least the upper two low-high velocity layer pairs are tectonically inactive and that they appear to have been accreted to the base of the continental crust. The refraction data suggest that the Contact fault between two similar terranes, the Chugach and Prince William terranes, is a deeply penetrating feature that separates lower crust (deeper than 10 km) with paired dipping reflectors, from crust without such reflectors.     

阿尔泰-阿尔金地学断面地壳结构

根据阿尔泰—阿尔金地学断面的地震纵、横波资料,建立了地壳速度及泊松比结构. 测区的地壳具有明显的三分结构特征,其纵波速度自上而下依次为6.0～6.3km/s、6.3～6.6km/s及6.9～7.0km/s;阿尔泰南缘的地壳最厚,为56km,准噶尔盆地的地壳最薄,为46km,大部分地区的地壳厚度为50km 左右. 准噶尔盆地与天山之间上地幔顶部的纵波速度为7.7～7.8km/s ;阿尔泰南缘及塔里木盆地上地幔顶部的纵波速度较高,为7.9～8.0km/s. 测线南部,包括东天山及塔里木东缘,自地表至30km深处的地壳纵波速度低,泊松比为0.25,表明上地壳主要为石英及花岗质成分;而测线北部(包括阿尔泰及准噶尔盆地)的中、上地壳则呈现较高的泊松比（0.26～0.27）,可能为基性地壳的体现. 厚15～30km的下地壳纵波速度（6.9～7.0km/s）较高,泊松比为0.26～0.28,可能以镁铁质的麻粒岩成分为主. 位于天山及其南侧地壳中部的低速层（VP=5.9km/s, σ=0.25）则可能为晚古生代的构造热事件中的花岗质侵入岩.     

A detailed abundance analysis of the hot post-AGB star ZNG-1 in M10

We present a model-atmosphere analysis for the bright ( V ∼13) star ZNG-1, in the globular cluster M10. From high-resolution ( R ∼40 000) optical spectra we confirm ZNG-1 to be a post-asymptotic giant branch (post-AGB) star. The derived atmospheric parameters are T _eff=26 500±1000 K and log  g =3.6±0.2 dex . A differential abundance analysis reveals a chemical composition typical of hot post-AGB objects, with ZNG-1 being generally metal poor, although helium is approximately solar. The most interesting feature is the large carbon underabundance of more than 1.3 dex. This carbon deficiency, along with an observed nitrogen enhancement relative to other elements, may suggest that ZNG-1 evolved off the AGB before the third dredge-up occurred. Also, iron depletions observed in other similar stars suggest that gas–dust fractionation in the AGB progenitor could be responsible for the observed composition of these objects. However, we need not invoke either scenario since the chemical composition of ZNG-1 is in good agreement with abundances found for a Population II star of the same metallicity.