Modification of a Parametrization of Shallow Convection in the Grey Zone Using a Mesoscale Model

In current operational numerical weather prediction models, the effect of shallow convection is parametrized. The grey zone of shallow convection is found between the horizontal resolutions of mesoscale numerical models (2–3 km) and large-eddy simulations (10–100 m or finer). At these horizontal scales the shallow convection is to some extent explicitly resolved by the model. The shallow-convection parametrization is still needed, but has to be regulated according to the model horizontal resolution. Here the behaviour of the non-hydrostatic mesoscale numerical weather prediction model Application of Research to Operations at Mesoscale is examined in the grey zone and a new scale-adaptive surface closure of its shallow-convection parametrization, dependent on horizontal resolution, is defined based on large-eddy simulation. The new closure is tested on a series of numerical experiments and validated on a 15-day-long real case period. Its impact on the development of deep convection is examined in detail. The idealized simulations show promising results, as the mean profiles of the subgrid and resolved turbulence change in the desired way. Based on the real case tests our modification has a low impact on model performance, but is part of a set of upgrades of the current parametrization that is aimed to treat the shallow convection grey zone.     

Water Resources Implications of Global Warming: A U.S. Regional Perspective

The implications of global warming for the performance of six U.S. water resource systems are evaluated. The six case study sites represent a range of geographic and hydrologic, as well as institutional and social settings. Large, multi-reservoir systems (Columbia River, Missouri River, Apalachicola-Chatahoochee-Flint (ACF) Rivers), small, one or two reservoir systems (Tacoma and Boston) and medium size systems (Savannah River) are represented. The river basins range from mountainous to low relief and semi-humid to semi-arid, and the system operational purposes range from predominantly municipal to broadly multi-purpose. The studies inferred, using a chain of climate downscaling, hydrologic and water resources systems models, the sensitivity of six water resources systems to changes in precipitation, temperature and solar radiation. The climate change scenarios used in this study are based on results from transient climate change experiments performed with coupled ocean-atmosphere General Circulation Models (GCMs) for the 1995 Intergovernmental Panel on Climate Change (IPCC) assessment. An earlier doubled-CO₂ scenario from one of the GCMs was also used in the evaluation. The GCM scenarios were transferred to the local level using a simple downscaling approach that scales local weather variables by fixed monthly ratios (for precipitation) and fixed monthly shifts (for temperature). For those river basins where snow plays an important role in the current climate hydrology (Tacoma, Columbia, Missouri and, to a lesser extent, Boston) changes in temperature result in important changes in seasonal streamflow hydrographs. In these systems, spring snowmelt peaks are reduced and winter flows increase, on average. Changes in precipitation are generally reflected in the annual total runoff volumes more than in the seasonal shape of the hydrographs. In the Savannah and ACF systems, where snow plays a minor hydrological role, changes in hydrological response are linked more directly to temperature and precipitation changes. Effects on system performance varied from system to system, from GCM to GCM, and for each system operating objective (such as hydropower production, municipal and industrial supply, flood control, recreation, navigation and instream flow protection). Effects were generally smaller for the transient scenarios than for the doubled CO₂ scenario. In terms of streamflow, one of the transient scenarios tended to have increases at most sites, while another tended to have decreases at most sites. The third showed no general consistency over the six sites. Generally, the water resource system performance effects were determined by the hydrologic changes and the amount of buffering provided by the system's storage capacity. The effects of demand growth and other plausible future operational considerations were evaluated as well. For most sites, the effects of these non-climatic effects on future system performance would about equal or exceed the effects of climate change over system planning horizons.     

How ready is ready? Measuring physical preparedness for severe storms

This paper investigates use of inventories, or checklists of activities, as an emergency management tool to motivate preparedness action in individuals. It develops the inventory concept to provide the foundation for a more targeted approach to storm preparation communication and community engagement. It also examines the potential efficacy of alternatives to paper-based checklists, such as web or smartphone applications. Academic and grey literature was reviewed to collect activities for a storm inventory for emergency agencies to measure individual preparedness and for individuals to measure their preparation progress. The resulting master list was refined for application and tested for useability in a pilot study of semi-structured interviews in a storm-susceptible community in Queensland, Australia. Also, clustering items by type of preparedness activity reveal where strengths and weaknesses exist in individual preparedness. For instance, preparation for leaving and safety planning were shown to be the areas of weakest activity in the pilot sample, while preparation of the house for a storm was the strongest area. In addition, behaviour change literature shows potential for effective use of an inventory-based smartphone application in motivating preparation activity. Data collected by a storm preparedness smartphone application could show where a communication or engagement program for targeted communities should be focused. It is supported by health literature that identifies preferences of individuals to make progress on complex tasks in stages, the value of lists to achievement of goals and demonstrated increase in uptake of activities prompted by smartphone applications over web or paper-based diaries.

     

Facies and sequence stratigraphic architecture of the Mural Limestone (Albian), Arizona: Carbonate response to global and local factors and implications for reservoir characterization

This study documents the detailed facies and sequence stratigraphic architecture of a multi-cyclic patch-reef and its associated ramp interior facies that formed during Oceanic Anoxic Event 1b in the Mural Limestone, Arizona, USA. Ramp interior facies are comprised of bedded wackestone/packstone, rudist build-up and coral–algal patch-reef facies located north of Bisbee, Arizona, at the Grassy Hill locality. The larger multi-cyclic patch-reef that developed coevally ca 5 km to the south of Grassy Hill consists of a high-angle windward margin with a narrow ca 70 m long reef frame containing vertically zonated Microsolena, Actinastrea, diverse branching coral and rudist assemblages, and an 870 m long low-angle leeward margin comprised of reef debris rudstone and grainstone shoal facies. Similar reef geomorphology and orientation is documented across the Gulf of Mexico and reflects the shelf-wide north to north-east-trending prevailing wind and current energies. Controls affecting reef formation and growth patterns include changes in accommodation space associated with low-amplitude global sea-level rise and regional thermotectonic subsidence, local accommodation space and nutrient fluctuations associated with the inner shelf depositional setting within a humid and siliciclastic-rich environment. Four aggradational to retrogradational high-frequency sequences are documented in Arizona: High-frequency sequences 1 and 2 represent the first pulse of patch-reef development in an overall second-order marine transgression over the Sonora/Bisbee Shelf. These sequences correlate to δ¹³C signatures associated with Oceanic Anoxic Event 1b across the Gulf of Mexico and suggest that carbonate reefs persisted on the ramp interior during this time. High-frequency sequences 3 and 4 record a second brief transgression and backstepping of reef facies followed by the final regression of shallow shelf carbonates that correlates to more robust patch-reef development in Sonora, Mexico. The patch-reef at Paul Spur is an excellent outcrop analogue for productive patch-reefs in the Maverick Basin (Comanche Shelf) of Texas. Detailed facies mapping of this outcrop analogue shows that the greatest reservoir potential is contained within the backreef grainstone shoals where primary porosity of up to 15% is observed.     

Use of terrestrial photogrammetry for monitoring and measuring bank erosion

This paper examines the use of terrestrial photogrammetry as a technique for measuring bank erosion in a rapidly changing fluvial environment. It has been recognized that there are a number of advantages when applying photogrammetric techniques to geomorphological situations. In this study the enhancement of spatial sampling combined with the ability to capture additional information, such as soil moisture, on film, is of particular importance in enabling the identification of specific processes involved in bank erosion as well as detailed volumetric analysis of losses. Metric terrestrial photography was taken of the river bank on several dates, and data were abstracted by the use of analytical photogrammetry. This enabled the generation of digital terrain models from which morphological and volumetric changes could be assessed. © 1997 John Wiley & Sons, Ltd.     

Nonlinear dynamic tests of a reinforced concrete frame building at different damage levels

This paper discusses the dynamic tests of a two-story infilled reinforced concrete (RC) frame building using an eccentric-mass shaker. The building, located in El Centro, CA, was substantially damaged prior to the tests due to the seismic activity in the area. During the testing sequence, five infill walls were removed to introduce additional damage states and to investigate the changes in the dynamic properties and the nonlinear response of the building to the induced excitations. The accelerations and displacements of the structure under the forced and ambient vibrations were recorded through an array of sensors, while lidar scans were obtained to document the damage. The test data provide insight into the nonlinear response of an actual building and the change of its resonant frequencies and operational shapes due to varying damage levels and changes of the excitation amplitude, frequency, and orientation.     

Instrumentation Development for In Situ 40Ar/39Ar Planetary Geochronology

The chronology of the Solar System, particularly the timing of formation of extra‐terrestrial bodies and their features, is an outstanding problem in planetary science. Although various chronological methods for in situ geochronology have been proposed (e.g., Rb‐Sr, K‐Ar), and even applied (K‐Ar), the reliability, accuracy, and applicability of the ⁴⁰Ar/³⁹Ar method makes it by far the most desirable chronometer for dating extra‐terrestrial bodies. The method however relies on the neutron irradiation of samples, and thus a neutron source. Herein, we discuss the challenges and feasibility of deploying a passive neutron source to planetary surfaces for the in situ application of the ⁴⁰Ar/³⁹Ar chronometer. Requirements in generating and shielding neutrons, as well as analysing samples are described, along with an exploration of limitations such as mass, power and cost. Two potential solutions for the in situ extra‐terrestrial deployment of the ⁴⁰Ar/³⁹Ar method are presented. Although this represents a challenging task, developing the technology to apply the ⁴⁰Ar/³⁹Ar method on planetary surfaces would represent a major advance towards constraining the timescale of solar system formation and evolution.     

An Analysis Platform for Multiscale Hydrogeologic Modeling with Emphasis on Hybrid Multiscale Methods

One of the most significant challenges faced by hydrogeologic modelers is the disparity between the spatial and temporal scales at which fundamental flow, transport, and reaction processes can best be understood and quantified (e.g., microscopic to pore scales and seconds to days) and at which practical model predictions are needed (e.g., plume to aquifer scales and years to centuries). While the multiscale nature of hydrogeologic problems is widely recognized, technological limitations in computation and characterization restrict most practical modeling efforts to fairly coarse representations of heterogeneous properties and processes. For some modern problems, the necessary level of simplification is such that model parameters may lose physical meaning and model predictive ability is questionable for any conditions other than those to which the model was calibrated. Recently, there has been broad interest across a wide range of scientific and engineering disciplines in simulation approaches that more rigorously account for the multiscale nature of systems of interest. In this article, we review a number of such approaches and propose a classification scheme for defining different types of multiscale simulation methods and those classes of problems to which they are most applicable. Our classification scheme is presented in terms of a flowchart (Multiscale Analysis Platform), and defines several different motifs of multiscale simulation. Within each motif, the member methods are reviewed and example applications are discussed. We focus attention on hybrid multiscale methods, in which two or more models with different physics described at fundamentally different scales are directly coupled within a single simulation. Very recently these methods have begun to be applied to groundwater flow and transport simulations, and we discuss these applications in the context of our classification scheme. As computational and characterization capabilities continue to improve, we envision that hybrid multiscale modeling will become more common and also a viable alternative to conventional single‐scale models in the near future.     

The changing role of ecohydrological science in guiding environmental flows

Abstract

The term “environmental flows” is now widely used to reflect the hydrological regime required to sustain freshwater and estuarine ecosystems, and the human livelihoods and well-being that depend on them. The definition suggests a central role for ecohydrological science to help determine a required flow regime for a target ecosystem condition. Indeed, many countries have established laws and policies to implement environmental flows with the expectation that science can deliver the answers. This article provides an overview of recent developments and applications of environmental flows on six continents to explore the changing role of ecohydrological sciences, recognizing its limitations and the emerging needs of society, water resource managers and policy makers. Science has responded with new methods to link hydrology to ecosystem status, but these have also raised fundamental questions that go beyond ecohydrology, such as who decides on the target condition of the ecosystem? Some environmental flow methods are based on the natural flow paradigm, which assumes the desired regime is the natural “unmodified” condition. However, this may be unrealistic where flow regimes have been altered for many centuries and are likely to change with future climate change. Ecosystems are dynamic, so the adoption of environmental flows needs to have a similar dynamic basis. Furthermore, methodological developments have been made in two directions: first, broad-scale hydrological analysis of flow regimes (assuming ecological relevance of hydrograph components) and, second, analysis of ecological impacts of more than one stressor (e.g. flow, morphology, water quality). All methods retain a degree of uncertainty, which translates into risks, and raises questions regarding trust between scientists and the public. Communication between scientists, social scientists, practitioners, policy makers and the public is thus becoming as important as the quality of the science.

Editor Z.W. Kundzewicz

Citation Acreman, M.C., Overton, I.C., King, J., Wood, P., Cowx, I.G., Dunbar, M.J., Kendy, E., and Young, W., 2014. The changing role of ecohydrological science in guiding environmental flows. Hydrological Sciences Journal, 59 (3–4), 433–450     

Development and Testing of a Field Screening Method Based on Bubbling Extraction and Photoionization Detection for Measurement of Benzene and Total VOCs

A field screening method was developed for rapid measurement of benzene and gasoline range total petroleum hydrocarbons (TPHg) concentrations in groundwater. The method is based on collecting photoionization detector (PID) measurements from vapor samples. The vapor samples are collected by bubbling air through groundwater samples (air sparging) with a constant volume, temperature and sparging rate. The level of accuracy, sensitivity, precision, and statistical significance of the estimated concentrations, derived from the screening method, are comparable to conventional laboratory analytical results at concentrations equal to or greater than 150 µg/L for benzene and greater than 50 µg/L for TPHg. The method's concentration estimations can assist in making real‐time decisions regarding location of dissolved plumes and light nonaqueous phase liquid (LNAPL) source zones at many fuel release sites. The screening method was tested in the laboratory and in the field with 208 and 107 samples, respectively. The study concludes that the screening method can be used as a tool to aid in completing a site conceptual model as well as analyzing groundwater from monitoring wells.