A mathematical morphology approach for a qualitative exploration of drought events in space and time

Drought events occur worldwide and possibly incur severe consequences. Trying to understand and characterize drought events is of considerable importance in order to improve the preparedness for coping with future events. In this paper, we present a methodology that allows for the delineation of drought events by exploiting their spatiotemporal nature. To that end, we apply operators borrowed from mathematical morphology to represent drought events as connected components in space and time. As an illustration, we identify drought events on the basis of a 35-year data set of daily soil moisture values covering mainland Australia. We then extract characteristics reflecting the affected area, duration and intensity from the proposed representation of a drought event in order to illustrate the impact of tuning parameters in the methodology presented. Yet, this paper we refrain from comparing with other drought delineation methods

A three dimensional vortex wake model for missiles at high angles on attack

A three dimensional model for the steady flow past missile and aircraft nose shaped bodies is presented based on augmenting a potential solution with a wake composed of vortex filaments. The vortex positions are determined by the requirement that they, in some sense, align with the flow. The aerodynamic loads on the body are compared with experimental values and used to evaluate the model. The vortex positions compare well with flow visualization results for slender bodies at high angles of attack. The approximations in the wake near the body cause peaks in the force distributions more severe than in the measured values. For given vortex strengths and body attachment points multiple steady vortex positions were not found

Structure of a linear array of hollow vortices of finite cross-section

Free-streamline theory is employed to construct an exact steady solution for a linear array of hollow, or stagnant cored, vortices in an inviscid incompressible fluid. If each vortex has area A and the separation is L, there are two possible shapes if A[1/2]/L is less than a critical value 0.38 and none if it is larger. The stability of the shapes to two-dimensional, periodic and symmetric disturbances is considered for hollow vortices. The more deformed of the two possible shapes is found to be unstable while the less deformed shape is stable

Contribution of LANDSAT-4 thematic mapper data to geologic exploration

The increased number of carefully selected narrow spectral bands and the increased spatial resolution of thematic mapper data over previously available satellite data contribute greatly to geologic exploration, both by providing spectral information that permits lithologic differentiation and recognition of alteration and spatial information that reveals structure. As vegetation and soil cover increase, the value of spectral components of TM data decreases relative to the value of the spatial component of the data. However, even in vegetated areas, the greater spectral breadth and discrimination of TM data permits improved recognition and mapping of spatial elements of the terrain. As our understanding of the spectral manifestations of the responses of soils and vegetation to unusual chemical environments increases, the value of spectral components of TM data to exploration will greatly improve in covered areas

Geologic exploration: The contribution of LANDSAT-4 thematic mapper data

The major advantages of the TM data over that of MSS systems are increased spatial resolution and a greater number of narrow, strategically placed spectral bands. The 30 meter pixel size permits finer definition of ground features and improves reliability of the photointerpretation of geologic structure. The value of the spatial data increases relative to the value of the spectral data as soil and vegetation cover increase. In arid areas with good exposure, it is possible with careful digital processing and some inventive color compositing to produce enough spectral differentiation of rock types and thereby produce facsimiles of standard geologic maps with a minimum of field work or reference to existing maps. Hue-saturation value images are compared with geological maps of Death Valley, California, the Big Horn/Wind River Basin of Wyoming, the area around Cement, Oklahoma, and Detroit. False color composites of the Ontario region are also examined

Descendants

The photographer discusses the photographs in Descendants, her Master of Fine Arts thesis exhibition which was held at Tipton Gallery, Johnson City, Tennessee from October 31, 2016 through November 23, 2016. The exhibit consisted of 19 large format color photographs. This body of work visually represents the artistʼs interest in those who participate in Civil War re-enactments. The historical and contemporary influences discussed are in accordance to Sheffieldʼs photographs. Historical influences include Matthew Brady, James Abbott McNeill Whistler, Walker Evans, and Helen Levitt, as well as those of contemporary artists; Martin Parr, Stacy Kranitz, and Anderson Scott

Developing high-quality meteorological data for East and West Africa from merged sources

Assessments of agricultural productivity and food security require process-based crop models to provide predictions of yields and diagnose past variations in the context of anthropogenic and climate factors. These models need detailed meteorological data as input, including precipitation, temperature, humidity, solar radiation and windspeed. This project aimed to apply existing methods to merge in situ, remotely sensed and modeled data sources in East and West Africa to produce high-quality daily meteorological data over at least 30 years. Specific objectives included: evaluation of the error structure of the dataset, its temporal and spatial characteristics and consistency and its suitability for forcing crop models, and to provide a framework for merging new data, in particular from the local stations of regional African partners, ensuring consistency across time and space and among variables, as well as the best use of information. The work successfully created a 10 kilometre, daily meteorological dataset for East and West Africa for the period 1979–2008, based on the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP–NCAR) reanalysis (NNR), merged with observational datasets, including the monthly gridded precipitation and temperature product of the University of East Anglia’s Climate Research Unit (CRU), the NASA Langley Surface Radiation Budget (SRB) product, and station data from the Global Summary of the Day (GSOD) database