Digital Data-Centric Geography: Implications for Geography's Frontier

The debate regarding geographic information systems (GIS) as tool, toolbox, or science still lingers in geography departments and among geographers. Analysis of geographic information is a vital component of decision making among business, governments, researchers, and academics. GIS users, geographers and nongeographers alike, use and benefit from problem-solving methods in numerous fields and contexts, making the use of GIS and the core competencies associated with using GIS a topic of intense debate. Complicating this ongoing discussion is the rise of data-centric approaches to research in geography that further expand the capabilities of spatial analysis and add to the expected knowledge of a GIS user and analyst. Building on a panel discussion at the 2016 American Association of Geographers (AAG) annual meeting, as well as informal dialogues on Twitter and other social media platforms that navigate this issue in academics and industry, this article explores how skills in research computing and programming operate in geography and GIS, especially given the rise of data-centric approaches to research in these realms. Some topics, like the costs and benefits of open and closed source software, are familiar from previous discussions in geography and GIS. Others, though, like the reward structures and recognition for computing skills or programming ability, have not been widely considered given the current landscape.     

RATES OF HEAVE AND SURFACE ROTATION OF PERIGLACIAL FROST BOILS IN THE WHITE MOUNTAINS,CALIFORNIA

The White Mountains of California have a cold semi-arid climate that has led to the development of large areas of periglacial patterned ground. Rates of activity vary widely, and no present activity has been noted below 3600 m. Three distinct scales of patterned ground—having average diameters of 3–5 m, 0.5–1.0 m, and 0.1–0.5 m—exist together in a nested fashion at a favorable location at 3914 m. Vertical heave, horizontal displacement, and surface rotation were investigated on landforms of each scale, to determine rates of activity and the spatial and temporal variation of heave. No movement was detected in the largest landforms, but frost boils located in the centers of the larger sorted polygons were highly active. Rates of heave increased dramatically at the beginning of the thaw season, approaching 3.6 mm per day. Dowels were heaved an average of 16.8 cm over ten months. Disks used as surface markers demonstrated exceptional rotational and radial displacement over a nine-month period; 29% of the markers were overturned. The processes responsible for the observed movement in the White Mountains are discussed in relation to processes affecting other alpine environments.     

Differential presence of anthropogenic compounds dissolved in the marine waters of Puget Sound, WA and Barkley Sound, BC

Organic compounds were evaluated in March 2010 at 22 stations in Barkley Sound, Vancouver Island Canada and at 66 locations in Puget Sound. Of 37 compounds, 15 were xenobiotics, 8 were determined to have an anthropogenic imprint over natural sources, and 13 were presumed to be of natural or mixed origin. The three most frequently detected compounds were salicyclic acid, vanillin and thymol. The three most abundant compounds were diethylhexyl phthalate (DEHP), ethyl vanillin and benzaldehyde (∼600 ng L⁻¹ on average). Concentrations of xenobiotics were 10-100 times higher in Puget Sound relative to Barkley Sound. Three compound couplets are used to illustrate the influence of human activity on marine waters; vanillin and ethyl vanillin, salicylic acid and acetylsalicylic acid, and cinnamaldehyde and cinnamic acid. Ratios indicate that anthropogenic activities are the predominant source of these chemicals in Puget Sound.     

Towards a spectral technique for determining material geometry around evolved stars: application to HD 179821

HD 179821 is an evolved star of unknown progenitor mass range (either post-asymptotic giant branch or post-red supergiant) exhibiting a double-peaked spectral energy distribution (SED) with a sharp rise from ∼8 to  20 μm  . Such features have been associated with ejected dust shells or inwardly truncated circumstellar discs. In order to compare SEDs from both systems, we employ a spherically symmetric radiative transfer code and compare it to a radiative, inwardly truncated disc code. As a case study, we model the broad-band SED of HD 179821 using both codes. Shortward of 40 μm, we find that both models produce equivalent fits to the data. However, longward of 40 μm, the radial density distribution and corresponding broad range of disc temperatures produce excess emission above our spherically symmetric solutions and observations. For HD 179821, our best fit consists of a   T _eff= 7000 K  central source characterized by  τ _V ∼ 1.95  and surrounded by a radiatively driven, spherically symmetric dust shell. The extinction of the central source reddens the broad-band colours so that they resemble a   T _eff= 5750 K  photosphere. We believe that HD 179821 contains a hotter central star than previously thought. Our results provide an initial step towards a technique to distinguish geometric differences from spectral modelling.     

Use of the Köppen–Trewartha climate classification to evaluate climatic refugia in statistically derived ecoregions for the People’s Republic of China

Changes in climate as projected by state-of-the-art climate models are likely to result in novel combinations of climate and topo-edaphic factors that will have substantial impacts on the distribution and persistence of natural vegetation and animal species. We have used multivariate techniques to quantify some of these changes; the method employed was the Multivariate Spatio-Temporal Clustering (MSTC) algorithm. We used the MSTC to quantitatively define ecoregions for the People’s Republic of China for historical and projected future climates. Using the Köppen–Trewartha classification system we were able to quantify some of the temperature and precipitation relationships of the ecoregions. We then tested the hypothesis that impacts to environments will be lower for ecoregions that retain their approximate geographic locations. Our results showed that climate in 2050, as projected from anthropogenic forcings using the Hadley Centre HadCM3 general circulation model, were sufficient to create novel environmental conditions even where ecoregions remained spatially stable; cluster number was found to be of paramount importance in detecting novelty. Continental-scale analyses are generally able to locate potentially static ecoregions but they may be insufficient to define the position of those reserves at a grid cell-by-grid cell basis.     

Accelerator measurement of NaI response to medium energy neutrons and application to a Satellite-Borne Spectrometer

We report on the response of a prototype detector to medium energy neutrons. The neutrons were produced by n-p scattering of a neutron beam on a hydrogen target. The measurements provide unique data on the efficiency and response of large NaI scintillators to neutrons in the energy range 36–709 MeV. We apply the results to the high-energy mode of the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission satellite by estimating its efficiency for neutron detection. This estimate is compared to earlier Monte Carlo calculations of the GRS efficiency.     

Potential impact on water resources from future volcanic eruptions at Long Valley,Mono County,California, U.S.A.

Earthquakes, ground deformation, and increased geothermal activity at Long Valley caldera after mid-1980 suggest the possibility of a volcanic eruption in the near future. An eruption there could have serious consequences for the City of Los Angeles, depending on the magnitude and volume of material ejected because surface water in Mono Basin plus surface and groundwater in Owens Valley accounts for about 80 percent of its water supply. Eruptions of moderate to very large magnitude could impede the supply of water from this area for several days, weeks, or even years by discharging small to large volumes of volcanic ash and causing lahars. Soon after an eruption, water quality would likely be affected by the accumulation of organic debris and microorganisms in surface waters.