We present a transport-reaction model (TRACTION) specifically designed to account for non-ideal transport effects in the presence of thermodynamic (e.g. salinity or temperature) gradients. The model ...relies on the most fundamental concept of solute diffusion, which states that the chemical potential gradient (Maxwell’s model) rather than the concentration gradient (Fick’s law) is the driving force for diffusion. In turn, this requires accounting for species interactions by applying Pitzer’s method to derive species chemical potentials and Onsager coefficients instead of using the classical diffusion coefficients. Electrical imbalances arising from varying diffusive fluxes in multicomponent systems, like seawater, are avoided by applying an electrostatic gradient as an additional transport contribution.
We apply the model to pore water data derived from the seawater mixing zone at the submarine Mercator mud volcano (MMV) in the Gulf of Cadiz. Two features are particularly striking at this site: (i) Ascending halite-saturated fluids create strong salinity (NaCl) gradients in the seawater mixing zone that result in marked chemical activity, and thus chemical potential gradients. The model predicts strong transport-driven deviations from the mixing profile derived from the commonly used Fick’s diffusion model, and is capable of matching well with the profile shapes observed in the pore water concentration data. Even better agreement to the observed data is achieved when ion pairs are transported separately. (ii) The formation of authigenic gypsum (several wt%) occurs in the surface sediments, which is typically restricted to evaporitic surface processes. Very little is known about the gypsum paragenesis in the subseafloor and we first present possible controls on gypsum solubility, such as pressure, temperature, and salinity (pTS), as well as the common ion and ion pairing effects. Due to leaching of deep diapiric salt, rising fluids of the MMV are saturated with respect to gypsum (as well as celestite and barite). Several processes that could drive these fluids towards gypsum supersaturation and hence precipitation were postulated and numerically quantified. In line with the varied morphology of the observed gypsum crystals, gypsum paragenesis at the MMV is likely a combination of two temperature-related processes. Gypsum solubility increases with increasing temperature, especially in strong electrolyte solutions and the first mechanism involves the cooling of saturated fluids along the geothermal gradient during their ascent. Secondly, local temperature changes, i.e. cooling during the transition from MMV activity towards dormancy results in the cyclic build-up of gypsum.
The model showed that the interpretation of field data can be majorly misguided when ignoring non-ideal effects in extreme diagenetic settings. While at first glance the pore water profiles at the Mercator mud volcano would indicate strong reactive influences in the seawater mixing zone, our model shows that the observed species distributions are in fact primarily transport-controlled. The model results for SO4 are particularly intriguing, as SO4 is shown to diffuse into the sediment along its increasing (!) concentration gradient. Also, a pronounced gypsum saturation peak can be observed in the seawater mixing zone. This peak is not related to the dissolution of gypsum but is simply a result of the non-ideal transport forces acting on the activity profile of SO4 and Ca profiles.
We study the ocean flow in Arctic gyres using a recent model for gyres derived in spherical coordinates on the rotating sphere. By projecting this model onto the plane using the Mercator projection, ...we obtain a semi-linear elliptic partial differential equation in an unbounded domain, difficulty which is then overcome by projecting the PDE onto the unit disk via a conformal map. We then study existence, regularity and uniqueness of solutions for constant and linear vorticity functions.
A World of Innovation Holzer, Gerhard; Newby, Valerie; Svatek, Petra ...
2015, 2015-02-27
eBook
Gerhard Mercator (1512-1594) was the most important cartographer and globemaker of the 16th century. He is particularly remembered for his publication Atlas sive Cosmographicae Meditationes de ...Fabrica Mundi et Fabricati Figura (1595), and for his specific cylindrical map projection (1569), which is still used widely today. This book brings together the latest research on Mercator with a view to his sources and his relationships with other scientific disciplines and cartographers of his time, as well as his role in the wider worlds of Renaissance cartography and Humanism.
Adaptive Composite Map Projections Jenny, B.
IEEE transactions on visualization and computer graphics,
12/2012, Letnik:
18, Številka:
12
Journal Article
Recenzirano
All major web mapping services use the web Mercator projection. This is a poor choice for maps of the entire globe or areas of the size of continents or larger countries because the Mercator ...projection shows medium and higher latitudes with extreme areal distortion and provides an erroneous impression of distances and relative areas. The web Mercator projection is also not able to show the entire globe, as polar latitudes cannot be mapped. When selecting an alternative projection for information visualization, rivaling factors have to be taken into account, such as map scale, the geographic area shown, the map's height-to-width ratio, and the type of cartographic visualization. It is impossible for a single map projection to meet the requirements for all these factors. The proposed composite map projection combines several projections that are recommended in cartographic literature and seamlessly morphs map space as the user changes map scale or the geographic region displayed. The composite projection adapts the map's geometry to scale, to the map's height-to-width ratio, and to the central latitude of the displayed area by replacing projections and adjusting their parameters. The composite projection shows the entire globe including poles; it portrays continents or larger countries with less distortion (optionally without areal distortion); and it can morph to the web Mercator projection for maps showing small regions.
The present study is an extension of our analysis of Russian basic color terms (BCTs) elicited in a web‐based psycholinguistic experiment. Color samples (N = 600) were approximately uniformly ...distributed in the Munsell color solid. An unconstrained color‐naming method was employed. Native Russian speakers (N = 713; 333 males) participated in the study. Among 1422 elicited unique color words, 698 terms (49%) were derived from object names. Here we explore object‐derived non‐BCTs, focusing on broad classes of names referred to objects, categories within these, and the inventory of color terms, as well as their frequency, patterns of derivation, and derivational productivity. Six classes of object referents were identified: flora, fauna, inanimate nature, food and beverages, man‐made objects, body and bodily products. In detail, 20 most frequent object‐derived terms are reported. These are accompanied by analysis of gender differences and representation of the terms' denotata on the Munsell Mercator projection. In addition, Russian object‐derived color terms are related to those in English; discussed are differences between the 2 languages in the color term classes, inventories and incidences. We conclude that Russian object‐derived color terms follow the generic metonymy pattern, that is, signifying color of objects in the speakers' natural environment. The inventory is also language‐specific, reflecting social practices, preferences and views entrenched in the traditional Russian culture. Furthermore, recent extensive development of the inventory signals 2 novel phenomena: marked globalization influence, surfacing as abundant transliteration of English referent loanwords, and noticeable sociolectal diversification that manifests itself by novel evocative color terms, particularly in marketing and advertisement.
Following Landsat’s practice, Sentinel-2 multispectral satellite products are delivered as raster images projected onto the Universal Transversal Mercator (UTM) spatial reference system, which ...divides Earth into 60 longitudinal zones. Locally, this guarantees high spatial accuracy, while also easing the interoperability with many regional and governmental datums. On top, the Sentinel-2 product grid uses the Military Grid Reference System (MGRS) tiling scheme to facilitate manageable data slices and straightforward multitemporal image stacking. Although most convenient for small-area applications, activities with a larger geographic scope suffer from this approach and its overhead, as both data duplication and ambiguity appear along UTM zone overlaps and MGRS tile borders. In practice, such areas that are covered by multiple and incongruent grid pixels are known but just tolerated, and their degree has not been measured so far.
In this paper, we illuminate the nature and patterns of these overlaps, and calculate the resulting spatial redundancy over the global land surface. We found that the total land area is enlarged in the Sentinel-2 grid definition by 33%, which is a value similar to the simple and single-zoned Plate Carrée projection. The number of co-located grid pixels for a single location ranges from 1 up to 6, with on average more redundancy at mid- and high-latitudes. With regard to global satellite archives in times of big data and increased energy costs, the examined grid appears as a suboptimal choice, inducing complexity and overhead at an unreasonable level. Owing to the grid design, e.g., the yearly Sentinel-2 user product volume (Level-1C and -2A) is inflated by 1 petabyte, entailing cascading downstream costs of storage, bandwidth, and computing.
•We scrutinise the geometry of zones and tiles of the Sentinel-2 UTM tiling grid.•UTM-MGRS’s grid-inherent overlaps inflate global land remote sensing datasets by 33%.•E.g. yearly Sentinel-2 Level-1C/-2A product volume is increased from 3 to 4 petabytes.•Data increase scales up hardware/energy costs, from dissemination to user application.
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The geometry of Adriatic Sea basin renderings on 12 portolan charts made from the late thirteenth to the late sixteenth century was compared to a modern map by applying Helmert transformation in ...order to preserve their initial geometry and by using the same 40 identical points per chart. In the first stage of the research, the geometry of the portolan charts was compared to six selected map projections in order to determine the geometrical 'best fit'. In the second stage, networks of lines plotted on charts were divided regionally and functionally and compared to the 'best fit' map projection to determine their geometric patterns in more detail. The research results showed that Adriatic Sea basin renderings on portolan charts were probably the result of a deliberately applied map projection which was geometrically most similar to the modern conformal cylindrical (Mercator) projection.
The Web Mercator projection is a projection of a relatively recent date. There has been a lot of controversy about its application. Some believe that this projection is not a projection of either the ...sphere or the surface of the ellipsoid. Therefore, in this paper, several projections of the surface of a rotational ellipsoid into a plane are investigated and it is shown that the Web Mercator projection is one of such projections. Namely, although the equations of this projection are identical to the equations for the projection of the sphere, the basic difference is in the choice of the area of definition, i.e., the domain of the projection. Furthermore, we have shown that the Web Mercator projection can also be interpreted as double mapping: mapping an ellipsoid to a sphere according to the normals and then mapping the sphere to the plane according to the formulas of the Mercator projection for the sphere. The Web Mercator projection is not a conformal projection, but it is close in properties to the Mercator projection.
Web-Mercatorova projekcija je projekcija relativno novijeg datuma o čijoj je primjeni bilo dosta kontroverzija. Neki smatraju da ta projekcija nije projekcija ni sfere ni plohe elipsoida. Stoga je u ovom radu istraženo nekoliko projekcija plohe rotacijskog elipsoida u ravninu i pokazano da je web-Mercatorova projekcija jedna od takvih projekcija. Naime, premda su jednadžbe te projekcije istovjetne jednadžbama za projekciju sfere, osnovna je razlika u odabiru područja definicije, odnosno domene projekcije. Nadalje, pokazali smo da se web-Mercatorova projekcija može interpretirati i kao dvostruko preslikavanje: preslikavanje elipsoida na sferu po normalama te preslikavanje sfere u ravninu po formulama Mercatorove projekcije za sferu. Web-Mercatorova projekcija nije konformna projekcija, ali je po svojstvima bliska Mercatorovoj projekciji.
Online interactive maps have become a popular means of communicating with spatial data. In most online mapping systems, Web Mercator has become the dominant projection. While the Mercator projection ...has a long history of discussion about its inappropriateness for general-purpose mapping, particularly at the global scale, and seems to have been virtually phased out for general-purpose global-scale print maps, it has seen a resurgence in popularity in Web Mercator form. This article theorizes on how Web Mercator came to be widely used for online maps and what this might mean in terms of data display, technical aspects of map generation and distribution, design, and cognition of spatial patterns. The authors emphasize details of where the projection excels and where it does not, as well as some of its advantages and disadvantages for cartographic communication, and conclude with some research directions that may help to develop better solutions to the problem of projections for general-purpose, multi-scale Web mapping.
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