Ten compactness properties of circles: measuring shape in geography

This essay sheds new light on the meaning and measurement of compactness—one of the most intriguing and least‐understood properties of geographic shapes. We articulate a unified theoretical foundation for the study of shape compactness that rests on two simple observations: First, that the circle is the most compact of shapes. And second, that there are 10—and possibly more—distinct geometrical properties of the circle that make it the most compact of shapes. We introduce these 10 properties, illustrate them with real‐world examples and define indices associated with these properties that can be calculated using a geographic information system.     

The changing biosphere: recent insights from paleoenvironmental science into drivers,mechanisms and impacts

Paleoenvironmental science has experienced a recent surge in interest and activity as concerns grow over global environmental change. Key research questions in the biotic realm of paleoenvironmental science focus on explaining climatic change at time scales of decades to centuries and understanding ecosystem responses to these changes. Biotic responses are increasingly being studied at smaller spatial scales to identify local factors that determine the sensitivity of a particular system to climatic change. These findings can then be applied to solving a variety of problems, such as setting conservation targets or testing mechanisms for observed climatic and biogeographic phenomena. Research approaches commonly used today include hypothesis testing, which has now become more sophisticated as paleoecologists and paleoclimatologists integrate with modellers. Other frameworks involve the quantitative integration of multiple proxy indicators and the use of extensive publicly available data networks to produce new datasets for paleoclimatic reconstructions and other applications.     

Has it become warmer in Alberta? Mapping temperature changes for the period 1950–2010 across Alberta,Canada

When a Canada‐wide daily climate time series, covering the period 1950–2010, became available, an opportunity arose to analyze the time series for trends of a variety of temperature indices. The 6,833 climate grid cells covering Alberta, each with an area of 10 km by 10 km, allowed the detailed mapping of 30 temperature indices across the province. From each time series, an annual series was computed, which then enabled trend analyses using the non‐parametric Mann‐Kendall and Sen Slope tests. New maps could be created at an unprecedented spatial resolution, and an associated website was developed to access all trends and changes between 1950 and 2010 for all grid cells at albertaclimaterecords.com . The confidence levels of some temperature trends exceed 99%, while others are below 80%. In Alberta's south, annual average temperatures have increased by 1°C to 2°C since the 1950s, but in Alberta's north the increase is 2°C to 4°C. The growing season has lengthened by between one and five weeks since the 1950s, while the number of frost days has declined. The most significant trends observed were increases in mean annual and winter temperatures, and declines in the number of days below ?20°C and heating degree days.     

Méthodologie de zonage aquicole régional à l'aide de la télédétection dans un SIRS: application dans la baie des Chaleurs, Québec

Les études sur les activités aquicoles utilisant des informations géographiques et des données de télédétection sont parmi les plus difficiles à manipuler dans le domaine de la géomatique. Même si, de prime abord, les paramètres semblent faciles à utiliser, cette utilisation est plus complexe si on les considère comme un simple ensemble de données. De façon habituelle, l'identification et la délimitation de sites propices pour des activités aquicoles sont basées sur de multiples critères, comprenant des paramètres comme l'accessibilité au site et la profondeur d'eau. Lorsqu'on a clairement identifié un site propice pour des activités aquicoles, on peut en identifier d'autres avec des critères de base semblables ou équivalents. Cette méthode, basée sur l'identification du particulier vers le général, semble bien fonctionner dans les milieux d'eau douce, dans les baies et dans les fjords. Cependant, en milieu marin, la complexité et la variabilité des paramètres ne peuvent être évaluées sans tenir compte d'une vue générale synoptique et quantitative de tout l'environnement régional. La méthode proposée, basée sur l'identification du général vers le particulier et fondée sur des informations géographiques et des données de télédétection, peut être utilisée à différentes échelles. En effet, une zone propice pour des activités aquicoles peut être identifiée et délimitée à une échelle moyenne (1 à 100 km) en utilisant certains paramètres primaires essentiels et, par la suite, on peut raffiner à grande échelle (moins de 1 km) en utilisant d'autres paramètres secondaires un peu moins importants. La méthode proposée a été appliquée sur le littoral de la côte nord de la baie des Chaleurs, au Québec. Plusieurs zones propices aux activités aquicoles ont été identifiées et délimitées. La carte issue des traitements est le résultat de l'utilisation d'indices de potentiel aquicole à partir de la fusion des différents paramètres, qui ont d'abord été standardisés. Le résultat d'une telle fusion de données géoréférencées est valable si on le compare aux résultats publiés avec la méthode précédente dans laquelle chaque paramètre est additionné sur une carte de base (i.e. bathymétrie) à un moment donné et sans standardisation. La sensibilité de l'analyse et la validité des résultats sont confirmées par des données in situ prises dans la région d'étude, par exemple pour l'élevage de la moule. The area of aquaculture activities using geographic information and space technologies is one of the most difficult to organize within the field of Geomatics. The parameters may appear to be simple; however there is more complexity than a simple set of data. Currently, the suitable aquaculture site selection is based on a few criteria that encompass parameters, such as site location proximity and water depth. Once the site is clearly identified as suitable to support aquaculture activity, then similar sites were identified based on the same or equivalent criteria. This bottom‐up method seems to work in inland waters, bays and fjords, marine waters. However it precludes an environment that inherits such variable parameter complexity, one that could be evaluated without taken into account the whole synoptic and quantitative overview of regional environment. The proposed top‐down method based on geographic information and remote sensing techniques can be used at different scales. In fact, an area suitable to support an aquaculture activity could be selected at a mesoscale level (1 to 100 km) using identified main or primary parameters. Then, refinement is undertaken at a large scale (less than 1 km) using other parameters that are less important or secondary. The proposed method was applied to the coastal north shore of baie des Chaleurs in Québec, Canada. Several areas suitable to support aquaculture activities were identified. The product map is a result of merging or fusing different parameters that are previously standardized using an aquaculture evaluation index. Such gridded data fusion is valid compared to the previous methods seen in the literature where each parameter is added to a base map (i.e. bathymetry) at a time without standardizing the units. The sensitivity analysis and the validity of the results itself are in accordance with in situ testing undertaken in that area for mussel nests.