Coralline algal Mg-O bond strength as a marine <i>p</i>CO₂ proxy

Past ocean acidification recorded in the geological record facilitates the understanding of rates and influences of contemporary &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; enrichment. Most pH reconstructions are made using boron, however there is some uncertainty associated with vital effects and isotopic fractionation. Here we present a new structural proxy for carbonate chemistry; Mg-O bond strength in coralline algae. Coralline algae were incubated in control (380 μatm &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt;), moderate (750 μatm&lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt;), and high (1000 μatm &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt;) acidification conditions for 24 months. Raman spectroscopy was used to determine skeletal Mg-O bond strength. There was a positive linear relationship between &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; concentration and bond strength mediated by positional disorder in the calcite lattice when accounting for seasonal temperature. The structural preservation of the carbonate chemistry system in coralline algal high-Mg calcite represents an alternative approach to reconstructing marine carbonate chemistry. Significantly, it also provides an important mechanism for reconstructing historic atmospheric CO&lt;sub&gt;2&lt;/sub&gt; concentrations

The SIMMS Program: A Study of Change and Variability within the Marine Cryosphere

This paper describes the scientific context of an experimental program for an eight year study of change and variability within the marine cryosphere in the Canadian Arctic and summarizes the field program since its inception in 1990. The focus is on understanding the process linkages between the atmosphere, cryosphere and ocean at the sea ice interface and in establishing a method by which these processes can be modeled numerically. Remote sensing plays a significant role as a major source of temporally and spatially consistent data in this relatively inaccessible region. In this program, we combine in situ measurement of geophysical characteristics of the sea ice interface, electromagnetic radiation interactions with the interface, and numerical modeling of marine cryosphere processes operating across this interface. Our primary objective is to observe and simulate the mechanisms that may contribute to change and variability. We conclude by proposing a conceptual spatial signature of an icescape as the basis for integration of these processes and illustrate how remote sensing data can be used to identify these functional signatures.Key words: Canadian Arctic, marine cryosphere, remote sensing, atmosphere-cryosphere interactions, snow and sea iceCet article d&eacute;crit le contexte scientifique d'un programme exp&eacute;rimental consistant en une &eacute;tude portant sur une p&eacute;riode de huit ans des changements et de la variabilit&eacute; au sein de la cryosph&egrave;re marine dans l'Arctique canadien, et il r&eacute;sume le programme de terrain depuis sa cr&eacute;ation en 1990. On se concentre sur la compr&eacute;hension des liens entre les processus &agrave; l'oeuvre, &agrave; l'interface de la glace de mer, qui impliquent l'atmosph&egrave;re, la cryosph&egrave;re et l'oc&eacute;an, ainsi que sur l'&eacute;laboration d'une m&eacute;thode permettant de faire une mod&eacute;lisation num&eacute;rique de ces processus. La t&eacute;l&eacute;d&eacute;tection joue un r&ocirc;le important comme source principale de donn&eacute;es coh&eacute;rentes sur les plans temporel et spatial provenant de cette r&eacute;gion relativement inaccessible. Dans ce programme on combine les mesures in situ des caract&eacute;ristiques g&eacute;ophysiques de l'interface de la glace de mer, les interactions du rayonnement &eacute;lectromagn&eacute;tique avec l'interface et la mod&eacute;lisation num&eacute;rique des processus de la cryosph&egrave;re agissant &agrave; cette interface. Notre objectif premier est d'observer et de simuler les m&eacute;canismes qui peuvent contribuer au changement et &agrave; la variabilit&eacute;. On conclut en proposant sur le plan conceptuel une signature spatiale d'un panorama glaciaire comme base d'int&eacute;gration de ces processus, et on illustre la fa&ccedil;on dont les donn&eacute;es obtenues par la t&eacute;l&eacute;d&eacute;tection peuvent servir &agrave; identifier ces signatures fonctionnelles.Mots cl&eacute;s: Arctique canadien, cryosph&egrave;re marine, t&eacute;l&eacute;d&eacute;tection, interactions atmosph&egrave;re-cryosph&egrave;re, neige et glace de me

Combining feature fusion and decision fusion for classification of hyperspectral and LiDAR data

This paper proposes a method to combine feature fusion and decision fusion together for multi-sensor data classification. First, morphological features which contain elevation and spatial information, are generated on both LiDAR data and the first few principal components (PCs) of original hyperspectral (HS) image. We got the fused features by projecting the spectral (original HS image), spatial and elevation features onto a lower subspace through a graph-based feature fusion method. Then, we got four classification maps by using spectral features, spatial features, elevation features and the graph fused features individually as input of SVM classifier. The final classification map was obtained by fusing the four classification maps through the weighted majority voting. Experimental results on fusion of HS and LiDAR data from the 2013 IEEE GRSS Data Fusion Contest demonstrate effectiveness of the proposed method. Compared to the methods using single data source or only feature fusion, with the proposed method, overall classification accuracies were improved by 10% and 2%, respectively

Optical water column properties of a coral reef environment: Towards correction of remotely sensed imagery

International Geoscience and Remote Sensing Symposium (IGARSS)62666-2668IGRS

Modeling synthetic aperture radar (SAR) scattering from a seasonally varying snow-covered sea ice volume at 5.3 and 9.25 GHz

A series of sensitivity analyses using dielectric, mixture and microwave scattering models is presented. Data from the Seasonal Sea Ice Monitoring and Modeling Site (SIMMS) in 1990 and 1991 are used to initialize the models. The objective of the research is to investigate the role of various geophysical and electrical properties in specifying the total relative scattering cross section (???) of snow covered first-year sea ice during the spring period. The seasonal transition period from the Winter SAR scattering season to Early Melt was shown to signal a transition in dielectric properties which caused the snow volume to become a factor in the microwave scattering process. The effect of the thermal insulation of a snow cover on sea ice was shown to be significant for both ?? and ???. Higher atmospheric temperatures caused proportionally greater changes in the dielectric properties of the sea ice at the base of the snow cover. Model ?0 was computed for a range of sensor, sensor-earth geometry, and geophysical properties. In the Winter season the surface roughness terms (ohand L) were shown to have a significant impact on ?0 when the ice surface was the primary scattering mechanism. Once the snow cover began to warm and water was available in a liquid phase, the ice surface became masked because of the decrease in microwave penetration depths. During this period the water volume variable dominated ?0, both from its impact on ?v0, and due to its control over the dielectric mismatch created at the air/snow interface

Measuring Climatic State Variables from SAR Images of Sea Ice: The SIMS SAR Validation Site in Lancaster Sound

ABSTRACT. In this paper we consider three aspects of arctic sea ice climate studies: a review of climate processes related to a seasonal sea ice cover, a review of how climate state variables related to the reviewed processes may be measured using remote sensing data, and an analysis of the relative utility of tonal versus textural classification of synthetic aperture radar (SAR) images of sea ice. The two reviews are presented in the context of a field validation experiment called the Seasonal Sea Ice Monitoring Site (SIMS) being conducted in Lancaster Sound/Barrow Strait, Northwest Territories (N.W.T.). The analysis of tone versus texture as a means of extracting ice type information from SAR images of sea ice is conducted using X-band, HH polarized data from the SIMS’90 field experiment and data collected over Mould Bay, N.W.T. Key words: climatology, remote sensing, synthetic aperture radar, sea ice RÉSUMÉ. Nous nous penchons dans cet article sur trois aspects concernant les études climatiques de la banquise arctique: une recension des processus climatiques liés it une couverture saisonnitre de la banquise, une recension des modes de mesure des variables de I’état climatique-en rapport avec les processus mentionnés ci-dessus- àl’aide de données obtenues par téI&amp;létection, et enfin une analyse de l’utilité relative de la classification des tons par opposition it celle des textures apparaissant sur les images de la banquise obtenues grâce au radar à antenne synthétique (RAAS). On présente les deux recensions dans le contexte d’une expérience de validité sur le terrain appelée Seasonal Sea Ice Monitoring Site (SIMS), actuellement en cours dans les détroits de Lancaster et de Barrow (Territoires du Nord-Ouest). L‘analyse des tons par opposition aux textures comme moyen d’extraire de l’information sur le type de glace à partir d’images RAAS est faite à l’aide de donnees polarisées HH dans l