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

On the Links between Microwave and Solar Wavelength Interactions with Snow-Covered First-Year Sea Ice

Electromagnetic (EM) energy at solar and microwavelengths will interact with a snow-covered sea ice volume as a function of its geophysical properties. The seasonal metamorphosis of the snow cover modulates the relative distribution of the three main interaction mechanisms of EM energy: reflection, transmission, and absorption. We use a combination of modeling and observational data to illustrate how the total relative scattering cross section (Sigma 0) at microwavelengths can be used to estimate the surface climatological shortwave albedo and the transmitted Photosynthetically Active Radiation (PAR) for a snow-covered, first-year sea ice volume typical of the Canadian Arctic. Modeling results indicate that both 5.3 and 9.25 GHz frequencies, at HH polarization and incidence angles of 20 degrees, 30 degrees, and 40 degrees can be used to estimate the daily averaged integrated climatological albedo (Alpha). The models at 5.3 GHz, HH polarization, at 20 degree, 30 degree, and 40 degree incidence angles were equally precise in predications of Alpha. The models at 9.25 GHz were slightly less precise, particularly at the 40 degree incidence angle. The reduction in precision at the 40 degree incidence angle was attributed to the increased sensitivity at both 5.3 and 9.25 GHz to the snow surface scattering term (Sigma 0 ss) used in computation of the total relative scattering cross section (Sigma 0). Prediction of subsnow PAR was also possible using the same combination of microwave sensor variables utilized in prediction of Alpha, but because subice algal communities have evolved to be low light sensitive, the majority of the growth cycle occurs prior to significant changes in Sigma 0. A method of remote estimation of snow thickness is required to be scientifically useful. Observational data from the European ERS-1 SAR were used to confirm the appropriateness of the modeled relationships between Sigma 0, Alpha, and PAR. Over a time series spanning all conditions used in the modeled relationships, the same general patterns were observed between Sigma, Alpha, and PAR.Key words: microwave scattering models, snow, sea ice, climatological shortwave radiation, photosynthetically active radiation, microwave remote sensingL'&eacute;nergie &eacute;lectromagn&eacute;tique &agrave; des ondes ultra-courtes et solaires va interagir avec un volume de glace de mer couverte de neige, en fonction de ses propri&eacute;t&eacute;s g&eacute;ophysiques. La m&eacute;tamorphose saisonni&egrave;re du couvert nival module la distribution relative des trois grands m&eacute;canismes d'interaction de l'&eacute;nergie &eacute;lectromagn&eacute;tique: r&eacute;flexion, transmission et absorption. On utilise une combinaison de r&eacute;sultats de mod&eacute;lisation et de donn&eacute;es d'observation pour illustrer la fa&ccedil;on dont la coupe transversale totale de diffusion relative (sigma-zero) &agrave; des longueurs d'onde ultra-courtes peut &ecirc;tre utilis&eacute;e pour estimer l'alb&eacute;do climatologique en ondes courtes de la surface et le rayonnement photosynth&eacute;tiquement utilisable (RPU) pour un volume de glace de mer nouvelle couverte de neige, typique de l'Arctique canadien. Les r&eacute;sultats de mod&eacute;lisation indiquent qu'on peut utiliser les deux fr&eacute;quences de 5,3 et 9,25 GHz, ayant une polarisation HH et des angles d'incidence de 20, 30 et 40&deg; pour estimer la moyenne quotidienne de l'alb&eacute;do climatologique int&eacute;gr&eacute; (alpha). Les mod&egrave;les &agrave; 5,3 GHz, ayant une polarisation HH et des angles d'incidence de 20, 30 et 40&deg; pr&eacute;disaient alpha avec le m&ecirc;me degr&eacute; de pr&eacute;cision. Les mod&egrave;les &agrave; 9,25 GHz &eacute;taient l&eacute;g&egrave;rement moins pr&eacute;cis, surtout en ce qui concerne l'angle d'incidence de 40&deg;. La r&eacute;duction de pr&eacute;cision &agrave; l'angle d'incidence de 40&deg; &eacute;tait attribu&eacute;e &agrave; une augmentation de sensibilit&eacute;, aux deux fr&eacute;quences de 5,3 et 9,25 GHz, au terme de diffusion de la surface nivale (sigma-zero-ss) utilis&eacute; dans le calcul de la coupe transversale totale de diffusion relative (sigma-zero). Pour pr&eacute;dire le RPU sous la couche nivale, on a &eacute;galement pu utiliser la m&ecirc;me combinaison de variables de capteurs d'ondes ultra-courtes que celle utilis&eacute;e pour pr&eacute;dire alpha. Mais parce que les communaut&eacute;s d'algues vivant sous la glace ont d&eacute;velopp&eacute; un niveau de photosensibilit&eacute; &eacute;lev&eacute;, la plupart du cycle de croissance se produit avant que des changements importants n'aient lieu dans sigma-zero. Il faut d&eacute;velopper une m&eacute;thode d'estimation de l'&eacute;paisseur nivale par la t&eacute;l&eacute;d&eacute;tection pour que cette m&eacute;thode soit utilisable du point de vue scientifique. On a utilis&eacute; des donn&eacute;es d'observation prises au RALS dans le cadre du ERS-1 europ&eacute;en pour confirmer la pertinence des rapports de mod&eacute;lisation entre sigma-zero, alpha et le RPU. Dans une s&eacute;rie chronologique couvrant toutes les conditions utilis&eacute;es dans les rapports de mod&eacute;lisation, on a observ&eacute; les m&ecirc;mes grandes tendances entre sigma-zero, alpha et le RPU.Mots cl&eacute;s: mod&egrave;les de diffusion d&rsquo;hyperfr&eacute;quences, neige, glace de mer, rayonnement climatologique de courtes longueurs d&rsquo;onde, rayonnement photosynth&eacute;tiquement utilisable, t&eacute;l&eacute;d&eacute;tection des ondes ultra-courte

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

The Evolution of Remote Sensing Education in Canada’s Universities and Colleges: Decades of Innovation and Expansion

During the rapid development of remote sensing technology and applications in the 1970’s in Canada, the Canadian Advisory Committee on Remote Sensing conducted a nation-wide review of relevant activities in post-secondary teaching and research. This was updated in the 1980’s. Similar reviews were solicited for the radar community in 2009 by the Canadian Space Agency and for the Geospatial community in Canada in 2016 by Natural Resources Canada. In this paper we report on a new Canadian survey conducted in 2021 which is discussed within the context of the previous profiles. In Canada today there are 65 post-secondary institutions directly involved in remote sensing teaching and 63 academic research centers in this field. At these institutions and others worldwide, significant changes were brought about in education practice in the spring of 2020 with shutdowns in many sectors of the economy in response to the rapid expansion of the COVID-19 virus. Classroom teaching transitioned to on-line communication. These experiences may have a direct influence on how teaching and training practice of ‘hands-on’ disciplines such as remote sensing may evolve and contribute to future growth. We discuss the potential impact of this upheaval for the future of remote sensing education within the remote sensing community in Canada based upon personal experience