C. D. Hardwick’s research while affiliated with National Research Council Canada and other places

... Conversely, measurements of the vertical and horizontal magnetic gradients have significant advantages over total magnetic field surveys with single-sensor magnetometry. These include the reductions in regional magnetic gradients, the elimination of short-term diurnal fluctuations, and the attenuation of longer wavelength anomalies due to deeper magnetic sources; thus, smaller-scale shallow anomalies are enhanced by removing the masking effects of longer wavelength anomalies (Young and Droege [42]; Marcotte et al. [78]), improving the resolution of minor anomalies, and resolving complex anomalies (Cowan et al. [79]). Another advantage of using a gradiometer is that the transient signals of the Earth's magnetic field are the same for the two sensors, so it completely cancels out any differences in signals that are unaffected by diurnal variations (Sharma [60]; Mussett and Khan [68]; Milsom and Eriksen [76]; Cowan et al. [79]). ...

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Integrated Shallow Geophysical Surveys at Two Caddo Period Archaeological Sites within the Limits of a Water Reservoir in Northeastern Texas, USA

... Methods that enhance trends are particularly important, and several techniques have been put forward to enhance trends in aeromagnetic maps. Using measured gradients can dramatically improve the trend of sharp features and/or linear structures at an acute angle with respect to flight lines (Marcotte et al., 1990;Cowan et al., 1995;McMullan et al., 1995;Hardwick, 1999;O'Connell et al., 2005;Reford, 2006). Yunxuan (1993) uses a band-limited Radon transform (RT) as applied to synthetic gravity maps to remove boudinage artifacts, but the technique remains limited to only one trend direction. ...

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Trend enhancement in aeromagnetic maps using constrained coherence-enhancing diffusion filtering

... No clear pattern of sea-floor spreading anomalies has yet been observed, partly because data distribution and quality are insufficient. An aeromagnetic survey program has been initiated over the Canadian polar continental margins (Nelson et al. 1991), but more data are needed on a regional scale. Given present and foreseeable technology, a regional airborne mapping program covering the entire Amerasian Basin appears to be an effective means to acquire that data. ...

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Reading the stripes: offshore discoveries in plate tectonics with examples from eastern Canada

... These yields detailed data about shallow geological characteristics, which remain unaltered by diurnal fluctuations and the magnetic field background of the region. As an illustration of the gradient tensor measurement's power, the Canadian Geological Survey initiated an aeromagnetic gradiometer program in Canada, developing short baseline aeromagnetic gradiometers back in 1975 [30][31][32]. ...

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Gradiometry Processing Techniques for Large-Scale of Aeromagnetic Data for Structural and Mining Implications: The Case Study of Bou Azzer Inlier, Central Anti-Atlas, Morocco

... The objective of the project is to achieve a regional, aeromagnetic coverage of the Greenland ice cap, and to produce magnetic anomaly maps for use in research on the large scale geological structures. Field work was carried out in 1983, 1984(Thorning et al. , 1984,1986. The work reported in this note was originally planned for April 1986, but for technical reasons it had to be postponed until April 1987. ...

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Greenland ice cap aeromagnetic survey 1987: completion of the survey over the southern end of the Greenland ice cap

... The magnetic anomaly pattern over North Greenland and the adjacent Lincoln Sea bears many similarities with the magnetic anomalies of the Yelverton Bay area (Damaske et al., 1997;Nelson et al., 1998;Damaske & Estrada, 2006;. A broad magnetic high over the southern Lincoln Sea (Damaske & Estrada, 2006, fig. 3) is comparable with the magnetic high H1 over Yelverton Bay. ...

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Multistage Cretaceous magmatism in the northern coastal region of Ellesmere Island and its relation to the formation of Alpha Ridge – evidence from aeromagnetic, geochemical and geochronological data

... It does not require storage of historical data and offers a high real-time advantage, with an exceptional filtering effect especially in the transient state of initial filtering. The Kalman filter was originally designed and developed for aircraft navigation [14]. It is used mainly to estimate the system state that can be observed only indirectly or imprecisely. ...

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Driving factors of interactions between the exchange rate market and the commodity market: A wavelet-based complex network perspective