Magnetic survey and ChinaGRF 2000

Xu, Weihua; Xia, Guo-Hui; An, Zhenchang; Chen, Gengxiong; Zhang, Fengyu; Wang, Yuehua; Tian, Yugang; Wei, Zigang; Ma, S.; Chen, Hongfei

doi:10.1186/bf03351750

Cited by 16 publications

(12 citation statements)

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“…In the research on geomagnetic field model in China, Chinese scientists have studied the Taylor polynomial models in China (Chen, 1948;Xia et al, 1988;Xu et al, 2003). In these studies of the Taylor polynomial model, the truncation order K of the models was taken as K = 2 (Chen, 1948), K = 3 (Xia et al, 1988) and K = 4 (Xu et al, 2003). The truncation order of the Taylor polynomial model is taken as K = 5 in this paper.…”

Section: Discussionmentioning

confidence: 99%

“…In the research on geomagnetic field model in China, Chen (1948) first established the Taylor polynomial model of geomagnetic field in Beipai region of Chongqing for 1946. Chinese scientists have studied the geomagnetic models by using the Taylor polynomial method, the rectangular harmonic analysis, the spline method and the spherical cap harmonic analysis (An et al, 1991;Xia et al, 1988;Xu et al, 2003;Gu et al, 2004;Gao et al, 2005). The above-mentioned results have greatly promoted the development of the research on geomagnetic field model.…”

Section: Introductionmentioning

confidence: 99%

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Geomagnetic survey and geomagnetic model research in China

Zhan

Gao

et al. 2006

Earth Planet Sp

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The geomagnetic survey at 135 stations in China were carried out in 2003. These stations are with better environmental condition and small magnetic field gradient (<5 nT/m). In the field survey, the geomagnetic declination D, the inclination I and the total intensity F were measured. Ashtech ProMark2 differential GPS (Global Positioning System) was used in measuring the azimuth, the longitude, the latitude and the elevation at these stations. The accuracy of the azimuth is 0.1 . The geomagnetic survey data were reduced using the data at geomagnetic observatories in China. The mean standard deviations of the geomagnetic reduced values are: <1.5 nT for F, <0.5 for D and I . Using the geomagnetic data which include the data at 135 stations and 35 observatories in China, and the data at 38 IGRF (International Geomagnetic Reference Field) calculation points in China's adjacent regions, the Taylor polynomial model and the spherical cap harmonic model were calculated for the geomagnetic field in China. The truncation order of the Taylor polynomial model is 5, and its original point is at 36.0• N and 104.5• E. Based on the geomagnetic anomalous values and using the method of spherical cap harmonic (SCH) analysis , the SCH model of the geomagnetic anomalous field was derived. In the SCH model, the pole of the spherical cap is at 36.0• N and 104.5• E, and the half-angle is 30• , the truncation order K = 8 is determined according to the mean square deviation between the model calculation value and the observation value, the AIC (Akaike Information Criterion) and the distribution of geomagnetic field.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Geomagnetic survey and geomagnetic model research in China

Zhan

Gao

et al. 2006

Earth Planet Sp

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“…In order to describe the normal field over the investigated region, the Taylor polynomial of the form (De Santis et al, 1997;De Santis et al, 2003;Xu et al, 2003) …”

Section: Discussionmentioning

confidence: 99%

“…This field can be obtained by fitting with the Taylor polynomial over geographic longitude and latitude, using e.g. the ground survey data (De Santis et al, 2003;Xu et al, 2003). Such polynomial model does not satisfy Laplace's equation for the scalar potential of the total field F (i.e.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the normal geomagnetic field and geological interpretation of the normal field anomalies over middle-northern Croatia

et al. 2011

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Based on the ground survey of total-field magnetic data at 53 sites, which recorded a time-series over the interval 20032005, the core field + long wavelength lithospheric field over the middle-northern Croatia region was calculated. The area of the survey was 18900 km 2 , an average distance between the neighbouring sites being 12 km. The results were reduced to 2004.5 epoch. This "normal" total-field was estimated using the firstorder Taylor polynomial as a function of geographic coordinates, and the polynomial coefficients were calculated with three methods of adjustment: simple and weighted least squares fits and adjustment according to the most frequent value. The stability of the normal field was tested using the Monte Carlo-type test, by decreasing the input data set in each adjustment (up to 90%). All obtained field residuals (measured-"normal") were mutually compared, as well as fit coefficients of the Taylor polynomials. The residual values indicate the presence of shorter-wavelength anomalies, specifically three major residual anomalies were found (106 nT, 74 nT and 57 nT). The geostatistical analysis of the ground survey data and the normal field residuals (respectively), using the median absolute deviation method, was further conducted in order to evaluate the calculated anomalies. The geological situation around the anomalies derived by the median absolute deviation method, and around the normal field residual anomalies, is given. The correlation was found between higher value anomalies of the normal field residuals, and shallow volcanic rocks and oil field, respectively.

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“…The Taylor polynomial was used to describe the geomagnetic normal field over Croatia (De Santis et al, 1997;De Santis et al, 2003;Xu et al, 2003;Brkić and Šugar 2008):…”

Section:  mentioning

confidence: 99%

Analysis of Croatian geomagnetic repeat station surveys in 2004 and 2007

2011

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Surveys of the geomagnetic declination, inclination and total field intensitywere carried out at eight stations of the Croatian Geomagnetic Repeat Stations Network in 2004 and 2007. The total field time series at repeat stations and observatories were compared by use of the multi-linear regression and linear correlation coefficients. The surveys' data were reduced to 2004.5 and 2007.5 epochs by a simple method proposed here, assuming the secular variations at the repeat station and observatory are equal or different, respectively. These reductions, obtained in reference to L'Aquila, Fürstenfeldbruck and Tihany observatories, and corresponding weighted as well as nonweighted averages, were compared. The preferred geomagnetic field elements as well as the corresponding annual changes between 2004.5 and 2007.5 epochs, were compared to the latest International Geomagnetic Reference Field. Additionally, the Croatian Geomagnetic Normal Reference Fields for 2004.5 and 2007.5 epochs were presented.

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Magnetic survey and ChinaGRF 2000

Cited by 16 publications

References 1 publication

Geomagnetic survey and geomagnetic model research in China

Geomagnetic survey and geomagnetic model research in China

Estimation of the normal geomagnetic field and geological interpretation of the normal field anomalies over middle-northern Croatia

Analysis of Croatian geomagnetic repeat station surveys in 2004 and 2007

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