scholarly journals Evaluation of W0 in Canada using tide gauges and GOCE gravity field models

2012 ◽  
Vol 2 (4) ◽  
pp. 290-301 ◽  
Author(s):  
T. Hayden ◽  
E. Rangelova ◽  
M. G. Sideris ◽  
M. Véronneau

AbstractThe existing Canadian Geodetic Vertical Datum of 1928 (CGVD28) does not meet the needs of the modern user in terms of accuracy and accessibility. As a result, Canada plans to implement a geoid-based and global navigation satellite system (GNSS)-accessible vertical datum by 2013. One of the primary concerns in realizing this new vertical datum is to determine a W0 value that will represent the potential of the zero height surface. The objective of this study is to evaluate W0 by averaging the potential of points on the mean sea water surface utilizing tide gauge recordings and gravity field and steady-state ocean circulation explorer (GOCE)-based global geopotential models. In order to assess the performance of the GOCE-based models for the computation of W0, the models are extended with the high resolution gravitational model EGM2008. Regional gravimetric geoid models are also used for the estimation of W0. Additionally, local sea surface topography models are utilized in order to validate the W0 results at the tide gauges. Excluding the Arctic coast, the W0 values obtained from both tide gauges and oceanic sea surface topography models are not statistically different from the International Earth Rotation and Reference Systems Service (IERS) 2010 global conventional value 62636856.00 m2/s2.

2007 ◽  
Vol 30 (4) ◽  
pp. 271-296 ◽  
Author(s):  
J. C. Iliffe ◽  
M. K. Ziebart ◽  
J. F. Turner

1986 ◽  
Vol 32 (112) ◽  
pp. 383-390 ◽  
Author(s):  
Konrad Steffen

AbstractThe surface condition of the North Water was investigated during two winters (i.e. the three polynyas: Smith Sound polynya, Lady Ann Strait polynya, and Barrow Strait polynya). Since no detailed information was available on ice conditions and the extent of open water during winter, radiometric temperature measurements of the sea surface had to be taken along a flight line of 2650 km from an altitude of 300 m. From November to March 1978-79 and 1980-81, 14 remote-sensing flights were carried out. On the basis of the radiometric measurements, the following ice types were identified: ice-free, dark nilas, light nilas, grey ice, grey-white ice, and white ice. A comparison between the thermal and the visual ice classification (the latter being based on grey tones of the aerial images) showed a deviation of 3%. The analysis showed that in November, December, and January more than 50% of the Smith Sound polynya was covered by young ice, nilas, and ice-free, whereas in February and March white ice was dominant. Moreover, it was found that the two polynyas in Smith Sound and Lady Ann Strait were much smaller than previously believed. In Barrow Strait, a semi-permanent polynya was observed in the winter of 1980-81. The occurrence of polynyas in Barrow Strait seems to be connected with the location of the fast-ice edge. On the basis of the calculated ice-type distribution and heat-flux rates for different ice types, an energy loss of 178 W m-2was found on the surface of the Smith Sound polynya due to open water and thin ice for the winter months November to March. Compared with other ice-covered sea surfaces in the Arctic, the heat release by the sea-water in the Smith Sound polynya is about 100 W m-2larger.


Eos ◽  
2013 ◽  
Vol 94 (13) ◽  
pp. 131-131
Author(s):  
Ernie Balcerak

1983 ◽  
Vol 7 (1-4) ◽  
pp. 101-126 ◽  
Author(s):  
C. L. Merry ◽  
P. Vaníček

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