Advanced helicopter aerogravity surveying system

Gumert, William R.; Phillips, D.

doi:10.1190/1.1438518

Cited by 3 publications

(3 citation statements)

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“…The GPS and the continuous improvements in accelerometers, platforms, and gravimeters throughout the 1990s fostered the advent of reliable aerogravity and marine surveys in early 1990s, particularly offshore (e.g., Brozena, 1992;Jensen, 1992). From 2000 on, aerogravity surveys became customary (e.g., Gummert and Phillips, 2000;Williams and Macqueen, 2001;Verdun et al, 2002).…”

Section: From 1990 To 2014mentioning

confidence: 99%

Fast gravity inversion of basement relief

2014

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Gravity interpretation of large sedimentary basins requires a large number of observations and of parameters estimations, so the development of very efficient gravity inversion methods applicable to such environments is of utmost importance. We found that the highly efficient Bott's method can be cast in the framework of Gauss-Newton's method for minimizing nonlinear functions. Also, we extended Bott's method to (1) be applicable to sedimentary basins with density contrast between the sediments and the basement decreasing with depth according to different laws, (2) optimize the modulus of the parameter correction vector, (3) stabilize the solution by imposing that it be smooth, and (4) quit the iteration according to an objective and effective criterion. To keep up the efficiency of Bott's method, stable solutions were obtained by applying a moving average to the usually unstable solution obtained at the last iteration. Solutions as efficacious as those obtained by the usual nonlinear method were produced by the present extension at a much smaller computation time. Nonlinear methods, with different implementations for solving a linear system of equations, required between one and two orders of magnitude more time to produce similar solutions using between 2000 and 3000 parameters and observations, for example.

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Section: From 1990 To 2014mentioning

confidence: 99%

Fast gravity inversion of basement relief

2014

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“…The gravimeter for helicopter use was also developed by Gumert and Cobb (1970) and Hammer (1983). But, these pioneering works seem to have had much difficulty in positioning as GPS was not available.…”

Section: Helicopter Gravimetermentioning

confidence: 99%

Examination of consistency of marine gravity with land gravity in and around the Japanese Islands using a helicopter-borne gravimeter

et al. 2005

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This paper reports a finding that marine gravity data around the Japanese Islands are inconsistent with nearby land gravity data. The comparison between land and marine gravity was made possible by the gravity measurements from the air using a helicopter-borne gravimeter (SEGAWA Model) developed by the present authors. The ground/sea truth gravity anomaly can be checked against the gravity from the air, though it is not free air gravity anomaly but gravity disturbance. The newly-developed airborne gravimeter first manufactured in 1998 shows a good performance with a 1-2 mgal average repeatability of measurement under a 90-knot flight speed. Thus we have found disagreements between ground truth and sea truth gravity anomalies on the basis of airborne gravity data in the areas in Japan where we have so far made measurements. Among them we will report the case in the area from Saitama and Ibaraki offshore to the Kashima-Nada Sea, Japan. Our conclusion about this area is that the past marine gravity data obtained by surface ship gravimeters involve systematic errors of more than 10 mgals. This kind of inconsistency between marine and land gravity is expected to be found in a number of other areas around the Japanese Islands.

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“…Actual implementations were reported by Jekeli and Kwon (1999) and Kwon and Jekeli (2001), adding to related efforts using gravity gradiometry reviewed in Jekeli (1993). Scalar gravimetry is now routine and operational for geophysical exploration (e.g., Gumert and Phillips, 2000). However, the determination of the other components of the gravity vector with airborne instrumentation has received only modest attention in this regard, mostly in connection with their derivatives obtained from gravity gradiometers (Vasco and Taylor, 1991), although most gradiometry studies and systems focus only on the vertical gradient (e.g., Gupta and Ramani, 1982;van Leeuwen, 2000).…”

Section: Introductionmentioning

confidence: 99%

The effect of stochastic gravity models in airborne vector gravimetry

Kwon

Jekeli

2002

GEOPHYSICS

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Measurements of specific force using inertial measurement units (IMU) combined with Global Positioning System (GPS) accelerometry can be used on an airborne platform to determine the total gravitational vector. Traditional methods, originating with inertial surveying systems and based on Kalman filtering, rely on choosing an appropriate stochastic model for the gravity disturbance components included in the set of system error states. An alternative procedure that uses no a priori stochastic model has proven to be as effective, or moreso, in extracting the gravity vector from airborne IMU/GPS data. This method is based on inspecting acceleration residuals from a Kalman filter that estimates only sensor biases. Using actual data collected over the Canadian Rocky Mountains, this method was compared to the traditional approach adapted for different types of stochastic models for the gravity disturbance vector. In all test cases, the estimation filter without a gravitational model yielded better results-up to 50%. This implies that accurate gravity vector determination from airborne IMU/GPS need not rely on an a priori stochastic model of the field, even though the theory of optimal estimation requests it. However, no filter was able to remove all systematic errors from the data; these remaining errors could only be reduced by elementary methods such as endpoint matching and correlative processing of adjacent passes of the system over the gravity field. The final, best gravity estimates had standard deviations with respect to control data of 6 mGal in the horizontal components and 3-4 mGal in the vertical component.

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Advanced helicopter aerogravity surveying system

Cited by 3 publications

References 0 publications

Fast gravity inversion of basement relief

Fast gravity inversion of basement relief

Examination of consistency of marine gravity with land gravity in and around the Japanese Islands using a helicopter-borne gravimeter

The effect of stochastic gravity models in airborne vector gravimetry

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