Open Session - SWISS GEOSCIENCE MEETINGs

1.26
Calculation of Orthometric Correction with Geopotential Models
Kordi Kobra*, Arabi Siavash*, *
*National Cartographic Center in IRAN(NCC) (kobra_kordi@yahoo.com)
In Presice Levelling for calculate height points with high accuracy, it is necessary that we estimate Orthometric Correction.
We need to height and Gravitty of two point. Height of point calculate in Precise Levelling and we should compute gravity
of point.
There are many way for determine Gravity acceleration. We can measure gravity of point directly. We can use Coordinate of
point and Geopotential Coefficients and compute its Gravity. Usually used of Direct measurement for determine Gravity. If
results of Geopotential model to be near the result of Direct measurement, we can use the Geopotential Models for our
aid.
In this paper, 3 Geopotential model use in research. These models are EGM96, Grace & Eigen-2. We focus on 3 loops of Iran
Precise Levelling Network. Result of four models show in fig(1), fig(2) and fig(3).
Orthomethric Correction calculated for Levelling Lines with used four model. There is difference between geopotential models
and measurements, so Directly measurements is better method for determine Orthometric correction.
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Symposium 1: Structural Geology, Tectonics and Geodynamics