Loading of the Earth's crust due to the redistribution of global air masses and associated pressure changes can displace the positions of geodetic sites by more than 1 cm both vertically and horizontally. The displacements are mainly dominated by the effects of synoptic scale systems with wavelengths of 1000 to 2000 km and periods of approximately two weeks. As can be seen from the figure below, peak-to-peak vertical displacements of 10 to 20 mm are common at mid-latitude regions, where large amplitude pressure systems can be found.
|Deformation of the Earth's surface due to atmosphere pressure loading for 1 August 2008, 6 h UTC. Units: [mm].|
Atmosphere pressure loading (APL) effects on geodetic sites have been observed in high-precision space geodetic data such as Global Positioning System data (van Dam et al., 1994) and Very Long Baseline Interferometry data (van Dam and Herring, 1994). As these observations are primarily used for geodynamic studies, i.e. plate tectonics, Earth rotation, post-glacial rebound, it is important to remove the displacement signals due to APL from the data. Thus, a rigorous computation of the displacements is imperative.
In the APL part of GGOS Atmosphere we focused on developing a standard procedure for the calculation of the displacements and on providing accurate correction values that would be suitable for routine analysis of space geodetic observations. In the course of this, we addressed the following aspects:
D.D. Wijaya, J. Böhm, M. Karbon, H. Krásná, H. Schuh. Atmospheric pressure loading, in J. Böhm and H. Schuh (eds): Atmospheric Effects in Space Geodesy, Springer Verlag, pp. 137-157, doi:10.1007/978-3-642-36932-2_4, 2013.
L. Petrov, J.-P. Boy. Study of the atmospheric pressure loading signal in very long baseline Interferometry observations, J. Geophys. Res., 109, B03405, doi:10.1029/2003JB002500, 2004.
T.M. Van Dam, T.A. Herring. Detection of atmospheric pressure loading using very long baseline Interferometry measurements, J. Geophys. Res., 99, 4505-4517, 1994.
T.M. Van Dam, G. Blewitt, M.B. Heflin. Atmospheric pressure loading effects on Global Positioning System coordinate determinations, J. Geophys. Res., 99, 23939-23950, 1994.
C. Hirt, W.E. Featherstone, S.J. Claessens. On the accurate numerical evaluation of geodetic convolution integrals, J. Geod., 85 (8), pp. 519-538, doi:10.1007/s00190-011-0451-5, 2011.