Analysis of self-attraction and loading effects on ocean mass using geophysical models and GRACE data

Author: Nadya Vinogradova, Rui M. Ponte and Katherine J. Quinn
December 7, 2011
Poster presentation
AGU Fall Meeting 2011

Nadya T. Vinogradova; Rui M. Ponte; Mark E. Tamisiea; Katherine J. Quinn; Emma M. Hill; James L. Davis (2011) Analysis of self-attraction and loading effects on ocean mass using geophysical models and GRACE data. AGU Fall Meeting 2011.

The exchange of water between the land, ocean and atmosphere is an essential factor driving changes in ocean mass and relative sea level, both of which are important indicators of climate change. Such changes in mass and relative sea level can be affected by the physics of self-attraction and loading (SAL). In this study we examine the impact of SAL effects on ocean mass redistribution under different surface loads (land hydrology, atmospheric pressure, ocean dynamics), using a number of geophysical models and GRACE observations. The results show that the effects of SAL physics lead to time-varying, non-uniform spatial patterns and are an important component of ocean mass variability on scales from months to years. With the exception of some small regions, annual variations account for the most variability in SAL-related mass signals and can be induced by all the loads considered, with land hydrology having the largest contribution. At sub-annual and inter-annual time scales, the impact of land hydrology is minimal and ocean dynamics and atmospheric pressure loads become more important. SAL effects produce additional variations in ocean mass ranging from a few mm to more than 1 cm and can be of the same order of magnitude as the variations in dynamic bottom pressure in several ocean regions. The role of SAL is also examined in the interpretation of GRACE-derived measurements of ocean mass. The results demonstrate the importance of SAL effects to the understanding of the annual cycle in ocean-bottom pressure observed by GRACE, showing that SAL effects can explain on average 0.2 cm2 (16%) of GRACE annual variances and more than 1 cm2 in some open-ocean and coastal regions.