Improved modeling of sea level patterns by incorporating self‐attraction and loading

Abstract

[1] We implement the effects of gravitational self-attraction and loading (SAL) into a global baroclinic ocean circulation model and investigate effects on sea level patterns, ocean circulation, and density distributions. We compute SAL modifications as an additional force on the water masses at every time step by decomposing the field of ocean bottom pressure anomalies into spherical harmonic functions and then applying Love numbers to account for the elastic properties of the solid Earth. Considering SAL in the postprocessing turns out to be insufficient, especially in coastal waters and on subweekly time scales, where SAL modifies local sea level by around 0.6-0.8 cm on average; in the open ocean, changes mostly remain around 0.3 cm. Modifications of water velocities as well as of heat and salt distributions are modeled, yet they are small. Simple parameterizations of SAL effects currently used in a number of ocean circulation models suffer from the process's inhomogeneity in space and time. These parameterizations improve the modeled sea level patterns but fail to reproduce SAL impacts on circulation and density distributions. We therefore suggest to explicitly consider the full SAL effect in ocean circulation models, especially when investigating sea level variations faster than around 4 days.Citation: Kuhlmann, J., H. Dobslaw, and M. Thomas (2011), Improved modeling of sea level patterns by incorporating selfattraction and loading,

A new high-resolution model of non-tidal atmosphere and ocean mass variability for de-aliasing of satellite gravity observations: AOD1B RL06

“…This includes testing the prospects of higher spatial and vertical resolution (von Storch et al 2012); reconsidering self-attraction and loading feedbacks to ocean dynamics (Ray 1998;Kuhlmann et al 2011); revisiting potential interactions between the general ocean circulation and the ocean tidal flow regime (Thomas et al 2001;Li et al 2015) and evaluating further modifications to the currently applied parametrizations of subgrid scale processes with the goal of improving the simulated bottom pressure variations in semi-enclosed seas, at the continental shelf, and in particular underneath the Antarctic ice shelves (Hellmer et al 2012).…”

Dynamically and Kinematically Consistent Global Ocean Circulation and Ice State Estimates

“…At the levels of accuracy appearing to be required, very careful attention must now be paid to modeling issues such as water self-attraction and load (Kuhlmann et al, 2011;Vinogradova et al, 2011) not normally accounted for in OGCMs. Conventional approximations to the moving freesurface boundary conditions generate systematic errors no longer tolerable (e.g., Huang, 1993;.…”

Dynamic Adjustment of the Ocean Circulation to Self-Attraction and Loading Effects

“…Among the first attempts of such implementation are studies by Stepanov and Hughes (2004) and Kuhlmann et al (2011), who considered SAL within barotropic and baroclinic ocean models, respectively. In particular, Stepanov and Hughes (2004) show that integrating a model with the calculation of SAL effects, using a ''prohibitively expensive'' global convolution integral at each grid point and time step, can ''occupy more than 90%'' of the computing time.…”

“…In particular, Stepanov and Hughes (2004) show that integrating a model with the calculation of SAL effects, using a ''prohibitively expensive'' global convolution integral at each grid point and time step, can ''occupy more than 90%'' of the computing time. Kuhlmann et al (2011) used a different computational approach based on spherical harmonics decomposition to incorporate SAL physics in their model. Their experiments were more successful in terms of computational efficiency, increasing computing time by only ;16%.…”