Interannual fluctuations in the Antarctic Circumpolar Current (ACC) were considered. In the present study we analyze a mode of variability in the Hamburg Large-Scale Geostrophic ocean general circulation model which was driven by stochastic atmospheric forcing. The short-term atmospheric weather fluctuations were represented by a number of spatially coherent patterns of momentum, heat, and fres...

Wavelet Analysis provides a new orthogonal basis set which is localized in both physical space and Fourier transform space. Empirical Orthogonal Functions (EOFs), on the other hand, provide a global representation of data sets. Here we investigate the various ways in which one can combine these basis sets for optimal representation of data. EOFs represent the global large scale information and ...

The coupling on decadal time scales of the midlatitude and tropical Pacific via an oceanic 'bridge' in the thermocline is investigated using ocean general circulation model hindcasts and a coupled ocean atmosphere model. Results indicate that in the tropics decadal anomalies of isopycnal depth are forced by Ekman pumping and are largely independent of the arrival of subducted anomalies in the t...

Short-range ocean forecast and reanalysis systems routinely combine observations from satellite altimetry, satellite sea surface temperature (SST), and in situ temperature and salinity, to initialise global and regional ocean models. The most critical observation type for eddy-resolving applications is arguably satellite altimetry. To quantify the impact of satellite altimetry observations on a...

Direct observations, satellite measurements and paleo records reveal strong variability in the Atlantic subpolar gyre on various time scales. Here we show that variations of comparable amplitude can only be simulated in a coupled climate model in the proximity of a dynamical threshold. The threshold and the associated dynamic response is due to a positive feedback involving increased salt trans...

The Agulhas Current system has been analyzed in a nested high-resolution ocean model and compared to observations. The model shows good performance in the western boundary current structure and the transports off the South African coast. This includes the simulation of the northward-flowing Agulhas Undercurrent. It is demonstrated that fluctuations of the Agulhas Current and Undercurrent around...

Propagation of subsurface North Pacific interdecadal variations is investigated with an ocean general circulation model forced by observed sea surface temperature anomalies. Subsurface temperature anomalies subducted in the central subtropical North Pacific take a more westward pathway than a passive “temperature” tracer and reach the western boundary to the north of the bifurcation latitude. T...

A new ocean mixed layer model (OMLM) was embedded into an ocean general circulation model (OGCM) with the aim of providing an OGCM that is ideal for application to a climate model by predicting the sea surface temperature (SST) more accurately. The results from the new OMLM showed a significant improvement in the prediction of SST compared to the cases of constant vertical mixing and the vertic...

[1] The ability to reconstruct the three-dimensional (3D) dynamics of the ocean by an effective version of Surface Quasi-Geostrophy (eSQG) is examined. Using the fact that surface density plays an analogous role as interior potential vorticity (PV), the eSQG method consists in inverting the QG PV generated by sea-surface density only. We also make the extra assumption that sea-surface temperatu...

We develop a simple model of the lower limb of the meridional overturning circulation in the Southern Ocean based on residual mean theory. We hypothesize that the strength of the lower limb (Ψ) is strongly controlled by the magnitude of abyssal diapycnal mixing (κ), and that of mesoscale eddy transfer (K). In particular, we argue that Ψ ∝ √ κK. The scaling and associated theory find support in ...