Many new studies have been published supporting the hypothesis that the Atlantic Meridional Overturning Circulation (AMOC) is experiencing a slowdown. These studies are based on proxies, climatemodel predictions, or a combination of both. The latest work (1) is only based on predictions. The AMOC is allegedly slowing down at an increased rate because of the Arctic ice melting as predicted by cl...

The strength of Atlantic meridional overturning circulation is believed to affect the climate over glacial-interglacial and millennial timescales. The marine sedimentary (231)Pa/(230)Th ratio is a promising paleocirculation proxy, but local particle effects may bias individual reconstructions. Here we present new Atlantic sedimentary (231)Pa/(230)Th data from the Holocene, the last glacial maxi...

Introduction: the concept of the MOC Climate models project a slow down of the Atlantic Meridional Overturning Circulation (MOC) in the twenty-first century. This slow down is expected to affect climate over Europe. In particular, it damps the temperature rise due to the emission of greenhouse gases. The MOC is associated with the thermohaline circulation (ThC), which is the large-scale ocean c...

The possibility that the oceanic general circulation is undergoing changes as part, or the cause, of major climate shifts is being intensely discussed, with some published results relying on data from moorings spanning the North Atlantic Ocean. The circulation is, however, extremely noisy. Here, I use existing estimates of the frequency and wavenumber content of geostrophic eddies in the ocean ...

A numerical model used to simulate global convection and magnetic field generation in stars is described. Nonlmear, three-dimensional, time-dependent solutions of the anelastic magnetohydrodynamic equations are presented for a stratified, rotating, spherical, fluid shell heated from below. The velocity, magnetic field, and thermodynamic perturbations are expanded in spherical harmonics to resol...

The generation of time-mean recirculation gyres from the nonlinear rectification of an oscillatory, spatially localized vorticity forcing is examined analytically and numerically. Insights into the rectification mechanism are presented and the influence of the variations of forcing parameters, stratification, and mean background flow are explored. This exploration shows that the efficiency of t...

We examine leakage and aliasing problems in a seasonal multiple linear regression model of data taken during the NORPAX Hawaii-to-Tahiti Shuttle Experiment. The model includes a mean, trend, annual harmonic, and semiannual harmonic. Inclusion of the trend can exacerbate leakage, particularly for record lengths of 13 months or less. This is not a major problem for the 15-month shuttle record. Th...

We calculate a grid of models with and without the effects of axial rotation for massive stars in the range of 9 to 60 M⊙ and metallicity Z = 0.004 appropriate for the SMC. Remarkably, the ratios Ω/Ωcrit of the angular velocity to the break–up angular velocity grow strongly during the evolution of high mass stars, contrary to the situation at Z = 0.020. The reason is that at low Z, mass loss is...

We present a three-dimensional numerical model for the generation and evolution of the magnetic field in the solar convection zone, in which sunspots are produced and contribute to the cyclic reversal of the large-scale magnetic field. We then assess the impact of this dynamo-generated field on the structure of the solar corona and solar wind. This model solves the induction equation in which t...

Elementary Sverdrup balance is tested in the context of the time-average of a 16-year duration time-varying ocean circulation estimate employing the great majority of globalscale data available between 1992 and 2007. The time-average circulation exhibits all of the conventional major features as depicted both through its absolute surface topography and vertically integrated transport stream fun...