It has been suggested that changes in the atmospheric circulation caused by anthropogenic forcings are highly uncertain, owing to the large natural variability intrinsic to the system. Here, to assess the statistical significance of such changes for the midlatitude, large-scale atmospheric circulation of the Southern Hemisphere, a new 40-member ensemble of integrations, from 1920 to 2080, of th...

Direct numerical simulations are performed to predict the three-dimensional unsteady flow interactions in the near-field of a square jet issuing normal to a cross-flow. The simulated flow features reveal the formation of an upstream horseshoe vortex system, which is the result of an interaction between the oncoming channel floor shear layer and the transverse jet; the growth of a sequence of Ke...

Eddying flow in the ocean develops as a result of baroclinic instability, and the environment in which the flow develops is vertically and horizontally inhomogeneous. A theory that takes into account the vertical inhomogeneities and predicts the magnitude and structure of the eddy potential vorticity flux for strongly baroclinically unstable mean shears is reviewed and extended to include the f...

Coherent large-scale vortices in the open ocean can retain their structure and properties for periods as long several years. However, patterns of potential vorticity such suggest that they are baroclinically unstable therefore should rapidly disintegrate. This study proposes a plausible explanation longevity rings based on bottom roughness, which restricts flow lower layer thereby stabilizes ed...

Abstract. Idealised baroclinic-wave life-cycle experiments are a widely used tool to study fundamental characteristics of mid-latitude baroclinic instability. A typical life cycle evolves from an initialised baroclinically unstable jet through exponential growth phase particular wave mode, followed by breaking during the mature and wave–mean flow interaction driving shift decay phase. Many auth...

[1] We survey the IPCC AR4 models’ responses to SRES A1B forcing in order to evaluate a prediction of climate change common to all models and testable using GPS radio occultation data over the coming decades. Of the IPCC AR4 models that submitted runs of the SRES A1B forcing scenario, we select twelve because of the timeliness of their submission. Trends in the global average surface air temper...

To understand the atmospheric response to a midlatitude oceanic front, this paper uses a quasigeostrophic (QG) model with moist processes. A well-known, three-level QG model on the sphere has been modified to include such processes in an aquaplanet setting. Its response is analyzed in terms of the upper-level atmospheric jet for sea surface temperature (SST) fronts of different profiles and loc...

Synoptic-scale eddy variance and fluxes of heat and momentum in midlatitude jets are sensitive to small changes in mean jet velocity, dissipation, and static stability. In this work the change in the jet producing the greatest increase in variance or flux is determined. Remarkably, a single jet structure change completely characterizes the sensitivity of a chosen quadratic statistical quantity ...

an experimental study has been performed to investigate the flow physics of an under-expanded axisymmetric supersonic jet exhausting transversely from a flat plate into a subsonic compressible cross flow. the goal was to study the effects of boundary layer thickness ratio (δ/d) and the jet to free stream dynamic pressure ratio (j) on surface pressure. the resulting measurements distinctly show ...