The first climatology of airmass origin in the Arctic is presented in terms of rigorously defined airmass fractions that partition air according to where it last contacted the planetary boundary layer (PBL). Results from a present-day climate integration of the Goddard Earth Observing System Chemistry–Climate Model (GEOSCCM) reveal that the majority of air in the Arctic below 700mb last contact...

Cyclonic barotropic shear of incrementally increasing magnitude is imposed on an idealized midlatitude jet, and the life cycles of baroclinically unstable wavenumber 6 perturbations growing on these jets are studied. When the barotropic shear parameter passes a critical value, the life cycle makes an abrupt transition from anticyclonic to cyclonic behavior. The abrupt transition in behavior is ...

Understanding the physical mechanism maintaining fluid turbulence remains a fundamental theoretical problem. The two-layer model is an analytically and computationally simple system in which the dynamics of turbulence can be conveniently studied; in this work, a maximally simplified model of the statistically steady turbulent state in this system is constructed to isolate and identify the essen...

Interaction between the midlatitude jet and gravity waves is examined, focusing on the nonnormality of the underlying linear dynamics, which plays an essential role in processing the wave activity and selecting structures that dominate wave momentum and energy transport. When the interior of a typical midlatitude jet is stochastically forced, waves with short horizontal wavelength are trapped i...

Satellite altimetry and high-resolution ocean models indicate that the Southern Ocean is comprised of an intricate web of narrow, meandering jets that undergo spontaneous formation, merger and splitting events, and rapid latitude shifts over periods of weeks to months. The role of topography in controlling jet variability is explored using over 100 simulations from a doubly-periodic, forced-dis...

We present a numerical study of 2D axisymmetric flows in a rotating annulus convectively forced by local thermal forcing via a heated annular ring at the bottom near the external wall and a cooled circular disk near the centre at the top surface of the annulus. Two vertically and horizontally displaced heat sources/sinks are arranged so thatstatically unstable Rayleigh-Bénard convection would b...

An 18-vertical level primitive equation general circulation model was developed from previous models of the Geophysical Fluid Dynamics Laboratory in order to study t,he lower stratosphere in detail. The altitude range covered was from the surface to 4 mb. (37.5 km.), the vertical resolution being optimized in the tropopause region to permit a more accurate calculation of the vertical transport ...

Broad-peak intraseasonal oscillations in large-scale Northern Hemisphere atmospheric circulation patterns provide a basis for extended-range weather prediction, given an understanding of the underlying mechanisms. Theoretical work and general circulation model (GCM) experiments suggest that the midlatitude jet stream's interaction with large-scale topography can drive such oscillations through ...