5 Tropospheric circulation shifts have strong potential to impact surface climate. But the magnitude 6 of these shifts in a changing climate, and the attending regional hydrological changes, are difficult 7 to project. Part of this difficulty arises from our lack of understanding of the physical mechanisms 8 behind the circulation shifts themselves. In order to better delineate circulation shif...

The tropospheric response to midlatitude SST anomalies has been investigated through a series of aquaplanet simulations using a high-resolution version of the Hadley Centre atmosphere model (HadAM3) under perpetual equinox conditions. Model integrations show that increases in the midlatitude SST gradient generally lead to stronger storm tracks that are shifted slightly poleward, consistent with...

During 6–7 June 2003, a Mei-Yu jet/front system over Southern China is characterized by appreciable horizontal temperature contrast below the 850 hPa level (>8 K), where cold, dry, postfrontal northeasterlies converge with warm, moist southwesterly flow, and above 400–hPa (>18 K) associated an upper-level front. The frontal baroclinic zone tilts northward slope of ~1/100. passage midlatit...

We consider a 2-layer quasi-geostrophic ocean model where the upper layer is forced by steady Kolmogorov wind stress in periodic channel domain, which allows to mathematically study nonlinear development of resulting flow. The supports parallel shear flow as response stress. As maximal velocity (equivalently amplitude forcing) exceeds critical threshold, zonal jet destabilizes due baroclinic in...

Theoretical work and general circulation model (GCM) experiments suggest that themidlatitude jet stream’s interaction with large-scale topography can drive intraseasonal oscillations in large-scale atmospheric circulation patterns. In support of this theory, we present new observational evidence that mountain-induced torques play a key role in 15–30-day oscillations of the Northern Hemisphere c...

[1] A consistent weakening and poleward expansion of the Hadley circulation is diagnosed in the climate change simulations of the IPCC AR4 project. Associated with this widening is a poleward expansion of the subtropical dry zone. Simple scaling analysis supports the notion that the poleward extent of the Hadley cell is set by the location where the thermally driven jet first becomes baroclinic...

[1] Changes in the variability of surface ozone can affect the incidence of ozone pollution events. Analysis of multi-century simulations from a chemistry climate model shows that present-day summertime variability of surface ozone depends strongly on the jet stream position over eastern North America. This relationship holds on decadal time scales under projected climate change scenarios, in w...

Turbulence in fluids is commonly observed to coexist with relatively large spatial and temporal scale coherent jets. These jets may be steady, vacillate with a definite period, or be irregular. A comprehensive theory for this phenomenon is presented based on the mutual interaction between the coherent jet and the turbulent eddies. When a sufficient number of statistically independent realizatio...