A simplified model of the moist axisymmetric Hadley circulation is examined in the asymptotic limit in which surface drag is strong and the meridional wind is weak compared to the zonal wind. Our model consists of the quasi-equilibrium tropical circulation model (QTCM) equations on an axisymmetric aquaplanet equatorial beta-plane. This model includes two vertical momentum modes, one baroclinic ...

A medium frequency spaced-antenna radar has been operating at Rothera station, Antarctica (67 S, 68 W) for two periods, between 1997–1998 and since 2002, measuring winds in the mesosphere and lower thermosphere. In this paper monthly mean winds are derived and presented along with three years of radiosonde balloon data for comparison with the HWM-93 model atmosphere and other high latitude sout...

The Southern Ocean (SO) limb of the meridional overturning circulation (MOC) is characterized by three vertically stacked cells, each with a transport of about 10 Sv (Sv [ 10 m s). The buoyancy transport in the SO is dominated by the upper and middle MOC cells, with the middle cell accounting for most of the buoyancy transport across the Antarctic Circumpolar Current. A SouthernOcean state esti...

The quasi-geostrophic global stratospheric model at MIT developed by is used to study the zonal and time-averaged transport of potential temperature and ozone by the planetary zonal wavenumbers 1-6. Several types of covariances between the winds, geopotential, and the tracers are calculated in order to evaluate the directions and strength of the fluxes and the winds causing the fluxes. The eddy...

This SI Appendix is formed by three sections. Section 1 contains a brief discussion of the derivations of the dynamical model and its low-order meridional truncation. The details of boundary conditions, numerical solvers as well as a list of the parameter values are also included. The mathematical formula of the anomalous Walker circulation is shown at the end of this section. Section 2 involve...

An oceanic general circulation model is used to investigate the annual cycle of the near-surface currents in the eastern equatorial Pacific Ocean; in particular, the causes of the springtime increase of eastward momentum that reverses the westward surface flow and intensifies the Equatorial Undercurrent are examined. A set of process experiments are carried out that isolates effects due to thre...

Long-period oscillations in the period range 2– 30 days, interpreted as planetary wave (PW) signatures, have been analysed using daily mesosphere/lower thermosphere wind measurements near 90 km over Collm (52 N, 15 E) in the time interval 1980–2005. Interannual and interdecadal variability of PW are found. Since the 1990s, a tendency for larger zonal amplitudes compared to meridional ones has b...

With data from 12 coupled models in the 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR4), climate under year 2000 greenhouse gas (GHG) + aerosol forcing was compared with climate under pre-industrial conditions. In the tropical Pacific, the warming in the mean sea surface temperatures (SST) was found to have an El Niño-like pattern, while both the equatorial zon...

The response of the Southern Hemisphere (SH), extratropical, atmospheric general circulation to transient, anthropogenic, greenhouse warming is investigated in a coupled climate model. The extratropical circulation response consists of a SH summer half-year poleward shift of the westerly jet and a year-round positive wind anomaly in the stratosphere and the tropical upper troposphere. Along wit...