The global analysis fields of the Met Office stratospheric assimilated data set have been investigated. Systematic biases for select years were identified through val- idation with independent satellite observations. Particular attention was given to analyses from January 2005 to October 2009 produced from a 50 level (L50) configuration of the UM with model lid at ∼0.1 hPa, and the impact on analyses fields from November 2009 to September 2010 when the middle atmospheric configuration of the UM was extended to ∼0.01 hPa using 70 levels (L70). Validation results from both the L50 and L70 analyses show that largest tem- perature biases occur at polar latitudes approaching the model lid in the meso- sphere, exhibiting a clear seasonal cycle. Here cold biases in the winter season of the L50 analyses and warm biases in the summer season of the L70 analyses would strongly suggest that the mean meridional circulation in the mesosphere is underestimated, and that small scale gravity wave forcing supplied by the op- erational Ultra Simple Spectral Parameterisation (USSP) scheme is insufficient. Based on the above validation results numerous experiments were conducted to investigate the temperature response in the mesosphere to increased gravity wave forcing. Such experiments concentrated on tuning the energy scale factor (β) in the USSP scheme and the application of a momentum conserving ”opaque” lid. Furthermore, the impact of developing the USSP scheme to include direct heating from gravity wave induced turbulent dissipation was also investigated. Maximum temperature responses in the summer polar upper mesosphere of ∼22 K were found when increasing the standard value of β=0.1 to β=0.14 combined with the application of an opaque lid. Magnitudes of direct heating rates due to gravity wave turbulent dissipation diagnosed via the USSP scheme were found to be consistent with previous estimates. However applying such heating would most likely have a negative impact on the L70 analyses, which already display warm biases in the upper mesosphere, strongly suggesting that additional phys- ical processes such as eddy diffusion must also be accounted for when applying direct heating from gravity wave breaking.

The profile of the poloidal velocity in the edge region of tokamak plasmas has been identified as playing a major role in the confinement of particles and energy. It has been suggested that a strongly sheared poloidal flow can reduce particle and energy losses by the stabilization of unstable modes and decorrelation of turbulence the edge region of the plasma. A Gundestrup probe, a Mach probe array, is used to measure both the parallel and perpendicular flow velocities in the Saskatchewan Torus-Modified (STOR-M) tokamak during several discharge conditions. It is observed that during Ohmic discharges there is no velocity shear and the direction of the parallel flow is independent of the direction of the toroidal magnetic field. During H-mode induced by a turbulent heating current pulse, a region of strong velocity shear develops in the plasma edge and an edge transport barrier develops. This results in a short period of improved particle and energy confinement with reduced fluctuation amplitudes. During electrode biasing experiments, a stainless steel biasing electrode is inserted into the plasma up to r = 82 mm and biased to +500 V relative to the vacuum chamber. It is observed that the particle confinement improves during the biasing phase while the energy confinement is degraded. A region of weak shear in the poloidal flow is observed in the plasma scrapeoff layer (SOL). The results from STOR-M are compared with results from data taken in the Czech Academy of Sciences Torus (CASTOR) tokamak during both Ohmic discharges and discharges with electrode biasing.

The profile of the poloidal velocity in the edge region of tokamak plasmas has been identified as playing a major role in the confinement of particles and energy. It has been suggested that a strongly sheared poloidal flow can reduce particle and energy losses by the stabilization of unstable modes and decorrelation of turbulence the edge region of the plasma. A Gundestrup probe, a Mach probe array, is used to measure both the parallel and perpendicular flow velocities in the Saskatchewan Torus-Modified (STOR-M) tokamak during several discharge conditions. It is observed that during Ohmic discharges there is no velocity shear and the direction of the parallel flow is independent of the direction of the toroidal magnetic field. During H-mode induced by a turbulent heating current pulse, a region of strong velocity shear develops in the plasma edge and an edge transport barrier develops. This results in a short period of improved particle and energy confinement with reduced fluctuation amplitudes. During electrode biasing experiments, a stainless steel biasing electrode is inserted into the plasma up to r = 82 mm and biased to +500 V relative to the vacuum chamber. It is observed that the particle confinement improves during the biasing phase while the energy confinement is degraded. A region of weak shear in the poloidal flow is observed in the plasma scrapeoff layer (SOL). The results from STOR-M are compared with results from data taken in the Czech Academy of Sciences Torus (CASTOR) tokamak during both Ohmic discharges and discharges with electrode biasing.

The profile of the poloidal velocity in the edge region of tokamak plasmas has been identified as playing a major role in the confinement of particles and energy. It has been suggested that a strongly sheared poloidal flow can reduce particle and energy losses by the stabilization of unstable modes and decorrelation of turbulence the edge region of the plasma. A Gundestrup probe, a Mach probe array, is used to measure both the parallel and perpendicular flow velocities in the Saskatchewan Torus-Modified (STOR-M) tokamak during several discharge conditions. It is observed that during Ohmic discharges there is no velocity shear and the direction of the parallel flow is independent of the direction of the toroidal magnetic field. During H-mode induced by a turbulent heating current pulse, a region of strong velocity shear develops in the plasma edge and an edge transport barrier develops. This results in a short period of improved particle and energy confinement with reduced fluctuation amplitudes. During electrode biasing experiments, a stainless steel biasing electrode is inserted into the plasma up to r = 82 mm and biased to +500 V relative to the vacuum chamber. It is observed that the particle confinement improves during the biasing phase while the energy confinement is degraded. A region of weak shear in the poloidal flow is observed in the plasma scrapeoff layer (SOL). The results from STOR-M are compared with results from data taken in the Czech Academy of Sciences Torus (CASTOR) tokamak during both Ohmic discharges and discharges with electrode biasing.