Site measurements were collected at Mount John University Observatory in 2005 and 2007 using a purpose-built scintillation detection and ranging system. C2N(h) profiling indicates a weak layer located at 12a€“14 km above sea level and strong low altitude turbulence extending up to 5 km. During calm weather conditions, an additional layer was detected at 6a€“8 km above sea level. V(h) profiling suggests that tropopause layer velocities are nominally 12a€“30m sa?’1, and near-ground velocities range between 2 and 20m sa?’1, dependent on weather. Little seasonal variation was detected in either C2N(h) and V(h) profiles. The average coherence length, r0, was found to be 7?±1 cm for the full profile at a wavelength of 589 nm. The average isoplanatic angle, ??0, was 1.0?±0.1 arcsec. The mean turbulence altitude, , was found to be 2.0?±0.7 km above sea level. No average in the Greenwood frequency, fG, could be established due to the gaps present in the V(h) profiles obtained. A modified Hufnagel-Valley model was developed to describe the C2N(h) profiles at Mount John, which estimates r0 at 6 cm and ??0 at 0.9 arcsec. A series of V(h) models were developed, based on the Greenwood wind model with an additional peak located at low altitudes. Using the C2N(h) model and the suggested V(h) model for moderate ground wind speeds, fG is estimated at 79 Hz.
展开▼
