Thermospheric gravity waves near the source: Comparison of variations in neutral temperature and vertical velocity at Sonore Stromfjord

A computation of the atmospheric response to heat sources in the thermosphere has shown that the local perturbations produced by impulsive sources depend critically on the parameter being observed (e.g., temperature), on the distance from the source, and on the source shape and time variation. A simulation has been done with a source at an altitude of 130 km, and it has been compared with nighttime observations of the neutral temperature and vertical wind velocity variations occurring between 250 and 300 km above Sondre Stromfjord. The data show two heating events, the first occurring away from the zenith and the second in the zenith, thus yielding observations away from and directly above the heated region. The computations reproduced all of the features observed but underestimated the vertical velocity amplitudes and the rapidity of the temperature decay. The observations also support the theoretical finding that the vertical velocity near the source shows maxima (minima) simultaneous with temperature increases (decreases), roughly resembling the time derivative of the source.