Comments on “Thermally Forced Gravity Waves in an Atmosphere at Rest”

Abstract

Abstract The transient linear response of a quiescent, two-dimensional, nonrotating atmosphere to prescribed heat sources and sinks is investigated. Analytical solutions of the hydrostatic Boussinesq equations are obtained for a rigid lid and for a semi-infinite region. For the rigid lid solution, vertically trapped gravity waves propagate away from the source with a speed that depends on the Brunt–Väisälä frequency and the vertical wavenumber of the heating. The amplitude of the disturbance field in the region of the forcing approaches a constant value. Two modes are of particular interest: 1) a deep fast-moving mode which is responsible for subsidence warming through the depth of the troposphere; 2) a slower moving mode which corresponds to midlevel inflow and lower- and upper-level outflows. A solution is also obtained for a semi-infinite region. Although gravity wave energy can now propagate upward, the structure of the low-level fields still shows many similarities with the rigid lid solution. An ana...