engleski

Large-Scale Modes of the Tropical Atmosphere. Part I: Analytical Modeling of Convectively Coupled Kelvin Waves Using the Boundary-Layer Quasiequilibrium Approximation

One way of modeling the convectively coupled Kelvin waves in an equatorial non-rotating atmosphere is presented. It implements a simple linear, analytical model using the boundary-layer quasiequilibrium approximation (BLQ) and wind-induced surface heat exchange (WISHE). The dynamics of the model is based on the assumption that the vertical heating profile has the shape o the first baroclinic mode. The vertical velocity has two sinusoidal components of different vertical wavelengths. One corresponds to deep convection and the imposed heating profile while the other component with shallower vertical wavelength defines the phase speed of the convectively coupled Kelvin wave. The modeled modes are fast Kelvin waves that resemble adiabatic modes with the vertical wavelength being twice the depth of the troposphere and convectively coupled Kelvin waves that are damped and propagate with phase speed of 18 m/s. WISHE makes the convectively coupled Kelvin waves unstable only for very long wavelengths. The value of the model is that under single dynamical assumption and using the boundary-layer quasiequilibrium assumption it yields the observed phase speed for the convectively couple Kelvin waves.

Kelvin waves; convection

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