| Raymond and Jiang (1990) and Synder and Lindzen (1991) independently introduced the notion of a diabatic Rossby wave [due to their anticipated vortical structure in three-dimensions, Moore and Montgomery (2004) referred to these features as a diabatic Rossby vortex (DRV); terminology that will be used hereafter]. For this type of disturbance growth, the diabatic generation of PV plays the role of the meridional advection of PV in the classical Rossby wave.; The goal of this work is to conduct an in-depth examination of the intrinsic characteristics of the DRV. To investigate the dynamics of these short-scale, diabatic disturbances we incorporate both a two-dimensional (2D), semigeostrophic (SG) model and the PSU/NCAR mesoscale modeling system (MM5).; Results from the 213, SG model clearly illustrate that both diabatic and baroclinic processes are integral to the DRV growth mechanism. In stark contrast to dry, long baroclinic waves, no upper boundary disturbance is necessary for DRV growth. Instead, it is the constant production of diabatically-generated PV (through the process of warm air advection, rising motion and latent heat release) that allows for amplification.; A number of idealized numerical simulations using MM5 confirm the basic results attained with the 2D, SG model: the three-dimensional structure of a DRV is found to be qualitatively very similar to that seen in the two-dimensional model simulations.; A subsequent sensitivity study illustrates that the intensity of a DRV is most sensitive to the magnitude of environmental baroclinicity and moisture content, while the vertical profile of moisture is the most dominant factor in determining the characteristic depth of the DRV. It is also found that the 'size' and 'strength' of a precursor perturbation vortex are important factors in determining the ultimate intensity and location of a DRV.; Due to the significant sensitivity to the initial condition, DRV formation and evolution pose a difficult challenge for the operational forecast community. This inherent problem is exacerbated by the remoteness of the preferred regions of DRV genesis: due to their reliance on environmental moisture, DRV's often form and grow over the ocean in regions where there is a distinct lack of observational data. |
