[ACG34-P04] Effects of Surface Fluxes and Latent Heating on Extratropical Cyclones in an Idealised Linear Framework
Keywords:surface fluxes, air-sea interactions, baroclinic development, latent heating, Eady model
In our linear framework, surface fluxes and latent heating/cooling are separable, but can still directly affect each other. With the possibility to more clearly disentangle the different diabatic processes, we can gain insights into how these processes alter the intensification and structure of extratropical cyclones. With strong latent heating and/or surface fluxes, short and shallow instabilities that are comparable to Diabatic Rossby Vortices emerge. Above the latent heating, a negative potential vorticity anomaly forms for Eady-like instabilities, supporting downstream ridging. For moderate heating intensities, evaporational cooling barely affects the instabilities, despite the intensification of the positive low-level potential vorticity anomaly. For strong heating intensities, however, unstable modes at shorter wavelengths intensify with weak evaporation, but become neutral for intense evaporation. Our results show that surface fluxes are detrimental to the growth of Eady-like instabilities at longer wavelengths, but enhance shallow instabilities at shorter wavelengths and low altitudes, especially when latent heat release is weak.