Using Finite-Amplitude Wave Activity to Examine the Impact of Latent Heating on Baroclinic Wave Activity

Using the dynamical diagnostic method of finite-amplitude local wave activity (LWA) and a moist two layer quasigeostrophic (QG) model, we investigate the impacts of diabatic heating on the mean states and the mean LWA budget, as well as statistical features and life cycles of baroclinic waves. Despite the overall positive LWA tendency due to diabatic heating, the total generation (baroclinic plus diabatic) of LWA decreases due to the impact of precipitation reduc ing the baroclinicity of the mean state, and thus, eddies are weaker in the moist model compared to the dry model forced with the same radiative forcing. On average, troughs are stronger than ridges in the dry model. However, this ceases to hold in the moist model due to the positive contributions of diabatic heating to the growth of ridges. Diabatic heating can dominate ridge growth in the upper layer, due to the generation of negative potential vorticity, but not troughs. It differs from the result of reanalysis data that diabatic heating can dominate the growth of some troughs. This difference is largely because of the lack of vertical structure in the diabatic heating profile in the two-layer model. Nevertheless, diabatic heat ing can still contribute to the growth of some troughs in the upper layer due to the nonlocal nature of its impact under the LWAframework.