Diagnosis of oceanic cyclogenesis using surface-based Q vectors

The use of quasigeostrophic Q-vector diagnosis for marine cyclogenesis is examined for two cases from the Experiment on Rapidly Intensifying Cyclones over the Atlantic. Surface observations plus aircraft observations and satellite imagery are used to objectively analyze these cases, and Q vectors are calculated from these surface analyses. Although application of omega equation diagnosis at the surface stretches the theory, the relationship between vertical motion in cyclones and Q vectors suggests that a useful diagnosis can be made. Results suggest that useful representations of the synoptic-scale vertical motion can be determined from a surface Q-vector diagnosis. This Q-vector diagnosis can be used to help assess the numerical model guidance routinely available to operational forecasters by highlighting regions of significant low-level forcing and providing insight into the future track of a developing cyclone. -from Authors