Mesoscale Processes

While coarse-gridded climate models are capable of simulating the broad-brush features of weather systems, the high correlation of improved weather forecast skill with finer model grids over the past few decades is evidence of the critical role of mesoscale processes (features such as wind jets or cloud bands with horizontal scales ranging from a few to several hundred kilometers). Characterization of mesoscale processes and their importance is fundamental to all my research but some highlights from our around 20 papers focused in this area are now given. We discriminated between CISK (Conditional Instability of the Second Kind) and WISHE (Wind Induced Surface Heat Exchange), two long-standing and much-debated mechanisms for tropical cyclone intensification using model experiments, finding consistency with WISHE and inconsistency with CISK (Craig and Gray, 1996). We have identified a new mechanism for the generation of multiply-banded frontal clouds (triggering by a propagating cold pool) though idealized modeling experiments (Pizzamei et al., 2005). A recently completed funded project on the sting jet feature in severe North European windstorms (leading to transient localized strong surface winds and gusts in a region of storms not usually associated with strong winds) has led to four papers to date. We have found substantial additional evidence for the existence of sting jets in some but not all extratropical cyclones (Gray et al., 2011), demonstrated that the existence of sting jets in model output is not model dependent (Martinez-Alvarado et al., 2010), and developed a diagnostic for the detection of sting-jet precursor conditions in low-resolution (climate) datasets (Martinez-Alvarado et al., 2011).