Understanding the Predictability of Initiation and Morphological Evolution of PECAN (Plains Elevated Convection at Night) Nocturnal Mesoscale Convective Systems

Iowa State University, Ames IA

Investigators

Abstract

The Plains Elevated Convection at Night (PECAN) field campaign will occur the Summer of 2015 in the central Great Plains. The scientific focus of PECAN is nocturnal convection, with four separate research topics to be addressed: 1) Nocturnal convection initiation and early evolution of mesoscale convective clusters; 2) Bore and other wave-like disturbances; 3) Dynamics and microphysics of nocturnal mesoscale convective systems; 4) Prediction of nocturnal convection initiation and evolution. The observational campaign plan calls for three research aircraft, seven mobile Doppler radars, and multiple sounding systems. A main part of the experimental design is the inclusion of fixed and mobile PECAN Integrated Sounding Array (PISA) units which consists of a variety of profiling instruments. The broader societal impact of PECAN is to improve forecasts of these nocturnal events for hydrology, energy, agriculture and public safety purposes. The field campaign would include a large number of students, including efforts to broaden participation and enhance diversity. Public outreach would also be conducted. Via this award, PI Gallus will serve as lead forecaster for PECAN. To facilitate this role, we will run a real-time configuration of the Weather Research and Forecasting (WRF) model using data assimilation. Intellectual Merit : Elevated mesoscale convective systems (MCSs), particularly those occurring at night, are a difficult challenge for forecasters. These events are more difficult to accurately simulate, partly because of insufficient observations above ground level, but also due to deficiencies in understanding of their initiation and maintenance. Initiation of and morphological evolution within MCSs is likely influenced by features such as bores, elevated boundaries, and other elevated convergence zones that are not initialized well in the models, and thus how these features modulate convection is not well-understood. These features often coexist with low-level jets (LLJ) whose simulation is also sensitive to errors in the simulated planetary boundary layer evolution. Tools and knowledge gained by this award will provide a better understanding of MCSs. Broader Impacts : This work will lead to both improved understanding of elevated nocturnal MCSs that should lead to improved forecasting of these challenging events, and enhanced education and training of students who will assist in conducting the research and also the forecasting in the field. This work has the potential to directly improve safety from this weather hazard.