Investigating the Impact of Urban Areas on Quasi-Linear Convective Systems

Metropolitan areas absorb and radiate heat at a higher rate compared to surrounding rural areas due to a number of factors, including a city’s tendency to have sparse vegetation and tree canopies and high incidences of pavement. This research involves analyzing how the structure of quasi-linear convective systems (QLCSs) are altered as they pass over urban areas. Archived radar data and idealized numerical model simulations are leveraged to quantify the extent to which urban areas modify QLCSs and the environments in which they form. Radar data from the GridRad (3-D Gridded NEXRAD WSR-88D Radar Data)-Severe database are analyzed to improve understanding of which city characteristics (e.g., size, land cover types, etc.) contribute the most to variations in observed QLCS structure and intensity. Idealized numerical model simulations are also conducted to supplement the observational analysis by varying aspects of urban areas that impact the surrounding environment – e.g., city size, turbulence strength, etc. – to see how these alterations may affect QLCSs. Due to every city’s unique distribution of various land cover types and population, their potential effectiveness at modifying QLCSs will vary. Because of this, cities of varying size and population will be analyzed to understand their effect on QLCS structure. Initial results reveal higher frequencies of intense rainfall associated with QLCSs over the downwind side of the urban areas studied.