Meteorological Islands: How the Atmosphere Interacts with Large Individual Patches of Heterogeneity

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Cities, lakes, small islands, and wind farms are various manifestations of a common pattern of land surface variability of significant relevance to humans: they tend to form a large, isolated patch with very distinct features (roughness, temperature, wetness) from the surroundings. This surface contrast perturbs the atmosphere at multiple scales ranging from 1 to 100 km, and previous research has established that these perturbations impact cloud formation and rainfall, extreme heat and pollution, and wind flow patterns, among others. While these various surface features have been examined individually before, their similarities have not yet been consolidated to develop a broad understanding of this class of heterogeneous surfaces, hindering the formulation of theoretical frameworks that are needed for better environmental prediction. This project will investigate this type of “Meteorological Islands” in all its manifestations; it will result in improved weather forecasting and climate projection models in the vicinity of these important areas; and will guide land use planning and policy aiming to avoid human perturbations to the land surface that can result in adverse impacts on the environment, ecosystems services, and society more broadly.The project will use a state-of-the-science turbulence simulation approach (large eddy simulation) to capture the energetic three-dimensional secondary circulations that these patches generate and through which they perturb atmospheric dynamics. The first goal is to use these simulation data for dimensional reduction: the overarching project hypothesis is that this class of heterogeneity is primarily modulated by four non-dimensional parameters that are sufficient to capture all its various manifestations. The second goal is to understand how the contrast in roughness, temperature, and wetness interact to impact the atmosphere in the vicinity of these patches. Finally, these analyses will be synthesized into a coherent theoretical framework that will allow better parametrization of the unresolved impact of such patches on the atmosphere in weather and climate models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.