Boundary-Layers of the Cold and Dark Atmospheres

University Of Alaska Fairbanks Campus, Fairbanks AK

Investigators

Abstract

This award is to investigate atmospheric boundary layers in the cold and dark atmospheres of the extreme Alaskan winters. The stringent radiation and atmospheric flow conditions in which the Alaskan boundary layer develops challenge our research in both experimental and modeling approaches. In such harsh winter conditions, the project will conduct a field intensive experiment to document radiation, turbulence, composition and dynamics using surface, remote sensing and in-situ unmanned aircraft systems. The research will advance our understanding of physical processes taking place in radiative-driven boundary layers combining the set of observations with mesoscale/microscale modeling. Research impacts are geared towards improving understanding of air pollution, meteorological forecasting and regional climate products in polar regions during winters. In specific, the project focuses on understanding how outstanding surface radiative cooling, surface inhomogeneity, atmospheric composition and thermodynamics result in specific boundary-layer turbulent and dynamic states and how they are represented in mesoscale models. This project will focus on the following physical processes: 1) the buildup and breakup of shallow-stratified surface-based temperature inversion layers during stagnant anticyclone synoptic conditions, 2) the boundary-layer behavior including surface-based temperature inversion layer and elevated synoptic temperature inversion layers during anticyclone and transitions to cyclone conditions, their radiative coupling and their feedback effects on the surface turbulence, and 3) the boundary-layer dynamic and turbulent regimes (vertical and horizontal) in the presence of shallow cold flows controlling mixing and transport resulting on transient boundary-layer states. The experimental datasets are unique in the sense that current surface parameterizations in models do not fully account for the indicated mechanisms and interactions in the meteorological framework and conditions. The importance of this research is highlighted by the need to advance understanding of the chemistry and microphysics of particulate matter and gases in the stringent conditions of the polar atmospheres. Inherent to the physical and chemical transformations of air pollution products is our ability to connect sources to receptors based on ground based or airborne observational platforms (IGAC-ALPACA field experiment). This project fills this specific gap providing critical observations, mesoscale modeling assessment and model validation to improve model representation of physical processes leading to extreme boundary-layer states. Similarly, improving forecasting of surface winds and air temperatures and advancing high resolution climate products in polar atmospheres requires a better representation of radiative boundary-layers. 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.