#22 Topic: Arctic Boundary Layers
Lecturer: Roel Neggers
Date: Monday, November 7, 2022 10:00 – 11:00 a.m.

In this lecture we will explore the Atmospheric Boundary Layer (ABL) at high latitudes and its role in the Arctic climate system. The ongoing rapid shift in the Arctic climate in response to global warming works through a variety of feedback mechanisms, many of which are not yet fully understood. The ABL plays a crucial role in many of these mechanisms. For example, it acts as an interface between Earth’s surface and the atmosphere, accommodating vertical transport of heat, moisture, momentum and aerosol. In addition, mixed-phase clouds as embedded in the ABL significantly affect the solar and terrestrial radiative fluxes, and with it the energy budget of the atmospheric column and surface. These ABL processes are typically maintained by physical/dynamical processes such as turbulence. The scales at which turbulence acts can be very small in the Arctic, which seriously complicates its representation in weather and climate models. The first part of this lecture is a brief review of key principles at the foundation of boundary layer meteorology in general, including governing equations, cloud physics, turbulent kinetic energy, and surface-atmosphere interactions. The second part is then dedicated to the ABL at high latitudes, and what makes it unique. Various ABL regimes will be explored, including stable clear conditions, mixed phase clouds, cold air outbreaks, and turbulence over leads. The lecture will conclude by giving a brief overview of ongoing scientific work related to the Arctic ABL.