Lecturer: CAESAR team
Date: 2024-03-07 10:00
Place: Aula

The Cold Air Outbreak Experiment in the Sub-Arctic Region (CAESAR): Overview, Weather Patterns, and Instrumentation

One of Earth's most intense air mass transformations happens when cold Arctic air flows out over the much warmer open oceans in so-called Cold-Air Outbreaks (CAOs). The surface heat fluxes are among the highest observed on Earth, supporting highly convective clouds capable of producing heavy snowfall and occasionally spawning intense "polar lows." Surprisingly little is known about their Lagrangian evolution, the relationship between up- and downstream conditions, and between the surface fluxes, boundary-layer structure, cloud and precipitation properties, and mesoscale circulations. These clouds provide a powerful modeling test bed for improving the representation of mixed-phase cloud processes in large eddy simulations, numerical weather prediction, and global climate models. CAESAR is examining the structure of marine boundary layer clouds during CAOs. For 45 days in early 2024, CAESAR is deploying the NSF/NCAR C-130 aircraft to sample Arctic air masses from the CAO origin at the ice edge throughout their transformation downstream. A rich array of airborne radars and lidars, aerosol, cloud, precipitation, and trace gas probes are providing data on CAO events over the open waters between northern Sweden and the Arctic ice edge. This will provide a detailed characterization that will form the backbone of modeling studies across a range of scales and form a long-lasting legacy dataset. The seminar will focus on an overview of the CAESAR field campaign along with short presentations by instrument and forecast teams to go into some of the details of the measurements and weather conditions that are important for the project. An additional short presentation will show that kinetic energy trends from 1940 to 2020 derived from reanalysis data show a poleward shift in extratropical cyclone track location and statistically significant increases in latent energy globally.

The seminar is also online. See emails for connection details.

Created 2024-03-04 13:47:07 by Uwe Raffalski
Last changed 2024-03-06 12:06:49 by Mats Holmström