We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Dependence of Cloud Macrophysical Properties and Phase Distributions on Environmental Conditions Over the North Atlantic and Southern Ocean: Results From COMBLE and MARCUS.
- Authors
Xia, Zeqian; McFarquhar, Greg M.
- Abstract
The accurate representation of Cold Air Outbreaks (CAOs) and affiliated mixed‐phase boundary layer (BL) clouds in models is challenging. How BL cloud properties evolve during CAOs and their dependence on meteorological conditions is not well understood but is important for the simulation of Earth's energy budgets. Here the properties of polar BL clouds over the North Atlantic (NA) and Southern Ocean (SO) are compared using observations from the Measurements of Aerosol Radiation and CloUds over the SO (MARCUS) and CAOs in the Marine BL Experiment (COMBLE) conducted over the NA. MARCUS observations show a stronger BL inversion than COMBLE, with a higher mean EIS (estimated inversion strength)/LTS (lower tropospheric stability) of −0.03 K/13 K compared to COMBLE's −3.2 K/9.3 K. 39% of CAOs observed during COMBLE were intense with M > 5 K, while MARCUS only had 1.3%. 78%/72% of clouds sampled in CAOs during COMBLE/MARCUS had cloud top heights <4 km. The mean BL cloud top height was over 400 m higher, and the BL was over 500 m deeper for M of 10 K compared to 0 K for both regions. MARCUS observed a 27% moister BL structure than COMBLE when M > 5 K due to stronger BL inversion trapping more moisture within the BL. Under the same LTS, EIS, and M conditions, MARCUS observed a 12% drier BL structure, and clouds were 46% more turbulent than COMBLE. During CAOs, 54% of single‐layer BL clouds sampled during MARCUS had liquid‐dominated bases compared to 39% during COMBLE. Plain Language Summary: The Arctic and SO have large areas of sea ice, providing ideal conditions for development of frequent and intense cold air outbreaks (CAOs). CAOs occur when cold air over ice moves away from the poles over warmer oceans. Clouds over high latitudes that occur during CAOs impact Earth's radiative balance, but prior observations of them are very limited and hence how the properties of these clouds depend on environmental conditions are not well known. Two field campaigns conducted over the Southern Ocean and North Atlantic provide measurements that allow the dependence of the environmental impact on clouds to be uncovered, and to determine whether the properties of these clouds differ whether they form in the Northern or Southern Hemisphere. The dependence of vertical cloud structure, the composition of clouds (whether ice or water dominates at temperatures <0°C), and the vertical structure of the lowest layer of the atmosphere on environmental conditions are presented. Results show that low‐level clouds dominate in both regions during CAOs, with clouds higher and deeper in more intense CAOs. Even accounting for dependence on environmental conditions, there are still differences in cloud properties over the North Atlantic and Southern Ocean that need further investigation. Key Points: Boundary layer clouds are common during cold air outbreaks in both North Atlantic and Southern Ocean regionsCold air outbreaks are more intense over the North Atlantic, whereas boundary layer inversion is stronger over the Southern OceanBoundary layer cloud properties differ with location even when accounting for environmental conditions
- Subjects
ARCTIC regions; STRATOCUMULUS clouds; OCEAN; SEA ice; ATMOSPHERIC boundary layer; ENVIRONMENTAL auditing; WATER temperature; RADIATION measurements
- Publication
Journal of Geophysical Research. Atmospheres, 2024, Vol 129, Issue 12, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2023JD039869