A ship-based characterization of coherent boundary-layer structures over the lifecycle of a marine cold-air outbreak

Duscha, Christiane, Barrell, Christopher, Renfrew, Ian A., Brooks, Ian M., Sodemann, Harald and Reuder, Jocahim (2022) A ship-based characterization of coherent boundary-layer structures over the lifecycle of a marine cold-air outbreak. Boundary-Layer Meteorology, 183 (3). 355–380. ISSN 0006-8314

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Abstract

Convective coherent structures shape the atmospheric boundary layer over the lifecycle of marine cold-air outbreaks (CAOs). Aircraft measurements have been used to characterize such structures in past CAOs. Yet, aircraft case studies are limited to snapshots of a few hours and do not capture how coherent structures, and the associated boundary-layer characteristics, change over the CAO time scale, which can be on the order of several days. We present a novel ship-based approach to determine the evolution of the coherent-structure characteristics, based on profiling lidar observations. Over the lifecycle of a multi-day CAO we show how these structures interact with boundary-layer characteristics, simultaneously obtained by a multi-sensor set-up. Observations are taken during the Iceland Greenland Seas Project’s wintertime cruise in February and March 2018. For the evaluated CAO event, we successfully identify cellular coherent structures of varying size in the order of 4 × 102 m to 104 m and velocity amplitudes of up to 0.5 m s−1 in the vertical and 1 m s−1 in the horizontal. The structures’ characteristics are sensitive to the near-surface stability and the Richardson number. We observe the largest coherent structures most frequently for conditions when turbulence generation is weakly buoyancy dominated. Structures of increasing size contribute efficiently to the overturning of the boundary layer and are linked to the growth of the convective boundary-layer depth. The new approach provides robust statistics for organized convection, which would be easy to extend by additional observations during convective events from vessels of opportunity operating in relevant areas.

Item Type: Article
Additional Information: Acknowledgements: This study was a part of the Iceland Greenland Seas Project. We are grateful for the constructive comments and insightful questions from the four anonymous reviewers, that helped to substantially improve the manuscript. We thank A. Seidl, A. Terpstra, S. Zou and Y. Weng for the set-up, maintenance and documentation of the ship-based instrumentation and measurements. We also thank M. Kähnert for helping with the formal editing and proofreading of the manuscript. J. Reuder acknowledges the Offshore Boundary Layer Observatory, OBLO, funded by the Research Council of Norway (NRF Grant No. 227777) for access to the WindCube V2 lidar system. H. Sodemann acknowledges the projects FARLAB (NRF Grant No. 245907) and SNOWPACE (NRF Grant No. 262710) for the stable water isotope instrumentation and measurements, respectively. The HATPRO and radiosounding system were provided by the Atmospheric Measurement and Observations Facility (AMOF) of the National Centre for Atmospheric Science (NCAS). The radiosondes were funded by the Atmospheric Forcing of the Iceland Sea project (AFIS) via the Natural Environment Research Council (NERC) Grant NE/N009754/1, which also partly funded the contribution of I. Renfrew and C. Barrell to the study.
Uncontrolled Keywords: cold-air outbreak,convective coherent structures,iceland–greenland sea,lidar wind profiling,atmospheric science,sdg 14 - life below water ,/dk/atira/pure/subjectarea/asjc/1900/1902
Faculty \ School: Faculty of Science > School of Environmental Sciences
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 02 Dec 2021 02:51
Last Modified: 22 Jun 2022 00:24
URI: https://ueaeprints.uea.ac.uk/id/eprint/82487
DOI: 10.1007/s10546-022-00692-y

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