Impact of Surface Heterogeneity Induced Secondary Circulations on the Atmospheric Boundary Layer

authored by: Sreenath Paleri, Luise Wanner, Matthias Sühring, Ankur R. Desai, Matthias Mauder, Stefan Metzger
Abstract: We investigate how effective surface length scales (Leff) and atmospheric boundary layer stability modulate surface-induced secondary circulations over a realistic heterogeneous surface. The evolution of the circulations and their impact on surface-atmosphere fluxes are studied using coupled large eddy simulations of the CHEESEHEAD19 field campaign. The heterogeneity-induced circulations were diagnosed using time and ensemble averaging of the atmospheric fields. Simulations were performed for summer (August) and autumn (September) Intensive Observation Periods of the field campaign, characterised differently in terms of normalised surface length scales and ABL stability. Quasi-stationary and persistent circulations were diagnosed in the daytime ABL that span the entire mixed layer height (zi). Their variation in time and space are presented. Homogeneous control runs were also performed to compare and contrast spatial organisation and validate the time-ensemble averaging operation. In the convective boundary layers simulated during the summer time simulations, wavelengths that scale as the effective surface heterogeneity length scales contribute the most to the heterogeneity-induced transport. Contributions from surface-induced circulations were lower in the simulated near-neutral BL for the autumn simulations. We find that both Leff/zi and ABL static stability control the relative contribution of surface-induced circulations to the area averaged vertical transport. This scale analysis supports prior work over the study domain on scaling tower measured fluxes by including low frequency contributions. We believe that the conceptual framework presented here can be extended to include the effects of sub-grid land surface heterogeneity in numerical weather prediction and climate models and also to further explore scale-aware scaling methodologies for near surface-atmosphere exchanges.
Organisation(s): Institute of Meteorology and Climatology
External Organisation(s): University of Wisconsin
University of Oklahoma
NOAA Air Resources Laboratory (ARL)
Technische Universität Dresden
Karlsruhe Institute of Technology (KIT)
Pecanode GmbH
AtmoFacts
CarbonDew
Type: Article
Journal: Boundary-Layer Meteorology
Volume: 191
ISSN: 0006-8314
Publication date: 28.12.2024
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Atmospheric Science
Sustainable Development Goals: SDG 13 - Climate Action
Electronic version(s): https://doi.org/10.21203/rs.3.rs-3439181/v1 (Access: Open)
https://doi.org/10.1007/s10546-024-00893-7 (Access: Closed)