The boundary layer characteristics of coastal urban environments

Publication Date

7-1-2024

Document Type

Article

Publication Title

Theoretical and Applied Climatology

Volume

155

Issue

7

DOI

10.1007/s00704-024-05036-z

First Page

6931

Last Page

6948

Abstract

The atmospheric boundary layer along the coastal-urban transect differs from that of urban or rural regions due to the distinctive interaction between the sea breeze and the urban heat island effect. In this manuscript, we present the observations of the atmospheric boundary layer in the Houston, Texas, area during the Coastal Urban Boundary Layer Experiment (CUBE) from June through September 2022. In order to understand the unique characteristics of the coastal urban boundary layer, we collected mean and turbulence data from micrometeorological towers and ground-based remote sensing instruments installed in the urban, coastal, bay, and rural sections within the greater Houston region. Furthermore, an urbanized weather research and forecast (WRF) model incorporating the Building Effect Parameterization and Building Energy Model (BEP-BEM) scheme is used to recognize the spatial variability of the meteorological conditions in the Houston Metro area. Compared to non-urban sites, the urban site exhibits a higher near-surface temperature throughout the day, with the highest temperature difference occurring at night due to the redistribution of the stored heat as sensible heat. During the dry period in June, we observed comparatively higher sensible heat flux in the urban site, demonstrating the heat island effect and lower latent heat flux due to lack of vegetation. The urban site had higher TKE values throughout the day than other sites because of the uneven roughness of the landscape. One of the unique findings of this study is the shift in spectral characteristics along the coastal-rural-urban transect. The power and co-spectra of zonal and vertical velocities and the vertical heat flux during the convective periods varied significantly across all the sites. The coastal site was influenced mainly by the local bay breeze shifting the peak to higher frequencies. The boundary layer height in the urban site was generally greater than in bay and rural sites due to increased convection in urban areas resulting from anthropogenic modification of land cover and waste heat from air conditioning use. The balance between the urban thermal and mechanical roughness effects was seen during the sea breeze front (SBF) event on the highest heat index day as SBF was triggered and accelerated by UHI.

Funding Number

1802226

Funding Sponsor

National Science Foundation

Department

Meteorology and Climate Science

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