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.
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Surface Thermodynamic Gradients Associated with Gulf of Mexico Sea-Breeze Fronts
High spatial/temporal resolution mobile transects were used to examine the thermal and moisture structure of the sea-breeze front (SBF) along the Mississippi coast during August 2014 and 2015. Compared to most similar studies, conditions were much warmer and more humid. Results show a 1-2 g/kg increase in mixing ratio across the mature SBF zone, and up to a 2.5°C temperature decrease. When SBF radar fine lines are identifiable, their position agrees very well with surface thermodynamic changes. Although temperatures were cooler at the coast, microscale offsets in location of thermal, moisture, and radiative features are noted in the vicinity of the SBF, particularly when the sea-breeze system is relatively weak or immature. At times, it seems that strong solar insolation causes the temperature to rise temporarily within the transition zone behind the kinematic SBF. These results are at variance with most other diagnostic studies. Some thermodynamic variations are noted within the marine air mass in connection to minor water bodies such as Biloxi Bay. The potential for passage of the SBF to at least temporarily increase human heat stress as described by heat index is also noted.
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- Award ID(s):
- 1644888
- PAR ID:
- 10098404
- Date Published:
- Journal Name:
- Advances in meteorology
- Volume:
- 2018
- ISSN:
- 1687-9317
- Page Range / eLocation ID:
- 2601346
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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