The role of local winds and a semi-persistent coastal front on the diurnal heat budget in an upwelling bay

Author Info

• April P. Thibodeau, California Polytechnic State University, San Luis Obispo
• Ryan K. Walter, California Polytechnic State University, San Luis ObispoFollow
• Piero L.F. Mazzini, Virginia Institute of Marine Science
• Thomas P. Connolly, San Jose State University
• Christopher A. Edwards, University of California, Santa Cruz
• Ian C. Robbins, California Polytechnic State University - San Luis ObispoFollow

Author ORCID Identifier

https://orcid.org/0000-0003-1907-001X

Recommended Citation

Published in Continental Shelf Research, Volume 300, August 1, 2026.

The definitive version is available at https://doi.org/10.1016/j.csr.2026.105702.

Abstract

Coastal embayments in nearshore upwelling systems (“upwelling bays”) play a disproportionately large role in regional oceanography. In these systems, local diurnal wind forcing and thermal gradients associated with an upwelling shadow front that forms between warmer sheltered waters inside the bay and colder recently upwelled waters outside the bay strongly influence local temperature dynamics. Despite their importance to local ecosystems, there are no long-term studies that assess the heat budget inside upwelling bays. In this study, we analyzed approximately two years of water temperature throughout the water column using an autonomous profiler in a small upwelling bay in central California (San Luis Obispo Bay). We coupled these measurements with local meteorological data and in-situ temperature measurements made outside the bay to investigate how local diurnal wind forcing and the presence of the upwelling shadow front modify the diurnal heat budget inside the bay. Over the study period, strong seasonality in regional upwelling coincided with changes in local wind forcing, front strength (bulk temperature difference between inside and outside the bay), and temperature structure, from which we identified various forcing regimes to quantify the diurnal heat budget. During the non-upwelling season when the front was largely absent, the heat budget was primarily a balance between changes in heat content and surface heat fluxes, regardless of local wind forcing strength. This was also the primary balance during the upwelling season when local winds were weak. In contrast, during the upwelling season when the upwelling shadow front was persistent and the local winds were strong, increasing front strength led to increasingly large residual heat fluxes, which were interpreted to be due to advection (advective fluxes not calculated directly). These results highlight the importance of both local wind forcing and frontal intensity on the heat budget inside the upwelling bay, with significant implications for residence time, temperature dynamics, and local biogeochemistry in similar systems that are ubiquitous globally.

Disciplines

Physics

Copyright

© 2026 The Authors

Number of Pages

12