Interactions between winds and sea surface temperature at timescales of several days

Recent results based on global coupled ocean-atmosphere modeling suggest a ubiquitous covariability between sea surface temperature (SST) and wind speed at timescales of several days. Preliminary work led by this team has confirmed such oscillation using in-situ observations in the California Current Region. This research involves the synergistic analysis of existing in-situ observations and modeling output to better understand the nature of the co-oscillation between winds and sea surface temperature at timescales of days in the global oceans. The exchange of heat, momentum, moisture, and gases across the air-sea transition zone plays critical roles in the Earth system predictability. Thus, an improved understanding of processes relevant to air-sea coupling has the potential to advance our understanding of many high-impact, societal-relevant phenomena, such as extreme weather events. This project will further our understanding of fundamental processes that control air-sea exchanges, essential to properly parametrizing them in numerical models and improving weather forecasting and climate projections. In particular, the research will deepen our understanding of interactions between two essential climate variables, i.e., wind and sea surface temperature. This study will investigate how the co-oscillation of these two variables impacts and responds to processes in the ocean mixed layer. The dynamics in this layer are fundamentally important for the Earth’s climate, as 95% of the anthropogenically created heat in the atmosphere is communicated to the ocean through the mixed layer. This project will support PI Bia Villas Bôas—a female, underrepresented minority, early career Assistant Professor—in her efforts to build her research program, and it will also support a Ph.D student who will be trained in physical oceanography at Colorado School of Mines. Villas Bôas is the only oceanographer at Mines, an institution that has historically focused on Earth resources, such as oil and gas. Establishing a strong presence in physical oceanography at Mines benefits the State of Colorado and the country because it will expose students that had little contact with environmental sciences to the role of the oceans in climate. Additionally, the PI and her group are committed to Open Science principles and are actively engaged in efforts to broaden participation and increase accessibility to oceanography and oceanographic data. The results from this project will be published in open access journals, and the data code will be made publicly available along with pedagogical Jupyter Notebooks examples for seamless reproducibility of the results. This covariability between wind and SST manifests itself in correlations as an oscillation between negative and positive correlation with a cyclic nature with a 3-6 day period. What physical processes drive this oscillation and what sets its time scale remains unknown. In particular, the study will test the hypothesis that this co-oscillation results from a combined response to surface heat fluxes, wind-driven mixing, Ekman pumping, and other processes at the air-sea transition zone; thus, the characteristic duration and strength of these wind-SST feedbacks will vary based on season and geographic location. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.