Browsing by Author "Edwing, Kelsea"
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Item Impact of marine heatwaves on air-sea carbon dioxide flux in the Northwest Atlantic coastal margins(University of Delaware, 2023) Edwing, KelseaThe sensitivity of the carbonate system to sea surface temperature variability suggests that extreme temperatures during marine heatwave (MHW) events could modulate the transfer of carbon between the atmosphere and ocean. To investigate this, I quantified the influence of MHW events on air-sea CO2 flux anomalies (FCO2’) in the Mid Atlantic Bight (MAB) and South Atlantic Bight (SAB) from 1992-2020. I first investigated the FCO2 changes during the longest MHW events in the MAB and SAB, respectively, before examining FCO2 changes during the ensemble of all MHW months in each region. Results show that MHWs primarily generated positive sea surface pCO2 anomalies (pCO2sea’) and had a larger impact on FCO2’ in the MAB. These positive anomalies attempt to reduce CO2 uptake during sink months and enhance outgassing during source months. While MHWs also aided in the creation of large positive FCO2’ values in the SAB, non-thermal drivers dominated pCO2sea’ values and therefore FCO2’ during MHWs. However, not all MHWs produced a large, positive FCO2’. For MHW influences to be reflected in FCO2’ values, both MHW and non-thermal drivers of pCO2sea’ must provide positive contributions to pCO2sea’. Otherwise, non-thermal drivers tended to counteract the influence of MHWs. Wind speed contributions were of secondary importance as FCO2’ drivers, but slower wind speeds were found to amplify the influence of MHWs on FCO2’ in winter months but reduce it in summer months. This work provides an important first look at the impact of MHW events on FCO2 in the northwest Atlantic coastal margin, bridging the gap between extreme SST events and the coastal carbonate system.Item Impact of Marine Heatwaves on Air-Sea CO2 Flux Along the US East Coast(Geophysical Research Letters, 2024-01-02) Edwing, Kelsea; Wu, Zelun; Lu, Wenfang; Li, Xinyu; Cai, Wei-Jun; Yan, Xiao-HaiMarine heatwaves (MHWs) are extremely warm ocean temperature events that significantly affect marine environments, but their effects on the coastal carbonate system are still uncertain. In this study, we systematically quantify MHWs' impacts on air-sea carbon dioxide (CO2) flux anomalies (FCO2′) in the Mid-Atlantic Bight (MAB) and South Atlantic Bight (SAB) from 1992 to 2020. During the longest MHW in both regions, oceanic CO2 uptake capabilities substantially decreased, primarily due to significant increases in the seawater partial pressure of CO2 (pCO2sea). For all cases, MHWs played a more significant role in driving pCO2sea changes in the MAB than the SAB, where non-thermal drivers dominated pCO2sea variability. In the MAB, weakened wind speeds related to wintertime atmospheric perturbations increase ocean temperatures and pCO2sea, further reducing CO2 uptake during winter MHWs. This work is the first to connect extreme temperatures to coastal air-sea CO2 fluxes. The reduction in CO2 absorption noted during MHWs in this study has important implications for coastal regions to act as continued sinks for excess CO2 emissions in the atmosphere. Key Points - Marine heatwaves (MHWs) primarily generated positive sea surface pCO2 (pCO2sea) anomalies in the Mid-Atlantic Bight (MAB) and South Atlantic Bight (SAB) but had a larger impact on air-sea CO2 flux anomalies in the MAB - Reduced wind speeds amplified MHW contributions during CO2 sink months and counteracted them during CO2 source months - In the MAB, wintertime atmospheric perturbations related to zonal shifts in the jet stream produce slower wind speeds which aid in generating air-sea heat flux type MHW events that ultimately reduce oceanic CO2 uptake Plain Language Summary The transfer of carbon dioxide (CO2) between the atmosphere and ocean is sensitive to sea surface temperature (SST) changes because warmer SSTs increase the sea surface partial pressure of CO2 and reduce the ocean's ability to absorb CO2 from the atmosphere. It is, therefore, conceivable that marine heatwaves (MHWs), which are extremely warm ocean temperature events, could modify how carbon moves between the ocean and the atmosphere. This study provides the first attempt to evaluate the impacts of MHWs on the air-sea CO2 flux (FCO2) anomalies along the US East Coast, encompassing the Mid-Atlantic Bight (MAB) and South Atlantic Bight (SAB) during 1992–2020. Both regions experienced reduced CO2 absorption in response to the longest MHWs in each region. These extreme temperatures had a larger impact on CO2 absorption in the MAB compared to the SAB, where non-temperature factors were more influential. The coastal ocean plays an important role in helping to mitigate human-induced climate change by absorbing excess CO2 from the atmosphere. As such, the demonstrated reduced absorption of the ocean associated with MHWs in this study, which might also apply to other coastal locations, has vital implications for the efficiency of the ocean in offsetting global warming impacts.