Bottom marine heatwaves along the continental shelves of North America

Amaya, Dillon J.; Jacox, Michael G.; Alexander, Michael A.; Scott, James D.; Deser, Clara; Capotondi, Antonietta; Phillips, Adam S.

doi:10.1038/s41467-023-36567-0

Cited by 45 publications

(28 citation statements)

References 57 publications

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“…This subsurface marine heat wave started in 2015 and therefore later than at the surface, which is consistent with in situ observations (Danielson et al, 2022). The timing of our modeled heat waves on the shelf seafloor is similar to the timing of events found in an ocean reanalysis study (Amaya et al, 2023), although they used the 90th percentile and considered a larger shelf area (bottom grid cells shallower than 400 m), which could have led to the differences in the spatial extent and duration of the heat waves.…”

Section: Quadruple Compound Extreme Events On Shelf Seafloor Influenc...supporting

confidence: 88%

More Than Marine Heatwaves: A New Regime of Heat, Acidity, and Low Oxygen Compound Extreme Events in the Gulf of Alaska

Hauri,

Pagès,

Hedstrom

et al. 2024

AGU Advances

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Recent marine heatwaves in the Gulf of Alaska have had devastating impacts on species from various trophic levels. Due to climate change, total heat exposure in the upper ocean has become longer, more intense, more frequent, and more likely to happen at the same time as other environmental extremes. The combination of multiple environmental extremes can exacerbate the response of sensitive marine organisms. Our hindcast simulation provides the first indication that more than 20% of the bottom water of the Gulf of Alaska continental shelf was exposed to quadruple heat, positive hydrogen ion concentration [H+], negative aragonite saturation state (Ωarag), and negative oxygen concentration [O2] compound extreme events during the 2018–2020 marine heat wave. Natural intrusion of deep and acidified water combined with the marine heat wave triggered the first occurrence of these events in 2019. During the 2013–2016 marine heat wave, surface waters were already exposed to widespread marine heat and positive [H+] compound extreme events due to the temperature effect on the [H+]. We introduce a new Gulf of Alaska Downwelling Index (GOADI) with short‐term predictive skill, which can serve as indicator of past and near‐future positive [H+], negative Ωarag, and negative [O2] compound extreme events near the shelf seafloor. Our results suggest that the marine heat waves may have not been the sole environmental stressor that led to the observed ecosystem impacts and warrant a closer look at existing in situ inorganic carbon and other environmental data in combination with biological observations and model output.

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Section: Quadruple Compound Extreme Events On Shelf Seafloor Influenc...supporting

confidence: 88%

More Than Marine Heatwaves: A New Regime of Heat, Acidity, and Low Oxygen Compound Extreme Events in the Gulf of Alaska

Hauri,

Pagès,

Hedstrom

et al. 2024

AGU Advances

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“…This is important since oxygen levels have generally decreased since the beginning of the time series while temperatures have increased (Murphy et al., 2011). Removing the trend from the data reduces the bias from the increased frequency of MHW events identified in the last decade (Jacox, 2019) and has been done in other MHW studies (Amaya et al., 2023a; Freeland & Ross, 2019; Marin et al., 2021). The zero intercept when detrending was at the midpoint of the timeseries so that the mean values averaged over the record did not change.…”

Section: Methodsmentioning

confidence: 99%

“…Lee et al., 2010). Nevertheless, a few noteworthy studies (e.g., Hu et al., 2021; Schaeffer & Roughan, 2017) have been able to identify MHWs in the subsurface using observations from buoys with daily temperature data (though such records are rare) and with hindcast models (Amaya et al., 2023a; Chen et al., 2015; Großelindemann et al., 2022; Oliver et al., 2018; Ryan et al., 2021). Additionally, less frequently sampled data sets (i.e., Argo floats, animal mounted sensors, and CTD casts), have been used to examine the subsurface temperature anomalies during identified surface events, allowing for an initial look at the subsurface temperature structure associated with MHWs (Elzahaby & Schaeffer, 2019; Freeland & Ross, 2019; Holser et al., 2022; Jackson et al., 2018; Scannell et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Impacts of Marine Heatwaves on Subsurface Temperatures and Dissolved Oxygen in the Chesapeake Bay

Shunk,

Mazzini,

Walter

2024

JGR Oceans

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Subsurface impacts associated with Marine Heatwaves (MHWs) in estuaries are not well understood, largely due to data scarcity. Using over three decades (1986–2021) of observations from several monitoring programs, this study investigates subsurface temperature and dissolved oxygen (DO) anomalies associated with surface MHWs in the Chesapeake Bay (CB). Seasonal variability in temperature anomalies followed a simple 1‐D response to surface heating with downward heat transport and diffusion controlled by seasonally variable stratification and mixing. Two distinct temperature regimes were found: a thermally stratified spring‐summer regime, when positive temperature anomalies were confined to the surface mixed layer (SML); and a homogeneous fall‐winter regime. Additionally, surface (subsurface) temperatures were elevated for months (days to weeks) before and after MHWs, indicating individual events were shorter than the timescales of elevated temperatures. A simple 1‐D SML heat budget identified air‐estuary heat flux changes as the leading driver of MHW onsets and declines, with latent heat flux being the dominant term. DO anomaly patterns were more complex, with considerable along‐channel gradients. Notable DO decreases (1–4 mg L−1) primarily occurred in the winter/spring below the SML, and the hypoxic zone expanded from spring through fall. Only a small fraction of these DO anomalies could be attributed to MHW temperature‐induced solubility changes, demonstrating that other physical and/or biogeochemical processes dominate changes in DO during these events. In CB, concurrent low DO and persistent high temperatures could compound the impacts of MHWs on this valuable ecosystem, with MHW event impacts likely to be exacerbated by climate change.

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“…This is largely a consequence of the easy accessibility of high resolution satellite sea surface temperature (SST) data, while no corresponding observation‐based product is available to study subsurface extremes (Oliver et al., 2021). But even model‐based studies have rarely analyzed MHWs beyond the surface (e.g., Amaya et al., 2023), such that the vertical structure of surface MHWs has remained largely elusive (Gruber et al., 2021). Gaining more insights into the vertical extent and structure of MHWs is crucial to better assess the MHW drivers and the mechanisms sustaining them (Oliver et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

“…This is largely a consequence of the easy accessibility of high resolution satellite sea surface temperature (SST) data, while no corresponding observation-based product is available to study subsurface extremes (Oliver et al, 2021). But even model-based studies have rarely analyzed MHWs beyond the surface (e.g., Amaya et al, 2023), such that the vertical structure of surface MHWs…”

mentioning

confidence: 99%

On the Vertical Structure and Propagation of Marine Heatwaves in the Eastern Pacific

Köhn,

Vogt,

Münnich

et al. 2024

JGR Oceans

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Marine heatwaves (MHWs) have been recognized as a serious threat to marine life, yet, most studies so far have focused on the surface only. Here, we investigate the vertical dimension and propagation of surface MHWs in the Eastern Pacific (EP) using results from a high‐resolution hindcast simulation (1979–2019), performed with the Regional Ocean Modeling System. We detect MHWs using a seasonally varying percentile threshold on a fixed baseline and track their vertical propagation across the upper 500 m. We find that nearly a third (∼29%) of the MHWs extend beyond the surface mixed layer depth (MLD). On average, these deep‐reaching MHWs (dMHWs) extend to 110 m below the MLD and last five times longer than MHWs that are confined to the mixed layer (184 vs. 36 days). The dMHWs can cause stronger temperature anomalies at depth than at the surface (maximum intensity of 5.0 vs. 1.9°C). This general subsurface MHW intensification even holds when scaling the temperatures with the respective local variability. A clustering of dMHWs reveals that 41% of them are block‐like, that is, continually remain in contact with the sea surface, 24% propagate downward, 20% propagate upward, while 15% appear at the surface multiple times. Although the water column MHW duration, intensity and severity are only moderately correlated with their corresponding surface‐based MHW characteristics, dMHWs have the potential to be detected from the surface. Our study can help to augment the remote sensing‐based monitoring of upper ocean exposure to MHWs.

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Bottom marine heatwaves along the continental shelves of North America

Cited by 45 publications

References 57 publications

More Than Marine Heatwaves: A New Regime of Heat, Acidity, and Low Oxygen Compound Extreme Events in the Gulf of Alaska

More Than Marine Heatwaves: A New Regime of Heat, Acidity, and Low Oxygen Compound Extreme Events in the Gulf of Alaska

Impacts of Marine Heatwaves on Subsurface Temperatures and Dissolved Oxygen in the Chesapeake Bay

On the Vertical Structure and Propagation of Marine Heatwaves in the Eastern Pacific

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