Coastal ocean variability in the US Pacific Northwest region: seasonal patterns, winter circulation, and the influence of the 2009–2010 El Niño

Durski, S. M.; Kurapov, A. L.; Allen, J. S.; Kosro, P. Michael; Egbert, G. D.; Shearman, R. Kipp; Barth, John A.

doi:10.1007/s10236-015-0891-1

Cited by 18 publications

(26 citation statements)

References 35 publications

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“…For reference, the multivariate El Niño index (MEI) [ Wolter , ] is shown in Figure a, where values in excess of 1 indicate El Niño conditions. The subsurface layer deepened at the second half of 2009, by about 20 m, associated with a moderate El Niño event [ Todd et al ., ; Durski et al ., ]. Then in transition to La Niña conditions,

z_{26.5}

bounced back at the beginning of 2010.…”

Section: Modelmentioning

confidence: 99%

“…Summer (winter) currents are predominantly to the south (north). The model captures the observed interannual variability, e.g., showing the contrast between winter 2009–2010 when the winds where anomalously strong [ Durski et al ., ] and winter 2013–2014 when the downwelling favorable winds were extremely low [ Bond et al ., ]. Model currents are weaker than observed in summer 2011 and 2014.…”

Section: Model‐data Comparisonsmentioning

confidence: 99%

“…Strong negative anomalies in

z_{26.5}

are found during two periods, both in response to El Niño events. It is understood [ Todd et al ., ; Durski et al ., ] that the 2009–2010 El Niño influenced the NE Pacific coast mostly through the atmospheric teleconnection mechanism [ Schwing et al ., ] that brought anomalously strong downwelling‐favorable winds in winter 2010. The

z_{26.5}

anomaly during that event is confined to latitudes north of 40°N.…”

Section: Seasonal and Interannual Variability In The Oceanic Propertimentioning

confidence: 99%

“…At any given point, data availability differs from day to day. Similar to Durski et al [2015], daily-averaged model surface currents are sampled where and when the data are available and area-average alongshore currents are compared for each day. Figure 3 shows results for an area off OR between 428N and 468N where the alongshore direction is defined as that to the north.…”

Section: Model-data Comparisonsmentioning

confidence: 99%

“…From south to north along the coast, geographical regions in our domain of interest include Mexico, Southern California (CA) between 328N and 348N, Central and Northern CA (348N-418N), Oregon (OR, 418N-468N), Washington State (WA, 468N-488N), and British Columbia in Canada (BC, 488N-548N). Seasonal variability over the shelf and slope in Northern CA, OR, and WA is strongly dominated by winddriven upwelling in summer and downwelling in winter [Durski et al, 2015]. During upwelling a cold southward surface intensified alongshore current develops [e.g., Huyer et al, 1989;Kosro et al, 1997;Kurapov et al, 2005aKurapov et al, ,2005b.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal and interannual variability in along‐slope oceanic properties off the US West Coast: Inferences from a high‐resolution regional model

2017

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A 6 year, 2009–2014 simulation using a 2 km horizontal resolution ocean circulation model of the Northeast Pacific coast is analyzed with focus on seasonal and interannual variability in along‐slope subsurface oceanic properties. Specifically, the fields are sampled on the isopycnal surface σ=26.5 kg m−3 that is found between depths of 150 and 300 m below the ocean surface over the continental slope. The fields analyzed include the depth z26.5, temperature T26.5, along‐slope current v26.5, and the average potential vorticity PV between σ = 26.5 and 26.25 kg m−3. Each field is averaged in the cross‐shore direction over the continental slope and presented as a function of the alongshore coordinate and time. The seasonal cycle in z26.5 shows a coherent upwelling‐downwelling pattern from Mexico to Canada propagating to the north with a speed of 0.5 m s−1. The anomalously deep ( −20 m) z26.5 displacement in spring‐summer 2014 is forced by the southern boundary condition at 24°N as a manifestation of an emerging strong El Niño. The seasonal cycle in T26.5 is most pronounced between 36°N and 53°N indicating that subarctic waters are replaced by warmer Californian waters in summer with the speed close 0.15 m s−1, which is consistent with earlier estimates of the undercurrent speed and also present v26.5 analyses. The seasonal patterns and anomalies in z26.5 and T26.5 find confirmation in available long‐term glider and shipborne observations. The PV seasonality over the slope is qualitatively different to the south and north of the southern edge of Heceta Bank (43.9°N).

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z_{26.5}

bounced back at the beginning of 2010.…”

Section: Modelmentioning

confidence: 99%

Section: Model‐data Comparisonsmentioning

confidence: 99%

“…Strong negative anomalies in

z_{26.5}

z_{26.5}

anomaly during that event is confined to latitudes north of 40°N.…”

Section: Seasonal and Interannual Variability In The Oceanic Propertimentioning

confidence: 99%

Section: Model-data Comparisonsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seasonal and interannual variability in along‐slope oceanic properties off the US West Coast: Inferences from a high‐resolution regional model

2017

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Intra‐ and inter‐annual variation in gray whale body condition on a foraging ground

et al. 2020

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Baleen whales store energy gained on foraging grounds to support reproduction and other metabolic needs while fasting for long periods during migration. Whale body condition can be used to monitor foraging success, and thus better understand and anticipate individual-and population-level trends in reproduction and survival. We assessed the body condition of eastern North Pacific gray whales (Eschrichtius robustus) on their foraging grounds along the Oregon coast, USA, from June to October of three consecutive years (2016)(2017)(2018). We used drone photogrammetry and applied the body area index (BAI) to measure and compare whale body condition, which is a continuous, unitless metric similar to the body mass index in humans. A total of 289 drone flights were carried out over 106 photo-identified whales, which were grouped into demographic units by sex, maturity, and female reproductive status. Calves and pregnant females displayed the highest BAIs, followed by resting females, mature males, and, finally, lactating females, reflecting the significant energetic demands on reproductive females. In all three years, gray whale body condition improved with the progression of feeding seasons, demonstrating the accumulation of body energy reserves on the foraging grounds. Yet, body condition was significantly better in 2016 than in 2017 and 2018 when overall body depletion was observed, indicating a difference in prey availability and/or quality between years. We analyzed local upwelling patterns between 2013 and 2018 as an oceanographic proxy for prey and determined significantly greater upwelling between 2013 and 2015 than low upwelling years between 2016 and 2018. We hypothesize that these upwelling patterns created ecosystem shifts in primary productivity and zooplankton prey of gray whales, causing carry-over effects between foraging success and body condition in subsequent years. This study demonstrates the value of monitoring whale body condition to better understand temporal variation in foraging success, and potentially detect and describe the causes of anomalous changes in whale population health, such as the 2019 gray whale mortality event.

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Cycles in oceanic teleconnections and global temperature change

Seip

Grøn

2018

Theor Appl Climatol

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Three large ocean currents are represented by proxy time series: the North Atlantic oscillation, NAO, the Southern oscillation index, SOI, and the Pacific decadal oscillation, PDO. We here show how proxies for the currents interact with each other and with the global temperature anomaly, GTA, applying a novel method which identifies running average leading lagging, LL-relations, between paired series. We find common cycle times for paired series of 6-7 years and 25-28 years and identify years when LL-relations switch. Switching occurs with XXX 20 years interval for the short 7 years cycles and with 27± 15 years intervals for the 25-28 years cycles. During the period 1940-50, the LL-relations for the long cycles were circular (nomenclature x leads y: x → y): GTA → NAO → SOI → PDO → GTA. However, after 1960, the LL-relations become more complex and there are indications that GTA leads both NAO and PDO. The switching years are related to ocean current tie points and reversal points reported in the literature.

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Coastal ocean variability in the US Pacific Northwest region: seasonal patterns, winter circulation, and the influence of the 2009–2010 El Niño

Cited by 18 publications

References 35 publications

Seasonal and interannual variability in along‐slope oceanic properties off the US West Coast: Inferences from a high‐resolution regional model

Seasonal and interannual variability in along‐slope oceanic properties off the US West Coast: Inferences from a high‐resolution regional model

Intra‐ and inter‐annual variation in gray whale body condition on a foraging ground

Cycles in oceanic teleconnections and global temperature change

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