Review of Ezer and Dangendorf, "Global sea level reconstruction for 1900-2015 reveals regional variability in ocean dynamics and an unprecedented long weakening in the Gulf Stream flow since the 1990s".

Abstract. A new monthly global sea level reconstruction for 1900–2015 was analyzed and compared with various observations to examine regional variability and trends in the ocean dynamics of the western North Atlantic Ocean and the US East Coast. Proxies of the Gulf Stream (GS) strength in the Mid-Atlantic Bight (GS-MAB) and in the South Atlantic Bight (GS-SAB) were derived from sea level differences across the GS. While decadal oscillations dominate the 116-year record, the analysis showed an unprecedented long period of weakening in the GS flow since the late 1990s. The only other period of long weakening in the record was during the 1960s–1970s, and red noise experiments showed that is very unlikely that those just occurred by chance. Ensemble empirical mode decomposition (EEMD) was used to separate oscillations at different timescales, showing that the low-frequency variability of the GS is connected to the Atlantic Multi-decadal Oscillation (AMO) and the Atlantic Meridional Overturning Circulation (AMOC). The recent weakening of the reconstructed GS-MAB was mostly influenced by weakening of the upper mid-ocean transport component of AMOC as observed by the RAPID measurements for 2005–2015. Comparison between the reconstructed sea level near the coast and tide gauge data for 1927–2015 showed that the reconstruction underestimated observed coastal sea level variability for timescales less than ∼5 years, but lower-frequency variability of coastal sea level was captured very well in both amplitude and phase by the reconstruction. Comparison between the GS-SAB proxy and the observed Florida Current transport for 1982–2015 also showed significant correlations for oscillations with periods longer than ∼5 years. The study demonstrated that despite the coarse horizontal resolution of the global reconstruction (1∘ × 1∘), long-term variations in regional dynamics can be captured quite well, thus making the data useful for studies of long-term variability in other regions as well.

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Global sea level reconstruction for 1900–2015 reveals regional variability in ocean dynamics and an unprecedented long weakening in the Gulf Stream flow since the 1990s

10.5194/os-2020-22 ◽

2020 ◽

Author(s):

Tal Ezer ◽

Sonke Dangendorf

Keyword(s):

Sea Level ◽

Time Scales ◽

Gulf Stream ◽

Tide Gauge ◽

Meridional Overturning Circulation ◽

Ocean Dynamics ◽

Regional Variability ◽

Coastal Sea ◽

Global Sea Level

Abstract. A new monthly global sea level reconstruction for 1900–2015 was analyzed and compared with various observations to examine regional variability and trends in the ocean dynamics of the western North Atlantic Ocean and the U.S. East Coast. A proxy of the Gulf Stream (GS) strength in the Mid-Atlantic Bight (GS-MAB) and in the South Atlantic Bight (GS-SAB) were derived from sea level differences across the GS in the two regions. While decadal oscillations dominate the 116-year record, the analysis showed an unprecedented long period of weakening in the GS flow since the late 1990s. The only other period of long weakening in the record was during the 1960s–1970s. Ensemble Empirical Mode Decomposition (EEMD) was used to separate oscillations at different time scales, showing that the low-frequency variability of the GS is connected to the Atlantic Multidecadal Oscillations (AMO) and the Atlantic Meridional Overturning Circulation (AMOC). The recent weakening of the reconstructed GS-MAB was mostly influenced by weakening of the upper mid-ocean transport component of AMOC as observed by the RAPID measurements for 2005–2015. Comparison between the reconstructed sea level near the coast and tide gauge data for 1927–2015 showed that the reconstruction underestimated observed coastal sea level variability for time scales less than ~ 5 years, but lower frequency variability of coastal sea level was captured very well in both amplitude and phase by the reconstruction. Comparison between the GS-SAB proxy and the observed Florida Current transport for 1982–2015 also showed significant correlations for oscillations with periods longer than ~ 5 years. The study demonstrated that despite the coarse horizontal resolution of the global reconstruction (1° x 1°), long-term variations in regional dynamics can be captured quite well, thus making the data useful for studies of long-term variability in other regions as well.

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Western boundary circulation and sea level patterns in northern hemisphere oceans

10.5194/egusphere-egu21-15743 ◽

2021 ◽

Author(s):

Samuel Diabaté ◽

Didier Swingedouw ◽

Joël Hirschi ◽

Aurélie Duchez ◽

Philip Leadbitter ◽

...

Keyword(s):

North America ◽

Sea Level ◽

Gulf Stream ◽

Atlantic Coast ◽

Ocean Dynamics ◽

Western Boundary ◽

Tide Gauges ◽

Sea Level Changes ◽

Coastal Sea ◽

The Kuroshio

The sea level changes along the Atlantic coast of the US have received a lot of attention recently because of an increased rate of rise north of the Gulf Stream separation point since the late 1980s (Sallenger et al., 2012 ; Boon, 2012). While sea-level rise is a major issue for coastal community, sea-level measurements in the region are key to understand the past of the nearby Gulf Stream and the large-scale ocean dynamics. Tide gauges on the coastline have measured the inshore sea-level for many decades and provide a unique window on past oceanic circulation. So far, numerous studies have linked the interannual to multi-decadal coastal sea-level changes to ocean dynamics, including the Gulf Stream strength, the divergence of the Sverdrup transport in the basin interior and the Atlantic meridional overturning circulation. However, other studies argue that local and regional processes, such as the alongshore winds or the river discharges, are processes of greater importance to the coastal sea level.The general picture in the Atlantic is hence unclear. Yet, the northwest Atlantic is not the only western boundary region where sea-level has been well sampled. In this study we extend the analysis to the northwest Pacific, where links between the state of the Kuroshio and sea-level are evident (Kawabe, 2005; Sasaki et al., 2014). We discuss similarities and dissimilarities between the western boundary regions. We show for each basin, that the inshore sea level upstream the separation points is in sustained agreement with the meridional shifts of the western boundary current extension. This indicates that long duration tide gauges, such as Fernandina Beach (US) and Hosojima (Japan) could be used as proxies for the Gulf Stream North Wall and the Kuroshio Extension state, respectively.References:Boon, J. D. (2012). Evidence of sea level acceleration at US and Canadian tide stations, Atlantic Coast, North America. Journal of Coastal Research, 28(6), 1437-1445.&#160;Kawabe, M. (2005). Variations of the Kuroshio in the southern region of Japan: Conditions for large meander of the Kuroshio. Journal of oceanography, 61(3), 529-537.Sallenger, A. H., Doran, K. S., & Howd, P. A. (2012). Hotspot of accelerated sea-level rise on the Atlantic coast of North America. Nature Climate Change, 2(12), 884-888.Sasaki, Y. N., Minobe, S., & Miura, Y. (2014). Decadal sea&#8208;level variability along the coast of Japan in response to ocean circulation changes. Journal of Geophysical Research: Oceans, 119(1), 266-275.

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EASTERN REGIONAL ROOTS, GLOBAL REACH: DEVELOPING GLOBAL SEA–LEVEL HISTORY AND A RECORD OF MAJOR EVENT BY DRILLING THE MID-ATLANTIC COASTAL PLAIN

10.1130/abs/2020se-344008 ◽

2020 ◽

Author(s):

Kenneth G. Miller ◽

◽

Peter J. Sugarman ◽

James V. Browning

Keyword(s):

Sea Level ◽

Coastal Plain ◽

Atlantic Coastal Plain ◽

Major Event ◽

Global Sea Level ◽

Atlantic Coastal ◽

Eastern Regional ◽

Global Reach

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A global sea-level curve for the late Quaternary: the impossible dream?

Marine Geology ◽

10.1016/0025-3227(95)00057-6 ◽

1995 ◽

Vol 125 (1-2) ◽

pp. 1-6 ◽

Cited By ~ 25

Author(s):

Daniel Jean Stanley

Keyword(s):

Sea Level ◽

Late Quaternary ◽

Level Curve ◽

Global Sea Level

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Late Quaternary Landscape Dynamics at the La Spezia Gulf (NW Italy): A Multi-Proxy Approach Reveals Environmental Variability within a Rocky Embayment

Water ◽

10.3390/w13040427 ◽

2021 ◽

Vol 13 (4) ◽

pp. 427

Author(s):

Veronica Rossi ◽

Alessandro Amorosi ◽

Marco Marchesini ◽

Silvia Marvelli ◽

Andrea Cocchianella ◽

...

Keyword(s):

Sea Level ◽

Environmental Variability ◽

Late Quaternary ◽

Landscape Dynamics ◽

Last Interglacial ◽

Core Depth ◽

Coastal Bay ◽

Nw Italy ◽

Global Sea Level ◽

Geomorphological Features

The Gulf of La Spezia (GLS) in Northwest Italy is a rocky embayment with low fluvial influence facing the Mediterranean Sea. Past landscape dynamics were investigated through a multi-proxy, facies-based analysis down to a core depth of 30 m. The integration of quantitative ostracod, foraminifera, and pollen analyses, supported by radiocarbon ages, proved to be a powerful tool to unravel the late Quaternary palaeoenvironmental evolution and its forcing factors. The complex interplay between relative sea-level (RSL), climatic changes, and geomorphological features of the embayment drove four main evolution phases. A barrier–lagoon system developed in response to the rising RSL of the Late Pleistocene (likely the Last Interglacial). The establishment of glacial conditions then promoted the development of an alluvial environment, with generalised erosion of the underlying succession and subsequent accumulation of fluvial strata. The Holocene transgression (dated ca. 9000 cal year BP) caused GLS inundation and the formation of a low-confined lagoon basin, which rapidly turned into a coastal bay from ca. 8000 cal year BP onwards. This latter environmental change occurred in response to the last Holocene stage of global sea-level acceleration, which submerged a morphological relief currently forming a drowned barrier-island complex in the embayment.

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Magnetic reversal rate and global sea level trends

Nature ◽

10.1038/336317d0 ◽

1988 ◽

Vol 336 (6197) ◽

pp. 317-317 ◽

Cited By ~ 2

Author(s):

M. R. RAMPINO

Keyword(s):

Sea Level ◽

Reversal Rate ◽

Magnetic Reversal ◽

Global Sea Level

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Periodically forced self-organization in the long-term evolution of planktic foraminifera

Canadian Journal of Earth Sciences ◽

10.1139/e00-037 ◽

2001 ◽

Vol 38 (2) ◽

pp. 293-308 ◽

Cited By ~ 4

Author(s):

Andreas Prokoph ◽

Anthony D Fowler ◽

R Timothy Patterson

Keyword(s):

Sea Level ◽

Logistic Map ◽

Late Eocene ◽

Self Organization ◽

Extinction Data ◽

Sea Level Fluctuations ◽

Global Sea Level ◽

Extinction Events ◽

The Impact

Wavelet transform and other signal analysis techniques suggest that the planktic foraminiferal (PF) long-term evolutionary record of the last 127 Ma can be attributed to complex periodic and nonlinear patterns. Correlation of the PF extinction pattern with other geological series favors an origin of the ~30 Ma periodicity and self-organization by quasi-periodic mantle-plume cycles that in turn drive episodic volcanism, CO2-degassing, oceanic anoxic conditions, and sea-level fluctuations. Stationary ~30 Ma periodicity and a weak secular trend of ~100 Ma period are evident in the PF record, even without consideration of the mass extinction at the KT boundary. The 2732 Ma periodicity in the impact crater record and lows in the global sea-level curve, respectively, are ~6.5 Ma and ~2.3 Ma out of phase with PF-extinction data, although major PF-extinction events correspond to the bolide impacts at the KT boundary and in late Eocene. Another six extinction events correspond to abrupt global sea-level falls between the late Albian and early Oligocene. Self-organization in the PF record is characterized by increased radiation rates after major extinction events and a steady number of baseline species. Our computer model of long-term PF evolution replicates this SO pattern. The model consists of output from the logistic map, which is forced at 30 Ma and 100 Ma frequencies. The model has significant correlations with the relative PF-extinction data. In particular, it replicates singularities, such as the KT event, nonstationary 2.510 Ma periodicities, and phase shifts in the ~30 Ma periodicity of the PF record.

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