scholarly journals Contributions of Atmospheric Forcing and Chaotic Ocean Variability to Regional Sea Level Trends Over 1993–2015

2018 ◽  
Vol 45 (24) ◽  
Author(s):  
William Llovel ◽  
Thierry Penduff ◽  
Benoit Meyssignac ◽  
Jean‐Marc Molines ◽  
Laurent Terray ◽  
...  
Keyword(s):  
Sea Level ◽  
Atmospheric Forcing ◽  
Ocean Variability ◽  
Regional Sea Level

Characterisation of the chaotic variability of the regional sea level and its components over 1993-2015 at interannual time scales

2021 ◽  
Author(s):  
Alice Carret ◽  
William Llovel ◽  
Thierry Penduff ◽  
Jean-Marc Molines
Keyword(s):  
Interannual Variability ◽  
Sea Level ◽  
Global Ocean ◽  
Atmospheric Forcing ◽  
Sea Level Changes ◽  
Ensemble Simulation ◽  
Ocean Variability ◽  
Ocean Area ◽  
Regional Sea Level ◽  
Global Mean Sea Level

<p>Satellite altimetry data have revealed a global mean sea level rise of 3.1 mm/yr since 1993 with large regional sea level trend variability. These remote data highlight complex structures especially in strongly eddying regions. A recent study showed that over 38% of the global ocean area, the chaotic variability that spontaneously emerges from the ocean may hinder the attribution to the atmospheric forcing of regional sea level trends from 1993 to 2015. This study aims at complementing this work by first focusing on the atmospherically-forced and chaotic contributions of regional sea level interannual variability and its components (steric and manometric sea level interannual variability). A global ¼° ocean/sea-ice 50-member ensemble simulation is considered to disentangle the imprints of the atmospheric forcing and of the chaotic ocean variability over 1993-2015. The atmospherically-forced and chaotic interannual variabilities of sea level mainly have a steric origin , except in coastal areas. The chaotic part of the interannual variability of sea level and its components is stronger in the Pacific and Atlantic oceans than in the Indian ocean. The chaotic part of the interannual variability of sea level and of its steric component exceeds 20% over 48% of the global ocean area; this fractional area reduces to 26% for the manometric component. As the chaotic part of the regional sea level interannual variability has a substantial imprint, this study then interested in quantifying the periods when it becomes dominant over the atmospherically-forced contribution. This is assessed using spectral analysis on the ensemble simulation in the frequency domain for the sea level and its steric and manometric components over the global ocean as well as in some basins of interest. This enables us to better characterise and quantify the chaotic ocean variability contribution to regional sea level changes and its components.</p>

scholarly journals Changes in extreme regional sea level under global warming

Ocean Science ◽  
2017 ◽  
Vol 13 (1) ◽  
pp. 47-60 ◽  
Author(s):  
S.-E. Brunnabend ◽  
H. A. Dijkstra ◽  
M. A. Kliphuis ◽  
H. E. Bal ◽  
F. Seinstra ◽  
...  
Keyword(s):  
Sea Level ◽  
North Atlantic ◽  
Climate Model ◽  
Return Time ◽  
Value Theory ◽  
Ocean Eddies ◽  
Ocean Variability ◽  
The North ◽  
Regional Sea Level ◽  
Ipcc Sres

Abstract. An important contribution to future changes in regional sea level extremes is due to the changes in intrinsic ocean variability, in particular ocean eddies. Here, we study a scenario of future dynamic sea level (DSL) extremes using a high-resolution version of the Parallel Ocean Program and generalized extreme value theory. This model is forced with atmospheric fluxes from a coupled climate model which has been integrated under the IPCC-SRES-A1B scenario over the period 2000–2100. Changes in 10-year return time DSL extremes are very inhomogeneous over the globe and are related to changes in ocean currents and corresponding regional shifts in ocean eddy pathways. In this scenario, several regions in the North Atlantic experience an increase in mean DSL of up to 0.4 m over the period 2000–2100. DSL extremes with a 10-year return time increase up to 0.2 m with largest values in the northern and eastern Atlantic.

Forced and chaotic variability of interannual variability of regional sea level and its causes scale over 1993-2015

2020 ◽  
Author(s):  
Alice Carret ◽  
William Llovel ◽  
Thierry Penduff ◽  
Jean-Marc Molines ◽  
Benoît Meyssignac
Keyword(s):  
Interannual Variability ◽  
Sea Level ◽  
Satellite Altimetry ◽  
Global Ocean ◽  
Western Boundary ◽  
Western Boundary Currents ◽  
Steric Sea Level ◽  
Boundary Currents ◽  
Ocean Variability ◽  
Regional Sea Level

<p>Since the early 1990s, satellite altimetry has become the main observing system for continuously measuring the sea level variations with a near global coverage. Satellite altimetry has revealed a global mean sea level rise of 3.3 mm/yr since 1993 with large regional sea level variability that differs from the mean estimate. These measurements highlight complex structures especially for the western boundary currents or the Antarctic Circumpolar Current. A recent study shows that the chaotic ocean variability may mask atmospherically-forced regional sea level trends over 38% of the global ocean area from 1993 to 2015. The chaotic variability is large for the western boundary currents and in the Southern Ocean. The present study aims to complement this previous work in focusing on the interannual variability of regional sea level. A global ¼° ocean/sea-ice 50-member ensemble simulation is considered to disentangle the imprints of the atmospheric forcing and the chaotic ocean variability on the interannual variability of regional sea level over 1993-2015. We investigate the forced (i.e., ensemble mean) versus the chaotic variability (i.e., ensemble standard deviation) for the interannual variability of regional sea level and its causes (i.e., steric sea level and manometric sea level contribution). We complement our investigations by partitioning the steric component into thermosteric sea level (i.e., temperature change only) and halosteric sea level (i.e., salinity change only). One of the goals of the study is to highlight the hot spots region of large chaotic variability for regional sea level and its different components.</p>

scholarly journals Changes in extreme regional sea level under global warming

2016 ◽  
Author(s):  
S.-E. Brunnabend ◽  
H. A. Dijkstra ◽  
M. A. Kliphuis ◽  
H. E. Bal ◽  
F. Seinstra ◽  
...  
Keyword(s):  
Sea Level ◽  
North Atlantic ◽  
Climate Model ◽  
Return Time ◽  
Coupled Climate Model ◽  
Ocean Eddies ◽  
Ocean Variability ◽  
The North ◽  
Regional Sea Level ◽  
Ipcc Sres

Abstract. An important contribution to future changes in regional sea level extremes is due to the changes in intrinsic ocean variability, in particular ocean eddies. Here, we study a scenario of future dynamic sea level (DSL) extremes using a strongly eddying version of the Parallel Ocean Program. This model is forced with atmospheric fluxes from a coupled climate model which has been integrated under the IPCC-SRES-A1B scenario over the period 2000–2100. Changes in 10-year return time DSL extremes are very inhomogeneous over the globe and are related to changes in ocean cur- rents and corresponding regional shifts in ocean eddy pathways. In this scenario, several regions in the North Atlantic experience an increase in mean DSL of up to 0.4 m over the period 2000–2100. DSL extremes with a 10-year return time increase up to 0.2 m with largest values in the northern and eastern Atlantic.

scholarly journals Reconciling global mean and regional sea level change in projections and observations

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jinping Wang ◽  
John A. Church ◽  
Xuebin Zhang ◽  
Xianyao Chen
Keyword(s):  
Sea Level ◽  
Climate Models ◽  
Tide Gauge ◽  
Sea Level Change ◽  
Global Network ◽  
Weighted Mean ◽  
Level Change ◽  
Regional Sea Level ◽  
Global Mean ◽  
Regional Sea Level Change

AbstractThe ability of climate models to simulate 20th century global mean sea level (GMSL) and regional sea-level change has been demonstrated. However, the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) and Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) sea-level projections have not been rigorously evaluated with observed GMSL and coastal sea level from a global network of tide gauges as the short overlapping period (2007–2018) and natural variability make the detection of trends and accelerations challenging. Here, we critically evaluate these projections with satellite and tide-gauge observations. The observed trends from GMSL and the regional weighted mean at tide-gauge stations confirm the projections under three Representative Concentration Pathway (RCP) scenarios within 90% confidence level during 2007–2018. The central values of the observed GMSL (1993–2018) and regional weighted mean (1970–2018) accelerations are larger than projections for RCP2.6 and lie between (or even above) those for RCP4.5 and RCP8.5 over 2007–2032, but are not yet statistically different from any scenario. While the confirmation of the projection trends gives us confidence in current understanding of near future sea-level change, it leaves open questions concerning late 21st century non-linear accelerations from ice-sheet contributions.

Coastal sea level variability in the Bohai Bay: influence of atmospheric forcing and prediction

2018 ◽  
Vol 37 (2) ◽  
pp. 486-497 ◽  
Author(s):  
Xianqing Lü ◽  
Daosheng Wang ◽  
Bing Yan ◽  
Hua Yang
Keyword(s):  
Sea Level ◽  
Bohai Bay ◽  
Atmospheric Forcing ◽  
Sea Level Variability ◽  
Coastal Sea

Imprint of intrinsic ocean variability on ocean heat content and thermosteric sea level over 2005-2015

2021 ◽  
Author(s):  
William Llovel ◽  
Nicolas Kolodziejczyk ◽  
Thierry Penduff ◽  
Jean-Marc Molines ◽  
Sally Close
Keyword(s):  
Sea Level ◽  
Heat Content ◽  
Ocean Heat Content ◽  
Uneven Distribution ◽  
Climate Variables ◽  
Intrinsic Variability ◽  
Large Ensemble ◽  
Ocean Variability ◽  
Spatial Coverage

<p>Ocean warming accounts for more than 90% of the net Earth energy imbalance. As oceans warm, sea level is rising due to the expansion of seawater. Therefore, estimating ocean heat content (OHC) and thermosteric sea level (TSL) appears of great importance to assess the impact of the on-going global warming.  Different research groups have estimated such climate variables for years now and even routinely (Boyer et al., 2016). These climate variables are derived from in situ temperature measurement at different depths with uneven spatial coverage. Two main sources of uncertainties are attributed to the evolving technology of temperature probes and to the uneven spatio-temporal distribution of in situ measurements (Boyer et al., 2016). A large ensemble of forced eddy-permitting ocean simulations revealed the existence of another uncertainty of regional OHC trend estimates (Sérazin et al 2017): a substantial intrinsic variability emerging from oceanic nonlinearities generates random multi decadal trends, which can mask its atmospherically-forced counterpart. This intrinsic variability can also leave a large imprint on regional sea level trends over the altimetry period (Llovel et al., 2018; Penduff et al., 2019). Less attention has been paid for estimating the imprint of such intrinsic ocean variability in OHC and TSL change associated with the uneven spatial coverage of in situ records. In this study, we investigate the imprint of ocean intrinsic variability and of the uneven distribution of in situ records on OHC and TLS change, by taking advantage of this large ensemble simulation. To do so, we extract synthetic in situ temperature profiles from the simulations in space, time and depth. We then interpolate these synthetic profiles using ISAS (Gaillard et al. 2016) to estimate both the imprint of intrinsic ocean variability and the uneven distribution of in situ data to OHC change and TSL change from 2005 to 2015.</p>

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