Effects of Sea State Bias on Global Mean Sea Level Trend

2018 ◽  
Author(s):  
Yongcun Cheng ◽  
Qing Xu ◽  
Xiaofeng Li
Keyword(s):  
Sea Level ◽  
Sea State ◽  
Mean Sea Level ◽  
Sea State Bias ◽  
Sea Level Trend ◽  
Global Mean Sea Level ◽  
Global Mean

scholarly journals Sea State Bias Variability in Satellite Altimetry Data

2019 ◽  
Vol 11 (10) ◽  
pp. 1176
Author(s):  
Yongcun Cheng ◽  
Qing Xu ◽  
Le Gao ◽  
Xiaofeng Li ◽  
Bin Zou ◽  
...  
Keyword(s):  
Sea Level ◽  
Sea Level Change ◽  
Sea State ◽  
Mean Sea Level ◽  
Level Change ◽  
Sea State Bias ◽  
Regional Sea Level ◽  
Sea Level Trend ◽  
Global Mean Sea Level ◽  
Global Mean

Sea State Bias (SSB) contributes to global mean sea level variability and it needs cm-level range adjustment due to the instrumental drift over time. To investigate its variations and correct the global and regional sea level trend precisely, we calculate the temporal and spatial variability of the SSB correction in TOPEX, Jason-1, Jason-2 and Jason-3 missions, separately, as well as in the combined missions over the period 1993–2017. The long-term trend in global mean operational 2D non-parametric SSB correction is about −0.03 ± 0.03 mm/yr, which accounts for 1% of current global mean sea level change rate during 1993–2016. This correction contributes to sea level change rates of −1.27 ± 0.21 mm/yr and −0.26 ± 0.13 mm/yr in TOPEX-A and Jason-2 missions, respectively. The global mean SSB varies up to 7–10 mm during the very strong ENSO events in 1997–1998 and 2015–2016. Furthermore, the TOPEX SSB trend, which is consistent with recently reported sea level trend drift during 1993–1998, may leak into the determined global sea level trend in the period. Moreover, the Jason-1/2 zonal SSB variability is highly correlated with the significant wave height (SWH). On zonal average, SSB correction causes about 1% uncertainty in mean sea level trend. At high SWH regions, the uncertainties grow to 2–4% near the 50°N and 60°S bands. This should be considered in the study of regional sea level variability.

Constraining Wind Stress Products with Sea Surface Height Observations and Implications for Pacific Ocean Sea Level Trend Attribution*

2012 ◽  
Vol 25 (23) ◽  
pp. 8164-8176 ◽  
Author(s):  
Shayne McGregor ◽  
Alexander Sen Gupta ◽  
Matthew H. England
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
Surface Wind ◽  
Sea Surface Height ◽  
Sea Surface ◽  
Water Model ◽  
Mean Sea Level ◽  
Sea Level Trend ◽  
Global Mean Sea Level ◽  
Global Mean

Abstract A number of global surface wind datasets are available that are commonly used to examine climate variability or trends and as boundary conditions for ocean circulation models. However, discrepancies exist among these products. This study uses observed Archiving, Validation, and Interpretation of Satellite Oceanographic (AVISO) sea surface height anomalies (SSHAs) as a means to help constrain the fidelity of these products in the tropical region. Each wind stress product is used to force a linear shallow water model (SWM) and the resulting hindcast thermocline depth anomalies are converted to SSHAs. The resulting SSHAs are then assessed to see how well they reproduce the dominant EOF modes of observed variability and the regional (global mean removed) sea level trend (1993–2007) in each of the three ocean basins. While the results suggest that all wind datasets reproduce the observed interannual variability with reasonable fidelity, the two SWM hindcasts that produce the observed linear trend with the highest fidelity are those incorporating interim ECMWF Re-Analysis (ERA-Interim) and Wave- and Anemometer-Based Sea Surface Wind (WASWind) forcing. The role of surface wind forcing (i.e., upper ocean heat content redistribution) versus global mean sea level change (i.e., including the additional contributions of glacier and ice sheet melt along with ocean thermal expansion) on the recent dramatic increase in western equatorial Pacific island sea level is then reassessed. The results suggest that the recent sea level increase cannot be explained solely by wind stress forcing, regardless of the dataset used; rather, the global mean sea level signal is required to fully explain this observed recent abrupt sea level rise and to better explain the sea level variability of the last 50–60 years.

scholarly journals Is there a 60-year oscillation in global mean sea level?

2012 ◽  
Vol 39 (18) ◽  
Author(s):  
Don P. Chambers ◽  
Mark A. Merrifield ◽  
R. Steven Nerem
Keyword(s):  
Sea Level ◽  
Mean Sea Level ◽  
Global Mean Sea Level ◽  
Global Mean

A 25-Year Satellite Altimetry-Based Global Mean Sea Level Record

2017 ◽  
pp. 187-210 ◽  
Author(s):  
R. Steven Nerem ◽  
Michaël Ablain ◽  
Anny Cazenave ◽  
John Church ◽  
Eric Leuliette
Keyword(s):  
Sea Level ◽  
Satellite Altimetry ◽  
Mean Sea Level ◽  
Global Mean Sea Level ◽  
Global Mean

scholarly journals The effect of lateral variations in Earth structure on Last Interglacial sea level

2021 ◽  
Author(s):  
Jacqueline Austermann ◽  
Mark Hoggard ◽  
Konstantin Latychev ◽  
Fred Richards ◽  
Jerry Mitrovica
Keyword(s):  
Sea Level ◽  
Earth Structure ◽  
Last Interglacial ◽  
Level Indicator ◽  
Mean Sea Level ◽  
Mineral Physics ◽  
Shear Wave Speed ◽  
Global Mean Sea Level ◽  
Lateral Variations ◽  
Global Mean

It is generally agreed that the Last Interglacial (LIG; ~130-115ka) was a time when global average temperatures and global mean sea level were higher than they are today. However, the exact timing, magnitude, and spatial pattern of ice melt is much debated. One difficulty in extracting past global mean sea level from local observations is that their elevations need to be corrected for glacial isostatic adjustment (GIA), which requires knowledge of Earth’s internal viscoelastic structure. While this structure is generally assumed to be radially symmetric, evidence from seismology, geodynamics, and mineral physics indicates that large lateral variations in viscosity exist within the mantle. In this study, we construct a new model of Earth’s internal structure by converting shear wave speed into viscosity using parameterisations from mineral physics experiments and geodynamical constraints on Earth’s thermal structure. We use this 3D Earth structure, which includes both variations in lithospheric thickness and lateral variations in viscosity, to calculate the first 3D GIA prediction for LIG sea level. We find that the difference between predictions with and without lateral Earth structure can be meters to 10s of meters in the near field of former ice sheets, and up to a few meters in their far field. We demonstrate how forebulge dynamics and continental levering are affected by laterally varying Earth structure, with a particular focus on those sites with prominent LIG sea level records. Results from three 3D GIA calculations show that accounting for lateral structure acts to increase local sea level by up to ~1.5m at the Seychelles and minimally decrease it in Western Australia. We acknowledge that this result is only based on a few simulations, but if robust, this shift brings estimates of global mean sea level from these two sites into closer agreement with each other. We further demonstrate that simulations with a suitable radial viscosity profile can be used to locally approximate the 3D GIA result, but that these radial profiles cannot be found by simply averaging viscosity below the sea level indicator site.

scholarly journals Effect of La Niña on The Global Mean Sea Level And North Pacifc Ocean Mass Over 2005-2011

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Habib B. Dieng ◽  
Anny Cazenave ◽  
Benoit Meyssignac ◽  
Olivier Henry ◽  
Karina von Schuckmann ◽  
...  
Keyword(s):  
Sea Level ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Mean Sea Level ◽  
The North ◽  
Ocean Mass ◽  
La Nina ◽  
Global Mean Sea Level ◽  
Global Mean

AbstractInterannual fluctuations of the global mean sea level are highly correlated with El Niño-Southern Oscillation (ENSO) events, with positive/negative anomalies during El Niño/La Niña. In a previous study we showed that during the 1997 - 1998 El Niño, a positive anomaly observed in the global mean sea level was mostly caused by an increase of the ocean mass component rather than by steric (thermal) effects. This result was related to an increase of precipitation over the tropical ocean and a deficit in land water storage. In the present study, we investigate the effect of the recent 2008 and 2011 La Niña events on the satellite altimetry-based global mean sea level. We find that the large global mean sea level drop associated with the 2011 La Niña results from the combined decrease of the steric and ocean mass components, with a slightly dominant contribution from the latter. We show that the ocean mass contribution to the global mean sea level drop is spatially confined over the north eastern tropical Pacific (just as was found previously for the 1997 - 1998 El Niño, but with opposite sign). Corresponding ocean mass spatial pattern is closely correlated to observed sea level and steric spatial patterns over the duration of the La Niña event. This is also observed for previous El Niño and La Niña events. Such a drop in ocean mass during ENSO in the eastern part of the tropical Pacific has not been reported before. It is possibly related to a temporary decrease in the net precipitation over the north eastern Pacific (opposite situation was found during the 1997 - 1998 El Niño).

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