Uncertainties in Steric Sea Level Change Estimation During the Satellite Altimeter Era: Concepts and Practices

Macintosh, Claire; Merchant, Christopher J.; Schuckmann, Karina von

doi:10.1007/s10712-016-9387-x

Cited by 25 publications

(22 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Sea level rise during the 21st century is expected to be larger than during the 20th century [13][14][15][16][17] even if greenhouse gas emissions stopped now [18] The regional increases may locally amplify further [19] due to, e.g., weakening of the thermohaline circulation [20], and have implications of unprecedented flooding risks in coastal areas [21], although large uncertainties are still present in the climate projections of mass-induced sea level changes [22]. It is therefore imperative to continuously assess and monitor sea level changes at both global and local scales using all possible tools that the climate science community has developed, such as in-situ and/or remote sensing-based observational products, model-based products, and products fusing models and observations (e.g., reanalysis), while taking care of the associated uncertainty estimates [23].…”

Section: Sea Level Rise As a Proxy Of Climate Change And Threat From mentioning

confidence: 99%

Steric Sea Level Changes from Ocean Reanalyses at Global and Regional Scales

Storto

Bonaduce

Feng

et al. 2019

Water

View full text Add to dashboard Cite

Sea level has risen significantly in the recent decades and is expected to rise further based on recent climate projections. Ocean reanalyses that synthetize information from observing networks, dynamical ocean general circulation models, and atmospheric forcing data offer an attractive way to evaluate sea level trend and variability and partition the causes of such sea level changes at both global and regional scales. Here, we review recent utilization of reanalyses for steric sea level trend investigations. State-of-the-science ocean reanalysis products are then used to further infer steric sea level changes. In particular, we used an ensemble of centennial reanalyses at moderate spatial resolution (between 0.5 × 0.5 and 1 × 1 degree) and an ensemble of eddy-permitting reanalyses to quantify the trends and their uncertainty over the last century and the last two decades, respectively. All the datasets showed good performance in reproducing sea level changes. Centennial reanalyses reveal a 1900–2010 trend of steric sea level equal to 0.47 ± 0.04 mm year−1, in agreement with previous studies, with unprecedented rise since the mid-1990s. During the altimetry era, the latest vintage of reanalyses is shown to outperform the previous ones in terms of skill scores against the independent satellite data. They consistently reproduce global and regional upper ocean steric expansion and the association with climate variability, such as ENSO. However, the mass contribution to the global mean sea level rise is varying with products and its representability needs to be improved, as well as the contribution of deep and abyssal waters to the steric sea level rise. Similarly, high-resolution regional reanalyses for the European seas provide valuable information on sea level trends, their patterns, and their causes.

show abstract

Section: Sea Level Rise As a Proxy Of Climate Change And Threat From mentioning

confidence: 99%

Steric Sea Level Changes from Ocean Reanalyses at Global and Regional Scales

Storto

Bonaduce

Feng

et al. 2019

Water

View full text Add to dashboard Cite

show abstract

“…Given that we use gridded data sets, we do not consider the uncertainty propagation from a single profile of temperature and salinity to steric height. The concept of uncertainty propagation was reviewed and discussed in detail in MacIntosh et al (2017).…”

Section: Methods and Datamentioning

confidence: 99%

Exploring Sources of Uncertainty in Steric Sea‐Level Change Estimates

et al. 2020

View full text Add to dashboard Cite

Recent studies disagree about the contribution of variations in temperature and salinity of the oceans-steric change-to the observed sea-level change. This article explores two sources of uncertainty to both global mean and regional steric sea-level trends. First, we analyze the influence of different temperature and salinity data sets on the estimated steric sea-level change. Next, we investigate the impact of different stochastic noise models on the estimation of trends and their uncertainties. By varying both the data sets and noise models, the global mean steric sea-level trend and uncertainty can vary from 0.69 to 2.40 and 0.02 to 1.56 mm/year, respectively, for 1993-2017. This range is even larger on regional scales, reaching up to 30 mm/year. Our results show that a first-order autoregressive model is the most appropriate choice to describe the residual behavior of the ensemble mean of all data sets for the global mean steric sea-level change over the last 25 years, which consequently leads to the most representative uncertainty. Using the ensemble mean and the first-order autoregressive noise model, we find a global mean steric sea-level change of 1.36 ± 0.10 mm/year for 1993-2017 and 1.08 ± 0.07 mm/year for 2005-2015. Regionally, a combination of different noise models is the best descriptor of the steric sea-level change and its uncertainty. The spatial coherence in the noise model preference indicates clusters that may be best suited to investigate the regional sea-level budget. Plain Language Summary Ocean temperature and salinity variations lead to changes in sea level, known as steric sea-level change. Steric variations are important contributors to sea-level change and reflect how the oceans have been responding to global warming. For this reason, several recent studies have quantified the contribution of steric variations to global and regional sea-level change. However, the reported rates largely differ between studies. In this paper, we look at how the use of different temperature and salinity data sets can be one of the causes of the different estimates of steric sea-level change published so far. We also investigate how different methods (noise models) used to obtain the rate of change can be another source of different results. We find that the rate of change can vary up to 2 mm/year for the global mean as a result of different data sets and methods used. Regionally, differences can reach up to several tens of millimeters per year. We show that the noise models should always be carefully chosen for each region, so that the rate of change is accurately estimated.

show abstract

“…A CTD profile was collected immediately before calibration operations. Utilizing a calibration sphere target strength model based on the work by Faran (1951) and MacLennan (1981) (MAT-LAB software;Dezhang Chu, personal communication, 2015), a calibration offset (C = 8.5 dB, averaged over the transducer beam width) was calculated using a temperature of 0 • C and a salinity of 34.5 at the sphere depth of approximately 80 m. This calibration offset represents the difference between the nominal target strength (TS) observed by the EK80, as predicted after match filtering, and the modeled TS of the calibration sphere. The offset is then applied to subsequent measurements of TS, yielding calibrated TS results for the EK80 datasets.…”

Section: Ek80 Extended Target Calibration Proceduresmentioning

confidence: 99%

“…Broad global coverage of the distribution of the MLD is becoming increasingly available through salinity and temperature stratification data from the ARGO float program (Freeland et al, 2010), but the high spatial frequency of ocean thermohaline variability is still strongly undersampled (Guinehut et al, 2012). Satellite-derived products provide global synoptic coverage of, for example, sea level (MacIntosh et al, 2016), sea surface temperature (Donlon et al, 2010), and sea surface salinity (Font et al, 2013;Lagerloef et al, 2012) but are essentially restricted to near-sea-surface properties.…”

Section: Introductionmentioning

confidence: 99%

Acoustic mapping of mixed layer depth

et al. 2018

View full text Add to dashboard Cite

Abstract. The ocean surface mixed layer is a nearly universal feature of the world oceans. Variations in the depth of the mixed layer (MLD) influences the exchange of heat, fresh water (through evaporation), and gases between the atmosphere and the ocean and constitutes one of the major factors controlling ocean primary production as it affects the vertical distribution of biological and chemical components in near-surface waters. Direct observations of the MLD are traditionally made by means of conductivity, temperature, and depth (CTD) casts. However, CTD instrument deployment limits the observation of temporal and spatial variability in the MLD. Here, we present an alternative method in which acoustic mapping of the MLD is done remotely by means of commercially available ship-mounted echo sounders. The method is shown to be highly accurate when the MLD is well defined and biological scattering does not dominate the acoustic returns. These prerequisites are often met in the open ocean and it is shown that the method is successful in 95 % of data collected in the central Arctic Ocean. The primary advantages of acoustically mapping the MLD over CTD measurements are (1) considerably higher temporal and horizontal resolutions and (2) potentially larger spatial coverage.

show abstract

Uncertainties in Steric Sea Level Change Estimation During the Satellite Altimeter Era: Concepts and Practices

Cited by 25 publications

References 72 publications

Steric Sea Level Changes from Ocean Reanalyses at Global and Regional Scales

Steric Sea Level Changes from Ocean Reanalyses at Global and Regional Scales

Exploring Sources of Uncertainty in Steric Sea‐Level Change Estimates

Acoustic mapping of mixed layer depth

Contact Info

Product

Resources

About