Annual sea level variability of the coastal ocean: The Baltic Sea‐North Sea transition zone

Passaro, Marcello; Cipollini, Paolo; Benvéniste, Jérôme

doi:10.1002/2014jc010510

Cited by 56 publications

(50 citation statements)

References 46 publications

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“…Notwithstanding concerns over potentially degraded quality of satellite altimetry data near the coast, the correspondence between standard altimetric products and tide gauge records can be good in some coastal regions (e.g., Vinogradov and Ponte 2011), and so it could be that the assimilation methods are discarding valuable data at the coast. Indeed, as specially tailored coastal altimetry products (e.g., Passaro et al 2015) come online and become more readily available, it will be important to bring them into ocean reanalyses for better representation of the coastal ocean.…”

Section: Discussionmentioning

confidence: 99%

Annual Sea Level Changes on the North American Northeast Coast: Influence of Local Winds and Barotropic Motions

et al. 2016

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Understanding the relationship between coastal sea level and the variable ocean circulation is crucial for interpreting tide gauge records and projecting sea level rise. In this study, annual sea level records (adjusted for the inverted barometer effect) from tide gauges along the North American northeast coast over 1980-2010 are compared to a set of data-assimilating ocean reanalysis products as well as a global barotropic model solution forced with wind stress and barometric pressure. Correspondence between models and data depends strongly on model and location. At sites north of Cape Hatteras, the barotropic model shows as much (if not more) skill than ocean reanalyses, explaining about 50% of the variance in the adjusted annual tide gauge sea level records. Additional numerical experiments show that annual sea level changes along this coast from the barotropic model are driven by local wind stress over the continental shelf and slope. This result is interpreted in the light of a simple dynamic framework, wherein bottom friction balances surface wind stress in the alongshore direction and geostrophy holds in the across-shore direction. Results highlight the importance of barotropic dynamics on coastal sea level changes on interannual and decadal time scales; they also have implications for diagnosing the uncertainties in current ocean reanalyses, using tide gauge records to infer past changes in ocean circulation, and identifying the physical mechanisms responsible for projected future regional sea level rise.

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Section: Discussionmentioning

confidence: 99%

Annual Sea Level Changes on the North American Northeast Coast: Influence of Local Winds and Barotropic Motions

et al. 2016

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“…an ideal, uncorrupted full-waveform case. This algorithm has been validated for sea level and SWH and used for different altimeters in number of case studies (Passaro et al 2014(Passaro et al , 2015aGómez-Enri et al 2016). Figure 5 shows an overpass of Jason-2 tangent to the coast of Elba Island in the Mediterranean Sea, where standard retracking algorithms yield unrealistic metre-level variations of the sea level while the adoption of ALES visually improves the height profile.…”

Section: Strategies For Improving the Coastal Altimetry Datamentioning

confidence: 99%

Monitoring Sea Level in the Coastal Zone with Satellite Altimetry and Tide Gauges

et al. 2016

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We examine the issue of sustained measurements of sea level in the coastal zone, first by summarizing the long-term observations from tide gauges, then showing how those are now complemented by improved satellite altimetry products in the coastal ocean. We present some of the progresses in coastal altimetry, both from dedicated reprocessing of the radar waveforms and from the development of improved corrections for the atmospheric effects. This trend towards better altimetric data at the coast comes also from technological innovations such as Ka-band altimetry and SAR altimetry, and we discuss the advantages deriving from the AltiKa Ka-band altimeter and the SIRAL altimeter on CryoSat-2 that can be operated in SAR mode. A case study along the UK coast demonstrates the good agreement between coastal altimetry and tide gauge observations, with root mean square differences as low as 4 cm at many stations, allowing the characterization of the annual cycle of sea level along the UK coasts. Finally, we examine the evolution of the sea level trend from the open to the coastal ocean along the western coast of Africa, comparing standard and coastally improved products. Different products give different sea level trend profiles, so the recommendation is that additional efforts are needed to study sea level trends in the coastal zone from past and present satellite altimeters. Further improvements are expected from more refined processing and screening of data, but in particular from the constant improvements in the geophysical corrections.

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“…Intiative (CCI) and from tide gauges in the Danish Straits to assess the sea level annual cycle with a view to climatic applications [13].…”

Section: Introductionmentioning

confidence: 99%

Coastal Altimetry Products in the Strait of Gibraltar

Gómez-Enri

Cipollini

Passaro³

et al. 2016

IEEE Trans. Geosci. Remote Sensing

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This paper analyzes the availability and accuracy of coastal altimetry sea level products in the Strait of Gibraltar. All possible repeats of two sections of the Envisat and AltiKa ground-tracks were used in the eastern and western portions of the Strait. For Envisat, along-track sea level anomalies (SLA) at 18-Hz posting rate were computed using ranges from two sources, the official Sensor Geophysical Data Records (SGDR) and the outputs of a coastal waveform retracker, the Adaptive Leading Edge Subwaveform (ALES) retracker; in addition, SLA at 1 Hz were obtained from the Centre for Topographic studies of the Ocean and Hydrosphere (CTOH). For AltiKa, along-track SLA at 40 Hz was also computed both from SGDR and ALES ranges. The Sea State Bias correction was recomputed for the ALES-retracked Envisat SLA. The quality of these altimeter products was validated using two tide gauges located on the southern coast of Spain. For Envisat, the availability of data close to the coast depends crucially on the strategy followed for data screening. Most of the rejected data were due to the radar instrument operating in a low-precision non-ocean mode. We observed an improvement of about 20% in the accuracy of the Envisat SLAs from ALES compared to the standard (SGDR) and the reprocessed CTOH data sets. AltiKa shows higher accuracy, with no significant differences between SGDR and ALES. The use of products from both missions allows longer times series, leading to a better understanding of the hydrodynamic processes in the study area.

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Annual sea level variability of the coastal ocean: The Baltic Sea‐North Sea transition zone

Cited by 56 publications

References 46 publications

Annual Sea Level Changes on the North American Northeast Coast: Influence of Local Winds and Barotropic Motions

Annual Sea Level Changes on the North American Northeast Coast: Influence of Local Winds and Barotropic Motions

Monitoring Sea Level in the Coastal Zone with Satellite Altimetry and Tide Gauges

Coastal Altimetry Products in the Strait of Gibraltar

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