TITLE

The impact of the dynamic sea surface topography on the quasi-geoid in shallow coastal waters

AUTHOR(S)
Slobbe, D.; Klees, R.
PUB. DATE
March 2014
SOURCE
Journal of Geodesy;Mar2014, Vol. 88 Issue 3, p241
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
In this study, we examine the impact of instantaneous dynamic sea surface topography (DT) corrections to be applied to altimeter-derived sea surface slopes on the quasi-geoid in the shallow and coastal waters of the North Sea. In particular, we investigate the added value of DT corrections obtained from a shallow-water hydrodynamic model. These corrections comprise the contributions of ocean tides, wind- and pressure-driven (surge), and density-driven (baroclinic) water-level variations including the interactions between them. As a reference, we used tidal corrections derived from the global ocean tide model GOT4.7, surge corrections derived from the MOG2D model, and corrections for the time-averaged baroclinic contribution computed as differences between the DTU10 mean sea surface model and the EGG08 quasi-geoid. From a spectral analysis, we found that the baroclinic and surge parts of the DT mainly contribute to improvements in the signal-to-noise ratio (SNR) at longer wavelengths down to $$100{-}200~\hbox {km}$$ and that the improvements increase towards the southern North Sea. We also found that the shallow-water hydrodynamic model provides better tidal corrections compared to the GOT4.7 global ocean tide model, which are most pronounced in the southern North Sea and affect almost the entire spectrum. Very small differences (mostly below $${\pm } 2~\hbox {cm}$$ ) are observed between the quasi-geoid solutions obtained using the different sets of DT corrections. We showed that the variance component estimation provides too optimistic variance factors for the shipboard data set relative to the altimeter-derived quasi-geoid slopes. Hence, the limited impact of DT corrections is due to the fact that altimeter-derived quasi-geoid slopes hardly contribute to the estimated quasi-geoid if shipboard gravity data are included. When computing quasi-geoid solutions without shipboard gravity data, we found that less accurate or incomplete DT corrections may cause errors in the quasi-geoid with systematic spatial patterns. These systematic patterns disappear or are reduced significantly when using the DT corrections provided by the shallow-water hydrodynamic model. The main contributor to this improvement is the better tidal correction provided by the shallow-water hydrodynamic model compared to the GOT4.7 global ocean tide model. Seen the improvements of the global ocean tide models over the last two decades, we expect that in the near future global ocean tide models perform as well as dedicated regional models such as DCSM. Critical issue is, however, access to high-quality local bathymetric data.
ACCESSION #
94517002

 

Related Articles

  • An Improved Method of Retrieving Sea Surface Wind Speed Based on a Four-Layer Medium Model at High Sea States. Jiasheng Tian; Qiaoyun Liu; Wan Pan; Jian Shi // International Journal of Geosciences;Jan2014, Vol. 5 Issue 1, p85 

    Considering about the effect of whitecaps and foams on pulse-limited Radar Altimeters, an improved algorithm of retrieving sea surface wind speed is proposed in this paper. Firstly, a four-layer dielectric model is established in order to simulate an air-sea interface. Secondly, the microwave...

  • Airborne Rain-Rate Measurement with a Wide-Swath Radar Altimeter. Walsh, Edward J.; PopStefanija, Ivan; Matrosov, Sergey Y.; Zhang, Jian; Uhlhorn, Eric; Klotz, Brad // Journal of Atmospheric & Oceanic Technology;Apr2014, Vol. 31 Issue 4, p860 

    The NOAA Wide-Swath Radar Altimeter (WSRA) uses 80 narrow beams spread over ±30° in the cross-track direction to generate raster lines of sea surface topography at a 10-Hz rate from which sea surface directional wave spectra are produced. A ±14° subset of the backscattered power data...

  • On the approximation of the inverse error covariances of high‐resolution satellite altimetry data. Yaremchuk, Max; D'Addezio, Joseph M.; Panteleev, Gleb; Jacobs, Gregg // Quarterly Journal of the Royal Meteorological Society;Jul2018, Vol. 144 Issue 715, p1995 

    High‐resolution (swath) altimeter missions scheduled to monitor the ocean surface in the near future have observation‐error covariances (OECs) with slowly decaying off‐diagonal elements. This property presents a challenge for the majority of the data assimilation algorithms...

  • Remote sensing the sea surface CO2 of the Baltic Sea using the SOMLO methodology. Parard, G.; Charantonis, A. A.; Rutgerson, A. // Biogeosciences;2015, Vol. 12 Issue 11, p3369 

    Studies of coastal seas in Europe have noted the high variability of the CO2 system. This high variability, generated by the complex mechanisms driving the CO2 fluxes, complicates the accurate estimation of these mechanisms. This is particularly pronounced in the Baltic Sea, where the mechanisms...

  • Estimation of upward radiances and reflectances at the surface of the sea from above-surface measurements. Kleiv, Ø.; Folkestad, A.; Høkedal, J.; Sørensen, K.; Aas, E. // Ocean Science Discussions;2015, Vol. 12 Issue 3, p1051 

    During four field days in the years 2009-2011, 22 series of measurement were collected in the Inner Oslofjord. The data consist of recordings of spectral sub-surface and above-surface nadir radiances, as well as spectral downward irradiance in air. The studied wavelengths are 351, 400 nm and the...

  • Slope correction for ocean radar altimetry. Sandwell, David; Smith, Walter // Journal of Geodesy;Aug2014, Vol. 88 Issue 8, p765 

    We develop a slope correction model to improve the accuracy of mean sea surface topography models as well as marine gravity models. The correction is greatest above ocean trenches and large seamounts where the slope of the geoid exceeds 100 $$\upmu $$ rad. In extreme cases, the correction to the...

  • Wave height characteristics in the Mediterranean Sea by means of numerical modeling, satellite data, statistical and geometrical techniques. Galanis, George; Hayes, Dan; Zodiatis, George; Chu, Peter; Kuo, Yu-Heng; Kallos, George // Marine Geophysical Research;Mar2012, Vol. 33 Issue 1, p1 

    In this paper the main wave height characteristics in the Mediterranean Sea are studied from both observational and numerical perspectives. The numerical wave model WAM is employed on a high spatial resolution mode and in two different versions, one of which incorporates information for sea...

  • Sea surface height oscillation with quasi-four-month period along the continental slope in the northern South China Sea. Chow, Chun; Liu, Qinyu // Chinese Journal of Oceanology & Limnology;Mar2012, Vol. 30 Issue 2, p352 

    The sea surface height oscillation with a quasi-four-month period (SSHO4) along continental slope in the northern South China Sea (NSCS) is detected using satellite altimeter data and an ocean model simulation. The SSHO4 is at southwest of Dongsha Island, and is characterized by a wavelength of...

  • Surface Quasigeostrophic Solutions and Baroclinic Modes with Exponential Stratification. LaCasce, J. H. // Journal of Physical Oceanography;Apr2012, Vol. 42 Issue 4, p569 

    The author derives baroclinic modes and surface quasigeostrophic (SQG) solutions with exponential stratification and compares the results to those obtained with constant stratification. The SQG solutions with exponential stratification decay more rapidly in the vertical and have weaker...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics