scholarly journals A 10-Year Comparison of Water Levels Measured with a Geodetic GPS Receiver versus a Conventional Tide Gauge

2017 ◽  
Vol 34 (2) ◽  
pp. 295-307 ◽  
Author(s):  
Kristine M. Larson ◽  
Richard D. Ray ◽  
Simon D. P. Williams
Keyword(s):  
Tide Gauge ◽  
Signal Propagation ◽  
Propagation Delay ◽  
Terrestrial Reference Frame ◽  
Water Levels ◽  
Sea Surface ◽  
Ocean Tide ◽  
Gps Receiver ◽  
Tide Gauge Data ◽  
Gauge Data

AbstractA standard geodetic GPS receiver and a conventional Aquatrak tide gauge, collocated at Friday Harbor, Washington, are used to assess the quality of 10 years of water levels estimated from GPS sea surface reflections. The GPS results are improved by accounting for (tidal) motion of the reflecting sea surface and for signal propagation delay by the troposphere. The RMS error of individual GPS water level estimates is about 12 cm. Lower water levels are measured slightly more accurately than higher water levels. Forming daily mean sea levels reduces the RMS difference with the tide gauge data to approximately 2 cm. For monthly means, the RMS difference is 1.3 cm. The GPS elevations, of course, can be automatically placed into a well-defined terrestrial reference frame. Ocean tide coefficients, determined from both the GPS and tide gauge data, are in good agreement, with absolute differences below 1 cm for all constituents save K1 and S1. The latter constituent is especially anomalous, probably owing to daily temperature-induced errors in the Aquatrak tide gauge.

scholarly journals The nodal dependence of long-period ocean tides in the Drake Passage

2018 ◽  
Author(s):  
Philip L. Woodworth ◽  
Angela Hibbert
Keyword(s):  
Tide Gauge ◽  
Drake Passage ◽  
Ocean Tide ◽  
Phase Lag ◽  
Tide Gauge Data ◽  
Long Period ◽  
The North ◽  
Ocean Tide Model ◽  
Gauge Data ◽  
Tidal Variability

Abstract. Almost three decades of bottom pressure recorder (BPR) measurements at the Drake Passage, and 31 years of hourly tide gauge data from Vernadsky station on the Antarctic Peninsula, have been used to investigate the temporal and spatial variations in this region of the three main long-period tides Mf, Mm and Mt (in order of decreasing amplitude, with periods of a fortnight, a month and third of a month respectively). The amplitudes of Mf and Mt, and the phase lags for all three constituents, vary over the nodal cycle (18.61 years) in essentially the same way as in the equilibrium tide, so confirming the validity of Doodson's nodal factors for these constituents. The amplitude of Mm is found to be essentially constant, and so inconsistent at the three-sigma level from the ±13 % (or ~ ±0.15 mbar) anticipated variation over the nodal cycle, which can probably be explained by energetic non-tidal variability in the records at monthly timescales and longer. The north-south differences in amplitude for all three constituents are consistent with those in a modern ocean tide model (FES2014), as are those in phase lag for Mf and Mt, while the difference for Mm is smaller than in the model. BPR measurements are shown to be superior to conventional tide gauge data in such tidal studies, thanks to the lower proportion of non-tidal variability in the records.

scholarly journals The nodal dependence of long-period ocean tides in the Drake Passage

Ocean Science ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 711-730 ◽  
Author(s):  
Philip L. Woodworth ◽  
Angela Hibbert
Keyword(s):  
Tide Gauge ◽  
Drake Passage ◽  
Ocean Tide ◽  
Phase Lag ◽  
Tide Gauge Data ◽  
Tide Gauge Records ◽  
Long Period ◽  
Ocean Tide Model ◽  
Gauge Data ◽  
Tidal Variability

Abstract. Almost three decades of bottom pressure recorder (BPR) measurements at the Drake Passage, and 31 years of hourly tide gauge data from the Vernadsky Research Base on the Antarctic Peninsula, have been used to investigate the temporal and spatial variations in this region of the three main long-period tides Mf, Mm and Mt (in order of decreasing amplitude, with periods of a fortnight, a month and one-third of a month, respectively). The amplitudes of Mf and Mt, and the phase lags for all three constituents, vary over the nodal cycle (18.61 years) in essentially the same way as in the equilibrium tide, so confirming the validity of Doodson's “nodal factors” for these constituents. The amplitude of Mm is found to be essentially constant, and so inconsistent at the 3σ level from the ±13 % (or ∼±0.15 mbar) anticipated variation over the nodal cycle, which can probably be explained by energetic non-tidal variability in the records at monthly timescales and longer. The north–south differences in amplitude for all three constituents are consistent with those in a modern ocean tide model (FES2014), as are those in phase lag for Mf and Mt, while the phase difference for Mm is smaller than in the model. BPR measurements are shown to be considerably superior to coastal tide gauge data in such studies, due to the larger proportion of non-tidal variability in the latter. However, correction of the tide gauge records for non-tidal variability results in the uncertainties in nodal parameters being reduced by a factor of 2 (for Mf at least) to a magnitude comparable (approximately twice) to those obtained from the BPR data.

scholarly journals Validation of recent altimeter missions at non-dedicated tide gauge stations in the Southeastern North Sea

2021 ◽  
Author(s):  
Saskia Esselborn ◽  
Julia Illigner ◽  
Tilo Schöne ◽  
Robert Weiß ◽  
Thomas Artz ◽  
...  
Keyword(s):  
North Sea ◽  
Tide Gauge ◽  
Sea Surface ◽  
Time Shift ◽  
Tide Gauges ◽  
Tide Gauge Data ◽  
Gauge Data ◽  
Sea Surface Heights ◽  
The Absolute ◽  
Rms Errors

<p>The absolute and relative accuracy of sea surface heights derived from six altimeter missions (Jason-1/2/3, Envisat, Saral, Sentinel-3A) is evaluated at five GNSS-controlled tide gauge stations in the German Bight (SE North Sea). The precision of the total water level envelope (TWLE) is assessed for the period 2000 to 2019 based on RMS errors and explained variances. The comparison is based on TWLE instead of dealiased sea level data since the tidal and barotropic dynamic is not known with sufficient accuracy in this area. The tide gauges are partly located at the open sea, partly at the coast close to mudflats. The tide gauge data is available every minute, the 20 Hz level 2 altimetry data is interpolated to virtual stations at distances between 2 and 15 km to the tide gauges. The altimeter data is based on standard retrackers, the correction models are adjusted to coastal applications and exclude the corrections for ocean tides and dynamic atmosphere to allow a direct comparison to the tide gauge data. To account for slight differences of the tidal dynamics between gauge and altimetry an optimal time shift and scale between each pair of locations is estimated and applied. This tidal correction improves the RMS errors by 15-75%. The explained variances are excellent at all stations (> 96%). The resultant RMS errors are mainly between 2-5 cm depending on location and mission. The RMS errors rise up to 10 cm where coastal dynamics play a dominant role or the altimeter approaches the land very closely (<7 km). The accuracy of the absolute biases is strongly dependent on the knowledge of the mean sea surface heights in the region.</p>

A New Methodology for Incorporating Tide Gauge Data in Sea Surface Topography Models

2007 ◽  
Vol 30 (4) ◽  
pp. 271-296 ◽  
Author(s):  
J. C. Iliffe ◽  
M. K. Ziebart ◽  
J. F. Turner
Keyword(s):  
Surface Topography ◽  
Tide Gauge ◽  
Sea Surface ◽  
Tide Gauge Data ◽  
Sea Surface Topography ◽  
Gauge Data
Sign in / Sign up

Export Citation Format

Share Document