The effect of ocean tides on the Earth's rotation as predicted by the results of an ocean tide model

1993 ◽  
Vol 20 (4) ◽  
pp. 293-296 ◽  
Author(s):  
Richard S. Gross
Keyword(s):  
Ocean Tide ◽  
Earth’S Rotation ◽  
Ocean Tides ◽  
Earth's Rotation ◽  
Ocean Tide Model ◽  
Tide Model

Impact of the stochastic model of the ocean tides on GRACE monthly gravity field solutions

2021 ◽  
Author(s):  
Natalia Panafidina ◽  
Rolf Koenig ◽  
Karl Neumayer ◽  
Christoph Dahle ◽  
Frank Flechtner
Keyword(s):  
Gravity Field ◽  
Spherical Harmonics ◽  
Research Unit ◽  
Ocean Tide ◽  
Model Errors ◽  
Ocean Tides ◽  
Tidal Waves ◽  
Ocean Tide Model ◽  
Tide Model ◽  
Grace Data

<p><span>I</span><span>n </span><span>GRACE data </span><span>processing</span><span> </span><span>t</span><span>he geophysical </span><span>background </span><span>models, which are needed to compute </span><span>the </span><span>monthly gravity field solutions, </span><span>usually </span><span>e</span><span>nter as</span><span> error-free. </span><span>This</span><span> </span><span>means that model errors could influence and distort the gravity field solution</span><span>.</span></p><p><span>The geophysical models </span><span>which influence the solution the most</span><span> a</span><span>re</span><span> the </span><span>atmosphere and ocean dealiasing product (AOD1B) and the ocean tide model. </span><span>In this presentation we focus on the </span><span>ocean tide model and on incorporati</span><span>ng</span><span> </span><span>its </span><span>stochastic information </span><span>in data processing</span><span>. </span></p><p><span>We use </span><span>the FES2014 ocean tide model presented as a spherical harmonic expansion till degree and order 180. The information about its uncertainties and the correlations between different spherical harmonics is provided by the research unit NEROGRAV (New Refined Observations of Climate Change from Spaceborne Gravity Missions). In a first step, the stochastic properties of the tide model are considered to be static and are expressed as variance-covariance matrices (VCM) of the spherical harmonics of the 8 main tidal waves till degree and order 30. The incorporation of this stochastic information is done by setting up the respective ocean tide harmonics as parameters to be solved for. Since ocean tides cannot be freely estimated within monthly GRACE solutions, the provided VCMs for the 8 tidal waves are used for constraining the tidal parameters.</span></p><p><span>T</span><span>his procedure was used to compute monthly gravity field solutions for the year 2007. For a comparison, we computed also monthly gravity fields without taking into account the stochastic information on ocean tides. In this contibution we present and discuss the first results of this comparison.</span></p>

scholarly journals Evaluation of global ocean tide models based on tidal gravity observations in China

2020 ◽  
Author(s):  
Hongbo Tan ◽  
Chongyong Shen ◽  
Guiju Wu
Keyword(s):  
High Precision ◽  
Earth Tide ◽  
Global Ocean ◽  
Ocean Tide ◽  
Ocean Tides ◽  
Ocean Tide Model ◽  
Tidal Forces ◽  
The Earth ◽  
Gravity Observation ◽  
Ocean Tide Models

<p>Solid Earth is affected by tidal cycles triggered by the gravity attraction of the celestial bodies. However, about 70% the Earth is covered with seawater which is also affected by the tidal forces. In the coastal areas, the ocean tide loading (OTL) can reach up to 10% of the earth tide, 90% for tilt, and 25% for strain (Farrell, 1972). Since 2007, a high-precision continuous gravity observation network in China has been established with 78 stations. The long-term high-precision tidal data of the network can be used to validate, verifying and even improve the ocean tide model (OTM).</p><p>In this paper, tidal parameters of each station were extracted using the harmonic analysis method after a careful editing of the data. 8 OTMs were used for calculating the OTL. The results show that the Root-Mean-Square of the tidal residuals (M<sub>0</sub>) vary between 0.078-1.77 μgal, and the average errors as function of the distance from the sea for near(0-60km), middle(60-1000km) and far(>1000km) stations are 0.76, 0.30 and 0.21 μgal. The total final gravity residuals (Tx) of the 8 major constituents (M<sub>2</sub>, S<sub>2</sub>, N<sub>2</sub>, K<sub>2</sub>, K<sub>1</sub>, O<sub>1</sub>, P<sub>1</sub>, Q<sub>1</sub>) for the best OTM has amplitude ranging from 0.14 to 3.45 μgal. The average efficiency for O<sub>1</sub> is 77.0%, while 73.1%, 59.6% and 62.6% for K<sub>1</sub>, M<sub>2</sub> and Tx. FES2014b provides the best corrections for O<sub>1</sub> at 12 stations, while SCHW provides the best for K<sub>1 </sub><sub>,</sub>M<sub>2</sub>and Tx at 12,8and 9 stations. For the 11 costal stations, there is not an obvious best OTM. The models of DTU10, EOT11a and TPXO8 look a litter better than FES2014b, HAMTIDE and SCHW. For the 17 middle distance stations, SCHW is the best OTM obviously. For the 7 far distance stations, FES2014b and SCHW model are the best models. But the correction efficiency is worse than the near and middle stations’.</p><p>The outcome is mixed: none of the recent OTMs performs the best for all tidal waves at all stations. Surprisingly, the Schwiderski’s model although is 40 years old with a coarse resolution of 1° x 1° is performing relative well with respect to the more recent OTM. Similar results are obtained in Southeast Asia (Francis and van Dam, 2014). It could be due to systematic errors in the surroundings seas affecting all the ocean tides models. It's difficult to detect, but invert the gravity attraction and loading effect to map the ocean tides in the vicinity of China would be one way.</p>

scholarly journals GPS estimates of ocean tide loading in NW-France: determination of ocean tide loading constituents and comparison with a recent ocean tide model

2008 ◽  
Vol 173 (2) ◽  
pp. 444-458 ◽  
Author(s):  
M. Vergnolle ◽  
M.-N. Bouin ◽  
L. Morel ◽  
F. Masson ◽  
S. Durand ◽  
...  
Keyword(s):  
Ocean Tide ◽  
Ocean Tide Loading ◽  
Ocean Tide Model ◽  
Tide Model
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