Set-up of Sydney Harbour by waves, wind and atmospheric pressure

1983 ◽  
Vol 34 (1) ◽  
pp. 97 ◽  
Author(s):  
RORY Thomson
Keyword(s):  
Water Level ◽  
Atmospheric Pressure ◽  
Tide Gauge ◽  
Confounding Factors ◽  
Average Depth ◽  
Tide Gauge Data ◽  
Sydney Harbour ◽  
Gauge Data ◽  
Set Up ◽  
The Waves

Nine years of hourly tide-gauge data from inside Sydney Harbour were detided and combined with wave- rider observations from outside, to test the effect of the waves on water level in the Harbour. Weather records were appended, to account for the confounding factors of wind and atmospheric pressure via a multiple regression analysis. The regression of water level on wave variance was found to be 2.88 cm m-2, in satisfactory agreement with the theoretical value of 3/4H, where H is the average depth of the Harbour entrance. Wind set up the Harbour most efficiently (0.48 cm perm s-1) when blowing toward 18� west of north. The regression of water level on atmospheric pressure was 0.74 cm mb-1, definitely less than 1.01 cm mb-1, the value of isostasy.

scholarly journals Tide prediction machines at the Liverpool Tidal Institute

2020 ◽  
Vol 11 (1) ◽  
pp. 15-29
Author(s):  
Philip L. Woodworth
Keyword(s):  
Tide Gauge ◽  
100Th Anniversary ◽  
Tide Gauge Data ◽  
Basic Principles ◽  
The World ◽  
Gauge Data ◽  
Set Up ◽  
The Uk ◽  
Made In

Abstract. The 100th anniversary of the Liverpool Tidal Institute (LTI) was celebrated during 2019. One aspect of tidal science for which the LTI acquired a worldwide reputation was the development and use of tide prediction machines (TPMs). The TPM was invented in the late 19th century, but most of them were made in the first half of the 20th century, up until the time that the advent of digital computers consigned them to museums. This paper describes the basic principles of a TPM, reviews how many were constructed around the world and discusses the method devised by Arthur Doodson at the LTI for the determination of harmonic tidal constants from tide gauge data. These constants were required in order to set up the TPMs for predicting the heights and times of the tides. Although only 3 of the 30-odd TPMs constructed were employed in operational tidal prediction at the LTI, Doodson was responsible for the design and oversight of the manufacture of several others. The paper demonstrates how the UK, and the LTI and Doodson in particular, played a central role in this area of tidal science.

scholarly journals Complex Extreme Sea Levels Prediction Analysis: Karachi Coast Case Study

Entropy ◽  
2020 ◽  
Vol 22 (5) ◽  
pp. 549
Author(s):  
Faisal Ahmed Khan ◽  
Tariq Masood Ali Khan ◽  
Ali Najah Ahmed ◽  
Haitham Abdulmohsin Afan ◽  
Mohsen Sherif ◽  
...  
Keyword(s):  
Water Level ◽  
Sea Level ◽  
Tide Gauge ◽  
Probability Method ◽  
Annual Maximum ◽  
Tide Gauge Data ◽  
Sea Levels ◽  
Extreme Sea Levels ◽  
Gauge Data ◽  
Pakistan Coast

In this study, the analysis of the extreme sea level was carried out by using 10 years (2007–2016) of hourly tide gauge data of Karachi port station along the Pakistan coast. Observations revealed that the magnitudes of the tides usually exceeded the storm surges at this station. The main observation for this duration and the subsequent analysis showed that in June 2007 a tropical Cyclone “Yemyin” hit the Pakistan coast. The joint probability method (JPM) and the annual maximum method (AMM) were used for statistical analysis to find out the return periods of different extreme sea levels. According to the achieved results, the AMM and JPM methods erre compatible with each other for the Karachi coast and remained well within the range of 95% confidence. For the JPM method, the highest astronomical tide (HAT) of the Karachi coast was considered as the threshold and the sea levels above it were considered extreme sea levels. The 10 annual observed sea level maxima, in the recent past, showed an increasing trend for extreme sea levels. In the study period, the increment rates of 3.6 mm/year and 2.1 mm/year were observed for mean sea level and extreme sea level, respectively, along the Karachi coast. Tidal analysis, for the Karachi tide gauge data, showed less dependency of the extreme sea levels on the non-tidal residuals. By applying the Merrifield criteria of mean annual maximum water level ratio, it was found that the Karachi coast was tidally dominated and the non-tidal residual contribution was just 10%. The examination of the highest water level event (13 June 2014) during the study period, further favored the tidal dominance as compared to the non-tidal component along the Karachi coast.

A RE-EXAMINATION AND RE-INTERPRETATION OF TIDE GAUGE DATA FOR CHURCHILL, MANITOBA

1966 ◽  
Vol 3 (1) ◽  
pp. 77-88 ◽  
Author(s):  
D.M. Barnett
Keyword(s):  
Statistical Analysis ◽  
Linear Regression ◽  
Water Level ◽  
Tide Gauge ◽  
Tide Gauge Data ◽  
Gauge Data

Tide gauge data from Churchill, Manitoba, for the period 1928–1939 are reviewed and rejected as inaccurate. The rate of uplift proposed by Gutenberg on the basis of these data therefore is rejected also. Data from 1940 to 1964 are subjected to statistical analysis, which indicates an apparent lowering trend of water level. Linear regression suggests a rate of 2 ft per century.

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.

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