Changing mean sea level and tidal constants on the west coast of Australia

Long time-series of sea-level observations spanning 21 years (1966-86) from four ports on the west coast of Australia are analysed in yearly sets to study the secular trends and periodic changes in the tidal harmonic constituents. Mean sea level and five harmonic consistuents-Sa from low frequency band, O1 and K1 from the diurnal band, M2 and S2 from the semi-diurnal band-are investigated for secular trend and other variations that are not accounted for by conventional methods. Secular trends at Darwin, Wyndham and Geraldton are such that the amplitudes of M2 and S2 tides are decreasing and their phases are retarding. The changes observed at Fremantle are similar in magnitude but opposite in sign. In the diurnal band, variations in the phases of 01 and K1 are similar to those of the M2 and S2 tides. The observed trends of the diurnal and semidiurnal tides of Wyndham and Fremantle are well above standard error. Secular changes in the annual tide are not significant. In addition to the secular trends, these constituents are also modulated by terms which are not present in the tide-generating potential and they cannot be resolved from observations of less than 18.61 years. For example, in the spectrum of the equilibrium tide, there is no nodal term associated with the S2 constituent because it is of the solar origin, whereas in the observed tide two nodal terms appear as side bands. At some ports the amplitudes of the new nodal terms are large enough to modulate the principal tide by 2%. The mean sea level has been rising at the average rate of 1.73 mm year-1 over this period. It is modulated by a tidal signal of 18.61 years' cycle and non-tidal signals which are spatially consistent but aperiodic. A strong correlation between the residual component of the annual mean sea level and Southern Oscillation Index suggests that non-tidal long-period perturbations of mean sea level (MSL) are mainly due to El Nino-Southern Oscillation effects.

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Monthly Mean Sea-Level Variability Along the West Coast of North America

Journal of Physical Oceanography ◽

10.1175/1520-0485(1982)012<0757:mmslva>2.0.co;2 ◽

1982 ◽

Vol 12 (8) ◽

pp. 757-784 ◽

Cited By ~ 298

Author(s):

Dudley B. Chelton ◽

Russ E. Davis

Keyword(s):

North America ◽

Sea Level ◽

West Coast ◽

The West ◽

Sea Level Variability ◽

Mean Sea Level ◽

Mean Sea Level Variability

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Monthly mean sea level variability along the west coast of southern Africa

South African Journal of Marine Science ◽

10.2989/02577618409504368 ◽

1984 ◽

Vol 2 (1) ◽

pp. 195-203 ◽

Cited By ~ 30

Author(s):

G. B. Brundrit

Keyword(s):

Sea Level ◽

Southern Africa ◽

West Coast ◽

The West ◽

Sea Level Variability ◽

Mean Sea Level ◽

Mean Sea Level Variability

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Tide and mean sea level trend in the west coast of the Arabian Gulf from tide gauges and multi-missions satellite altimeter

Oceanologia ◽

10.1016/j.oceano.2019.05.003 ◽

2019 ◽

Vol 61 (4) ◽

pp. 401-411 ◽

Cited By ~ 3

Author(s):

Nada Abdulraheem Siddig ◽

Abdullah Mohammed Al-Subhi ◽

Mohammed Ali Alsaafani

Keyword(s):

Sea Level ◽

West Coast ◽

Arabian Gulf ◽

Tide Gauges ◽

The West ◽

Satellite Altimeter ◽

Mean Sea Level ◽

Sea Level Trend

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DYNAMIC OF SEA LEVEL ANOMALY OF INDONESIAN WATERS

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.29244/jitkt.v7i1.9943 ◽

2015 ◽

Vol 7 (1) ◽

Cited By ~ 2

Author(s):

Bisman Nababan ◽

Sri Hadianti ◽

Nyoman M.N. Natih

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Southern Oscillation ◽

Average Rate ◽

Seasonal Pattern ◽

Sea Level Anomaly ◽

Mean Sea Level ◽

Enso Events ◽

The Pacific ◽

Global Sea Level

A trend in sea level rise as a result of global warming could be a threat to small islands and coastal areas in Indonesia. The objective of this study was to determine the trend and variability of mean sea level anomaly (MSLA) in Indonesian waters during the 20 years of observation. The data used in this study were monthly MSLA data obtained from the AVISO website (ftp://ftp.aviso.oceanobs.com). Supporting data were the Southern Oscillation Index (SOI) (http://www.gom.gov.au/climate/enso), Dipole Indian Mode (DIM) index (http://gcmd.nasa.gov/records/GCMD_Indian_Ocean_Dipole.html), and the Pacific Decadal Oscillation (PDO) index (http://research.jisao.washington.edu/pdo/). Eigth stations of Indonesian waters were selected to study the variability of MSLA. In general, MSLA variabilities of Indonesian waters had a seasonal pattern, positively correlated with the SOI index, and negatively correlated with DIM and PDO indexes. The partial correlation of DIM was more dominant in west of Sumatra (r=-0.52) and south of Java (r=-0.44), PDO was more dominant in the northern waters of Papua (r=-0.37) and Makassar Strait (r=-0.33), and SOI was more dominant in northern Papua (r=0.52) and less toward the west of Indonesian waters. Overall, the MSLA variability of Indonesian waters can be explained by the variabilities of SOI, DIM, and PDO indexes with the lowest value in Natuna waters by 12% (R2=0.12) and the highest value in the northern waters of Papua by 54% (R2=0.54). Interannual variabilities were observed during ENSO events (SOI<-10) along with the maximum value of DIM index resulted in the lowest value of MSLA. Meanwhile, the highest value of MSLA was found during La Nina events (SOI>10) in conjunction with a minimum value of DIM and PDO indexes. The average rate of sea level rise in Indonesian waters was 5.84 mm/yr, almost two times higher than the average rate of global sea level rise (3.2 mm/yr). Keywords: mean sea level, anomaly, SOI, DIM, PDO, interannual, ENSO

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Coldspot of Decelerated Sea-Level Rise on the Pacific Coast of North America

Quaestiones Geographicae ◽

10.1515/quageo-2016-0024 ◽

2016 ◽

Vol 35 (3) ◽

pp. 31-37 ◽

Cited By ~ 7

Author(s):

Albert Parker

Keyword(s):

United States ◽

Sea Level Rise ◽

Sea Level ◽

San Francisco ◽

West Coast ◽

Average Rate ◽

The United States ◽

The West ◽

Sea Levels

Abstract We show here the presence of significant “coldspot” of sea level rise along the West Coast of the United States and Canada (including Alaska). The 30-years sea level for the area are mostly falling also at subsiding locations as San Francisco and Seattle where subsidence is responsible for a long term positive rate of rise. The 20 long term tide gauges of the area of length exceeding the 60-years length have a naïve average rate of rise −0.729 mm/year in the update 30-Apr-2015, down from −0.624 mm/year in the update 14-Feb-2014. Therefore, along the West Coast of the United States and Canada the sea levels are on average falling, and becoming more and more negative.

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VARIATION OF CHART DATUM TOWARDS MARITIME DELIMITATION DUE TO RISING SEA LEVEL

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-4-w5-73-2017 ◽

2017 ◽

Vol XLII-4/W5 ◽

pp. 73-80

Author(s):

A. R. M. Faizuddin ◽

M. M. Razali

Keyword(s):

Sea Level ◽

West Coast ◽

East Coast ◽

Linear Trend ◽

Peninsular Malaysia ◽

The West ◽

Mean Sea Level ◽

Base Points ◽

Rising Sea Level

The importance of Chart Datum in hydrographic surveying is inarguable because its determination is part of the process to obtain the actual depth of bathymetry. The Chart Datum has a relationship with the determination of base points because any uncertainty of the base points would definitely cause uncertainty to the determination of the maritime baseline. If there is any doubt on the baselines, it will then cause doubt on the maritime zones as well which includes the equidistant line that forms the border between the two countries. However, due to the ongoing rising sea level, there has been some variations of the Chart Datum in some areas in Malaysia. This research discusses about the variation of Mean Sea Level and Chart Datum for the tide gauge stations at Geting, Cendering, Sedili and Tioman at East Coast and Kukup, Langkawi, Lumut and Penang at the West Coast of Peninsular Malaysia. The tidal analysis was carried out by using the 23 years of data beginning at 1993 to 2015. The observed tidal data for 23 years were processed and analysed by using GeoTide software. In this research, the Harmonic Analysis technique was used in order to calculate the values of Mean Sea Level and the Chart Datum while the slope of the shoreline is modelled by using Global Mapper. The linear trend of the Mean Sea Level and the Chart Datum was analysed to determine the increase of the annual sea level in millimetres accuracy and also to determine the variation of the Chart Datum for each tidal station and its impact towards maritime baseline. The result has shown that the linear trend of sea level rise varies from 24 millimetres per year up to 168 millimetres per year at the East Coast and 24 millimetres per year up to 96 millimetres per year at the West Coast of Peninsular Malaysia. As for the maritime baseline, results has indicated that there exist shifting in the horizontal which are varies from 1.564 metres per year to 3.299 metres per year at the East Coast and from 1.331 metres per year up to 5.857 metres per year at the West Cost of Peninsular Malaysia. From the analysis, it can be stated that the horizontal shift occur greater at the East Coast rather than at the West Coast of Peninsular Malaysia. As a conclusion, the sea level rise does have significant impact towards maritime baseline. Furthermore, the determination of a stable Chart Datum is important to define the maritime baseline in other to avoid conflict with other neighbouring countries.

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DYNAMIC OF SEA LEVEL ANOMALY OF INDONESIAN WATERS

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.28930/jitkt.v7i1.9943 ◽

2015 ◽

Vol 7 (1) ◽

Author(s):

Bisman Nababan ◽

Sri Hadianti ◽

Nyoman M.N. Natih

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Southern Oscillation ◽

Average Rate ◽

Seasonal Pattern ◽

Sea Level Anomaly ◽

Mean Sea Level ◽

Enso Events ◽

The Pacific ◽

Global Sea Level

A trend in sea level rise as a result of global warming could be a threat to small islands and coastal areas in Indonesia. The objective of this study was to determine the trend and variability of mean sea level anomaly (MSLA) in Indonesian waters during the 20 years of observation. The data used in this study were monthly MSLA data obtained from the AVISO website (ftp://ftp.aviso.oceanobs.com). Supporting data were the Southern Oscillation Index (SOI) (http://www.gom.gov.au/climate/enso), Dipole Indian Mode (DIM) index (http://gcmd.nasa.gov/records/GCMD_Indian_Ocean_Dipole.html), and the Pacific Decadal Oscillation (PDO) index (http://research.jisao.washington.edu/pdo/). Eigth stations of Indonesian waters were selected to study the variability of MSLA. In general, MSLA variabilities of Indonesian waters had a seasonal pattern, positively correlated with the SOI index, and negatively correlated with DIM and PDO indexes. The partial correlation of DIM was more dominant in west of Sumatra (r=-0.52) and south of Java (r=-0.44), PDO was more dominant in the northern waters of Papua (r=-0.37) and Makassar Strait (r=-0.33), and SOI was more dominant in northern Papua (r=0.52) and less toward the west of Indonesian waters. Overall, the MSLA variability of Indonesian waters can be explained by the variabilities of SOI, DIM, and PDO indexes with the lowest value in Natuna waters by 12% (R2=0.12) and the highest value in the northern waters of Papua by 54% (R2=0.54). Interannual variabilities were observed during ENSO events (SOI<-10) along with the maximum value of DIM index resulted in the lowest value of MSLA. Meanwhile, the highest value of MSLA was found during La Nina events (SOI>10) in conjunction with a minimum value of DIM and PDO indexes. The average rate of sea level rise in Indonesian waters was 5.84 mm/yr, almost two times higher than the average rate of global sea level rise (3.2 mm/yr). Keywords: mean sea level, anomaly, SOI, DIM, PDO, interannual, ENSO

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SEA LEVEL FLUCTUATIONS OF THE LAST FIVE MILLENNIA RECORDED IN MACROTIDAL FLATS ALONG THE WEST COAST OF KOREA

10.1130/abs/2016am-282485 ◽

2016 ◽

Author(s):

Wook-Hyun Nahm ◽

Keyword(s):

Sea Level ◽

West Coast ◽

The West ◽

Sea Level Fluctuations ◽

West Coast Of Korea

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Mean Sea Level as a Reference for Geodetic Leveling

The Canadian Surveyor ◽

10.1139/tcs-1974-0095 ◽

1974 ◽

Vol 28 (5) ◽

pp. 524-530 ◽

Cited By ~ 3

Author(s):

G. W. Lennon

Keyword(s):

Sea Level ◽

World Ocean ◽

Equipotential Surface ◽

Scientific Discipline ◽

Mean Sea Level ◽

Sea Levels ◽

Coastal Sea ◽

Long Time ◽

Marine System

The use of mean sea level as a surface of reference that might provide an independent control for geodetic leveling has been a long term goal arising from the classical analogy between the geoid as an equipotential surface and the surface assumed by a hypothetical undisturbed world ocean. The problems associated with this aim are now known to be vast, and are associated with the dynamics of the marine system, notably its response to meteorological forces, to variations in density and to the effects of basic circulation patterns. In consequence the mean sea level surface varies rapidly in both time and space. This identifies in fact a distinctive scientific discipline, coastal geodesy, in which contributions are required by both geodesists and oceanographers. It has come to be recognized that the coastal zone is a hazardous environment for all observational techniques concerned. On the one hand, the difficulties of measurement of coastal sea levels have only recently been understood; on the other hand, precise leveling procedures are now known to be influenced by the attraction of marine tides and by crustal deformation of tidal loading. Much of the data available for study are therefore inadequate and, moreover, it should be noted that long-time series are required. It is now possible to lay plans for both geodetic and oceanographic procedures to remedy these deficiencies in the long-term interests of the study.

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