Sea Level in the British Isles: Combining Absolute Gravimetry and Continuous GPS to Infer Vertical Land Movements at Tide Gauges

Researchers investigating climate change have used historical tide-gauge measurements from all over the world to investigate the changes in sea-level that have occurred over the last century or so. However, such estimates are a combination of any true sea-level variations and any vertical movements of the land at the specific tide-gauge. For a tide- gauge record to be used to determine the climate related component of changes in sea-level, it is therefore necessary to correct for the vertical land movement component of the observed change in sea-level. In 1990, the Institute of Engineering Surveying and Space Geodesy and Proudman Oceanographic Laboratory started developing techniques based on the Global Positioning System (GPS) for measuring vertical land movements (VLM) at tide-gauges in the UK. This paper provides brief details of these early developments and shows how they led to the establishment of continuous GPS (CGPS) stations at a number of tide-gauges. The paper then goes on to discuss the use of absolute gravity (AG), as an independent technique for measuring VLM at tide-gauges. The most recent results, from CGPS time-series dating back to 1997 and AG time-series dating back to 1995/1996, are then used to demonstrate the complementarity of these two techniques and their potential for providing site-specific estimates of VLM at tide-gauges in the UK.

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State-of-the-art in studies of glacial isostatic adjustment for the British Isles: a literature review

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691016000074 ◽

2015 ◽

Vol 106 (3) ◽

pp. 145-170 ◽

Cited By ~ 3

Author(s):

Julia Stockamp ◽

Paul Bishop ◽

Zhenhong Li ◽

Elizabeth J Petrie ◽

Jim Hansom ◽

...

Keyword(s):

Literature Review ◽

Sea Level ◽

Glacial Isostatic Adjustment ◽

British Isles ◽

Data Types ◽

Geological Evidence ◽

Trend Surface ◽

Isostatic Adjustment ◽

Absolute Gravimetry ◽

Mantle Rheology

ABSTRACTUnderstanding the effects of glacial isostatic adjustment (GIA) of the British Isles is essential for the assessment of past and future sea-level trends. GIA has been extensively examined in the literature, employing different research methods and observational data types. Geological evidence from palaeo-shorelines and undisturbed sedimentary deposits has been used to reconstruct long-term relative sea-level change since the Last Glacial Maximum. This information derived from sea-level index points has been employed to inform empirical isobase models of the uplift in Scotland using trend surface and Gaussian trend surface analysis, as well as to calibrate more theory-driven GIA models that rely on Earth mantle rheology and ice sheet history. Furthermore, current short-term rates of GIA-induced crustal motion during the past few decades have been measured using different geodetic techniques, mainly continuous GPS (CGPS) and absolute gravimetry (AG). AG-measurements are generally employed to increase the accuracy of the CGPS estimates. Synthetic aperture radar interferometry (InSAR) looks promising as a relatively new technique to measure crustal uplift in the northern parts of Great Britain, where the GIA-induced vertical land deformation has its highest rate. This literature review provides an in-depth comparison and discussion of the development of these different research approaches.

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A review of the trends observed in British Isles mean sea level data measured by tide gauges

Geophysical Journal International ◽

10.1046/j.1365-246x.1999.00751.x ◽

1999 ◽

Vol 136 (3) ◽

pp. 651-670 ◽

Cited By ~ 107

Author(s):

P. L. Woodworth ◽

M. N. Tsimplis ◽

R. A. Flather ◽

I. Shennan

Keyword(s):

Sea Level ◽

British Isles ◽

Tide Gauges ◽

Mean Sea Level ◽

Level Data

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Observations of postglacial uplift at Churchill, Manitoba

Canadian Journal of Earth Sciences ◽

10.1139/e92-189 ◽

1992 ◽

Vol 29 (11) ◽

pp. 2418-2425 ◽

Cited By ~ 4

Author(s):

A. Mark Tushingham

Keyword(s):

Sea Level ◽

Tide Gauge ◽

Ice Sheet ◽

Laurentide Ice Sheet ◽

Glacial Isostatic Adjustment ◽

Tide Gauge Record ◽

Isostatic Adjustment ◽

Absolute Gravimetry ◽

The Earth ◽

Level Data

Churchill, Manitoba, is located near the centre of postglacial uplift caused by the Earth's recovery from the melting of the Laurentide Ice Sheet. The value of present-day uplift at Churchill has important implications in the study of postglacial uplift in that it can aid in constraining the thickness of the ice sheet and the rheology of the Earth. The tide-gauge record at Churchill since 1940 is examined, along with nearby Holocene relative sea-level data, geodetic measurements, and recent absolute gravimetry measurements, and a present-day rate of uplift of 8–9 mm/a is estimated. Glacial isostatic adjustment models yield similar estimates for the rate of uplift at Churchill. The effects of the tide-gauge record of the diversion of the Churchill River during the mid-1970's are discussed.

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Sea level variations in the Mediterranean Sea and Black Sea from satellite altimetry and tide gauges

Global and Planetary Change ◽

10.1016/s0921-8181(02)00106-6 ◽

2002 ◽

Vol 34 (1-2) ◽

pp. 59-86 ◽

Cited By ~ 67

Author(s):

A Cazenave

Keyword(s):

Mediterranean Sea ◽

Sea Level ◽

Black Sea ◽

Satellite Altimetry ◽

Tide Gauges ◽

Sea Level Variations ◽

The Mediterranean

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Testing an “IoT” Tide Gauge Network for Coastal Monitoring

IoT ◽

10.3390/iot2010002 ◽

2021 ◽

Vol 2 (1) ◽

pp. 17-32

Author(s):

Philip Knight ◽

Cai Bird ◽

Alex Sinclair ◽

Jonathan Higham ◽

Andy Plater

Keyword(s):

Sea Level ◽

Morphological Changes ◽

Tide Gauge ◽

Low Cost ◽

Pressure Sensors ◽

Wave Activity ◽

Tide Gauges ◽

Coastal Monitoring ◽

Level Data ◽

Operational Constraints

A low-cost “Internet of Things” (IoT) tide gauge network was developed to provide real-time and “delayed mode” sea-level data to support monitoring of spatial and temporal coastal morphological changes. It is based on the Arduino Sigfox MKR 1200 micro-controller platform with a Measurement Specialties pressure sensor (MS5837). Experiments at two sites colocated with established tide gauges show that these inexpensive pressure sensors can make accurate sea-level measurements. While these pressure sensors are capable of ~1 cm accuracy, as with other comparable gauges, the effect of significant wave activity can distort the overall sea-level measurements. Various off-the-shelf hardware and software configurations were tested to provide complementary data as part of a localized network and to overcome operational constraints, such as lack of suitable infrastructure for mounting the tide gauges and for exposed beach locations.

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Global mapping of seasonal variations in tides from tide gauge and satellite altimeter data

10.5194/egusphere-egu21-10717 ◽

2021 ◽

Author(s):

Inger Bij de Vaate ◽

Henrique Guarneri ◽

Cornelis Slobbe ◽

Martin Verlaan

Keyword(s):

Seasonal Variation ◽

Sea Level ◽

Seasonal Variations ◽

Large Scale ◽

Arctic Region ◽

The Arctic ◽

Altimeter Data ◽

Tide Gauges ◽

Tidal Constituents ◽

The Arctic Region

The existence of seasonal variations in major tides has been recognized since decades. Where Corkan (1934) was the first to describe the seasonal perturbation of the M2 tide, many others have studied seasonal variations in the main tidal constituents since. However, most of these studies are based on sea level observations from tide gauges and are often restricted to coastal and shelf regions. Hence, observed seasonal variations are typically dominated by local processes and the large-scale patterns cannot be clearly distinguished. Moreover, most tide models still perceive tides as annually constant and seasonal variation in tides is ignored in the correction process of satellite altimetry. This results in reduced accuracy of obtained sea level anomalies. To gain more insight in the large-scale seasonal variations in tides, we supplemented the clustered and sparsely distributed sea level observations from tide gauges by the wealth of data from satellite altimeters. Although altimeter-derived water levels are being widely used to obtain tidal constants, only few of these implementations consider seasonal variation in tides. For that reason, we have set out to explore the opportunities provided by altimeter data for deriving seasonal modulation of the main tidal constituents. Different methods were implemented and compared for the principal tidal constituents and a range of geographical domains, using data from a selection of satellite altimeters. Specific attention was paid to the Arctic region where seasonal variation in tides was expected to be significant as a result of the seasonal sea ice cycle, yet data availability is particularly limited. Our study demonstrates the potential of satellite altimetry for the quantification of seasonal modulation of tides and suggests the seasonal modulation to be considerable. Already for M2 we observed changes in tidal amplitude of the order of decimeters for the Arctic region, and centimeters for lower latitude regions.&#160;<div>Corkan, R. H. (1934). An annual perturbation in the range of tide. Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, 144(853), 537-559.</div>

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Recent sea level rise on Ireland's east coast based on multiple tide gauge analysis

10.5194/os-2020-81 ◽

2020 ◽

Author(s):

Amin Shoari Nejad ◽

Andrew C. Parnell ◽

Alice Greene ◽

Brian P. Kelleher ◽

Gerard McCarthy

Keyword(s):

Time Series ◽

Sea Level Rise ◽

Sea Level ◽

Continuous Time ◽

East Coast ◽

Tide Gauge ◽

Tide Gauges ◽

Missing Value ◽

Global Average ◽

Good Agreement

Abstract. We analysed multiple tide gauges from the east coast of Ireland over the period 1938–2018. We validated the different time series against each other and performed a missing value imputation exercise, which enabled us to produce a homogenised record. The recordings of all tide gauges were found to be in good agreement between 2003–2015, though this was markedly less so from 2016 to the present. We estimate the sea level rise in Dublin port for this period at 10 mm yr−1. The rate over the longer period of 1938–2015 was 1.67 mm yr−1 which is in good agreement with the global average. We found that the rate of sea level rise in the longer term record is cyclic with some extreme upward and downward trends. However, starting around 1980, Dublin has seen significantly higher rates that have been always positive since 1996, and this is mirrored in the surrounding gauges. Furthermore, our analysis indicates an increase in sea level variability since 1980. Both decadal rates and continuous time rates are calculated and provided with uncertainties in this paper.

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