Pacific sea level and geodetic monitoring

Delivering long-term sea level and land movement information for the Pacific

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About Pacific Sea Level and Geodetic Monitoring (PSLGM)

Measuring long-term sea level and land movement changes

This project records sea level, climate and geodetic data for the Pacific region. It has been operating since 1991.

Long-term sea level data is essential for understanding the impact of changing climate and sea levels.

The project generates, processes and analyses data from sites in 15 Pacific countries and territories.

Video: Highlights – Pacific sea level and geodetic monitoring

The Pacific Sea Level and Geodetic Monitoring, or PSLGM, is a network that provides vital sea level data for decision-making.

So the tide stations, they measure sea level to a high degree of accuracy. So we have a network throughout the Pacific of 14 tide stations, which form part of the Pacific Sea Level and Geodetic Monitoring Project (PSLGM), which operates under COSPPac.

For the decision-makers, it is very important to understand how much there is a sea level rise, or the sea level fall.

The information received from this tide gauge is a contribution towards reality that sea level rise is a concern. And by having this information at our fingertips, we can portray that across into regional, international forum that it is a concern. Especially with those islands that are barely above sea level.

PSLGM supports a range of critical services including: mapping maritime boundaries; supporting forecast services; supporting emergency response; informing scientific research.

So the Pacific network has been around for 30 years, they just celebrated the 30 year anniversary. The benefit of having good, accurate and consistent long term data is that scientists can be confident that they're using good quality data to provide information for the Pacific communities.

It started off with the sea level stations in early 1990s, where we were able to collect the sea level variations over the years.

And then in early 2000, we incorporated it with the land monitoring station, which is known as the Global Navigation Satellite System Continuous Operating Reference Station. So in short, it’s called GNSS CORS.

So land movement stations were installed within 5 kilometres of these tide stations. The idea being that vertical land movement was considered when assessing sea level.

Vertical land motion is important. It gives us an understanding of the absolute impact of sea level within that area.

To link the vertical land motion from the GNSS reference station to the sea level gauge, we work with our colleagues at SPC, who have surveyors who connect those different sensors.

The key value to Tonga has been the ability and the availability of information to allow Tonga to determine the impacts of sea level rise, the variability of sea level rise, and how that impacts on our coastal areas.

In terms of the recent eruption event here in Tonga, the new tidal gauge very much provided timely information, information that was able to be distributed. I think most important was analysis of how the event impacted on Tonga, particularly with the coastal areas, and the devastation that we suffered. We are using that information in the recovery period.

The scientific community were able to take data from our reference stations to determine the disturbances in the ionosphere that were caused by the volcanic eruption and subsequent tsunami. This research will help improve alerting of natural disasters in the Pacific region.

The PSLGM network also supports a range of daily forecasting products, including the Pacific Ocean portal and the Pacific Tides App.

So one of the most significant achievements over the last five years is building closer relationships with the National Met services in each country.

We developed an infrastructure maintenance program, which has helped to build the skills and capacity of local technicians. So it allows them to carry out their own maintenance on the infrastructure.

So the six monthly infrastructure maintenance program has helped build better relationships among technicians from the Bureau, SPC, GA and the local Met services.

We have common threats of sea level rise, common threats of environmental degradation. It makes very strong sense to share our resources, to be able to address these issues as a region.

Products and services

The project provides information about the processes, scale and implications of rising sea-levels.

We also use tide and sea level data to provide products and services for countries in the Pacific. For example, tide calendars and survey/location data to inform coastal infrastructure planning.

Information from the tide gauges and land monitoring stations are also used for:

  • tide predictions and warnings
  • long term climate trends
  • tsunami warnings
  • spatial information management
  • disaster risk reduction
  • coastal zone infrastructure management.

Sea level and geodetic monitoring network

The network of tide gauges and earth monitoring stations collect sea level, land movement and weather data.

The network spans 14 Pacific locations and forms one of the world’s most important ocean-monitoring networks. It provides crucial information for a range of industries across the Pacific Ocean, such as:

  • meteorological agencies
  • emergency services
  • shipping operators.

Thirteen of the participating countries host a permanent sea level monitoring station. These provide information on sea levels and tides. Palau does not have a permanent station, so tidal predictions for Palau are calculated from other sources.

The network also has earth monitoring stations on land to record geodetic observations. These record vertical land movements and provide other land-based measurements. These are implemented and maintained by Geoscience Australia.

Land surveying work is undertaken by the Pacific Community and partner country Lands and Survey departments. Sea level and land movement data are analysed together with land survey information. This makes the assessment of sea-level rise more precise.

Learn more about how Pacific communities manage and use the network:

Map of the Pacific region with the Australian continent and Indonesian archipelago on the left. The map shows gauges are located in the Federated States of Micronesia, Marshall Islands, Nauru, Kiribati, Papua New Guinea, Solomon Islands, Tuvalu, Vanuatu, Fiji, Samoa, Niue, Tonga and Cook Islands.
Enlarge image

Sea level monitoring tide gauges and geodetic earth monitoring stations are located in 13 Pacific countries

Tidal information and sea level data

Tide predictions

Many Pacific Island livelihoods rely on ocean and coastal activities that are affected by the highs and lows of daily tides. This includes tourism, fisheries and shipping.

We use data from tide gauges to generate monthly and annual tidal predictions.

You’ll find tide prediction calendars and tide tables for the Pacific on our current website – we’re still building this new one.

Tide predictions are included in annual tide calendars produced for 30 Pacific locations and distributed by the Pacific Community (SPC).

Video: Kiribati tide gauge

For most of the people in atoll island nations, they rely on fisheries resources. Going out to the ocean is part of their daily lives.

The information on sea level rise and as well as the tides information are very critical and useful for them in their planning, and their day to day work.

The tide gauge is measuring real time sea level, or tides.

And with the instruments, we're able to capture that to millimetre accuracy.

We managed to produce and share to the public the tide calendars that are useful for them in terms of going out fishing. They know when this will be the high tides and the low tide.

So civil engineering departments can be aware of what support structures that they need to build for future king tides.

Data from the tide gauges are also used in risk assessments for future development along the coast.

At the moment we've collected almost 30 years' worth of data, the GNSS, or the land movement data, and it's now becoming a baseline with the scientific community.

Going on through the next generation, it will allow the scientists in future COP events and other climate forums to feel confident that they're out actually using good scientific data and quality measured data.

Those sorts of information are also important when it comes to disaster risk reduction, because they now know in advance the dates they might expect the extreme spring tides, so they can prepare in advance to minimise the risks.

Kiribati is one site of a network of 14 tide gauges we have operating in the Pacific that are maintained by the Australian Bureau of Meteorology. And with partnerships with SPC and Geoscience Australia. Geoscience Australia assists with measuring the land movement.

And then we've got six monthly maintenance done by the in-country support from the Kiribati Met Service in this case.

The network of 14 sites, also then, apart from just being climate monitoring, is also a tsunami warning network for the Pacific area. That data goes back to the Pacific Warning Center. And that's where the warnings are then issued for a tsunami event.

In the case of the recent events in January, regarding the volcano eruption in Tonga, we were able to provide data to the scientific community around the world regarding that event from data that we captured at the tide station.

That ongoing data helps transportation to the community, and the Kiribati Met. authority provides that information to the local ports and other industries around.

The tide gauge is very crucial in looking at a much longer term impact due to climate change to atoll islands.

Real-time data

Our real-time data display shows sea level and weather information from the tide gauge network.

This includes:

  • sea level
  • air and water temperature
  • air pressure
  • wind direction
  • wind speed.

Real-time data is captured each minute and sent by satellite to the Bureau. It's available to all partner national meteorological services.

Pacific region sea level data, statistics and reports

The project provides quality controlled historical sea level data and meteorological statistics. These are available as hourly and monthly datasets.

We also produce monthly data reports for the Pacific region. These provide regional and historical context for the data, and a summary of:

  • the recent month’s observations
  • longer-term variations over the life of the project to date.

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