Jeffrey Pugh

New Data Systems and Products at the Permanent Service for Mean Sea Level

ABSTRACT Holgate, S.J.; Matthews, A.; Woodworth, P.L.; Rickards, L.J.; Tamisiea, M.E.; Bradshaw, E.; Foden, P.R.; Gordon, K.M.; Jevrejeva, S., and Pugh, J., 2013. New data systems and products at the Permanent Service for Mean Sea Level. Sea-level rise remains one of the most pressing societal concerns relating to climate change. A significant proportion of the global population, including many of the worlds large cities, are located close to the coast in potentially vulnerable regions such as river deltas. The Permanent Service for Mean Sea Level (PSMSL) continues to evolve and provide global coastal sea-level information and products that help to develop our understanding of sea-level and land motion processes. Its work aids a range of scientific research, not only in long-term change, but also in the measurement and understanding of higher frequency variability such as storm surges and tsunamis. The PSMSL has changed considerably over the past 10 years, and the aim of this paper is to update the community about these changes as well as provide an overview of our continuing work.

The Use of Ships of Opportunity for Irish Sea Based Oceanographic Measurements

Ships of opportunity such as scheduled ferry services offer the potential for cost effective oceanographic measurements to be undertaken with a high temporal resolution. This provides a convenient mechanism to measure near surface water properties as a series of transects along regularly scheduled routes. There are many potential applications for this kind of system which can effectively compliment more traditional approaches to marine based monitoring such as instrumented moorings, buoys, satellite image analysis and dedicated research cruises. Typical applications include environmental monitoring, scientific studies of coastal and shelf seas, and the provision of validation data for numeric modeling and assimilation purposes. One such system or FerryBox has been implemented by Proudman Oceanographic Laboratory (POL) aboard an Irish Sea passenger ferry servicing the Birkenhead to Dublin/Belfast, Ireland routes. This paper discusses the design, implementation and proposed future development of the FerryBox from an engineering based perspective. It is believed that this kind of approach represents a relatively new and novel contribution to marine based measurements and science that is progressively increasing in popularity.

Real time sea level data transmission from tide gauges for tsunami monitoring and long term sea level rise observations

The authors present the development and implementation of a ‘tsunami enabled’ tide gauge which allows real time data to be returned from almost anywhere on Earth. At its centre is a low power, embedded Linux platform, which performs the data logging and communications. This is attached to a radar and pressure sensors that are queried over a serial interface. Telemetry is through the Inmarsat Broadband Global Area Network (BGAN) system which allows a bi-directional broadband connection over Ethernet, permitting remote reconfiguration when required, and faster, more frequent tide gauge data. Data transmission is over an internet connection with files containing one minute values from three sensors returned every five minutes

Water Surface Height Determination with a GPS Wave Glider: A Demonstration in Loch Ness, Scotland

AbstractA geodetic GPS receiver has been installed on a Wave Glider, an unmanned water surface vehicle. Using kinematic precise point positioning (PPP) GPS, which operates globally without directly requiring reference stations, surface heights are measured with ~0.05-m precision. The GPS Wave Glider was tested in Loch Ness, Scotland, by measuring the gradient of the loch’s surface height. The experiment took place under mild weather, with virtually no wind setup along the loch and a wave field made mostly of ripples and wavelets. Under these conditions, the loch’s surface height gradient should be approximately equal to the geoid slope. The PPP surface height gradient and that of the Earth Gravitational Model 2008 geoid heights do indeed agree on average along the loch (0.03 m km−1). Also detected are 1) ~0.05-m-sized height changes due to daily water pumping for hydroelectricity generation and 2) high-frequency (0.25–0.5 Hz) oscillations caused by surface waves. The PPP heights compare favorably (~0.02-m...

A Study of Delays in Making Tide Gauge Data Available to Tsunami Warning Centers

Abstract This short note provides conclusions of a study of the various factors that determine the delay between tsunami arrival at a tide gauge station and data being made available at tsunami warning centers. The various delays involved include those associated with the tide gauge hardware and measurement methods and with the form of telemetry employed. It is shown that the most widely used form of telemetry in existing tsunami networks (meteorological satellite data collection platforms) can be improved upon significantly with the use of modern telemetry alternatives [notably Inmarsat’s Broadband Global Area Network (BGAN)], enabling faster, more frequent, more secure, and higher bandwidth transmissions of tide gauge data.

Sea level changes at Ascension Island in the last half century

An exercise in ‘data archaeology’ at Ascension Island has provided an estimate of sea level change between 1955 and 2001.5 (the mid-point of a recent dataset spanning 1993–2009). That average trend of 0.93 mm y−1 (SE 0.69) compares to a larger rate during 1993–2009 itself of 2.55 (SE 0.13) and 2.07 (SE 0.30) mm y−1 from tide gauge and altimeter data respectively, suggesting a recent acceleration in sea level rise. An ocean model and steric height datasets have been used for comparison to the measurements, with the conclusion that the acceleration was probably at least partly due to a steric height increase. This exercise is based on only one month of historical tide gauge data and is admittedly on the useful limit for long-term sea level studies. In addition, it is unfortunate that the tide gauge benchmark installed in 1955 has disappeared, even if one can estimate its height relative to modern marks. Nevertheless, the study does provide information of interest to climate studies, enables limits to be inferred on the real changes, and provides background information for other coastal studies. Most importantly, it is intended as a demonstration of the value of similar exercises where short historical records exist.