Sea Surface Height Measurement Using a GNSS Wave Glider

To overcome spatial and temporal limitations of sea surface height instruments such as tide gauges, satellite altimetry, and Global Navigation Satellite Systems (GNSS) buoys, we investigate the use of an unmanned, self‐propelled Wave Glider surface vehicle equipped with a geodetic GNSS receiver. Centimetric precision instantaneous sea surface height measurement is demonstrated from a 13‐day deployment in the North Sea, during which the glider traversed a track of about 600 km. Ellipsoidal heights were estimated at 5 Hz using kinematic GNSS precise point positioning and, after correcting for tides using the Finite Element Solution 2014b model and for the geoid using the Earth Gravitational Model 2008, hourly dynamic ocean topography measurements agreed with those from the UK Met Office Forecasting Ocean Assimilation Model‐Atlantic Margin Model 7 to 6.1‐cm standard deviation. Conversely, on correcting for the tides and dynamic ocean topography, 5.1‐cm standard deviation agreement with Earth Gravitational Model 2008 at its North Sea spatial resolution was obtained. Hourly measurements of significant wave height agreed with the WAVEWATCH III model and WaveNet buoy observations to 17 and 24 cm (standard deviation), respectively, and dominant wave periods to 1.4 s. These precisions were obtained in winds gusting up to 20 m/s. Plain Language Summary High‐rate (subsecond), continuous sea surface height measurement is demonstrated using an unmanned, self‐propelled, surf‐board sized Wave Glider surface vehicle equipped with a Global Navigation Satellite Systems (GNSS) receiver and antenna. GNSS data postprocessing determined centimetric precision sea surface heights over a user‐defined, remotely piloted route of about 600 km in the North Sea over 13 days, measuring the waves and the variation in the sea surface from the geoid (the surface it would occupy due to Earth's gravity alone) caused by winds and currents, plus tides. Our portable, bespoke, in situ measurement method is applicable globally, subject to sufficient light for on‐board instrumentation solar power, 10‐m water depth, and GNSS signal tracking (outages attributed to waves breaking over the antenna arose when local winds became near gale force). The GNSS Wave Glider overcomes sea surface height measurement spatial resolution limitations of coastline‐based tide gauges, single location GNSS buoys and ships following fixed routes, and the temporal and spatial resolution limitations of radar measurements from satellites. Such sea surface height measurements are needed for studies on coastal erosion; for the transport of sediments, pollutants, and heat; for understanding coastal ecosystems and climate change; and for coastal structural design and navigation management

Roflumilast in moderate-to-severe chronic obstructive pulmonary disease treated with longacting bronchodilators: two randomised clinical trials

Background Patients with chronic obstructive pulmonary disease (COPD) have few options for treatment. The efficacy and safety of the phosphodiesterase-4 inhibitor roflumilast have been investigated in studies of patients with moderate-to-severe COPD, but not in those concomitantly treated with longacting inhaled bronchodilators. The effect of roflumilast on lung function in patients with COPD that is moderate to severe who are already being treated with salmeterol or tiotropium was investigated. Methods In two double-blind, multicentre studies done in an outpatient setting, after a 4-week run-in, patients older than 40 years with moderate-to-severe COPD were randomly assigned to oral roflumilast 500 mu g or placebo once a day for 24 weeks, in addition to salmeterol (M2-127 study) or tiotropium (M2-128 study). The primary endpoint was change in prebronchodilator forced expiratory volume in 1s (FEV(1)). Analysis was by intention to treat. The studies are registered with ClinicalTrials.gov, number NCT00313209 for M2-127, and NCT00424268 for M2-128. Findings In the salmeterol plus roflumilast trial, 466 patients were assigned to and treated with roflumilast and 467 with placebo; in the tiotropium plus roflumilast trial, 371 patients were assigned to and treated with roflumilast and 372 with placebo. Compared with placebo, roflumilast consistently improved mean prebronchodilator FEV(1) by 49 mL (p<0.0001) in patients treated with salmeterol, and 80 mL (p<0.0001) in those treated with tiotropium. Similar improvement in postbronchodilator FEV(1) was noted in both groups. Furthermore, roflumilast had beneficial effects on other lung function measurements and on selected patient-reported outcomes in both groups. Nausea, diarrhoea, weight loss, and, to a lesser extent, headache were more frequent in patients in the roflumilast groups. These adverse events were associated with increased patient withdrawal. Interpretation Roflumilast improves lung function in patients with COPD treated with salmeterol or tiotropium, and could become an important treatment for these patients

Global protected area expansion is compromised by projected land-use and parochialism

Peer reviewe

The King Edward Point Geodetic Observatory in Support of Sea Level Research

During February 2013 the King Edward Point (KEP) Geodetic Observatory was established in South Geor- gia, South Atlantic Ocean, through a University of Luxembourg funded research project and in collaboration with the United Kingdom’s National Oceanography Centre, British Antarctic Survey and Unavco, Inc. Due to its remote location in the South Atlantic Ocean, as well as, being one of few subaerial exposures of the Scotia plate, South Georgia Island has been a key location for a number of global monitoring networks, e.g. seismic, geomagnetic and oceanic. However, no geodetic monitoring station has been established, e.g. by the International Global Navigation Satellite System (GNSS) Service (IGS) community, despite the lack of such observations from this region. In this study we give details of the establishment of the KEP Geodetic Observatory, i.e. the installation of the continuous GNSS station KEPA on Brown Mountain and the estab- lishment of a new height datum for the tide gauge through a network of benchmarks at the KEP research station. We will present an evaluation of the GNSS positioning results for the period from February to August 2013 and of the survey/levelling work carried out for the height reference. We will discuss the installation in terms of its potential contributions to sea level observations using tide gauges and satellite altimetry, studies of tectonics, glacio-isostatic adjustment and atmospheric processes

A New Datum-Controlled Tide Gauge Record for Sea Level Studies in the South Atlantic Ocean: King Edward Point, South Georgia Island

In 2008 a new pressure tide gauge with Global Sea Level Observing System Number 187 was installed at King Edward Point (KEP), South Georgia Island, South Atlantic Ocean. This installation was carried out as part of the Antarctic Circumpolar Current Levels by Altimetry and Island Measurements (ACCLAIM) programme. In 2013 the KEP Geodetic Observatory was established in support of various scientific applications including the monitoring of vertical land movements at KEP. Currently, the observatory consists of two state-of-the-art Global Navigation Satellite System (GNSS) stations with local benchmark networks. In 2014 a tide board was added to the tide gauge, which, together with the measurements from the KEP Geodetic Observatory, now enables a calibration of the tide gauge. This will make it possible to include the KEP tide gauge in the Permanent Service for Mean Sea Level (PSMSL) database and make it available for future sea level studies. In this study, we will present the GNSS and levelling observations from the KEP Geodetic Observatory for the period from February 2013 to May 2015 used for the calibration of the tide gauge. While it is still too early to obtain accurate vertical land movement estimates from the GNSS data, the levelling campaigns in 2013 and 2014 indicated 7-9 mm of subsidence near the tide gauge. For the computation of the new height datum, geoid undulations derived from a seamless combination of the latest Gravity Observation Combination (GOCO) and Earth Gravitational Model (EGM) 2008 models were used. The use of this combined gravity model introduced a datum shift of approximately -24 cm compared to the previous datum

The King Edward Point Geodetic Observatory, South Georgia, South Atlantic Ocean: A First Evaluation and Potential Contributions to Geosciences

During February 2013 the King Edward Point (KEP) Geodetic Observatory was established in South Georgia, South Atlantic Ocean, through a University of Luxembourg funded research project and in collaboration with the United Kingdom National Oceanography Centre, British Antarctic Survey, and Unavco, Inc. Due to its remote location in the South Atlantic Ocean, as well as being one of few subaerial exposures of the Scotia tectonic plate, South Georgia Island has been a key location for a number of global monitoring networks, e.g. seismic, geomagnetic and oceanic. However, no permanent geodetic monitoring station has been established previously, despite the lack of observations from this region. In this study we will present an evaluation of the GNSS and meteorological observations from the KEP Geodetic Observatory for the period from 14 February to 31 December 2013. We calculate multipath and positioning statistics and compare these to those from IGS stations using equipment of the same type. The on-site meteorological data are compared to those from the nearby KEP meteorological station and the NCEP/NCAR reanalysis model, and the impact of these data sets on integrated water vapour estimates is evaluated. We discuss the installation in terms of its potential contributions to sea level observations using tide gauges and satellite altimetry, studies of tectonics, glacio-isostatic adjustment and atmospheric processes

Calibration of the Tide Gauge at King Edward Point, South Georgia Island, South Atlantic Ocean

In 2008 a new pressure tide gauge with Global Sea Level Observing System Number 187 was installed at King Edward Point (KEP), South Georgia Island, South Atlantic Ocean. This installation was carried out as part of the Antarctic Circumpolar Current Levels by Altimetry and Island Measurements (ACCLAIM) programme. In 2013 the KEP Geodetic Observatory was established in support of various scientific applications including the monitoring of vertical land movements at KEP. Currently, the observatory consists of two state-of-the-art Global Navigation Satellite System (GNSS) stations with local benchmark networks. This ties all benchmarks and the tide gauge into the International Terrestrial Reference Frame 2008, and allows the establishment of a local height datum in a global height system through the use of a global gravitational model. In 2014 a tide board was added to the tide gauge, which, together with the GNSS and levelling observations, now enables a calibration of the tide gauge. This will make it possible to include the KEP tide gauge in the Permanent Service for Mean Sea Level (PSMSL) database. In this study, we will present the results from the calibration of the tide gauge using the GNSS observations from the KEP Geodetic Observatory for the period from February 2013 to present, the levelling campaigns in 2013 and 2014, and geoid undulations derived from a seamless combination of the latest Gravity Observation Combination (GOCO) 05S and Earth Gravitational Model (EGM) 2008 models

Installation and First Evaluation of the King Edward Point Geodetic Observatory, South Georgia

During February 2013 the King Edward Point (KEP) Geodetic Observatory was established in South Georgia through a University of Luxembourg funded research project in collaboration with the National Oceanography Centre and the British Antarctic Survey. Due to its remote location in the South Atlantic Ocean as well as being one of few subaerial exposures of the Scotia plate, South Georgia has been a key location for a number of global monitoring networks, e.g. seismic, magnetic and oceanic. However, no geodetic monitoring station had been established previously despite the global network of Global Navigation Satellite System (GNSS) stations is lacking observations from this region. In this presentation we will present a first evaluation of the observations from the KEP Geodetic Observatory for the period from 14 February to 14 April 2013. We calculate multipath characteristics and positioning statistics from precise point positioning (PPP) and discuss the installation in terms of benefits for studies of tectonics and glacio-isostatic adjustment processes. The meteorological data is evaluated by comparison to the data from the existing KEP meteorological station and a widely used numerical weather model

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 world's 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