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Data processing procedures for SNOMS project 2007 to 2012. Version-1: 28 August 2012
Full text linkThe Swire NOC Monitoring System (SNOMS) has enabled the collection of a global set of surface hydrological and dissolved gas measurements from the MV Pacific Celebes. The data is being used to assess the rate of transfer of carbon dioxide between the atmosphere and the sea in different regions and to assess the forces that control this exchange. During the period from summer 2007 through to summer 2009 the ship crossed the North Atlantic, North Indian and Equatorial Pacific oceans with one voyage via the Cape of Good Hope. From 2009 until March 2012 repeat transects of the Pacific Ocean were made between Australia, New Zealand and North America. Its route has included areas of the World Ocean that are largely under sampled in terms of the carbonate system, the daily sampling of salinity, total alkalinity and dissolved inorganic carbon has provided valuable additional coverage to this data set. The system was a novel design developed to require a minimum of maintenance that was provided by the ship’s crew. This report describes the bespoke processes that were developed in the SNOMS project to assemble and check the quality of the data being returned. The purpose of this report is to provide a complete description of the processing used to move from the raw data collected on the ship to the final archived data set. This document forms part of the meta-data set produced by the SNOMS project, and will be available with the main data set when it is provided to users by BODC and CDIAC
Pride of Bilbao FerryBox 2005 - an overview of the data obtained and improvements in procedures
Full text linkThe collection of high quality, long term data from diverse environments is required if the interplay of the complex factors affecting phytoplankton bloom development is to be investigated. With this in mind the English Channel and Bay of Biscay between Portsmouth and Bilbao has been intensively monitored starting in 2002. In 2005 the ‘FerryBox’ suite of sensors measured temperature, salinity, fluorescence, oxygen and turbidity. The data are merged with position and can be viewed in real time at http://www.noc.soton.ac.uk/ops. The ferry travels between Portsmouth and Bilbao completing a round trip every 3 days; measurements in water pumped in from 5 metres depth provide data which are collected every second. In 2005 the ‘FerryBox’ methods were improved to reduce the affects of bio fouling on the sensors; the sensors were systematically cleaned weekly and sensor calibrations madefrom samples collected during monthly ferry crossings. These showed that the fluorescence and oxygen sensors were stable and a high quality dataset was produced. Calibration of the fluorescence sensor was monitored using extracted chlorophyll suspended in solid Perspex blocks. The ‘FerryBox’ dataset has been mapped against time and latitude to show the occurrence of phytoplankton blooms, using fluorescence, along with calculations of oxygen anomaly. Such continuous monitoring allows us to pinpoint the timings of phytoplankton bloom initiation and duration. The detailed data from the FerryBox allows the occurrence of these blooms to be correlated with other changes in the oceanic system, such as tidal energy, light and fresh water run off.The methods used to process the data from the initial raw 1Hz ASCII files through to the quality controlled 5 minute set are documented together with the post processing resolution of system faults that caused errors in the measured salinity. The quality controlled data are archived as 5 minuteaverages and are held by the British Oceanographic Data Centre (BODC)
Evaluation of the Aanderaa Oxygen Optode in continuous use in the NOC Portsmouth Bilbao FerryBox system 2005, 2006, with an assessment of the likely errors in the estimation of oxygen concentration anomalies
Full text linkAn Aanderaa Oxygen Optode has been used as part of the “FerryBox” system on the P&O Ferries vessel the MV Pride of Bilbao since the beginning of 2005. This report covers data collected through 2005 and 2006. The accuracy, precision and stability of the Optode have been compared with (1) measurements of oxygen in water samples collected and processed on board the ship by Winkler titration and (2) estimates of the oxygen anomaly. The comparison of the Winkler data with the output from the Optode suggests that the accuracy of the Optode in both years was close to 98% of the true value when compared to the Winkler measurements. The data suggest that the precision based on the comparison of the two data sets was equivalent to a standard deviation of 5 ?M or 2% of the average value in 2005 and 2.9 or 1% of the average value in 2006. The resolution of the recorded a data is better than 1 ?M. Two sources of error in measurement of temperature which are significant for the calculation of the oxygen anomaly have been identified. Temperatures measured using sensors in board the ship are higher than “true” temperatures. The error changes through the year as the difference in temperature between inside the ship and the external water temperature changes. This error may be as large as 0.5 °C. The anomaly has to be calculated using temperature measurement in the water flowing past the Optode. This is because of delays and mixing in the water being pumped into the ship have smoothing effect on the data, and can enhance the difference between the internal and external temperature to being as high as 1.0 °C. Consequently to avoid this large error due to the timing of the measurements the oxygen anomaly should be calculated from the temperature measured in the pumped water stream adjusted by an offset to the “true” outside temperature
First Annual Report on the SNOMS Project
Full text linkIn 2006 the Swire Group Charitable Trust funded the development and installation of a system to measure the partial pressure of carbon dioxide dissolved in the surface ocean from one of the Swire Group’s ships. The system was fitted on the MV Pacific Celebes in June 2007. The Celebes trades on a global route out of Singapore. It takes about 5 months to go round the world. Measurements are made of the partial pressure of carbon dioxide in seawater and air, also of water temperature, salinity, dissolved oxygen and nitrogen, air temperature, pressure and humidity. Data are collected automatically on the ship and then transmitted to shore where they are transferred to a public web page. The data are vital to enabling the prediction of change in the ocean’s ability to absorb carbon dioxide and hence the rate of climate change induced by anthropogenic release of carbon dioxide. Key observations to date are: (1) potentially high inputs of gasses into the ocean during sustained storm conditions, (2) a substantial natural flux of carbon dioxide into the atmosphere of the western equatorial Pacific under the ‘La Nina’ conditions of 2007, (3) the potential of the western North Atlantic to absorb more carbon dioxide in autumn than previously predicted
5 years of plankton monitoring in Southampton Water and the Solent including FerryBox, Dock Monitor and discrete sample data
Full text linkThe Environment Agency (EA) has to make a eutrophication status assessment of the Solent and its harbours every four years. This requires a review of the frequency and magnitude of phytoplankton blooms. To assist with this process SOC has prepared this report to provide a "meta-data base" describing the relevant data sets collected by SOC between 1999 and 2003. It provides details of :- (1) methods used to collect the data (2) errors associated with the methods (3) calibration and quality control procedures used (4) changes in procedures (5) references to technical reports and theses containing detailed descriptions of the methods used. Changes in concentrations of chlorophyll in relation to concentrations of nutrients at SOC study sites in Southampton Water are plotted in graphs. The occurrence of bloom events and processes of bloom limitation are described. In particular observations of the variation of chlorophyll concentrations made using the FerryBox route between Town Quay Southampton and Cowes Isle of Wight are described and the development of the systems and associated problems are detailed. The information is presented as (i) graphs of the whole data set at all locations against time for each year (ii) 3D maps of the variation in concentrations with location and time (iii) time series for single locations along the FerryBox track
A report on the Red Funnel FerryBox 2004 - an overview of the data obtained, improvements and calibration procedures
Full text linkThis report aims to provide a complete record of the work done as part of the ‘FerryBox’ activities on the Red Funnel Ltd ‘Red Falcon’ ferry in Southampton Water and the Solent in 2004. The procedures, hardware and software used are described and listed in detail. The results are summarised. Details are provided of the content and location of all of the data files produced, both observational data and data collected to calibrate the instruments. The collection of high quality, long term data in as many environments as possible is required to investigate the interplay of different factors affecting phytoplankton bloom development. With this in mind the Southampton Water and Solent estuarine system has been intensively monitored over the last 6 years using the FerryBox system. The ferry travels the length of the estuary up to 16 times a day. The ‘FerryBox’ suite of sensors measurestemperature, salinity, fluorescence and turbidity. These data are collected with at a frequency of 1Hz and are merged with position data, collected using a GPS system.In 2004 the FerryBox methods were improved to reduce the affects of bio fouling on the sensors. The sensors were systematically cleaned and the sensors calibrated during weekly ferry crossings. Calibrations of the turbidity and fluorescence sensors were monitored using materials suspended in solid Perspex blocks. The sensors were found to be stable and a high quality dataset was produced. Variations were seen in the ratio of fluorescence to chlorophyll throughout the estuary and with the time of year. Using the ‘FerryBox’ dataset the occurrence of phytoplankton blooms has been related to environmental factors such as light and to the tides. Such continuous monitoring allows us to pinpoint the timings of phytoplankton bloom initiation and duration. In 2004 a series of regular peaks influorescence occurred throughout the summer months. The detailed data from the FerryBox allows the occurrence of these blooms to be correlated with changes in the tidal energy of the system, light and fresh water run off
Measurement of dissolved oxygen using optodes in a FerryBox system
No full textOptode sensors can provide detailed information on concentrations of dissolved oxygen, which in turn may be used to quantify variations in net primary productivity. Throughout 2005 and 2006 the performance of commercially available oxygen optodes was examined, one in each year. The optode was part of an autonomous measurement system (FerryBox) on a ferry operating between Portsmouth (UK) and Bilbao (Spain). On crossings during which water samples were collected manually, the optode outputs were compared to measurements of dissolved oxygen made by Winkler titrations. The optodes maintained good stability with no evidence of instrumental drift during the course of a year. Over the observed concentration range (230–330 mM m?3) the optode data were approximately 2% low in both years. By fitting the optode data to the Winkler data the median difference between the optode and Winkler measurements is reduced to less than 1 mM m?3 (0.3%) in both years. The most appropriate calibration factor for 2005 was corrected O2 = Optode O2 × 1.018 and for 2006 the corresponding equation is corrected O2 = Optode O2 × 0.884 + 36.8. The standard deviation (95%) of the difference between the individual Winkler measurements was 5 mM m?3 and 3 mM m?3 in 2005 and 2006 respectively.Calculation of the oxygen saturation anomaly is required for calculation of the air sea exchange of oxygen and net biological production. This calculation requires the use of both salinity and temperature data. Salinity is measured to better than 0.1 so the corresponding error in anomaly is less than 0.2 mM m?3. Distortion of the temperature data is present due to warming of the water pumped to the optode. In winter this warming at the optode may be as great as 0.4 °C. The difference in the pumped water temperature can be corrected for by reference to other measurements of sea surface temperature reducing the error to less than 1 mM m?3.<br/
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