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EARTH SCIENCE > OCEANS > TIDES > TIDAL HEIGHT

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  • Tides were measured using a portable pressure transducer secured just below low water line. A 22 hour record was obtained. A connection was made to the local Pageos benchmark by leveling and a 2 hour GPS observation. Additionally, the National Tidal Centre also has tidal data from Heard Island for 1948, 1980 and from 1986-1987. Documentation dated 2001-03-07 Heard Island Tide Gauge. A Platypus Engineering tide gauge was deployed in a heavy steel tetrahedral mooring in Atlas Cove in 1993. Two attempts have been made to recover the gauge without success. In March 1997 a temporary tide gauge was used to obtain a 22 hour record. A rock bolt was placed in the rock close to the deployment site and a connection was made to the Pageos Site by a 2 hour GPS observation. A level and staff was used to measure the height of the temporary gauge relative to the BM (AUS258). From these observations an approximate MSL can be found. Some further information about the data can be found in the download file.

  • Over time there have been a number of tide gauges deployed at Davis Station, Antarctica. The data download files contain further information about the gauges, but some of the information has been summarised here. Note that this metadata record only describes tide gauge data from 1993 to 2017. More recent data are described elsewhere. Tide Gauge 3 (TG003) This folder contains the following folders:- early_tg_files monthly_tg_files monthly download files from the submerged tide gauge at Davis deployed in March 1993. These files are ASCII hexadecimal files. They need to be converted to decimal. The resultant values are absolute seawater pressures in mbar. Remaining files are downloaded in normal format obtained directly from tide gauge. raw memory images from submerged tide gauge. file extension is memory bank number. These files are processed by a utility called tgxtract.exe which creates files in same format as those in old_tidedata folder. These file have extension .srt. They are then converted to decimal pressure values. output output file (.srt) which have been sent to BoM. Tide Gauge 6 (TG006) This folder contains the following folders:- raw memory images from submerged tide gauge. file extension is memory bank number. These files are processed by a utility called tgxtract.exe which creates files in same format as original download format. These file have extension .srt. These files are ASCII hexadecimal files. They need to be converted to decimal. The resultant values are absolute seawater pressures in mbar. output output file (.srt) which have been sent to BoM. Tide Gauge 12 (TG012) and Tide Gauge 12i (TG012i) Documentation notes from the older metadata records: Documentation dated 2001-03-07 Davis Submerged Tide Gauge The gauge used at Davis was designed in 1991/2 by Platypus Engineering, Hobart, Tasmania . It was intended to be submerged in about 7 metres of water in a purpose made concrete mooring in the shape of a truncated pyramid. The gauge measures pressure using a Paroscientific Digiquartz Pressure Transducer with a full scale pressure of 30 psi absolute. The accuracy of the transducer is 1 in 10,000 of full scale over the calibrated temperature. The overall accuracy of the system is better than +/- 3 mm for a known water density. Data is retrieved from the gauges by lowering a coil assembly on the end of a cable over a projecting knob on the top of the gauge and by use of an interface unit, a serial connection can be established to the gauge. Time setting and data retrieval can be then achieved. One of these of these gauges was deployed at Davis in early 1993 in a mooring in ???? bay. Data has been retrieved from these gauges irregularly since then. The records are complete since deployment except for a few days in late 1995. The loss was caused by a fault in the software which allows directory entries to overwrites data when the directory memory has been filled. Conversion of raw data to tidal records is done as detailed in document DATAFORMAT1.DOC . As the current gauge is expected to require a new battery soon, a new mooring has been placed close to the original. A new gauge is at Davis ready to be deployed as time permits. Levelling Levelling of the gauge at Davis was done by installing a temporary pressure type gauge in shallow water and recording sealevel for 10 days. The temporary gauge was precisely levelled to a permanent benchmark. The temporary gauge was then calibrated using a known height of seawater from the bay at the same temperature as the water in the bay. The density of the seawater was accurately measured. This work, in conjunction with the tidal records from the submerged gauge have enabled a MSL for Davis to be established. Permanent Tide Gauge. No suitable sites for an Aquatrak type gauge at Davis have been identified. Documentation dated 2008-10-17 There are two submerged tide gauges at Davis. One is soon to be removed to have its battery replaced. These gauges record pressure and temperature values. The download software only formats these records to produce 10 minute average presure values (hPa) and unscaled temperature values.

  • Over time there have been a number of tide gauges deployed at Mawson Station, Antarctica. The data download files contain further information about the gauges, but some of the information has been summarised here. Note that this metadata record only describes tide gauge data from 1992 to 2016. More recent data are described elsewhere. Tide Gauge 1 (TG001) 1992-03-05 - 1992-05-13 This folder contains monthly download files from the first deployment of a submerged tide gauge at Mawson in March 1992. These files are ASCII hexadecimal files. They need to be converted to decimal. The resultant values are absolute seawater pressures in mbar. Tide Gauge 4 (TG004) 1993-03-22 - 1999-12-29 This folder contains the following folders:- old_tidedata monthly download files from the second deployment of a submerged tide gauge at Mawson in March 1993. These files are ASCII hexadecimal files. They need to be converted to decimal. The resultant values are absolute seawater pressures in mbar. raw memory images from submerged tide gauge. file extension is memory bank number. These files are processed by a utility called tgxtract.exe which creates files in same format as those in old_tidedata folder. These file have extension .srt. They are then converted to decimal pressure values. interim files produced during processing of .raw files. output output file (.srt) which have been sent to BoM. Tide Gauge 13 (TG013) 2014-06-04 - 2016-11-04 Tide Gauge 20 (TG020) 1999-11-05 - 2009-12-21 This folder contains the following folders:- raw memory images from submerged tide gauge. file extension is memory bank number. These files are processed by a utility called tgxtract.exe which creates files in same format as original download format. These file have extension .srt. These files are ASCII hexadecimal files. They need to be converted to decimal. The resultant values are absolute seawater pressures in mbar. interim files produced during processing of .raw files. output output file (.srt) which have been sent to BoM. Tide Gauge 41 (TG041) 2008-03-02 - 2010-11-16 This folder contains the following folders:- raw memory images from submerged tide gauge. file extension is memory bank number. These files are processed by a utility called tgxtract.exe which creates files in same format as original download format. These file have extension .srt. These files are ASCII hexadecimal files. They need to be converted to decimal. The resultant values are absolute seawater pressures in mbar. interim files produced during processing of .raw files. output output file (.srt) which have been sent to BoM. Documentation from older metadata record: Documentation dated 2001-03-26 Mawson Submerged Tide Gauge The gauge used at Mawson was designed in 1991/2 by Platypus Engineering, Hobart, Tasmania. It was intended to be submerged in about 7 metres of water in a purpose made concrete mooring in the shape of a truncated pyramid. The gauge measures pressure using a Paroscientific Digiquartz Pressure Transducer with a full scale pressure of 30 psi absolute. The accuracy of the transducer is 1 in 10,000 of full scale over the calibrated temperature range. The overall accuracy of the system is better than +/- 3 mm for a known water density. Data is retrieved from the gauges by lowering a coil assembly on the end of a cable over a projecting knob on the top of the gauge and by use of an interface unit ,a serial connection can be established to the gauge. Time setting and data retrieval can be then achieved. The first of these gauges were first deployed Mawson in early 1992 in a a mooring in Horseshoe Harbour. The gauge was found to have some communications problems and was removed in May 1992. Tidal records from 6/3/92 to present have been retrieved from it. A new gauge was deployed at Mawson in March 1993. Data has been retrieved from these gauges irregularly since then. The records are complete since deployment except for a few days in late 1995. The loss was caused by a fault in the software which allows directory entries to overwrites data when the directory memory has been filled. The first gauge used at Mawson in 1992 was refitted with a higher pressure transducer and was later deployed at Heard Island in Atlas Cove. Conversion of raw data to tidal records is done as detailed in document DATAFORMAT1.DOC . As the current gauge is expected to require a new battery soon, a new mooring has been placed close to the original and a new gauge has been deployed. Levelling Several attempts have been made at precise levelling of the gauge. The first was in the Summer of 1995/6. Roger Handsworth, Tom Gordon and Natasha Adams physically measured the level of the top of the gauge in its mooring and derived a reading when a known column of water was over the gauge. The next attempt was in the Summer of 1996/7 when Roger Handsworth and Paul Delaney made timed water level measurements close to the gauge and the tide gauge benchmark. From this work, and from tidal records, a value for MSL for Mawson was derived. Permanent Gauge In the summer of 1995/6 two possible sites for a permanent Aquatrak type tide gauge were identified. As neither of these sites were approved, a survey in the Summer of 1996/7 identified two more suitable sites. One of these, the site at the base of East arm, near the Variometer Building, was approved and a bore hole was drilled to exit about 6 metres below MSL. A power cable was run from the variometer building to provide two phase 240V power to the site. A heated borehole liner containing an Aquatrak wave guide and a Druck pressure transducer was inserted into the bore hole. Two datalogger will be added to the installation in 2001 to complete the installation. A radio modem will be used to link the dataloggers to the AAD network. Documentation dated 2008-10-17 Mawson A new submerged gauge ,TG41, was deployed at Mawson on 2008-03-03. Submerged Tide gauge TG20 was removed on 2008-08-26. There is a useful overlap of data between the gauges of about 104 days. The dataloggers used in the shored based tide gauge installation have been replaced with Campbell Scientific CR1000 dataloggers. The aquatrak shore based gauge at Mawson has not been operating since march 2008. The shore base pressure gauge is still operating.

  • Tide gauge data collected from two platypus gauges (TG040 and TG041 - barometric) at Commonwealth Bay. Data were collected between 2007-11-27 and 2010-02-16. The gauge was a bottom mounted pressure sensor with a self-contained logger. Sea temperature and barometric pressure were also recorded. Further information is also available from the National Tidal Centre at the Bureau of Meteorology.

  • Tides were measured using a portable pressure transducer secured to fast ice at the mouth of Pagodroma Gorge with the transducer about 4 metres below low water line. A 30 day record was obtained. Documentation dated 2001-03-07 Beaver Lake and the Stillwell Hills In Dec 1996 - Jan 1997 a temporary pressure type tide gauge was deployed at Beaver Lake and the Stillwell Hills in open water. Timed water level measurements were made over this period. From these data a value for MSL was found for Beaver Lake and the Stillwell Hills.

  • Over time there have been a number of tide gauges deployed at Macquarie Island Station. The data download files contain further information about the gauges, but some of the information has been summarised here. Note that this metadata record only describes tide gauge data from 1993 to 2007. More recent data are described elsewhere. Macquarie Island used Aquatrak and Druck tide gauges during this period. Documentation from the older metadata record: Documentation dated 2001-06-12 The Macquarie Island Tide Gauge System The Macquarie Island Tide Gauge was first commissioned in November 1993. Since then every year attempts have been made to improve the performance of the system. The next improvement involves the installation of radio modems to effect a network link to the tide gauge dataloggers. Other improvements planned are include using the wave guide temperatures to correct the water heights for variations in the velocity of sound in air due to temperature gradients in the waveguide. The system consists of two separate sensors contained in separate housings on a rock shelf on the northern side of Garden Cove. One of the sensors is an Aquatrack acoustic type and the other is a Druck pressure transducer. Both housings contain a Platypus Engineering data logger and a battery. The housings consist each of an Admiralty Bronze ring bolted down to a concrete plinth and a glass fibre reinforced cover held down by a single central bolt and nut. Primary power for both installations comes from a solar panel array mounted on the northern side of the rock ridge behind the rock shelf. The solar panels are attached to an aluminium frame which is bolted to a galvanized steel frame cemented into holes in the rock face. The bolts are made of nylon with nylon washers so that the aluminium frame is not in contact with the galvanized frame. Mounted below the panels is a sealed plastic box with a hinged door. A multicore data cable runs from this box to the tide gauge housings. This cable is run inside a length of plastic conduit along with the power cable. The conduit is concealed in the vegetation and at the lower level is cemented into slots cut into the rock The batteries in the housing are kept charged by the solar panels but are isolated via power diodes, one in each housing. Either or both of the housing batteries or only the solar panel battery may be removed without interruption to data logging. The voltage of either housing battery may be found by interrogation of the appropriate data logger. Tide Gauge Bore Holes. Both gauges obtain access to the ocean via an inclined hole about 12 metres long inclined at approximately 34 and 39 degrees to the horizontal. Both holes are lined with a plastic pipe which is normally not removable. In the Aquatrack sensor hole a 50mm ABS pressure pipe runs down inside the liner and is fitted with a brass strainer and orifice at the lower end. This strainer protrudes into the ocean somewhat clear of the sea floor (see figure). Inside the 50mm pipe runs a 15mm diameter plastic pipe. The bottom end of this is fitted with a 600mm length of red brass tubing and stops about 100mm from the orifice at the bottom of the pipe. The 15mm pipe is held central in the 50mm pipe by three armed spiders placed about every metre down the pipe. The top end of both pipes is secured by a flange with two O rings and stainless steel screws. On top of the 15mm pipe is mounted the Aquatrack acoustic sensor the 15mm pipe acting as a waveguide for sound pulses from the sensor (see figure ). The Aquatrack sensor measures the distance of the water surface from a reference point on the sensor. About one metre down the wave guide is a small hole. This has two functions. One is to act as vent to allow water to rise and fall in the wave guide and the other is to provide an acoustic reflection at a known distance down the wave guide. This allows compensation for velocity of sound changes due to temperature changes. The Aquatrak wave guide has a series of thermistors placed along its length. The bottom one is always submerged and is used to measure the seawater temperature..The top one is placed just below the Sensor and the others evenly spaced along the length of the waveguide. The temperature readings from these can be used to compensate for the change in the velocity of sound due to density changes. This feature has not yet been used. The Druck Sensor has a single thermistor placed beside it which measures seawater temperature. System Components. The Aquatrak Installation houses four main components. 1. The Aquatrack Sensor and Waveguide Assembly. The sensor itself is in a waterproof plastic tube with a cable with a waterproof connector which plugs into the Bartek controller. 2. The Bartek Controller, housed in a waterproof diecast box with waterproof connectors. This lies in the centre of the installation housing. 3. The Platypus Engineering Datalogger 4. The Battery, a 15 Ah, 12 volt sealed gel cell lead acid battery. It is charged from the solar a diode. The battery lies in the main housing opposite the Datalogger . The Druck Installation houses four main components 1. The Druck Pressure Sensor, fitted to the end of a 13 metre cable, submerged in seawater about 10 metres down the borehole. The cable has five conductors and an air vent enclosed within it. 2. The Pressure Sensor Amplifier housed in a waterproof diecast box. This box has a vent leading to a vented bottle filled with silica gel to keep the transducer air vent dry. 3. A Datalogger As above. 4. A battery as above The Solar Panel Installation has three main parts. 1. Three Photo Voltaic Solar Panels, two 60 Watt and one 30 Watt. These are mounted on an aluminium frame attached to a hotdip galvanised steel frame with insulating bolts. 2. A sealed plastic box mounted below the panels containing a12V 24 Ah Battery and a regulator and the radio modem equipment. (The modems are not currently fitted.) 3. Antennae and cables protected with flexible conduit. Data Retrieval Data have been retrieved at approximately 30 day intervals from the Garden Cove gauges by using a portable computer to download the data loggers. The connector for this is in the enclosure by the solar panels allowing the loggers to be accessed during bad weather. Documentation dated 2008-10-17 1. In April 2007, the dataloggers and radio modems at Macquarie Island Tide Gauge site were replaced with Campbell Scientific CR1000 dataloggers. 2. This change enabled data to be streamed from the pressure sensor datalogger every 30 seconds. 3. There has been no change to scaling of records from the Aquatrak sensor as generation of ranges is done by the Aquatrak controller, the datalogger only saving and transmitting the records. Records from the pressure sensor however are now not converted to heights but saved and streamed as raw A/D conversion values. It is intended that appropriate scales and offsets for this sensor be derived after a Floating GPS Buoy exercise. 4. Data is streamed from the pressure sensor logger as this is the only sensor that can be supply 30 seconds average values. This logger also streams 3 minute average values. 5. The aquatrak sensor logger streams 3 minute average value ranges. 6. Data is streamed in NVP (name/Value Pair) format as defined by BoM. 7. Embedded in the streams are battery voltage and aquatrak waveguide temperature values.

  • Over time there have been a number of tide gauges deployed at Casey Station, Antarctica. The data download files contain further information about the gauges, but some of the information has been summarised here. Note that this metadata record only describes tide gauge data from 1996 to 2007. More recent data are described elsewhere. Old Tide Gauge 2 (TG002_Old) Oldtg02 is a download from the first gauge submerged deployed at Casey in 1992. This gauge was lost but later recovered standing upright in the mud. The gauge overwrote its memory and stopped. The record runs from 02/04/97 to 08/09/99. It is highly probable that the position of the gauge was stable during this period. There is data from the same period from gauge TG06. Tide Gauge 2 (TG002) These folders contain data downloaded from the redeployed gauge TG02. TG02 was redeployed in November 2003. The Record runs from 12/11/03 to 4/3/05. It is expected that data will be downloaded from this gauge for the next 4-5 years. This gauge was deployed after the previously deployed gauge ran out of battery energy. There is therefore a substantial gap in the record prior to 12/11/03. Tide Gauge 6 (TG006) Tg06 was deployed at Casey in March 1996. The battery became exhausted in June 2003. The gauge was replaced by TG02 in Novenber 2003. There is therefore a gap in the data between June and November 2003. Tide Gauges 33, 34 and 36 (TG033, TG034, TGA001, TG036) There are two wharf pressure sensors at Casey separated vertically by 2.007 m. There is also a barometer in the wharf hut. The files in this folder are from the old tide gauge data loggers. There are three loggers, TG33 records pressures from lower water pressure gauge as 30 second average values (absolute pressure mbar). It also records wharf tube water temperatures. This logger also streams 30sec average pressure. TG34 records pressures from upper water pressure gauge. This logger also streams 30sec average values as and 10minute average water pressure data. TGA01 (and later replaced by TG36) records air pressure as 10 minute average values in mbar. Further documentation from the old metadata records: Documentation dated 2001-03-07 Casey Submerged Tide Gauge The gauge used at Casey was designed in 1991/2 by Platypus Engineering, Hobart, Tasmania. It was intended to be submerged in about 7 metres of water in a purpose made concrete mooring in the shape of a truncated pyramid. The gauge measures pressure using a Paroscientific Digiquartz Pressure Transducer with a full scale pressure of 30 psi absolute. The accuracy of the transducer is 1 in 10,000 of full scale over the calibrated temperature. The overall accuracy of the system is better than +/- 3 mm for a known water density. Data is retrieved from the gauges by lowering a coil assembly on the end of a cable over a projecting knob on the top of the gauge and by use of an interface unit, a serial connection can be established to the gauge. Time setting and data retrieval can be then achieved. One of these of these gauges was deployed at Casey in early 1992 in a mooring in Geoffrey Bay. The mooring was apparently moved by sea ice and was later found, but the gauge is missing. A new mooring, one which was originally made for Harry Burton for use in one of the Vestfold Hills lakes, was taken by ship to Casey and was placed in Geoffrey Bay using a collection of 200 litre fuel drum to float the mooring into position. A new gauge was deployed in March 1996. The gauge was lowered into position with the holding grab wired closed to check that the device fitted in the mooring. The gauge became jammed so was left in situ with the grab preventing access to downloading. In April that year Roger Handsworth attached weights to the floating ropes of the grab to sink them out of the way of the freezing surface water. Divers located the mooring and gauge in late 1997 and 22 months of tidal records were retrieved. The gauge was restarted to clear the memory and allow another two years of data to be collected without any problems from a small software bug. Conversion of raw data to tidal records is done as detailed in document DATAFORMAT1.DOC . Levelling In December 1997 a set of water level observations were made by the station leader. These observations have been sent to National Tidal Facility, Flinders University, SA to derive a value for mean sea level. Documentation dated 2008-10-17 There is one submerged bottom mounted gauge at Casey. (TG02) The wharf based tide gauge installation at Casey has been upgraded with 2 Campbell Scientific CR1000 dataloggers. One logger (Main) receives signals from two wharf installed submerged Paroscientific Digiquartz pressure sensors and a barometer. The other logger (Backup) receives signals from only the two submerged sensors. Pressures are recorded in hPa, temperatures from the Digiquartz sensors in degrees C and temperatures from thermistors in the water column in unscaled A/D values. The two submerged pressure sensors are separated vertically by 2.007 metre. The backup logger streams 30 second average pressure values from both submerged sensors. The main datalogger records 3 pressure and 6 temperatures and controls the water heaters.

  • Tides were measured using a portable pressure transducer secured just below low water line. A 30 day record was obtained. Numerous manual water level measurements were made to connect the tide gauge to the local benchmark. From these observations a local mean sea level was obtained. Documentation dated 2001-03-07 Beaver Lake and the Stillwell Hills In Dec 1996 - Jan 1997 a temporary pressure type tide gauge was deployed at Beaver Lake and the Stillwell Hills in open water. Timed water level measurements were made over this period. From these data a value for MSL was found for Beaver Lake and the Stillwell Hills.

  • Geoscience Australia surveyors Bart Thomas and Ryan Ruddick travelled to Macquarie Island on the Australian Antarctic Division's voyage VMI in November/December 2016. Survey work for a number of Australian Antarctic projects was undertaken at the station on Macquarie Island. Project 4092 - Geoscience Australia geodetic and geophysical monitoring program: - Upgrade and modernise the GNSS equipment. - Undertake a local monitoring survey of the GNSS equipment. Project 5067 – Tide Gauges: - Validate tide gauge reference marks on station and at tide gauge. Project 5092 – Modernisation and Infrastructure: - Survey the pits and lights between the ANARESAT dome and the fire hydrant. - Spot heights along the isthmus. - Survey the corners of the spa and sauna building and Riometer. Project 4036 – Remediation of petroleum contaminants in the Antarctic and sub-Antarctic: - Provide heights on Piezo Tubes.

  • Tide gauge data collected from pressure tide gauge at Hurd Point, Macquarie Island. Data were collected between 1996-03-07 and 1996-10-27. A temporary tide gauge was installed at Hurd Point as it was suspected that there was a 6 minute wave around the island. The installation was made to determine whether this is correct. Photo Oblique aerial photos showing location of tide gauge, bench mark AUS188 and Hurd Point trig and photo mof GPS set up. Gravity meter set up adjacent tide gauge Temporary Bench Mark Survey Scans of survey field notes showing location of tide gauge in relation to Hurd Point huts, AUS188 and old Auroral Camera stand, vertical differences between AUS188, tide gauge temporary mark and tide gauge housing.