Davis Tide Gauge Data 1993-2017

Brief description

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.

Lineage

Progress Code: completed

Statement: See the data download for more details. Each tide gauge typically encountered some problems throughout its life, resulting in data gaps, or poorer quality data. Apart from a gap of 4 days in Sept/Oct 1995 and in Sept 1998, the data set is complete since the time of deployment. These data have been through an extensive 'clean-up' to improve their quality as much as possible (see the document in the download file).

Notes

Purpose
Measurement of tides and determination of sea levels.