Metadata Report for BODC Series Reference Number 981251

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Quality Report

No quality control has been performed on these scanned images.

Due to the age of the registers and charts, there was very little metadata available and several assumptions had to be made regarding the parameters applied. It was assumed that all times are in UTC, though there is nothing to indicate this. Very generic parameters were selected. All images have been assigned the very general sea level parameter of ASLVZZ01 (Surface elevation (unspecified datum) of the water body).

Where two measurements exist per day (e.g. measurements made at high water only), a sample interval of 45000 seconds (12.5 hours) has been assigned, though the actual time between successive high waters might be less than or greater than 12.5 hours (through modifications to the tidal signal, such as bathymetry or metrological forcing). Where there are four measurements a day (taken at both high and low water), a sample interval of 22500 seconds (6.25 hours) has been applied. For the continuous measurements, the sample interval could not be left null, so a value of 1 second was assigned.

Standard BODC parameters have been used, even though the scientific units mentioned in the parameters are metric, and most of the measurements in the scanned images are made in imperial units. Because it is possible to convert between imperial and metric units, no new parameter codes were created.

Where wind speed was given in units that appeared to be the Beaufort scale, then it was assumed that they had come from manual observations, and the parameter WMOCWFBF (Wind speed in the atmosphere by visual estimation and conversion to Beaufort scale) was selected.

Where wind speed was given in units that went above 12 (which would be a hurricane on the Beaufort scale, and unlikely to occur often) it was assumed that they were measurements taken by an instrument, and the parameter EWSBSS01 (Wind speed in the atmosphere by in-situ anemometer) was used.

For some of the registers, a Maximum hourly wind speed was listed. Upon consultation with archivists at the Met Office, who reported that Maximum hourly speed was '...the maximum mean wind speed recorded...during the 24 hours ending at 0900 GMT.', the parameter code ESSAMX01 (Wind speed hourly maximum in the atmosphere by in-situ anemometer) was applied. These registers also include a maximum gust speed which is '...the highest gust recorded during the 24 hours to 0900 GMT and the time is the time of the highest gust.' These have been assigned the parameter EGTSSS01 (Wind speed (gust) in the atmosphere by in-situ anemometer).

Where wind speed was measured on the Beaufort scale, it is assumed that the wind direction measurements were also visual measurements, and so the parameter WMOCDWXX (Wind from direction in the atmosphere by visual estimation and conversion to WMO code using table 0885/0877) was applied. Where wind speed has been assigned the parameter EWSBSS01, it was assumed that the wind direction was also measured by an instrument, and so the parameter EWDASS01 (Wind from direction in the atmosphere by in-situ anemometer) has been assigned.

Where visibility observations exist, using Beaufort letters, it was assumed that the readings were made manually, and so the parameter WMOCPWXX (Present weather in the atmosphere by visual estimation and conversion to WMO code using table 4677/4501) was applied, as conversions can be made between Beaufort weather notation and the WMO Codes.

Barometer measurements have been assigned the parameter code CAPHZZ01 (Pressure (measured variable) exerted by the atmosphere) which is using an unspecified method to make the measurements.

Some registers also include measurements of rainfall, for the previous 24 hours to 0900 GMT. These have been assigned the parameter CPRPRG01 (Thickness of precipitation amount (liquid water equivalent) in the atmosphere by in-situ rain gauge).

Some registers appear to contain measurements of air temperature, in degrees Fahrenheit. This is just an assumption, based on the range of these measurements and the changes that can be seen over the year. These measurements have been assigned the parameter CDTAZZ01 (Temperature of the atmosphere by thermometer).

Data Access Policy

Public domain data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

Data Processing Notes

Long term sea level records have a wide range of scientific and practical applications. They are important to climate change studies (to give an indication of sea level rise), operational oceanography (looking at storm surges and tides) and civil engineering (flood defences) amongst others.

The British Oceanographic Data Centre (BODC) was in possession of, or aware of, several large historic analogue sea level datasets which could be made available to the general community, but were in need of digitising and/or quality controlling before they could be added to the National Oceanographic Database.

BODC bid for funding from MEDIN, matched by BODC funds, and worked commenced on the rescue of the historical UK sea level data in September 2009.

BODC selected several long historic analogue records, which could extend back existing long records, and sent them to an external company, Digitise-it.com Ltd, for scanning. The company used a bookeye scanner to preserve the delicate records, and supplied 300x300dpi jpeg images, in colour or greyscale as appropriate.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

No Data Activity or Cruise Information held for the Series

Fixed Station Information

Fixed Station Information

Sheerness (Kent) Site History

History Summary

Instrument History

Benchmarks

ODN = Ordnance Datum Newlyn

Levelling

The benchmarks were incorporated into the Ordnance Survey levelling network in 1960. Benchmarks were reconfirmed in 1961, twice in 1963,1964, annually from 1977 onwards, and every 6 months between 1965 and 1976. No levelling was carried out in 1962.

The table below shows TGZ relative to ODN and the TGBM, calculated from an average of mean well soundings.

Heights have been adjusted by the data relative to ACD values, so that all data are now referred to Admiralty Chart Datum.

Datum information

Also see document 83375

Notes

• A tide staff was sited on Cornwallis jetty 610m from the recorder between 1960 and 1962. Tide staff zero (TSZ) was defined as Ordnance Datum Newlyn (ODN) minus 2.55m.
• The tide staff was resited directly below the Munro recorder in February 1963, with TSZ = ODN - 2.60m.
• In April 1963 the gauge was resited and a new tide staff was sited 22.5m from the recorder; TSZ = ODN - 2.57m.
• In June 1965 a new tide staff was installed 50.3m from the tide gauge, TSZ = ODN - 2.54m.
• On 9 September the lower part of the tide staff was carried away in a gale. A new tide staff was installed in December 1966, 22.9m from the recorder; TSZ = ODN - 2.59m.
• On 1 April 1968 the tide staff was reset to Admiralty Chart Datum (ACD) i.e. TSZ = ODN - 2.90m. In April 1972 the tide staff was removed to a temporary position 80m from the recorder; TSZ = ODN - 2.91m.
• On 27 September 1973 a new tide staff was installed 20m from the new Munro recorder; TSZ = ODN - 2.88m. The tide staff was resited 2m from the recorder after March 1974 TSZ = ODN - 2.88m.
• On 14 September 1977 the tide staff was disturbed; TSZ = ODN - 2.89m. On 7 September a new tide staff was installed in the same position as the previous one; TSZ = ODN - 2.90m.
• ACD (Sheerness) was quoted as ODN - 2.55m in 1931 and ODN - 2.60m between 1951 and 1964. At this time ACD was defined locally as 2.74m above the sill of the Great Basin. In 1964 there was a new connection and ACD became ODN - 2.59m; it was readjusted to ODN - 2.90m in 1968.

Corrected Timing Errors

The table below lists the notified time errors for which corrections have been made (if the time error is positive the clock was fast, and if negative the clock was slow).

1970 - Possible time error ending on 5 Nov.
1974 - Regular residual pattern and high low waters 22 Jun - 3 Jul. Timing looks ok - possibly silt.
1985 - Battery exhaustion causing many scan errors from 5 Apr onwards. Data suspect until 22 Apr.

Corrected Datum Errors

The table below lists the notified datum errors for which corrections have been made:

Data Quality Assessment

No quality control has been performed on the scanned tide gauge registers.

All digital data have been compared with the current Harmonic Constants library, and residuals checked. Records have been visually inspected for spikes, datum shifts and timing errors.

• ASLVZZ01 = Sea Level, Unspecified Method (metres)
• ASLVBG01 = Bubbler, Sea Level (metres)
• ASLVBG02 = Bubbler, Sea Level (metres)
• ASLVBH01 = Bubbler, Half Tide (metres)

Please Note: The Completeness index has been calculated for the primary channel only. Where there are multiple channels, the primary channel is ASLVBG02.

Problems

• General assessment of the data by TCSS suggests that the data between 1964 to 1973 (inclusive) are UNRELIABLE and should be treated with CAUTION .
• Early in the history of the gauge there were problems in electical transmission leading to many gaps in the data. During 1965 to 1967 the float wire caused problems overriding itself and producing inaccurate data values. Additionally the mean well soundings show a lot of variation, possibly due to siltation in the stilling well, hence the datums are probably only reliable to the nearest decimetre.

Data Quality Summary

Sheerness (Kent) Datum Information 1987-

Benchmark Relationships

• TGZ = Chart Datum = 2.90m below ODN
• TGZ = Chart Datum = 7.532m below TGBM
• TGZ = Chart Datum = 7.386m below Aux 1
• TGZ = Chart Datum = 6.239m below Aux 2

Glossary

• TGZ = Tide Gauge Zero
• TGBM = Tide Gauge Benchmark
• Aux = Auxiliary Benchmark
• ODN = Ordnance Datum Newlyn
• CD = Chart Datum

Related Fixed Station activities are detailed in Appendix 1

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Appendix 1: Sheerness

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.