List of all metadata reports |  This report's TOC |  Previous Page |  Next Page

Database Title	9.6 Ocean currents database
Keywords Type1. Type 11.	Ocean currents, New Zealand EEZ
Abstract	Ocean/geostrophic currents are semi-permanent meso-scale currents that fluctuate about a mean. In contrast wind currents change over days and tidal currents by the hour. This dataset addresses ocean currents and their fluctuations over weeks and months.
Geographical Coverage	Throughout NZ EEZ, especially the East Coast , North Island. Coverage is not continuous and there can be several measurements in one location at different depths.
Dataset start date.	Current meter data - 1970 Satellite altimetry data - 1992
Dataset end date.	Current
Status/currency.	In progress
Update frequency.	Unknown
Maintenance.	NIWA

 

Technical Evaluation
Parameters- what is measured	Method 1: Current speed and direction. Method 2: Height of the sea surface relative to another level. Salinity, temperature; depth.
Parameters- what is calculated	Mean ocean current speed and direction
Methods used to measure parameters	Current meters in water column. These are usually left recording in a given location for a few days to 2 years with the average being 1-2 months. Satellite altimetry. Every 10 days a satellite measures the relative height of the sea surface. This is used to determine the current speed and direction . This is ground truthed using salinity/temperature and depth data collected from a conductivity/temperature/depth instrument attached to a ship. Argo Floats (future method) sponsored by the USA National Science Foundation and Office of Naval Research, Argo will be a global network of 3,000 profiling floats, spaced about 300km apart. When deployed at the surface, each float will sink to a typical depth of 2,000m. After drifting with the ocean current at that depth for 10 days, it will rise to the surface, measuring the temperature and salinity of the layers through which it rises. On the surface, the float will transmit its data and position to an orbiting satellite before returning to depth and continuing another cycle. Floats will continue cycling throughout their design life of four to five years. Satellites will relay the float data to land-based receiving stations. ADP (acoustic doppler profiler). This is a downward sonar that measures the velocity of the water by reflecting off particles in the water. It provides a profile of water velocity through the water column to 200m.
Scale of use.	N/A
Number of records	450-460 records.
GIS compatibility.	Station locations are geographically referenced.
Available formats for users.	Published papers of interpreted results. Electronic database
Access constraints.	Database owned by NIWA. Data is not freely available.
Measurement Accuracy	To be completed by database manager.
Completeness of dataset	To be completed by database manager.
Positional accuracy	To be completed by database manager.
Database custodian	NIWA
Database custodian contact person	Malcolm Greig
Database custodian Contact Address Phone Fax Email	P.O.Box 14901 Kilbirnie Wellington +64 4 386 0339 +64 4 386 2153 m.greig@niwa.co.nz
References	Stanton, B. 1997. The East Auckland Current 1994-95. New Zealand Journal of Marine and Freshwater Research 31: 537-549. NIWA. 1998. Ocean circulation New Zealand.(maps of currents)
Date metadata record prepared.	June 2000
Author of metadata record.	Victoria Froude

 

Management Evaluation
Original purpose.	For studies of water mass including assessing how long it takes water to circulate the globe. Research on ocean warming.
Relationships with classification systems.	N/A
Relationships with other databases	Use temperature and salinity data
Known relationships with proposed EPIP indicators.	Not known.
Database uses?	Research purposes including research on ocean warming
Public awareness of the database	None
Database strengths.	Data is of known quality and accuracy as quality control measures are in place.
Database limitations.	Not public data. It is the property of NIWA and NIWA clients for whom the data was collected. This means that permissions to use the data are needed and there are retrieval costs before the data can be made available to other users.

 

What are the Current and Emerging Uses of the Database for:
Assisting with determining historic state/baseline.	Only where the data exists.
Assisting with determining current state/baseline.	Where there is data.
Assisting with modeling possible future outcomes.	Models of ocean currents
Risk assessment.	Can monitor changes in currents which can affect climate, fisheries etc. Models that combine tidal current, wind current and meso scale ocean currents can be used to help locate missing items(eg boats)
Monitoring site selection and sample design.	Possibly
Aggregating and reporting data locally, regionally or nationally.	N/A

A tidal current model allows the prediction of tide heights and currents. This can be done for historic, present and future. The model can be used for risk assessment for search and rescue and oil spill management purposes.