Environmental Reporting, Ministry for the Environment and Statistics New Zealand
Position Name
Analyst
Contact Info
Contact
Address
Address
Delivery Point
23 Kate Sheppard Place, PO Box 10362
City
Wellington 6143
Country
New Zealand
Electronic Mail Address
Environmental.Reporting@mfe.govt.nz
Role
Role Code
distributor
Date Stamp
Date
2016-10-23
Metadata Standard Name
ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata
Metadata Standard Version
1.1
Reference System Info
Reference System
Reference System Identifier
Identifier
Code
2193
Identification Info
Data Identification
Citation
Citation
Title
Number of extreme wave events exceeding 8m in coastal regions, 2008–15
Date
Abstract
Extreme wave indexes estimate the occurrence of extreme wave events in coastal and oceanic waters. Extreme wave indexes estimate the number of times a significant wave height exceeds one of three threshold values for at least 12 hours in 24 marine regions. The three wave-height thresholds are four metres, six metres, and eight metres. This indicator estimates the exceedances of a wave-height threshold for each year from 2008 to 2015 in coastal regions. Significant wave height is a measure of the ‘typical’ wave height in a place over a time period. It is four times the standard deviation of the water surface if, for example, you were to measure water moving up and down a jetty piling for an hour. The largest individual wave will typically have a height around twice the significant wave height. We use three wave-height thresholds because of the regional variation in extreme wave events. In general, the north experiences less exposure to consistently strong winds, and the waves generated by them, than the south. Four-metre tall waves are considered extreme in the northern-most parts of New Zealand but are more common in the south. For the southern-most parts of New Zealand, eight-metre waves better represent extreme wave events. This dataset relates to the number of extreme wave events exceeding the eight metre threshold in coastal regions.
Status
Progress Code
completed
Point Of Contact
Responsible Party
Organisation Name
Environmental Reporting, Ministry for the Environment and Statistics New Zealand
Method: We only include wave events where the relevant height threshold was exceeded for a minimum of 12 hours. This means that there was both a high tide (when overtopping and damage to coastal infrastructure, for example, is most likely) and a low tide during an event. We estimate extreme wave indexes for 24 regions around New Zealand, comprising 18 coastal and six oceanic regions. The 18 coastal regions cover the area from the shoreline to 100km from the coast and correspond to those used by the MetService for marine weather forecasts. The six oceanic regions cover New Zealand’s Exclusive Economic Zone. The indexes were generated using NIWA’s operational wave forecasting model (NZWAVE-12). This model has a 12km resolution and models wave heights using: - wind from NIWA’s NZLAM-12 weather forecast model - swell from NIWA’s global wave forecast model For more information on methodology, including limitations, please refer to Gorman (2016).
Metadata Constraints
Legal Constraints
Use Limitation
Creative Commons Attribution 3.0 New Zealand by Ministry for the Environment
Access Constraints
Restriction Code
license
Metadata Constraints
Legal Constraints
Use Limitation
Creative Commons Attribution 3.0 New Zealand by Ministry for the Environment
