This data set measures the rise in annual mean sea level relative to land referenced to the latest Intergovernmental Panel on Climate Change (IPCC) 1995 to 2014 baseline period mean sea level at four longer-term sites between 1901 and 2020:
• Auckland
• Wellington
• Lyttelton
• Dunedin
and two additional sites with shorter time series:
• Moturiki, Mount Maunganui (1951 to 2020)
• New Plymouth (1920 to 2020).
Relative sea-level rise includes the vertical land movement of the surrounding area (for example, a sinking landmass increases the relative rise in sea level).
We report on linear trends for sea-level rise for the full period between 1901 and 2020 for the four longer-term sites. We also publish the linear trends for these sites for two time periods: 1901 to 1960 and 1961 to 2020. For Moturiki and New Plymouth, we publish linear trends for the 1961 to 2020 period only.
Variables:
site: The location of the tide gauge used to measure coastal sea level. Site refers to the name of nearest settlement. This dataset provides sea-level data for: (i) Auckland - Port of Auckland, Waitemata Harbour; (ii) Moturiki - Moturiki Island (Mount Maunganui); (iii) New Plymouth - Port Taranaki (New Plymouth); (iv) Wellington - Lambton Harbour (Wellington); (v) Lyttelton - Lyttelton inner harbour, and; (vi) Dunedin - Dunedin harbour basin (Otago Harbour)."
trend_start_year: The first year in the annual mean sea level time series that the trend relates to.
trend_end_year: The last year in the annual mean sea level time series that the trend relates to.
msl_trend: The estimated annual change in coastal sea level based on the trend assessment (in other words, the slope of the linear trend line). Trends were calculated using weighted linear regression models. The models used annual mean sea level data (relative the baseline) that was weighted to account for years that had less than 12 monthly average mean sea level values. Models also accounted for climatic conditions of temperature and pressure. Refer to the technical report that NIWA supplied alongside the data for more information https://environment.govt.nz/publications/update-to-2020-of-the-annual-mean-sea-level-series-and-trends-around-new-zealand/
standard_deviation: The standard deviations of the estimated annual mean sea level values based on the trend assessment.
units: The units of the estimated annual mean sea level values based on the trend assessment.
lat: Latitude.
long: Longitude
