Backgrounder

Backgrounder

Pacific ENSO signal

The orange-yellow shading along the Equator, stretching west from Ecuador, is a typical ‘footprint’ of the El Niño phase of the El Niño–Southern Oscillation. The shading indicates that sea surface temperatures in the area are 1–2 °C or more above normal.

An unusual feature of the current situtation is the higher than normal sea surface temperatures around the Antarctic.

Mean sea surface temperature departures from normal.

Update on the SOI

The mean Southern Oscillation Index (SOI) for December was -1.3, with the three month average now -1.0. The present moderate El Niño is expected to last through summer, and is likely to be weaker than the 1997–98 event. Further general information on El Niño is available on the World Meteorological Organization web site, www.wmo.ch

The Southern Oscillation Index (SOI).

Online climate graphics

Climate maps and line plots of climate site observations are updated each week on the Climate Now website.

Climate data network

Instrument sites where a range of meteorological parameters are measured are often referred to as climate stations. In addition to rainfall and air temperature, many aspects of the climate that influence our lives are measured (different parameters are listed below). Most climate stations record only a selection of these parameters.

New Zealand’s climate network dates back to 1841 but records were sporadic until the 1860s. In 1867 there were 13 observatories reporting to Dr James Hector who, among other duties at The New Zealand Institute, was Director of Meteorological Stations and Officers in charge of stations in the various Provinces. Today there are more than 200 climate stations from Raoul Island to Scott Base. The National Climate Database also includes data from many islands in the South Pacific.

Since the late 1860s responsibility for meteorological observations has been under the control of seven different government departments, with the Royal New Zealand Air Force taking responsibility during World War 2. In 1992 MetService and NIWA were formed. Currently, observations are made by the former to assist with weather forecasting, and by the latter for climate research. MetService observations are archived in NIWA’s climate database along with those observations made by many private individuals and businesses, other crown research institutes, and government departments.

As well as the open stations, the database includes observations of several hundred now closed stations. These figures are used to identify climate variations and cyclical trends, such as the influence of the Southern Oscillation on New Zealand’s weather.

The likelihood of successful diversification of the agriculture and horticulture sectors into new livestock farming and crop production is increased with detailed knowledge of climate patterns.

Knowledge of patterns of rain, wind, and sunshine hours or solar radiation allow the development of renewable sources of energy like hydro-electricity, wind farms, and solar energy powered water heating.

List of meteorological parameters

  • Rainfall – total, intensity
  • Air temperature
  • Ground temperature
  • Soil temperature at 5, 10, 20, 30, 100 cm
  • Radiation
  • Wind – gusts, direction and speed
  • Sunshine hours
  • Evaporation
  • Relative humidity
  • Barometric pressure

Taranaki Falls, Whakapapa River, on the slopes of Mt Ruapehu. The climate of Tongariro National Park has a significant impact on North Island river flows. Photograph: Alan Porteous