South Pacific tropical cyclone


A South Pacific tropical cyclone is a non frontal, low pressure system that has developed, within an environment of warm sea surface temperatures and little vertical wind shear aloft in the South Pacific Ocean. Within the Southern Hemisphere there are officially three areas where tropical cyclones develop on a regular basis, these areas are the South-West Indian Ocean between Africa and 90°E, the Australian region between 90°E and 160°E and the South Pacific basin between 160°E and 120°W. The South Pacific basin between 160°E and 120°W is officially monitored by the Fiji Meteorological Service and New Zealand's MetService, while others like the Australian Bureau of Meteorology and the United States National Oceanic and Atmospheric Administration also monitor the basin. Each tropical cyclone year within this basin starts on July 1 and runs throughout the year, encompassing the tropical cyclone season which runs from November 1 and lasts until April 30 each season. Within the basin, most tropical cyclones have their origins within the South Pacific Convergence Zone or within the Northern Australian monsoon trough, both of which form an extensive area of cloudiness and are dominant features of the season. Within this region a tropical disturbance is classified as a tropical cyclone, when it has 10-minute sustained wind speeds of more than 65 km/h, that wrap halfway around the low level circulation centre, while a severe tropical cyclone is classified when the maximum 10-minute sustained wind speeds are greater than 120 km/h.

Basin history

The ancient mariners of the South Seas who roamed the tropical Pacific before the arrival of the Europeans, knew of and feared the hurricanes of the South Pacific. They were keen and accurate observers of nature with traditional myths and legends, reflecting their knowledge of these systems. On his voyages around the Pacific, it is thought that Captain James Cook did not collect any information about cyclones in the Pacific. The European whalers, traders and missionaries that followed Cook soon realised that the South Pacific was not free of hurricanes, and were the first to publish accounts about the systems. During 1853, Thomas Dobson subsequently became the first person to collect information about these systems, in order to attempt to understand and explain the characteristics of 24 tropical cyclones. However, these descriptions were vague and of little value, because he only had a small amount of data and no synoptic weather charts.
Over the next 40 years various reports, journals and log books on the storms were published, before E. Knipping consolidated these reports and extended Dobson's list out to 120 tropical cyclones during 1893. During the 1920s Stephen Sargent Visher did some research into tropical cyclones in the Pacific and visited several island nations; including Fiji, Japan and the Philippines to obtain information on potential systems. He also consulted various journals and reports as well as Dobson's and Knipping's work, before he authored a number of papers on tropical cyclones in the Pacific. These papers contained information about 259 tropical storms in the South Pacific between 160°E and 140°W, two of which occurred during 1789 and 1819, while the rest occurred between 1830 and 1923. Visher also tried to estimate how many systems were occurring on an annual basis in each area, but overcompensated for his incomplete records and came up with a figure of 12 severe tropical cyclones per year.
During Visher's time and until the start of World War Two, there was insufficient information available to allow for an accurate depiction of tropical cyclone tracks. However, in the buildup to and during World War Two, meteorological operations in the Pacific were greatly expanded, to meet the needs of international aviation and military operations. As a result, J W Hutchings decided to write a paper on 43 tropical cyclones between 1940 and 1951, using data that had been collected from the tropics by the New Zealand Meteorological Service in the area between the 150°E and 150°W. In the paper, systems were only included if they had a wind speed on the Beaufort scale of Force 9 or above, while located between the Equator and 30°S. Hutchings also examined where tropical cyclones originated from in the South Pacific and claimed that the place where most tropical cyclones develop could be accurately determined. The paper also drew attention to a marked difference in the tracks of South Pacific tropical cyclones and systems in other basins. This work was subsequently extended in 1956, by the then director of the New Zealand Meteorological Service: John Fletcher Gabites, to cover the seasons between 1952–53 and 1955–56. Gabites subsequently wrote a series of papers during 1963 on various aspects of South Pacific tropical cyclones including on the wide variety of tracks that occur over the Pacific.
During June 1995, the Fiji Meteorological Service's Nadi — Tropical Cyclone Centre, was designated as a Regional Specialized Meteorological Center by the World Meteorological Organization.

Seasons

1980s

During the 1980s there were three major Southern Oscillation episodes; two El Niño's when the Southern Oscillation Index was negative and one La Nina when the SOI was positive.
SeasonTotal
TD's		Total
TC's		Total
STC's		Strongest
storm		DeathsDamagesNotes and
References
1980–8112124Freda
1981–82665Gyan
1982–83141410Oscar
1983–84751Beti
1984–85995Hina
1985–86773Ima>150
1986–8713126Uma50
1987–88653Anne
1988–8914146Harry
1989–901152Ofa8
TotalsHina-

1990s

2000s

During the 2000s, activity was generally below the long term average, with 60 tropical cyclones developing out of 160 tropical disturbances and tropical depressions. However activity during the 2002–03, 2004–05 and 2009–10 seasons all experienced activity, near the long term average of about 8 - 9 tropical cyclones.
SeasonTotal
TD's		Total
TC's		Total
STC's		Strongest
storm		DeathsDamages
Retired namesNotes and
References
2000–011641Paula7Paula, Sose
2001–021652Waka1Trina, Waka
2002–0318107Zoe50Zoe, Ami, Beni, Cilla
2003–041532Heta16Heta, Ivy
2004–051895Percy2Meena, Nancy, Olaf, Percy
2005–061553Wati--
2006–071562Xavier4Cliff
2007–081643Daman8Daman, Funa, Gene
2008–091560Lin11-
2009–101585Ului12Mick, Oli, Pat, Tomas, Ului
Totals1596030Zoe--

2010s