Island Climate Update 77 - February 2007

The Southwest Pacific climate in 2006
Stuart Burgess and Dr Jim Salinger, NIWA

Figure 1. The Southern Oscillation Index (SOI). (Click for enlargement)

Figure 2: Sea Surface temperature (SST) anomalies (departure from average,°C).(Click for enlargement)

Figure 3. Outgoing Long-wave Radiation (OLR) anomalies (departure from average).(Click for enlargement)

This year saw a change from a La Niña to an El Niño climate pattern in the Pacific. The first quarter of the year was dominated by weak La Niña-like (cold episode) characteristics, followed by a neutral period.

Climate developments in January 2007

Outgoing Long-wave Radiation anomalies for January 2007. (Click for enlargement and detail)

The South Pacific Convergence Zone (SPCZ) was located further north and east of its normal location in January, which is characteristic during an El Niño. Enhanced convection occurred extending from the region north of the Solomon Islands, southeast to Central French Polynesia, including Nauru, Tokelau, and the Northern Cook Islands. The Inter-Tropical Convergence Zone (ITCZ) continued to be more active than normal north of the Equator.

Tropical cyclones
Two named tropical cyclones occurred in the Southwest Pacific in January, being Zita from the 23rd-24th *, and Arthur from the 24th-26th. This brings the total to four so far this season, for the region east of 150°E.Tropical cyclone Zita’s estimated maximum sustained wind speeds reached 50 knots on the 23rd near the Austral Islands, with damage reported in some areas. Arthurs’s estimated maximum sustained wind speeds reached 65 knots on the 25th between the Southern Cook Islands and Central French Polynesia.