Intertropical Convergence Zone Intertropical Convergence Zone The Intertropical Convergence Zone (ITCZ), known by sailors as the doldrums or the calms, is the area encircling Earth near the Equator, where the northeast and southeast trade winds converge. The ITCZ was originally identified from the 1920s to the 1940s as the "Intertropical Front" ("ITF"), but after the recognition in the 1940s and the 1950s of the significance of wind field convergence in tropical weather production, the term "ITCZ" was then applied. When it lies near the Equator, it is called the near-equatorial trough. Where the ITCZ is drawn into and merges with a monsoonal circulation,
1987–88 South Pacific cyclone season New Zealand Meteorological Service, while the United States Joint Typhoon Warning Center and Naval Pacific Meteorology and Oceanography Center also monitored the region. During December 1987, the South Pacific Convergence Zone started to intensify as upper level westerly winds appeared near the equator, with two depressions forming near Tuvalu towards the end of December as a result. Despite the low-level conditions being ideal for the development of a tropical cyclone at this stage, the surrounding upper-level conditions were unfavourable and the depressions dissipated while still in the low-latitudes. Tropical Cyclone 04P was monitored near Tuvalu, by the JTWC and the