Search

The southwest Pacific (SWP) region is vulnerable to tropical cyclone (TC) related impacts which adversely affect people, infrastructure and economies across several nations and territories. Skilful TC outlooks are needed for this region, but the erratic nature of SWP TCs and the complex ocean–atmosphere interactions that influence TC behaviour on seasonal timescales presents significant challenges. Here, we present a new TC outlook tool for the SWP using multivariate Poisson regression with indices of multiple climate modes. This approach provides skilful, island-scale TC count outlooks from July (four months ahead of the official TC season start in November). Monthly island-scale TC frequency outlooks are generated between July and December, enabling continuous refinement of predicted TC counts before and during a TC season. Use of this approach in conjunction with other seasonal climate guidance (including dynamical models) has implications for preparations ahead of severe weather events, resilience and risk reduction. [ABSTRACT FROM AUTHOR]

The new South Pacific Enhanced Archive for Tropical Cyclones (SPEArTC) dataset provides an opportunity to develop a more complete climatology of tropical cyclones (TCs) in the southwest Pacific. Here, spatial patterns and characteristics of TCs for the 41-yr period beginning with the 1969/70 season are related to phases of the El Niño-Southern Oscillation (ENSO), taking into account the degree of ocean-atmosphere coupling. Twentieth-century reanalysis data and the coupled ENSO index (CEI) were used to investigate TC genesis areas and climate diagnostics in the extratropical transition (ETT) region at and south of 25°S during different CEI ENSO phases. This is the first study looking at CEI-based ENSO phases and the more detailed relationship of TCs to the coupling of the ocean and atmosphere during different ENSO phases. Consistent with previous findings, positive relationships exist among TCs, sea surface temperature, and atmospheric circulation. A statistically significant greater frequency of major TCs was found during the latter half of the study period (1991-2010) compared to the 1970-90 period, again consistent with the findings of other studies. Also found were significant and consistent linkages highlighting the interplay of TCs and sea surface temperature (SSTs) in the southwest Pacific basin west of 170°E and a closer connection to atmospheric circulation east of 170°E. Moreover, this study demonstrates subtle differences between a fully coupled El Niño or La Niña and atmospheric- or ocean-dominated phases, or neutral conditions. [ABSTRACT FROM AUTHOR]

The ecosystems and economies of small island nation states and territories of the tropical southwest Pacific region are widely agreed to be among the most vulnerable to climate variability and weather extremes anywhere in the world. Tropical Cyclones (TCs) are capable of exacerbating existing hazards and those made more severe by climate change (e.g. local sea level rise). In order to properly understand TC impacts in this region, a comprehensive database of TC tracks is required. This work has collated TC best track data from forecast centres around the globe with the aim of producing a unified global best TC track dataset for the historical period. Data from the International Best Tracks for Climate Stewardship (IBTrACS) project information for the southwest Pacific (135°E-120°W, 5°-25°S) is built upon and included in this effort. We document the construction of an enhanced TC database for the southwest Pacific, the quality controls needed to construct the database, and discuss how it has enhanced the chronology of region-wide historical TC activity in light of newly discovered data. We suggest this enhanced dataset can be used in forthcoming climate and weather studies to better characterize the climatology and behaviour of TCs in the southwest Pacific. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]