On tropical cyclone activity in the Southern Hemisphere: Trends and the ENSO connection

Kuleshov, Yuriy; Qi, Lixin; Fawcett, Robert; Jones, David A.

doi:10.1029/2007gl032983

Cited by 167 publications

(171 citation statements)

References 15 publications

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“…Australia is no exception -ENSO is known to have significant impacts on the weather and climate, and consequently, many other aspects of Australia (e.g. Evans and Allan, 1992; and Trewin, 2006;Murphy and Timbal, 2008;Wang et al, 2008;Kuleshov et al, 2008;Sturman and Tapper, 2008). Studies have demonstrated that changes in the frequency of synoptic-scale circulations are associated with the SOI and other large-scale climate modes (e.g.…”

Section: Correlation Between Type Frequencies and Soimentioning

confidence: 99%

On two different objective procedures for classifying synoptic weather types over east Australia

Jiang

Cheung

Luo

et al. 2011

Intl Journal of Climatology

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Synoptic weather typing depends on the method and its implementation. This paper demonstrates the utility of a 2-phase batch self-organising map procedure (CP2) in comparison with a procedure (CP1) consisting of T-mode principal component analysis followed by convergent K-means clustering, for classifying the synoptic weather types over east Australia. Four classifications were obtained for the 52-year NCEP/NCAR dataset, one from CP1 and three from CP2. These classifications were examined in terms of grouping quality, mean type maps, type frequencies, lifetime and transitions, and in relation to the Southern Oscillation Index (SOI).The results showed that the classifications derived from different procedures are inter-confirmative and capture a similar set of major synoptic situations influencing east Australia, each having counterparts in previous studies and conforming well to local synoptic experience. In particular, this study demonstrates that CP2 is a promising tool for the purpose of weather typing with a two-fold utility: CP2 can perform data projection (neighbourhood width > = 1) and provide a flexible means for visualising the broad distribution of the daily weather patterns in the dataset; and the procedure can also conduct cluster analysis (neighbourhood width = 0) and produce results equivalent to those from CP1. It was found that performing data clustering or data projection may affect the inference associated with type frequencies. While focusing on methodology, the analysis has also shown that the frequency of synoptic weather types fluctuates on the seasonal, interannual, and decadal scales. From the 1970s to 1995 there was a decline in the occurrence of a few weather types associated with an east-coast trough extending over New South Wales from the north, and a slight increase in the activity of some anticyclonic types. Significant correlations were also identified between SOI and frequencies of synoptic weather types on the annual and seasonal timescales.

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Section: Correlation Between Type Frequencies and Soimentioning

confidence: 99%

On two different objective procedures for classifying synoptic weather types over east Australia

Jiang

Cheung

Luo

et al. 2011

Intl Journal of Climatology

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“…The interannual variability of the SPCZ location and TC activity in the Australian/western Pacific have been investigated mainly with respect to their relationship with El Niño Southern Oscillation (ENSO). It has been shown that El Niño (La Niña) events tend to occur accordingly with a north-eastward (south-westward) displacement of the SPCZ (Trenberth 1976;Folland et al 2002) and of a similar displacement of the TC genesis region in the south-western Pacific (Revell and Goulter 1986;Hastings 1990;Basher and Zheng 1995;Kuleshov et al 2008), while decreasing (increasing) TC activity near Australia (Nicholls 1985;Holland et al 1988;Evans and Allan 1992;Ramsay et al 2008). Although the SPCZ and the region of TC activity in the southwest Pacific are displaced in a similar fashion during ENSO events, the detailed mechanisms and the extent to which SPCZ controls the large scale environment favouring cyclonic activity have not yet been investigated.…”

Section: Introductionmentioning

confidence: 99%

Interannual variability of the South Pacific Convergence Zone and implications for tropical cyclone genesis

et al. 2009

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The interannual variability of the South Pacific Convergence Zone (SPCZ) and its influence on tropical cyclone (TC) genesis in the South Pacific are investigated using observations and ERA40 reanalysis over the 1979-2002 period. In austral summer, the SPCZ displays four typical structures at interannual timescales. The first three are characterized by a diagonal orientation of the SPCZ and account for 85% of the summer seasons. One is close to climatology and the other two exhibit a 3°northward or southward departure from the SPCZ climatological position. In contrast, the fourth one, that only encompasses three austral summer seasons (the extreme 1982/1983 and 1997/1998 El Niño events and the moderate 1991/1992 El Niño event), displays very peculiar behaviour where the SPCZ largely departs from its climatological position and is zonally oriented. Variability of the western/central Pacific equatorial sea surface temperature (SST) is shown to modulate moisture transport south of the equator, thereby strongly constraining the location of the SPCZ. The SPCZ location is also shown to strongly modulate the atmospheric circulation variability in the South Pacific with specific patterns for each class. However, independently of its wide year-to-year excursions, the SPCZ is always collocated with the zero relative vorticity at low levels while the maximum vorticity axis lies 6°to the south of the SPCZ position. This coherent atmospheric organisation in the SPCZ region is shown to constrain tropical cyclogenesis to occur preferentially within 10°south of the SPCZ location as this region combines all the large-scale atmospheric conditions that favour the breeding of TCs. This analysis also reveals that cyclogenesis in the central Pacific (in the vicinity of French Polynesia) only occurs when the SPCZ displays a zonal orientation while this observation was previously attributed to El Niño years in general. Different characteristics of El Niño Southern Oscillation (ENSO)-related Pacific equatorial warming are shown to impact differently on the SPCZ position, suggesting that for regional scales, such as the South Pacific, the SPCZ classification is more appropriate than a simple ENSO index to characterize TC interannual variability. These findings suggest that forecasting the strength of El Niño through SST variations in the eastern Pacific may not be sufficient to accurately predict cyclogenesis in the South Pacific, especially east of the dateline.

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“…While a number of studies [Emanuel, 2005;Kuleshov et al, 2008;Webster et al, 2005] suggest significant increases in extreme tropical cyclone activity since the 1970s, in terms of occurrence, intensity and lifetime, the significance of such trends has been disputed due to the heterogeneity of the available tropical cyclone data which may introduce artificial trends [Landsea, 2007], and the large interdecadal variability in tropical cyclone activity [Chan, 2006]. Pugh [1987] suggests that in tropical areas classical extreme value theory is unable to calculate return levels accurately due to the influence of few large events dominated by intense tropical cyclones.…”

Section: Introductionmentioning

confidence: 99%

Sea level extremes in the Caribbean Sea

Torres

Tsimplis

2014

JGR Oceans

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Sea level extremes in the Caribbean Sea are analyzed on the basis of hourly records from 13 tide gauges. The largest sea level extreme observed is 83 cm at Port Spain. The largest nontidal residual in the records is 76 cm, forced by a category 5 hurricane. Storm surges in the Caribbean are primarily caused by tropical storms and stationary cold fronts intruding the basin. However, the seasonal signal and mesoscale eddies also contribute to the creation of extremes. The five stations that have more than 20 years of data show significant trends in the extremes suggesting that flooding events are expected to become more frequent in the future. The observed trends in extremes are caused by mean sea level rise. There is no evidence of secular changes in the storm activity. Sea level return periods have also been estimated. In the south Colombian Basin, where large hurricane-induced surges are rare, stable estimates can be obtained with 30 years of data or more. For the north of the basin, where large hurricane-induced surges are more frequent, at least 40 years of data are required. This suggests that the present data set is not sufficiently long for robust estimates of return periods. ENSO variability correlates with the nontidal extremes, indicating a reduction of the storm activity during positive ENSO events. The period with the highest extremes is around October, when the various sea level contributors' maxima coincide.

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On tropical cyclone activity in the Southern Hemisphere: Trends and the ENSO connection

Cited by 167 publications

References 15 publications

On two different objective procedures for classifying synoptic weather types over east Australia

On two different objective procedures for classifying synoptic weather types over east Australia

Interannual variability of the South Pacific Convergence Zone and implications for tropical cyclone genesis

Sea level extremes in the Caribbean Sea

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