The South Pacific Convergence Zone (SPCZ): A Review

Vincent, Dayton G.

doi:10.1175/1520-0493(1994)122<1949:tspcza>2.0.co;2

Cited by 291 publications

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“…The average MEI value determines which season is considered El Niño (MEI > 0.5), La Niña (MEI < À0.5), or ENSO neutral (À0.5 < MEI < 0.5). Based on this categorization El Niño years include 1982, 1986, 1987, 1991, 1992, 1994, 1997, 2002, 2004, and 2009, La Niña years include 1984, 1988, 1995, 1998, 1999, 2000, 2005, 2007, 2008, 2010, and ENSO neutral years include 1980, 1981, 1983, 1985, 1989, 1990, 1993, 1996, 2001, 2003 for a total of 10 El Niño years, 11 La Niña years, and 11 neutral years.…”

Section: Impact Of Enso On the Amplitude Of The Spcz Diurnal Cyclementioning

confidence: 99%

Diurnal cycle of the South Pacific Convergence Zone in 30 years of satellite images

Haffke

Magnúsdóttir

2015

JGR Atmospheres

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A data set of three-hourly South Pacific Convergence Zone (SPCZ) location and extent, from which IR temperature within the SPCZ may be obtained, for 1980-2012, November-April is used to examine the diurnal cycle of the SPCZ. Maximum SPCZ area occurs at 15:00-18:00 local standard time (LST). Two minima in mean IR temperature are evident, one at 13:00-16:00 LST, nearly coinciding with the maximum in area, and the second in the early morning hours at 05:00-07:00 LST, when area is at a minimum. The morning minimum in mean IR temperature is associated with a peak in deep convection while the afternoon minimum is associated with a peak in midlevel clouds. On average, the morning minimum in IR temperature dominates in the tropical regions of the SPCZ, while the afternoon IR temperature minimum dominates in the subtropical regions of the SPCZ. The relative strength of the two IR temperature minima is affected by the seasonal cycle, intraseasonal variability associated with active Madden Julian Oscillation events, and interannual variability due to the El Niño Southern Oscillation. The morning IR temperature minimum becomes more dominant when the SPCZ is more frequently present or when the SPCZ is shifted toward the equator. In terms of cloud height, midlevel clouds dominate at all times in all regions of the SPCZ and peak in abundance between 15:00-18:00 LST. Low-level clouds peak near midnight and then transition to high-level clouds, which peak between 03

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Section: Impact Of Enso On the Amplitude Of The Spcz Diurnal Cyclementioning

confidence: 99%

Diurnal cycle of the South Pacific Convergence Zone in 30 years of satellite images

Haffke

Magnúsdóttir

2015

JGR Atmospheres

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“…In austral summer (DJF), the SPCZ is very active, its eastern portion reaches the west-box, and P is high [see Vincent, 1994], decreasing SSS in the west-box (Figure 5b). The surface forcing is damped by the opposite effect of subsurface processes, which is more efficient as the surface freshening increases the vertical salinity gradient.…”

Section: Causes Of the High-salinity Core Formationmentioning

confidence: 99%

Formation and variability of the South Pacific Sea Surface Salinity maximum in recent decades

Hasson

Delcroix

Boutin

2013

J. Geophys. Res. Oceans

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International audienceThis study investigates causes for the formation and variability of the Sea Surface Salinity maximum (SSS > 36) centered near 18°S-124°W in the South Pacific Ocean over the 1990-2011 period at the seasonal time scale and above. We use two monthly gridded products of SSS based on in situ measurements, high-resolution along-track Voluntary Observing Ships thermo-salinograph data, new SMOS satellite data, and a validated ocean general circulation model with no direct SSS relaxation. All products reveal a seasonal cycle of the location of the 36-isohaline barycenter of about ±400 km in longitude in response to changes in the South Pacific Convergence Zone location and Easterly winds intensity. They also show a low frequency westward shift of the barycenter of 1400 km from the mid 1990s to the early 2010s that could not be linked to the El Nino Southern Oscillation phenomena. In the model, the processes maintaining the 22 year equilibrium of the high salinity in the mixed layer are the surface forcing (˜+0.73 pss/yr), the horizontal salinity advection (˜-0.37 pss/yr), and processes occurring at the mixed layer base (˜-0.35 pss/yr)

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“…1; see review by Vincent 1994). It is the only intertropical convergence zone (ITCZ) of the southern hemisphere present all year round, although it is best developed during austral summer.…”

Section: Introductionmentioning

confidence: 99%

“…It is the only intertropical convergence zone (ITCZ) of the southern hemisphere present all year round, although it is best developed during austral summer. It has been suggested that the summertime SPCZ consists of a zonal portion located over the western Pacific warm-pool region and a diagonal portion oriented along a northwest-southeast axis east of 170°E (Vincent 1994). The climatological characteristics of its eastern portion have been thought to rely on the interactions with higher latitude depressions (Kiladis et al 1989) and on the existence of a dry zone in the southeastern Pacific, controlled by the presence of the Andes (Takahashi and Battisti 2007).…”

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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The South Pacific Convergence Zone (SPCZ): A Review

Cited by 291 publications

References 0 publications

Diurnal cycle of the South Pacific Convergence Zone in 30 years of satellite images

Diurnal cycle of the South Pacific Convergence Zone in 30 years of satellite images

Formation and variability of the South Pacific Sea Surface Salinity maximum in recent decades

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

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