Coincident recruitment patterns of Southern Hemisphere fishes

2016 ◽  
Vol 73 (2) ◽  
pp. 270-278 ◽  
Author(s):  
Claudio Castillo-Jordán ◽  
Neil L. Klaer ◽  
Geoffrey N. Tuck ◽  
Stewart D. Frusher ◽  
Luis A. Cubillos ◽  
...  
Keyword(s):  
South Africa ◽  
New Zealand ◽  
Southern Hemisphere ◽  
Southern Oscillation ◽  
Global Climate ◽  
Southern Annular Mode ◽  
Fish Stock ◽  
Climate Indices ◽  
Dynamic Factor ◽  
Recruitment Patterns

Three dominant recruitment patterns were identified across 30 stocks from Australia, New Zealand, Chile, South Africa, and the Falkland Islands using data from 1980 to 2010. Cluster and dynamic factor analysis provided similar groupings. Stocks exhibited a detectable degree of synchrony among species, in particular the hakes and lings from Australia, New Zealand, Chile, and South Africa. We tested three climate indices, the Interdecadal Pacific Oscillation (IPO), Southern Annular Mode (SAM), and Southern Oscillation Index (SOI), to explore their relationship with fish stock recruitment patterns. The time series of IPO and SOI showed the strongest correlation with New Zealand hoki (blue grenadier, Macruronus novaezelandiae) and Australian jackass morwong (Nemadactylus macropterus) (r = 0.50 and r = –0.50), and SAM was positively related to Australian Macquarie Island Patagonian toothfish (Dissostichus eleginoides) (r = 0.49). Potential linkages in recruitment patterns at sub-basin, basin, and multibasin scales and regional and global climate indices do account for some of the variation, playing an important role for several key Southern Hemisphere species.

scholarly journals Improved Detection of Interannual Cloud Variability over the Southern Hemisphere Using Legacy Satellites

2020 ◽  
Vol 33 (19) ◽  
pp. 8225-8236
Author(s):  
Shay Liu ◽  
Paul W. Staten ◽  
Brian H. Kahn
Keyword(s):  
Brightness Temperature ◽  
Southern Hemisphere ◽  
Southern Oscillation ◽  
Global Climate ◽  
Southern Annular Mode ◽  
South Pacific Convergence Zone ◽  
Jet Streams ◽  
High Cloud ◽  
Modes Of Variability ◽  
Cloud Properties

AbstractShifts in deep tropical convection and midlatitude jet streams both manifest themselves in high cloud anomalies. Such anomalies may play a significant role in local to global climate processes. This work investigates how high cloud properties covary with two primary interannual modes of variability in the Southern Hemisphere (SH): El Niño–Southern Oscillation (ENSO) and the southern annular mode (SAM). In contrast to several recent studies that utilize the latest remote sensing datasets (e.g., CloudSat), we employ a novel combination of imager and sounder data from legacy satellite instruments. Using these legacy data, we confirm the poleward shift of high cloud fields in the SH midlatitudes with SAM seen in other recent studies and characterize the opposing impacts of SAM and ENSO on the South Pacific convergence zone and Southern Hemisphere storm tracks. Furthermore, we demonstrate that the standard deviation of brightness temperature data from the window channel acts as a surrogate for high cloud fraction in the tropics and midlatitudes. Our results reconcile apparent differences in recent studies and suggest that brightness temperature standard deviations are climate relevant, in addition to being largely insensitive to instrument calibration.

scholarly journals Late Holocene intensification of the westerly winds at the subantarctic Auckland Islands (51° S), New Zealand

2017 ◽  
Author(s):  
Imogen M. Browne ◽  
Christopher M. Moy ◽  
Christina R. Riesselman ◽  
Helen L. Neil ◽  
Lorelei G. Curtin ◽  
...  
Keyword(s):  
New Zealand ◽  
Late Holocene ◽  
Drainage Basin ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Ice Age ◽  
The Pacific ◽  
Westerly Winds ◽  
Latitudinal Position ◽  
Paleoclimate Records

Abstract. The Southern Hemisphere westerly winds (SHWW) play a major role in controlling wind-driven upwelling of Circumpolar Deep Water (CDW) and outgassing of CO2 in the Southern Ocean on interannual to glacial-interglacial timescales. Despite their significance in the global carbon cycle, our understanding of millennial-scale changes in the strength and latitudinal position of the westerlies during the Holocene (especially since 5000 yr BP) is limited by a scarcity of paleoclimate records from comparable latitudes. Here, we reconstruct middle to late Holocene variability in the SHWW using a fjord sediment core collected from the subantarctic Auckland Islands (51° S, 166° E), located in the modern centre of the westerly wind belt. Drainage basin response to variability in the strength of the SHWW at this latitude is reconstructed from downcore variations in magnetic susceptibility (MS) and bulk organic δ13C and atomic C/N, which monitor influxes of lithogenous and terrestrial vs marine organic matter, respectively. The hydrographic response to SHWW variability is reconstructed using benthic foraminifer δ18O and δ13C, both of which are influenced by the isotopic composition of shelf water masses entering the fjord. Using these data, we provide marine and terrestrial-based evidence for increased wind strength from ~ 1600–900 yr BP at subantarctic latitudes that is broadly consistent with previous studies of vegetation response to climate at the Auckland Islands. Comparison with a SHWW reconstruction using similar proxies from Fiordland suggests a northward migration of the SHWW over New Zealand at the beginning of the Little Ice Age (LIA). Comparison with paleoclimate and paleoceanographic records from southern South America and the western Antarctic Peninsula indicates a late Holocene strengthening of the SHWW after ~ 1600 yr BP that appears to be broadly symmetrical across the Pacific basin, although our reconstruction suggests that this symmetry breaks down during the LIA. Contemporaneous increases in SHWW at localities either side of the Pacific in the late Holocene are likely controlled atmospheric teleconnections between the low and high latitudes and by variability in the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO).

scholarly journals Triggering the Indian Ocean Dipole from the Southern Hemisphere

2021 ◽  
Author(s):  
Lian-Yi Zhang ◽  
Yan Du ◽  
Wenju Cai ◽  
Zesheng Chen ◽  
Tomoki Tozuka ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Southern Hemisphere ◽  
Indian Ocean Dipole ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Triggering Mechanism ◽  
Phase Development ◽  
The Indian Ocean ◽  
High System ◽  
The Tropics

<p>This study identifies a new triggering mechanism of the Indian Ocean Dipole (IOD) from the Southern Hemisphere. This mechanism is independent from the El Niño/Southern Oscillation (ENSO) and tends to induce the IOD before its canonical peak season. The joint effects of this mechanism and ENSO may explain different lifetimes and strengths of the IOD. During its positive phase, development of sea surface temperature cold anomalies commences in the southern Indian Ocean, accompanied by an anomalous subtropical high system and anomalous southeasterly winds. The eastward movement of these anomalies enhances the monsoon off Sumatra-Java during May-August, leading to an early positive IOD onset. The pressure variability in the subtropical area is related with the Southern Annular Mode, suggesting a teleconnection between high-latitude and mid-latitude climate that can further affect the tropics. To include the subtropical signals may help model prediction of the IOD event.</p>

scholarly journals Changes in Andes snow cover from MODIS data, 2000–2016

2018 ◽  
Vol 12 (3) ◽  
pp. 1027-1046 ◽  
Author(s):  
Freddy A. Saavedra ◽  
Stephanie K. Kampf ◽  
Steven R. Fassnacht ◽  
Jason S. Sibold
Keyword(s):  
Snow Cover ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Significant Loss ◽  
Climate Indices ◽  
Climate Data ◽  
Large Area ◽  
Temperature And Precipitation ◽  
The Andes ◽  
Snow Cover Extent

Abstract. The Andes span a length of 7000 km and are important for sustaining regional water supplies. Snow variability across this region has not been studied in detail due to sparse and unevenly distributed instrumental climate data. We calculated snow persistence (SP) as the fraction of time with snow cover for each year between 2000 and 2016 from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensors (500 m, 8-day maximum snow cover extent). This analysis is conducted between 8 and 36∘ S due to high frequency of cloud (> 30 % of the time) south and north of this range. We ran Mann–Kendall and Theil–Sens analyses to identify areas with significant changes in SP and snowline (the line at lower elevation where SP = 20 %). We evaluated how these trends relate to temperature and precipitation from Modern-Era Retrospective Analysis for Research and Applications-2 (MERRA2) and University of Delaware datasets and climate indices as El Niño–Southern Oscillation (ENSO), Southern Annular Mode (SAM), and Pacific Decadal Oscillation (PDO). Areas north of 29∘ S have limited snow cover, and few trends in snow persistence were detected. A large area (34 370 km2) with persistent snow cover between 29 and 36∘ S experienced a significant loss of snow cover (2–5 fewer days of snow year−1). Snow loss was more pronounced (62 % of the area with significant trends) on the east side of the Andes. We also found a significant increase in the elevation of the snowline at 10–30 m year−1 south of 29–30∘ S. Decreasing SP correlates with decreasing precipitation and increasing temperature, and the magnitudes of these correlations vary with latitude and elevation. ENSO climate indices better predicted SP conditions north of 31∘ S, whereas the SAM better predicted SP south of 31∘ S.

Southern skies: Australian atmospheric research and global climate change

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ruth A. Morgan
Keyword(s):  
Climate Change ◽  
Environmental History ◽  
Southern Hemisphere ◽  
Southern Oscillation ◽  
Global Climate ◽  
Global Environmental Change ◽  
Published Data ◽  
Global Knowledge ◽  
Content Type ◽  
Leading Role

PurposeThe purpose of this paper is to examine the role of Australian climate scientists in advancing the state of knowledge about the causes and mechanisms of climatic change and variability in the Southern Hemisphere during the 1970 and 1980s.Design/methodology/approachThe paper uses the methods and insights of environmental history and the history of science to analyse archival and published data pertaining to research on atmospheric pollution, the Southern Oscillation and the regional impacts of climate change.FindingsAustralia's geopolitical position, political interests and environmental sensitivities encouraged Australian scientists and policymakers to take a leading role in the Southern Hemisphere in the study of global environmental change.Originality/valueThis article builds on critiques of the ways in which planetary and global knowledge and governance disguise the local and situated scientific and material processes that construct, sustain and configure them.

scholarly journals Bioclimatic Modelling Identifies Suitable Habitat for the Establishment of the Invasive European Paper Wasp (Hymenoptera: Vespidae) across the Southern Hemisphere

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 784
Author(s):  
Matthew W. F. Howse ◽  
John Haywood ◽  
Philip J. Lester
Keyword(s):  
South Africa ◽  
New Zealand ◽  
South America ◽  
Southern Hemisphere ◽  
Range Expansion ◽  
Paper Wasp ◽  
Potential Range ◽  
Suitable Habitat ◽  
Climate Data ◽  
Distribution Models

Species distribution models (SDMs) are tools used by ecologists to help predict the spread of invasive species. Information provided by these models can help direct conservation and biosecurity efforts by highlighting areas likely to contain species of interest. In this study, two models were created to investigate the potential range expansion of Polistes dominula Christ (Hymenoptera: Vespidae) in the southern hemisphere. This palearctic species has spread to invade North and South America, South Africa, Australia, and more recently New Zealand. Using the BIOCLIM and MAXENT modelling methods, regions that were suitable for P. dominula were identified based on climate data across four regions in the southern hemisphere. In South America areas of central Chile, eastern Argentina, parts of Uruguay, and southern Brazil were identified as climatically suitable for the establishment of P. dominula. Similarly, southern parts of South Africa and Australia were identified by the model to be suitable as well as much of the North Island and east of the South Island of New Zealand. Based on outputs from both models, significant range expansion by P. dominula is possible across its more southern invaded ranges.

Does the El Niño–Southern Oscillation control the interhemispheric radiocarbon offset?

2007 ◽  
Vol 67 (1) ◽  
pp. 174-180 ◽  
Author(s):  
Chris S.M. Turney ◽  
Jonathan G. Palmer
Keyword(s):  
Southern Hemisphere ◽  
El Niño ◽  
Atmospheric Carbon Dioxide ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Ice Age ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Mean Values

AbstractSince the 1970s it has been recognised that Southern Hemisphere samples have a lower radiocarbon content than contemporaneous material in the Northern Hemisphere. This interhemispheric radiocarbon offset has traditionally been considered to be the result of a greater surface area in the southern ocean and high-latitude deepwater formation. This is despite the fact that the El Niño–Southern Oscillation (ENSO) is known to play a significant role in controlling the interannual variability of atmospheric carbon dioxide by changing the flux of ‘old’ CO2 from the tropical Pacific. Here we demonstrate that over the past millennium, the Southern Hemisphere radiocarbon offset is characterised by a pervasive 80-yr cycle with a step shift in mean values coinciding with the transition from the Medieval Warm Period to the Little Ice Age. The observed changes suggest an ENSO-like role in influencing the interhemispheric radiocarbon difference, most probably modulated by the Interdecadal Pacific Oscillation, and supports a tropical role in forcing centennial-scale global climate change.

Amylostereum areolatum.

2021 ◽  
Author(s):  
Keyword(s):  
South Africa ◽  
New Zealand ◽  
South America ◽  
Southern Hemisphere ◽  
North Africa ◽  
White Rot ◽  
Symbiotic Association ◽  
Southern South America ◽  
Western Asia ◽  
The Usa

Abstract A. areolatum is a basidiomycete that causes a white rot of a broad range of conifers. Its invasiveness arises from a symbiotic association with woodwasps of the genus Sirex. The species Sirexnoctilio is listed as "highly invasive" on the ISSG/IUCN website (ISSG, 2008) and is a Regulated Pest for the USA (APHIS, 2009a). The wasp and the fungus are native to Europe, North Africa and western Asia where their damage is considered secondary (Spradbery and Kirk, 1978). Introduced to areas of the Southern Hemisphere where exotic pine species are grown in plantations, these organisms have caused major losses. The insect invaded New Zealand by at least 1900, but did not cause serious concern until the 1940s (Talbot, 1977). It later spread to Tasmania and the southern parts of Australia and the wasp/fungus association was introduced into southern South America, beginning in Uruguay in 1980 (Ciesla, 2003). Invasion of South Africa occurred in 1994 (Tribe, 1995). Woodwasps are repeatedly detected in material imported to the USA, but were successfully excluded until 2004 (Wilson et al., 2009). The wasp and fungus were later found in nearby Canada (Ontario), although apparently due to a separate introduction (Bergeron et al., 2008; Wilson et al., 2009). Recent surveys found the wasp in four states of the USA (Evans-Goldner and Bunce, 2009) and 25 counties of Ontario in Canada (Shields, 2009). Schiff (2008) summarizes differences in complexity of the ecological situations in the Southern Hemisphere countries and North America that could affect spread and impact of the fungus and wasp.

ENSO and SAM influence on the generation of long episodes of Rossby Wave Packets during Southern Hemisphere Summer

2021 ◽  
Author(s):  
Iago Perez ◽  
Marcelo Barreiro ◽  
Cristina Masoller
Keyword(s):  
Interannual Variability ◽  
Southern Hemisphere ◽  
Rossby Wave ◽  
Southern Oscillation ◽  
Wave Packets ◽  
Southern Annular Mode ◽  
Frequency Of Occurrence ◽  
Atmospheric Conditions ◽  
Mean Flow ◽  
Time Duration

<p>Rossby Wave Packets (RWPs) are key to the improvement of  long-range forecasting and for the prediction of sub-seasonal extremes. Several studies have focused on their properties, such as time duration, trajectory, areas of detection and dissipation as well as interannual variability in the northern hemisphere, but only a few of them have focused in the southern hemisphere. Here we study the influence of low-frequency climate modes on RWPs during southern hemisphere summer using NCEP DOE 2 Reanalysis data. Focusing on long-lived RWPs, which we define as RWPs with a lifespan above 8 days,  we determine how El Niño-Southern Oscillation (ENSO) and the Southern Annular Mode (SAM) modify their frequency of occurrence and their main areas of detection and dissipation. We found that during El Niño and negative SAM years, the number of long-lived RWPs is maximum. In addition, years with the highest amount of long-lived RWPs show a zonally symmetric and narrow upper level jet that is shifted northward from its climatological position. On the other hand, when the jet is shifted southward, particularly in the southeastern Pacific, during positive SAM phases, only a small number of long-lived RWPs is detected. Therefore, negative SAM conditions provide a background mean flow that favours the occurrence of long-lived RWPs while positive SAM conditions have the opposite effect. The dependence on ENSO phase is not as symmetric: while El Niño sets atmospheric conditions that favour the formation of long-lived RWPs, La Niña years present high interannual variability in the frequency of occurrence. Furthermore, in El Niño events the main formation area is between 61-120ºE and the main dissipation area between 300-359ºE. During La Niña events, the main formation area is located by 241-300ºE and no main dissipation area is identified. In the case of positive SAM two main formation areas appear at 61-120ºE and 241-300ºE and two main dissipation areas within 121-180 and 301-359ºE. Lastly in the case of negative SAM one main formation area at 241-300ºE is detected and no main dissipation area is detected. The robustness of the results was tested repeating the analysis using data from the ERA5 Reanalysis and supports the finding that the maximum number of long-lived RWPs occur during negative SAM and El Niño years</p>

scholarly journals Interactions of ENSO, the IOD, and the SAM in CMIP3 Models

2011 ◽  
Vol 24 (6) ◽  
pp. 1688-1704 ◽  
Author(s):  
Wenju Cai ◽  
Arnold Sullivan ◽  
Tim Cowan
Keyword(s):  
Southern Oscillation ◽  
Global Climate ◽  
Coupled Model ◽  
Southern Annular Mode ◽  
Enso Events ◽  
Intercomparison Project ◽  
Wave Trains ◽  
Induced Signal ◽  
The Impact ◽  
The Relationship

Abstract Simulations of individual global climate drivers using models from the Coupled Model Intercomparison Project phase 3(CMIP3) have been examined; however, the relationship among them has not been assessed. This is carried out to address several important issues, including the likelihood of the southern annular mode (SAM) forcing Indian Ocean dipole (IOD) events and the possible impact of the IOD on El Niño–Southern Oscillation (ENSO) events. Several conclusions emerge from statistics based on multimodel outputs. First, ENSO signals project strongly onto the SAM, although ENSO-forced signals tend to peak before ENSO. This feature is similar to the situation associated with the IOD. The IOD-induced signal over southern Australia, through stationary equivalent Rossby barotropic wave trains, peak before the IOD itself. Second, there is no control by the SAM on the IOD, in contrast to what has been suggested previously. Indeed, no model produces a SAM–IOD relationship that supports a positive (negative) SAM driving a positive (negative) IOD event. This is the case even in models that do not simulate a statistically significant relationship between ENSO and the IOD. Third, the IOD does have an impact on ENSO. The relationship between ENSO and the IOD in the majority of models is far weaker than the observed. However, the ENSO’s influence on the IOD is boosted by a spurious oceanic teleconnection, whereby ENSO discharge–recharge signals transmit to the Sumatra–Java coast, generating thermocline anomalies and changing IOD properties. Without the spurious oceanic teleconnection, the influence of the IOD on ENSO is comparable to the impact of ENSO on the IOD. Other model deficiencies are discussed.

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