scholarly journals Anomalies Of Isobaric Fields In The Southwestern Indian Ocean During El Nino Climatic Events

2020 ◽  
Vol 3 (4) ◽  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Global Climate ◽  
Ocean Basin ◽  
The South ◽  
The North ◽  
South West Indian Ocean ◽  
Climate Event ◽  
West Indian Ocean

The el Nino climate event has produced upheavals in the global climate. Among many others is the prolonged drought in the Sahel. In fact, these upheavals are the direct consequences of changes in the centers of action. Therefore, we are interested in knowing their configuration in the South-West Indian Ocean basin, SWOI, both on the ground and at altitude during the two seasons, summer and winter in the southern hemisphere. It has been observed that there are negative pressure anomalies in the western part of the SWOI and positive ones in its eastern part; moreover the geopotential levels 700hPa and 500hPa include positive anomalies in the north and negative anomalies in the south. These mid-altitude results continue at high altitude, with the tropopause experiencing low anomalies on the equator side and high anomalies on the south pole side. As a result on the other hand, the southern winter experiences more moisture than normal. The significance of the images showing isobaric field anomalies was tested by the Student t-test.

scholarly journals ReNovRisk: a multidisciplinary programme to study the cyclonic risks in the South-West Indian Ocean

2021 ◽  
Author(s):  
Pierre Tulet ◽  
Bertrand Aunay ◽  
Guilhem Barruol ◽  
Christelle Barthe ◽  
Remi Belon ◽  
...  
Keyword(s):  
Indian Ocean ◽  
West Indian ◽  
Ocean Basin ◽  
Transport Processes ◽  
The South ◽  
South West Indian Ocean ◽  
South West ◽  
The Face ◽  
West Indian Ocean ◽  
Solid Transport

AbstractToday, resilience in the face of cyclone risks has become a crucial issue for our societies. With climate change, the risk of strong cyclones occurring is expected to intensify significantly and to impact the way of life in many countries. To meet some of the associated challenges, the interdisciplinary ReNovRisk programme aims to study tropical cyclones and their impacts on the South-West Indian Ocean basin. This article is a presentation of the ReNovRisk programme, which is divided into four areas: study of cyclonic hazards, study of erosion and solid transport processes, study of water transfer and swell impacts on the coast, and studies of socio-economic impacts. The first transdisciplinary results of the programme are presented together with the database, which will be open access from mid-2021.

scholarly journals Diversity and Geographical Structure of Xanthomonas citri pv. citri on Citrus in the South West Indian Ocean Region

2021 ◽  
Vol 9 (5) ◽  
pp. 945
Author(s):  
Olivier Pruvost ◽  
Damien Richard ◽  
Karine Boyer ◽  
Stéphanie Javegny ◽  
Claudine Boyer ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Host Range ◽  
Disease Surveillance ◽  
West Indian ◽  
Copper Resistance ◽  
The South ◽  
South West Indian Ocean ◽  
South West ◽  
Strain Collection ◽  
West Indian Ocean

A thorough knowledge of genotypic and phenotypic variations (e.g., virulence, resistance to antimicrobial compounds) in bacteria causing plant disease outbreaks is key for optimizing disease surveillance and management. Using a comprehensive strain collection, tandem repeat-based genotyping techniques and pathogenicity assays, we characterized the diversity of X. citri pv. citri from the South West Indian Ocean (SWIO) region. Most strains belonged to the prevalent lineage 1 pathotype A that has a wide host range among rutaceous species. We report the first occurrence of genetically unrelated, nonepidemic lineage 4 pathotype A* (strains with a host range restricted to Mexican lime and related species) in Mauritius, Moheli and Réunion. Microsatellite data revealed that strains from the Seychelles were diverse, grouped in three different clusters not detected in the Comoros and the Mascarenes. Pathogenicity data suggested a higher aggressiveness of strains of one of these clusters on citron (Citrus medica). With the noticeable exception of the Comoros, there was no sign of recent interisland movement of the pathogen. Consistent with this finding, the copL gene, a marker for the plasmid-borne copLAB copper resistance that was recently identified in Réunion, was not detected in 568 strains from any islands in the SWIO region apart from Réunion.

scholarly journals Spurious North Tropical Atlantic precursors to El Niño

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenjun Zhang ◽  
Feng Jiang ◽  
Malte F. Stuecker ◽  
Fei-Fei Jin ◽  
Axel Timmermann
Keyword(s):  
El Niño ◽  
Cross Correlation ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Tropical Atlantic ◽  
The North ◽  
Sst Variability ◽  
Primary Driver ◽  
North Tropical Atlantic

AbstractThe El Niño-Southern Oscillation (ENSO), the primary driver of year-to-year global climate variability, is known to influence the North Tropical Atlantic (NTA) sea surface temperature (SST), especially during boreal spring season. Focusing on statistical lead-lag relationships, previous studies have proposed that interannual NTA SST variability can also feed back on ENSO in a predictable manner. However, these studies did not properly account for ENSO’s autocorrelation and the fact that the SST in the Atlantic and Pacific, as well as their interaction are seasonally modulated. This can lead to misinterpretations of causality and the spurious identification of Atlantic precursors for ENSO. Revisiting this issue under consideration of seasonality, time-varying ENSO frequency, and greenhouse warming, we demonstrate that the cross-correlation characteristics between NTA SST and ENSO, are consistent with a one-way Pacific to Atlantic forcing, even though the interpretation of lead-lag relationships may suggest otherwise.

The South-West Indian Ocean: Discussion

1910 ◽  
Vol 36 (3) ◽  
pp. 268 ◽  
Author(s):  
Stanley Gardiner ◽  
J. C. F. Fryer
Keyword(s):  
Indian Ocean ◽  
West Indian ◽  
The South ◽  
South West Indian Ocean ◽  
South West ◽  
West Indian Ocean

scholarly journals Fishes from Bassas Da India Atoll in the Mozambique Channel

2021 ◽  
Author(s):  
Rudy van der Elst ◽  
Simon Chater ◽  
Dennis King
Keyword(s):  
Climate Change ◽  
Indian Ocean ◽  
West Indian ◽  
Small Island ◽  
Fish Diversity ◽  
Apex Predators ◽  
The South ◽  
Biodiversity Survey ◽  
South West Indian Ocean ◽  
West Indian Ocean

Bassas da India is a remote, uninhabited coral atoll in the West Indian Ocean. Its inaccessibility had historically precluded study of its ichthyofauna until a small group of scientists from the Oceanographic Research Institute in South Africa undertook a two-week biodiversity survey in 1991. Since then, the discourse on climate change has taken on a higher relevance, calling for protection and study of biodiversity hotspots such as Bassas da India. The survey recorded 309 fish species, including a number of vulnerable teleosts and elasmobranchs. As the only published information on the biodiversity of this remote small island, it is intended that this dataset will contribute to increased relevance as an ecological baseline for detecting impacts relating to climate change in the South West Indian Ocean. Each species is listed in terms of its individual abundance, IUCN status as well as its museum and photographic record. Comparisons are made with survey results of other small coral islands in the region, notably Europa Island, revealing several distinct differences in fish diversity. There is evidence that giant groupers will replace sharks as apex predators when there is no local exploitation. A total of 86 species were photographed to confirm identity, and a further 84 species were provided to the South African Institute for Aquatic Biodiversity museum in Grahamstown and also to several international species experts.

scholarly journals Isolated Effects of Indian Ocean Basin-Wide and El Niño–Southern Oscillation on Austral Winter Rainfall over South America

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1605
Author(s):  
Mary T. Kayano ◽  
Wilmar L. Cerón ◽  
Rita V. Andreoli ◽  
Rodrigo A. F. Souza ◽  
Itamara P. Souza
Keyword(s):  
Indian Ocean ◽  
South America ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Indian Ocean ◽  
Ocean Basin ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Partial Correlations

Contrasting effects of the tropical Indian and Pacific Oceans on the atmospheric circulation and rainfall interannual variations over South America during southern winter are assessed considering the effects of the warm Indian Ocean basin-wide (IOBW) and El Niño (EN) events, and of the cold IOBW and La Niña events, which are represented by sea surface temperature-based indices. Analyses are undertaken using total and partial correlations. When the effects of the two warm events are isolated from each other, the contrasts between the associated rainfall anomalies in most of South America become accentuated. In particular, EN relates to anomalous wet conditions, and the warm IOBW event to opposite conditions in extensive areas of the 5° S–25° S band. These effects in the 5° S–15° S sector are due to the anomalous regional Hadley cells, with rising motions in this band for the EN and sinking motions for the warm IOBW event. Meanwhile, in subtropical South America, the opposite effects of the EN and warm IOBW seem to be due to the presence of anomalous anticyclone and cyclone and associated moisture transport, respectively. These opposite effects of the warm IOBW and EN events on the rainfall in part of central South America might explain the weak rainfall relation in this region to the El Niño–Southern Oscillation (ENSO). Our results emphasize the important role of the tropical Indian Ocean in the South American climate and environment during southern winter.

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