scholarly journals A lightning climatology of the South-West Indian Ocean

2012 ◽  
Vol 12 (8) ◽  
pp. 2659-2670 ◽  
Author(s):  
C. Bovalo ◽  
C. Barthe ◽  
N. Bègue
Keyword(s):  
Indian Ocean ◽  
West Indian ◽  
Dry Season ◽  
Lightning Activity ◽  
The South ◽  
Wet Season ◽  
Inter Tropical Convergence Zone ◽  
South West Indian Ocean ◽  
South West ◽  
West Indian Ocean

Abstract. The World Wide Lightning Location Network (WWLLN) data have been used to perform a lightning climatology in the South-West Indian Ocean (SWIO) region from 2005 to 2011. Maxima of lightning activity were found in the Maritime Continent and southwest of Sri Lanka (>50 fl km−2 yr−1) but also over Madagascar and above the Great Lakes of East Africa (>10–20 fl km−2 yr−1). Lightning flashes within tropical storms and tropical cyclones represent 50 % to 100 % of the total lightning activity in some oceanic areas of the SWIO (between 10° S and 20° S). The SWIO is characterized by a wet season (November to April) and a dry season (May to October). As one could expect, lightning activity is more intense during the wet season as the Inter Tropical Convergence Zone (ITCZ) is present over all the basin. Flash density is higher over land in November–December–January with values reaching 3–4 fl km−2 yr−1 over Madagascar. During the dry season, lightning activity is quite rare between 10° S and 25° S. The Mascarene anticyclone has more influence on the SWIO resulting in shallower convection. Lightning activity is concentrated over ocean, east of South Africa and Madagascar. A statistical analysis has shown that El Niño–Southern Oscillation mainly modulates the lightning activity up to 56.8% in the SWIO. The Indian Ocean Dipole has a significant contribution since ~49% of the variability is explained by this forcing in some regions. The Madden–Julian Oscillation did not show significative impact on the lightning activity in our study.

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.

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

Acoustic localization of two distinct blue whale (Balaenoptera musculus) subspecies in the South‐West Indian Ocean

2008 ◽  
Vol 123 (5) ◽  
pp. 3774-3774
Author(s):  
Flore Samaran ◽  
Olivier Adam ◽  
Jean‐François Motsch ◽  
Yves Cansi ◽  
Gérard Ruzié ◽  
...  
Keyword(s):  
Indian Ocean ◽  
West Indian ◽  
Balaenoptera Musculus ◽  
The South ◽  
Blue Whale ◽  
Acoustic Localization ◽  
South West Indian Ocean ◽  
South West ◽  
West Indian Ocean

scholarly journals Estimates of marine turtle nesting populations in the south-west Indian Ocean indicate the importance of the Chagos Archipelago

Oryx ◽  
2020 ◽  
Vol 54 (3) ◽  
pp. 332-343 ◽  
Author(s):  
Jeanne A. Mortimer ◽  
Nicole Esteban ◽  
Antenor Nestor Guzman ◽  
Graeme C. Hays
Keyword(s):  
Indian Ocean ◽  
Green Turtle ◽  
West Indian ◽  
The South ◽  
Green Turtles ◽  
South West Indian Ocean ◽  
South West ◽  
West Indian Ocean ◽  
Hawksbill Turtles ◽  
Chagos Archipelago

AbstractGlobal marine turtle population assessments highlight the importance of the south-west Indian Ocean region, despite data gaps for the Chagos Archipelago. The archipelago hosts nesting hawksbill Eretmochelys imbricata and green turtles Chelonia mydas, both heavily exploited for 2 centuries until protection in 1968–1970. We assessed available nesting habitat and spatial distribution of nesting activity during rapid surveys of 90% of the archipelago's coastline in 1996, 1999, 2006 and 2016. We quantified seasonality and mean annual egg clutch production from monthly track counts during 2006–2018 along a 2.8 km index beach on Diego Garcia island. An estimated 56% (132 km) of coastline provided suitable nesting habitat. Diego Garcia and Peros Banhos atolls accounted for 90.4% of hawksbill and 70.4% of green turtle nesting. Hawksbill turtles showed distinct nesting peaks during October–February, and green turtles nested year-round with elevated activity during June–October. Estimates of 6,300 hawksbill and 20,500 green turtle clutches laid annually during 2011–2018 indicate that nesting on the Chagos Archipelago has increased 2–5 times for hawksbill turtles and 4–9 times for green turtles since 1996. Regional estimates indicate green turtles produce 10 times more egg clutches than hawksbill turtles, and the Chagos Archipelago accounts for 39–51% of an estimated 12,500–16,000 hawksbill and 14–20% of an estimated 104,000–143,500 green turtle clutches laid in the south-west Indian Ocean. The improved status may reflect > 40 years without significant exploitation. Long-term monitoring is needed to captureinterannual variation in nesting numbers and minimize uncertainty in population estimates.

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