Search results for "Indian Ocean"
showing 10 items of 42 documents
Sea Surface Temperature Fields Associated with West African Rainfall Anomaly Types
1996
Abstract Four West African rainfall anomaly types are defined in relation to the northern summer rainfall departure signs in the Sahel and in the Guinean region in order to investigate the statistical links between interannual variability of West African rainfall and sea surface temperature (SST) through the period 1950–90. Composite analysis depicts the setup of four different mean SST anomaly fields. Drought over all of West Africa is associated with the growth of positive SST anomalies in the eastern Pacific and in the Indian Ocean, and negative SST anomalies in the northern Atlantic and in the Gulf of Guinea. In contrast, drought limited to the Sahel corresponds mostly to a northward ex…
Modification of the southern African rainfall variability/ENSO relationship since the late 1960s
2000
Analysis of 149 raingauge series (1946–1988) shows a weak positive correlation between late summer rainfalls (January–March) in tropical southern Africa and the Southern Oscillation Index (SOI). The correlation coefficients have been unstable since World War II. They were close to zero before 1970 and significant thereafter. Before 1970, southern African late summer rainfalls were more specifically correlated with regional patterns of sea surface temperature (SST), mainly over the southwestern Indian Ocean. After 1970, teleconnections with near global SST anomaly patterns, i.e. over the central Pacific and Indian oceans, dominate the regional connections. The increase in the sensitivity of …
Temperature changes in the mid- and high- latitudes of the Southern Hemisphere
2012
A Hierarchical Ascending Classification is used to regionalize monthly temperature anomalies measured at 24 weather stations in Antarctica and the Sub-Antarctic and mid-latitude southern islands from 1973 to 2002. Three principal regions are identified that are geographically coherent: Eastern Antarctica, the Antarctic Peninsula and the Sub-Antarctic and mid-latitude islands. Within each region, consistent trends are observed: namely, stationary temperatures in ‘East-Antarctica’; a robust warming in the ‘Sub-Antarctic and mid-latitude islands’, most pronounced in austral summer (nearly 0.5 °C per decade); and a strong but more recent warming in the ‘Antarctic Peninsula’. Austral summer temp…
The Extratropical Transition of Tropical Cyclones. Part II: Interaction with the Midlatitude Flow, Downstream Impacts, and Implications for Predictab…
2019
Abstract The extratropical transition (ET) of tropical cyclones often has an important impact on the nature and predictability of the midlatitude flow. This review synthesizes the current understanding of the dynamical and physical processes that govern this impact and highlights the relationship of downstream development during ET to high-impact weather, with a focus on downstream regions. It updates a previous review from 2003 and identifies new and emerging challenges and future research needs. First, the mechanisms through which the transitioning cyclone impacts the midlatitude flow in its immediate vicinity are discussed. This “direct impact” manifests in the formation of a jet streak …
Sea-surface temperature co-variability in the Southern Atlantic and Indian Oceans and its connections with the atmospheric circulation in the Souther…
2003
The relationship between sea-surface temperature (SST) inter-annual variability at the subtropical and midlatitudes of the southern Atlantic and Indian Oceans and its links with the atmospheric circulation in the Southern Hemisphere are investigated over the 1950–1999 period. Exploratory analysis using singular value decomposition and further investigations based on simple indices show that a large part of regional SST variability is common between the southwestern parts of both basins at subtropical and midlatitudes during the austral summer. Interestingly, these areas are also significantly associated with the far southwestern Pacific (Tasman Sea area). The patterns and time series of co-…
Effect of the conversion of mangroves into shrimp farms on carbon stock in the sediment along the southern Red Sea coast, Saudi Arabia
2019
The conservation of coastal ecosystems and specially mangroves ‘‘blue carbon’’ is receiving more attention as consequence of their recognition as high ecosystem carbon stocks and for the fact that these areas are undergoing land conversion. The aim of the present study is to evaluate the impact of land use changes due to conversion of mangroves to shrimp farms on the bulk density (SBD), organic carbon (SOC) concentration, and SOC stock in the sediments along the southern Saudi Arabian Red Sea coast. Shrimp farms and mangrove locations showed significant (P < 0.001) differences in SBD with high mean values in the sediments of shrimp farms. Shrimp farms and mangrove locations showed significa…
On the determination of coherent solar climates over a tropical island with a complex topography
2020
Abstract Many tropical islands aim at developing a greener self-sufficient energy production systems based on renewable energy, notably solar-generated electricity. This work explores the mean diurnal and annual solar cycles over La Reunion island (southwest Indian Ocean: 21°S, 55.5°E), and their spatial behavior, using the Solar surfAce RAdiation Heliosat – East (SARAH-E) satellite-derived data at high spatial ( 0.05 ° × 0.05 ° ) and time (hourly) resolutions over period 1999–2016. Comparisons of the SARAH-E data with ground-based measurements over the period 2011–2015 show differences of ~ 15 % for diurnal-seasonal variations. The solar resource over the island displays strong spatial var…
Diversity and distribution of marine heterotrophic bacteria from a large culture collection
2020
16 pages, 5 figures, 3 tables, supplementary information https://doi.org/10.1186/s12866-020-01884-7
Back to Gondwanaland: can ancient vicariance explain (some) Indian Ocean disjunct plant distributions?
2015
Oceans, or other wide expanses of inhospitable environment, interrupt present day distributions of many plant groups. Using molecular dating techniques, generally incorporating fossil evidence, we can estimate when such distributions originated. Numerous dating analyses have recently precipitated a paradigm shift in the general explanations for the phenomenon, away from older geological causes, such as continental drift, in favour of more recent, long-distance dispersal (LDD). For example, the ‘Gondwanan vicariance’ scenario has been dismissed in various studies of Indian Ocean disjunct distributions. We used the gentian tribe Exaceae to reassess this scenario using molecular dating with mi…
A new species ofLimonium(Plumbaginaceae) from Soqotra (Yemen)
2009
Abstract Limonium guigliae, from the island of Soqotra (Yemen) is described. This new species, close to L. paulayanum differs from it by its size, flower morphology and ecology.