scholarly journals Climatology of the Mascarene High and Its Influence on Weather and Climate over Southern Africa

Climate ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 86 ◽  
Author(s):  
Nkosinathi G. Xulu ◽  
Hector Chikoore ◽  
Mary-Jane M. Bopape ◽  
Nthaduleni S. Nethengwe
Keyword(s):  
Indian Ocean ◽  
Southern Africa ◽  
Lower Troposphere ◽  
Western Indian Ocean ◽  
Vital Role ◽  
Tropical Cyclone Genesis ◽  
Trade Winds ◽  
Mascarene High ◽  
Weather And Climate ◽  
Cyclone Genesis

Globally, subtropical circulation in the lower troposphere is characterized by anticyclones over the oceans. Subtropical anticyclones locate over subtropical belts, modulating weather and climate patterns in those regions. The Mascarene High is an anticyclone located over the Southern Indian Ocean and has a vital role in weather and climate variability over Southern Africa. The warm Western Indian Ocean is a major source of moisture for the subcontinent also permitting tropical cyclone genesis. In this study, we review the dynamics of the Mascarene High, its interactions with the ocean, and its impact on weather and climate over Southern Africa. We also review studies on the evolution of subtropical anticyclones in a future warmer climate. The links between SST modes over the Indian Ocean and the strengthening and weakening of the Mascarene High have been demonstrated. One important aspect is atmospheric blocking due to the Mascarene High, which leads to anomalous rainfall and temperature events over the subcontinent. Blocking leads to landfall of tropical cyclones and slow propagation of cut-off lows resulting in severe weather and flooding over the subcontinent. Understanding how expansion of the Mascarene High due to warming will alter trade winds and storm tracks and change the mean climate of Southern Africa is crucial.

scholarly journals Variability in the Mozambique Channel Trough and Impacts on Southeast African Rainfall

2020 ◽  
Vol 33 (2) ◽  
pp. 749-765 ◽  
Author(s):  
Rondrotiana Barimalala ◽  
Ross C. Blamey ◽  
Fabien Desbiolles ◽  
Chris J. C. Reason
Keyword(s):  
Indian Ocean ◽  
Austral Summer ◽  
Western Indian Ocean ◽  
Strong Relationship ◽  
Ocean Basin ◽  
Moist Convection ◽  
South Indian Ocean ◽  
Mozambique Channel ◽  
Mascarene High ◽  
South Indian

AbstractThe Mozambique Channel trough (MCT) is a cyclonic region prominent in austral summer in the central and southern Mozambique Channel. It first becomes evident in December with a peak in strength in February when the Mozambique Channel is warmest and the Mascarene high (MH) is located farthest southeast in the Indian Ocean basin. The strength and the timing of the mean MCT are linked to that of the cross-equatorial northeasterly monsoon in the tropical western Indian Ocean, which curves as northwesterlies toward northern Madagascar. The interannual variability in the MCT is associated with moist convection over the Mozambique Channel and is modulated by the location of the warm sea surface temperatures in the south Indian Ocean. Variability of the MCT shows a strong relationship with the equatorial westerlies north of Madagascar and the latitudinal extension of the MH. Summers with strong MCT activity are characterized by a prominent cyclonic circulation over the Mozambique Channel, extending to the midlatitudes. These are favorable for the development of tropical–extratropical cloud bands over the southwestern Indian Ocean and trigger an increase in rainfall over the ocean but a decrease over the southern African mainland. Most years with a weak MCT are associated with strong positive south Indian Ocean subtropical dipole events, during which the subcontinent tends to receive more rainfall whereas Madagascar and northern Mozambique are anomalously dry.

Terminalia catappa (Singapore almond).

2021 ◽  
Author(s):  
Julissa Rojas-Sandoval
Keyword(s):  
Indian Ocean ◽  
Plant Communities ◽  
Western Indian Ocean ◽  
Agroforestry Systems ◽  
The Philippines ◽  
Vital Role ◽  
South East Asia ◽  
Edible Fruit ◽  
Tree Component ◽  
The Tropics

Abstract T. catappa is a hardy, fast-growing, deciduous multipurpose tree, reaching 25 (-40) m tall and producing an edible fruit. It plays a vital role in coastline stabilization as a tree component of strandline plant communities in the western Indian Ocean, South-East Asia and the South Pacific. Under suitable conditions it is a well-formed tree and has been widely planted throughout the tropics for shade, ornament and nuts, especially along sandy seashores (Heinsleigh and Holaway, 1988; Little and Skolmen, 1989). It is much used in agroforestry systems in the Philippines.

scholarly journals Madagascar corals reveal a multidecadal signature of rainfall and river runoff since 1708

2013 ◽  
Vol 9 (2) ◽  
pp. 641-656 ◽  
Author(s):  
C. A. Grove ◽  
J. Zinke ◽  
F. Peeters ◽  
W. Park ◽  
T. Scheufen ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Southern Africa ◽  
River Runoff ◽  
Decadal Variability ◽  
Rainfall Variability ◽  
Western Indian Ocean ◽  
Phase Changes ◽  
Monsoon Circulation ◽  
Eastern Australia ◽  
Instrumental Records

Abstract. Pacific Ocean sea surface temperatures (SST) influence rainfall variability on multidecadal and interdecadal timescales in concert with the Pacific Decadal Oscillation (PDO) and Interdecadal Pacific Oscillation (IPO). Rainfall variations in locations such as Australia and North America are therefore linked to phase changes in the PDO. Furthermore, studies have suggested teleconnections exist between the western Indian Ocean and Pacific Decadal Variability (PDV), similar to those observed on interannual timescales related to the El Niño Southern Oscillation (ENSO). However, as instrumental records of rainfall are too short and sparse to confidently assess multidecadal climatic teleconnections, here we present four coral climate archives from Madagascar spanning up to the past 300 yr (1708–2008) to assess such decadal variability. Using spectral luminescence scanning to reconstruct past changes in river runoff, we identify significant multidecadal and interdecadal frequencies in the coral records, which before 1900 are coherent with Asian-based PDO reconstructions. This multidecadal relationship with the Asian-based PDO reconstructions points to an unidentified teleconnection mechanism that affects Madagascar rainfall/runoff, most likely triggered by multidecadal changes in North Pacific SST, influencing the Asian Monsoon circulation. In the 20th century we decouple human deforestation effects from rainfall-induced soil erosion by pairing luminescence with coral geochemistry. Positive PDO phases are associated with increased Indian Ocean temperatures and runoff/rainfall in eastern Madagascar, while precipitation in southern Africa and eastern Australia declines. Consequently, the negative PDO phase that started in 1998 may contribute to reduced rainfall over eastern Madagascar and increased precipitation in southern Africa and eastern Australia. We conclude that multidecadal rainfall variability in Madagascar and the western Indian Ocean needs to be taken into account when considering water resource management under a future warming climate.

Cryptic lineages of little free-tailed bats,Chaerephon pumilus(Chiroptera: Molossidae) from southern Africa and the western Indian Ocean islands

2009 ◽  
Vol 44 (1) ◽  
pp. 55-70
Author(s):  
Peter John Taylor ◽  
Jennifer Lamb ◽  
Devendran Reddy ◽  
Theshnie Naidoo ◽  
Fanja Ratrimomanarivo ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Southern Africa ◽  
Western Indian Ocean ◽  
Ocean Islands

CONSTRUCTING ARGUMENTS AND INSTITUTIONS OF ISLAMIC BELONGING: M. O. ABBASI, COLONIAL TANZANIA, AND THE WESTERN INDIAN OCEAN WORLD, 1925–61

2014 ◽  
Vol 55 (2) ◽  
pp. 211-228 ◽  
Author(s):  
James R. Brennan
Keyword(s):  
Indian Ocean ◽  
Western Indian Ocean ◽  
Organizational Structures ◽  
Vital Role ◽  
Colonial Era ◽  
The Public ◽  
Public Role ◽  
Organizational Work ◽  
Intellectual Networks ◽  
Indian Ocean World

AbstractThis article explores the intellectual life and organizational work of an Indian Muslim activist and journalist, M. O. Abbasi, a largely forgotten figure who nonetheless stood at the center of colonial-era debates over the public role of Islam in mainland Tanzania. His greatest impact was made through the Anjuman Islamiyya, the territory's leading pan-Islamic organization that he co-founded and modeled on Indian modernist institutions. The successes and failures of Abbasi and the Anjuman Islamiyya demonstrate the vital role played by Western Indian Ocean intellectual networks, the adaptability of transoceanic, pan-Islamic organizational structures, and, ultimately, the limits imposed on pan-Islamic activism by racial politics in colonial Tanzania.

Dynamics of an Interhemispheric Teleconnection across the Critical Latitude through a Southerly Duct during Boreal Winter*

2015 ◽  
Vol 28 (19) ◽  
pp. 7437-7456 ◽  
Author(s):  
Sen Zhao ◽  
Jianping Li ◽  
Yanjie Li
Keyword(s):  
Indian Ocean ◽  
South Asia ◽  
Southern Africa ◽  
Western Indian Ocean ◽  
Wave Theory ◽  
Stationary Wave ◽  
Boreal Winter ◽  
Stationary Waves ◽  
The North ◽  
Critical Latitude

Abstract In this study, an interhemispheric teleconnection pattern across the critical latitude from southern Africa through South Asia to the North Pacific was revealed in boreal winter monthly averaged 250-hPa streamfunction fields obtained from both the 40-yr ECMWF Re-Analysis (ERA-40) and the NCEP–NCAR reanalysis data from 1957/58 to 2001/02. Classical Rossby wave theory for zonally varying flow in which the effects of the basic-state meridional wind are ignored predicts that stationary Rossby waves cannot propagate across easterlies. To elucidate the underlying mechanisms responsible for this interhemispheric teleconnection, the theoretical basis for stationary wave propagation across the critical latitude is considered, taking into account meridional ambient flow. The theoretical results suggest that the southerly flow over East Africa, the western Indian Ocean, and South Asia creates a path for the northward propagation of stationary waves across the critical latitude. Stationary wavenumber and group velocity analysis, ray tracing, and simple model experiments applied to nearly realistic boreal winter mean flows confirm that disturbances excited in southern Africa and the western Indian Ocean can propagate across the critical latitude to South Asia through the southerly duct and then continue downstream along the North African–Asian subtropical jet.

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