Impact of Mascarene High variability on the East African ‘short rains’

Manatsa, Desmond; Morioka, Yushi; Behera, Swadhin K.; Matarira, C. H.; Yamagata, Toshio

doi:10.1007/s00382-013-1848-z

Cited by 59 publications

(52 citation statements)

References 30 publications

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“…2a). Many studies on the variability of the location and strength of the Mascarene High (Terray et al 2003;Suzuki et al 2004;Xue et al 2004;Fischer et al 2005;Feng et al 2013;Manatsa et al 2014;Morioka et al 2015) have noted that the Mascarene High influences monsoonal flow and SST variation over the Indian Ocean. According to the large-scale environmental conditions shown here, the weakening and southward shift of the Mascarene High could be one of the favorable environmental conditions enabling the MJO onset to break the convective suppressed period of P1 over the equatorial Indian Ocean.…”

Section: Large-scale Environmental Conditions Aroundmentioning

confidence: 99%

Equatorially Antisymmetric Features in the Initiation Processes of the Madden-Julian Oscillation Observed in Late October during CINDY2011

Moteki

2015

Journal of the Meteorological Society of Japan

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In this study, we investigated the equatorially antisymmetric features in the initiation processes of the MaddenJulian oscillation (MJO) event in late October during the cooperative Indian Ocean experiment on intraseasonal variability in the year 2011. This MJO event developed when the thermal equator was drastically shifted from the Northern Hemisphere to the equator from September to October as the Mascarene High over the southern Indian Ocean decayed and shifted southward. The large-scale fields of sea level pressure, temperature, and moisture around the MJO exhibited equatorially antisymmetric features. According to their different features in terms of surface convergence, temperature, and moisture, MJO convection over the Indian Ocean after its onset consisted of four distinct convective components: the southern intertropical convergence zone between 10°S and 0° along the meridional sea surface temperature (SST) gradients (s-ITCZ), the northern-ITCZ at the southern edge of the high SST above 29°C over the Bay of Bengal, the vortex disturbance over the Arabian Sea (VDAS) in association with the zonal SST gradients, and the westward-propagating diurnal convection originating from Sumatra. In particular, the double-ITCZ and VDAS were characterized by a steady, low-level convergence zone along the surface potential temperature gradients forced by the SST. Before the onset of the MJO convection, the double-ITCZ was characterized by cross-equatorial vertical circulation that was baroclinically tilted northward, and s-ITCZ convection was inhibited owing to the strong Mascarene High. After the onset, single, larger-scale upward motion was barotropically formed over the equator because of the equatorward shift of the double-ITCZ. Such changes in the equatorially antisymmetric meridional circulation are relevant for the organization of the MJO convection.

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Section: Large-scale Environmental Conditions Aroundmentioning

confidence: 99%

Equatorially Antisymmetric Features in the Initiation Processes of the Madden-Julian Oscillation Observed in Late October during CINDY2011

Moteki

2015

Journal of the Meteorological Society of Japan

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“…However, the influence of these systems on seasonal and annual rainfall over East Africa has not been intensively investigated. A recent study by Manatsa et al (2014) on impact of Mascarene High (MH) variability on the East African 'short rains' established that droughts in East Africa are associated with a westward migration of the MH eastern ridge. However, the study pointed out that the relationship between MH and flood events and their link to an eastward migration of the MH is unclear.…”

Section: Introductionmentioning

confidence: 99%

“…The weather over East Africa is also influenced by the four high pressure systems: Mascarene, St. Hellena, Azores and Arabian Ridge (Manatsa, et al 2014;Sun, et al, 1999). The weather systems have been widely used in short to extended -range forecasting (Sun, et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Influence of Mascarene High and Indian Ocean dipole on East African extreme weather events

Xiao¹,

Ogou²

2015

Geogr Pannon

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“…Manatsa et al . () have shown that precipitating convective systems on the African coast are mainly associated with the ITCZ, but are also influenced by local factors (orography, presence of lakes, oceanic influence) and by the southeasterly trade winds associated with the variability of the Mascarene High (Figure ). These two regions of strong deep convective activity also correspond to the location of the maximum lightning activity in the southwest Indian Ocean (Bovalo et al ., ), at (8°S–16°S; 35°E–40°E) and at (12°S–20°S; 45°E–50°E).…”

Section: Seasonal Cloud Distribution Over the Southwest Indian Oceanmentioning

confidence: 99%

Spatial and seasonal variability of clouds over the southwest Indian Ocean based on the DARDAR mask product

Vérèmes

Listowski

Delanoë

et al. 2019

Quart J Royal Meteoro Soc

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We present a characterization of the variability of clouds over the southwest Indian Ocean between 2007 and 2010. Cloud occurrence is derived from the DARDAR (raDAR/liDAR) mask, a synergistic product based on Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat measurements. It provides a target classification for hydrometeors. We demonstrate that this product is suitable for studying the vertical, spatial and seasonal cloud distribution in the southwest Indian Ocean. The variability of cloud occurrence increases approaching the tropics: the average maximum amplitude of monthly occurrence is ∼7% between 30°S and 60°S and ∼14% between 10°S and 30°S. The 10–30°S latitudinal band exhibits the largest contrasts: summer (winter) total cloud occurrence is mainly driven by high‐ (low‐) level clouds. The vertical distribution of clouds differs on either side of 55°E and this is related to a land–ocean contrast and to large‐scale influence. In winter, east of 55°E, the maximum of cloud occurrence corresponds to warm and mixed‐phased precipitating clouds associated with the Mascarene High. In summer, west of 55°E, the vertical distribution of cloud occurrence is driven by deep convection associated with the InterTropical Convergence Zone and the Near Equatorial Trough. The vertical distribution of cloud occurrence shows an interannual variability that is related to El Niño events. The influence of other oscillation modes should be further investigated.

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Impact of Mascarene High variability on the East African ‘short rains’

Cited by 59 publications

References 30 publications

Equatorially Antisymmetric Features in the Initiation Processes of the Madden-Julian Oscillation Observed in Late October during CINDY2011

Equatorially Antisymmetric Features in the Initiation Processes of the Madden-Julian Oscillation Observed in Late October during CINDY2011

Influence of Mascarene High and Indian Ocean dipole on East African extreme weather events

Spatial and seasonal variability of clouds over the southwest Indian Ocean based on the DARDAR mask product

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