scholarly journals Smoke in the river: an AEROCLO-sA case study

2021 ◽  
Author(s):  
Cyrille Flamant ◽  
Marco Gaetani ◽  
Jean-Pierre Chaboureau ◽  
Patrick Chazette ◽  
Juan Cuesta ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Southern Africa ◽  
Average Height ◽  
Pressure System ◽  
Vertical Extent ◽  
Easterly Wave ◽  
Biomass Burning Aerosol ◽  
Complementary Set ◽  
Southwestern Indian Ocean

Abstract. The formation of a river of smoke crossing southern Africa is investigated during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) campaign in September 2017. A complementary set of global and mesoscale numerical simulations as well as ground-based, airborne and space-borne observations of the dynamics, thermodynamics and composition of the atmosphere are used to characterize the river of smoke in terms of timing and vertical extent of the biomass burning aerosol (BBA) layer. The study area was under the synoptic influence of a coastal low rooted in a tropical easterly wave, a high-pressure system over the continent and westerly waves in mid-latitudes, one of which had an embedded cut-off low (CoL). The coastal low interacted with the second of two approaching westerly waves and ultimately formed a mid-level temperate tropical trough (TTT). The TTT created the fast moving air mass transported to the southwestern Indian Ocean as a river of smoke. The CoL, which developed and intensified in the upper levels associated with the first (easternmost) westerly wave, remained stationary above northern Namibia prior to the formation of the TTT and was responsible for the thickening of the BBA layer. This shows that the evolution of the river of smoke is very much tied to the evolution of the TTT while its vertical extent is related to the presence of the CoL. The mechanisms by which the CoL, observed over Namibia in the entrance region of the river of smoke, influences the vertical structure of the BBA layer is mainly associated with the ascending motion above the BBA layer. In the presence of the CoL, the top of the BBA layer over northern Namibia reaches altitudes above 8 km. This is much higher than the average height of the top of the BBA layer over the regions where the smoke comes from (Angola, Zambia, Zimbabwe, Mozambique) which is 5 to 6 km. The results suggest that the interaction between the TTTs and the CoLs which form during the winter may have a role in promoting the transport of BBA from fire-prone regions in the tropical band to the temperate mid-latitudes and southwestern Indian Ocean.

scholarly journals Potential Sources of Decadal Climate Variability over Southern Africa

2015 ◽  
Vol 28 (22) ◽  
pp. 8695-8709 ◽  
Author(s):  
Yushi Morioka ◽  
Francois Engelbrecht ◽  
Swadhin K. Behera
Keyword(s):  
Indian Ocean ◽  
Climate Variability ◽  
Southern Africa ◽  
South Atlantic ◽  
Decadal Climate Variability ◽  
The South ◽  
Sst Anomaly ◽  
Decadal Climate ◽  
Southwestern Indian Ocean ◽  
Sst Anomalies

Abstract Potential sources of decadal climate variability over southern Africa are examined by conducting in-depth analysis of available datasets and coupled general circulation model (CGCM) experiments. The observational data in recent decades show a bidecadal variability noticeable in the southern African rainfall with its positive phase of peak during 1999/2000. It is found that the rainfall variability is related to anomalous moisture advection from the southwestern Indian Ocean, where the anomalous sea level pressure (SLP) develops. The SLP anomaly is accompanied by anomalous sea surface temperature (SST). Both SLP and SST anomalies slowly propagate eastward from the South Atlantic to the southwestern Indian Ocean. The analysis of mixed layer temperature tendency reveals that the SST anomaly in the southwestern Indian Ocean is mainly due to eastward advection of the SST anomaly by the Antarctic Circumpolar Current. The eastward propagation of SLP and SST anomalies are also confirmed in the 270-yr outputs of the CGCM control experiment. However, in a sensitivity experiment where the SST anomalies in the South Atlantic are suppressed by the model climatology, the eastward propagation of the SLP anomaly from the South Atlantic disappears. These results suggest that the local air–sea coupling in the South Atlantic may be important for the eastward propagation of the SLP anomaly from the South Atlantic to the southwestern Indian Ocean. Although remote influences from the tropical Pacific and Antarctica were widely discussed, this study provides new evidence for the potential role of local air–sea coupling in the South Atlantic for the decadal climate variability over southern Africa.

Isotopic niches of the blue shark Prionace glauca and the silky shark Carcharhinus falciformis in the southwestern Indian Ocean

2012 ◽  
Vol 17 (1) ◽  
pp. 83-92 ◽  
Author(s):  
N Rabehagasoa ◽  
A Lorrain ◽  
P Bach ◽  
M Potier ◽  
S Jaquemet ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Silky Shark ◽  
Carcharhinus Falciformis ◽  
Southwestern Indian Ocean

THE ROLE OF EDUCATION ON DISASTER PREPAREDNESS CASE STUDY OF 2012 INDIAN OCEAN EARTHQUAKES ON THAILAND’S

2018 ◽  
Author(s):  
Raya Muttarak ◽  
Wiraporn Pothisiri
Keyword(s):  
Indian Ocean ◽  
Emergency Preparedness ◽  
Disaster Preparedness ◽  
Formal Education ◽  
Disaster Experience ◽  
Individual Household ◽  
The Indian Ocean ◽  
The Individual

In this paper we investigate how well residents of the Andaman coast in Phang Nga province, Thailand, are prepared for earthquakes and tsunami. It is hypothesized that formal education can promote disaster preparedness because education enhances individual cognitive and learning skills, as well as access to information. A survey was conducted of 557 households in the areas that received tsunami warnings following the Indian Ocean earthquakes on 11 April 2012. Interviews were carried out during the period of numerous aftershocks, which put residents in the region on high alert. The respondents were asked what emergency preparedness measures they had taken following the 11 April earthquakes. Using the partial proportional odds model, the paper investigates determinants of personal disaster preparedness measured as the number of preparedness actions taken. Controlling for village effects, we find that formal education, measured at the individual, household, and community levels, has a positive relationship with taking preparedness measures. For the survey group without past disaster experience, the education level of household members is positively related to disaster preparedness. The findings also show that disaster related training is most effective for individuals with high educational attainment. Furthermore, living in a community with a higher proportion of women who have at least a secondary education increases the likelihood of disaster preparedness. In conclusion, we found that formal education can increase disaster preparedness and reduce vulnerability to natural hazards.

scholarly journals Circulation pattern controls of wet days and dry days in Free State, South Africa

2021 ◽  
Author(s):  
Chibuike Chiedozie Ibebuchi
Keyword(s):  
South Africa ◽  
Indian Ocean ◽  
Atmospheric Circulation ◽  
Southern Africa ◽  
Austral Summer ◽  
Free State ◽  
Austral Spring ◽  
Study Region ◽  
Southwest Indian Ocean ◽  
South Indian

AbstractAtmospheric circulation is a vital process in the transport of heat, moisture, and pollutants around the globe. The variability of rainfall depends to some extent on the atmospheric circulation. This paper investigates synoptic situations in southern Africa that can be associated with wet days and dry days in Free State, South Africa, in addition to the underlying dynamics. Principal component analysis was applied to the T-mode matrix (variable is time series and observation is grid points at which the field was observed) of daily mean sea level pressure field from 1979 to 2018 in classifying the circulation patterns in southern Africa. 18 circulation types (CTs) were classified in the study region. From the linkage of the CTs to the observed rainfall data, from 11 stations in Free State, it was found that dominant austral winter and late austral autumn CTs have a higher probability of being associated with dry days in Free State. Dominant austral summer and late austral spring CTs were found to have a higher probability of being associated with wet days in Free State. Cyclonic/anti-cyclonic activity over the southwest Indian Ocean, explained to a good extent, the inter-seasonal variability of rainfall in Free State. The synoptic state associated with a stronger anti-cyclonic circulation at the western branch of the South Indian Ocean high-pressure, during austral summer, leading to enhanced low-level moisture transport by southeast winds was found to have the highest probability of being associated with above-average rainfall in most regions in Free State. On the other hand, the synoptic state associated with enhanced transport of cold dry air, by the extratropical westerlies, was found to have the highest probability of being associated with (winter) dryness in Free State.

THE ‘NATIVE’ UNDEFINED: COLONIAL CATEGORIES, ANGLO-AFRICAN STATUS AND THE POLITICS OF KINSHIP IN BRITISH CENTRAL AFRICA, 1929–38

2005 ◽  
Vol 46 (3) ◽  
pp. 455-478 ◽  
Author(s):  
CHRISTOPHER JOON-HAI LEE
Keyword(s):  
Southern Africa ◽  
Central Africa ◽  
Mixed Race ◽  
Court Case ◽  
Colonial State ◽  
Colonial Policy ◽  
Ultimate Failure ◽  
Definition Of ◽  
Determining Factor

This article examines the categorical problem that persons of ‘mixed-race’ background presented to British administrations in eastern, central and southern Africa during the late 1920s and 1930s. Tracing a discussion regarding the terms ‘native’ and ‘non-native’ from an obscure court case in Nyasaland (contemporary Malawi) in 1929, to the Colonial Office in London, to colonial governments in eastern, central and southern Africa, this article demonstrates a lack of consensus on how the term ‘native’ was to be defined, despite its ubiquitous use. This complication arrived at a particularly crucial period when indirect rule was being implemented throughout the continent. Debate centered largely around the issue of racial descent versus culture as the determining factor. The ultimate failure of British officials to arrive at a clear definition of the term ‘native’, one of the most fundamental terms in the colonial lexicon, is consequently suggestive of both the potential weaknesses of colonial state formation and the abstraction of colonial policy vis-à-vis local empirical conditions. Furthermore, this case study compels a rethinking of contemporary categories of analysis and their historical origins.

Geochemistry of gas emanations: A case study of the Réunion Hot Spot, Indian Ocean

1993 ◽  
Vol 8 (2) ◽  
pp. 141-152 ◽  
Author(s):  
B. Marty ◽  
V. Meynier ◽  
E. Nicolini ◽  
E. Griesshaber ◽  
J.P. Toutain
Keyword(s):  
Indian Ocean ◽  
Hot Spot

scholarly journals Forest fire danger rating in complex topography – results from a case study in the Bavarian Alps in autumn 2011

2013 ◽  
Vol 13 (9) ◽  
pp. 2157-2167 ◽  
Author(s):  
C. Schunk ◽  
C. Wastl ◽  
M. Leuchner ◽  
C. Schuster ◽  
A. Menzel
Keyword(s):  
Forest Fire ◽  
Temperature Inversion ◽  
Fire Danger ◽  
Complex Topography ◽  
Pressure System ◽  
Drought Period ◽  
Bavarian Alps ◽  
Forest Fire Danger ◽  
Fire Danger Indices

Abstract. Forest fire danger rating based on sparse meteorological stations is known to be potentially misleading when assigned to larger areas of complex topography. This case study examines several fire danger indices based on data from two meteorological stations at different elevations during a major drought period. This drought was caused by a persistent high pressure system, inducing a pronounced temperature inversion and its associated thermal belt with much warmer, dryer conditions in intermediate elevations. Thus, a massive drying of fuels, leading to higher fire danger levels, and multiple fire occurrences at mid-slope positions were contrasted by moderate fire danger especially in the valleys. The ability of fire danger indices to resolve this situation was studied based on a comparison with the actual fire danger as determined from expert observations, fire occurrences and fuel moisture measurements. The results revealed that, during temperature inversion, differences in daily cycles of meteorological parameters influence fire danger and that these are not resolved by standard meteorological stations and fire danger indices (calculated on a once-a-day basis). Additional stations in higher locations or high-resolution meteorological models combined with fire danger indices accepting at least hourly input data may allow reasonable fire danger calculations under these circumstances.

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