Ancient Analogues for Recent Environmental Changes at Lake Victoria, East Africa

1998 ◽  
pp. 37-46 ◽  
Author(s):  
J. C. Stager
Keyword(s):  
East Africa ◽  
Environmental Changes ◽  
Lake Victoria

scholarly journals Prolific Lightning and Thunderstorm Initiation over the Lake Victoria Basin in East Africa

2020 ◽  
Vol 148 (5) ◽  
pp. 1971-1985 ◽  
Author(s):  
Katrina S. Virts ◽  
Steven J. Goodman
Keyword(s):  
East Africa ◽  
Hot Spots ◽  
Seasonal Cycle ◽  
Lake Victoria ◽  
Intertropical Convergence Zone ◽  
Lake Victoria Basin ◽  
The Earth ◽  
Total Lightning ◽  
Average Cluster

Abstract The Lake Victoria basin of East Africa is home to over 30 million people, over 200 000 of whom are employed in fishing or transportation on the lake. Approximately 3000–5000 individuals are killed by thunderstorms yearly, primarily by outflow winds and resulting large waves. Prolific lightning activity and thunderstorm initiation in the basin are examined using continuous total lightning observations from the Earth Networks Global Lightning Network (ENGLN) for September 2014–August 2018. Seasonal shifts in the intertropical convergence zone produce semiannual lightning maxima over the lake. Diurnally, solar heating and lake and valley breezes produce daytime lightning maxima north and east of the lake, while at night the peak lightning density propagates southwestward across the lake. Cluster analysis reveals terrain-related thunderstorm initiation hot spots northeast of the lake; clusters also initiate over the lake and northern lowlands. The most prolific clusters initiate between 1100 and 1400 LT, about 1–2 h earlier than the average cluster. Most daytime thunderstorms dissipate without reaching Lake Victoria, and annually 85% of clusters producing over 1000 flashes over Lake Victoria initiate in situ. Initiation times of prolific Lake Victoria clusters exhibit a bimodal seasonal cycle: equinox-season thunderstorms initiate most frequently between 2200 and 0400 LT, while solstice-season thunderstorms initiate most frequently from 0500 to 0800 LT, more than 12 h after the afternoon convective peak over land. More extreme clusters are more likely to have formed over land and propagated over the lake, including 36 of the 100 most extreme Lake Victoria thunderstorms. These mesoscale clusters are most common during February–April and October–November.

scholarly journals Expressions of climate perturbations in western Ugandan crater lake sediment records during the last 1000 yr

2013 ◽  
Vol 9 (5) ◽  
pp. 5183-5226 ◽  
Author(s):  
K. Mills ◽  
D. B. Ryves ◽  
N. J. Anderson ◽  
C. L. Bryant ◽  
J. J. Tyler
Keyword(s):  
Environmental Change ◽  
East Africa ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Ice Age ◽  
Ecosystem Response ◽  
Large Lakes ◽  
Crater Lakes ◽  
Continental Scale ◽  
Western Uganda

Abstract. Equatorial East Africa has a complex, regional patchwork of climate regimes, with multiple interacting drivers. Recent studies have focussed on large lakes and reveal signals that are smoothed in both space and time, and, whilst useful at a continental scale, are of less relevance when understanding short-term, abrupt or immediate impacts of climate and environmental changes. Smaller-scale studies have highlighted spatial complexity and regional heterogeneity of tropical palaeoenvironments in terms of responses to climatic forcing (e.g. the Little Ice Age [LIA]) and questions remain over the spatial extent and synchroneity of climatic changes seen in East African records. Sediment cores from paired crater lakes in western Uganda were examined to assess ecosystem response to long-term climate and environmental change as well as testing responses to multiple drivers using redundancy analysis. These archives provide annual to sub-decadal records of environmental change. The records from the two lakes demonstrate an individualistic response to external (e.g. climatic) drivers, however, some of the broader patterns observed across East Africa suggest that the lakes are indeed sensitive to climatic perturbations such as a dry Mediaeval Climate Anomaly (MCA; 1000–1200 AD) and a relatively drier climate during the main phase of the LIA (1500–1800 AD); though lake levels in western Uganda do fluctuate. The relationship of Ugandan lakes to regional climate drivers breaks down c. 1800 AD, when major changes in the ecosystems appear to be a response to sediment and nutrient influxes as a result of increasing cultural impacts within the lake catchments. The data highlight the complexity of individual lake response to climate forcing, indicating shifting drivers through time. This research also highlights the importance of using multi-lake studies within a landscape to allow for rigorous testing of climate reconstructions, forcing and ecosystem response.

scholarly journals Imagining ‘Atlanta’: The Cultural Politics and Poetics of Experimental Medicine in East Africa

2014 ◽  
Vol 20 (1) ◽  
Author(s):  
Denielle Elliott
Keyword(s):  
East Africa ◽  
State Of The Art ◽  
Lake Victoria ◽  
Field Research ◽  
Experimental Medicine ◽  
Research Station ◽  
Scientific Practices ◽  
Global Science ◽  
Rural Town ◽  
The Social

In East Africa there is a field research station that locals call ‘Atlanta.’ It sits on the outskirts of a rural town, near Lake Victoria, equipped with ‘state-of-the-art’ biotechnological and entomological equipment for monitoring and exploring malaria, HIV, tuberculosis, rotavirus, and other tropical diseases. Drawn from ethnographic fieldwork with clinical trials in East Africa, this paper considers the stories people tell about the landscapes and spaces of experimental medicine to explore the uneven movement of knowledge, scientific practices, and scientists in global medicine. I begin this analytical journey at ‘Atlanta’ to consider what local idioms about such places might tell us about the encounters and travels of science and scientists in East Africa. Last, I draw attention to the social and material effects of global science projects on the lives and landscapes of East Africa.

Late Palæolithic Finds in East Africa

1924 ◽  
Vol 4 (2) ◽  
pp. 177-178
Author(s):  
M. C. Burkitt
Keyword(s):  
South Africa ◽  
East Africa ◽  
Lake Victoria ◽  
Stone Age ◽  
Upper Palaeolithic ◽  
Cambridge University ◽  
Group 2 ◽  
University Museum ◽  
Cultural Movement ◽  
Late Palaeolithic

Whilst engaged in arranging the Stone Age collections of the Cambridge University Museum of Archæology and Ethnology a series of implements from Naivasha “turned up.” This locality lies a little to the East of lake Victoria Nyanza. The tools shew certain Upper Palæolithic characters and it is therefore important to note their existence. Some folk consider the continent of Africa to be a museum of cultures, others a cradle. In either case it is necessary to collect any information as to the possible lines of cultural movement. The paintings of the Spanish group 2 in rock shelters in Eastern Spain are in all probability quaternary in age and date from some moment in Upper Palæolithic times; but the Bushman art of South Africa bears such a remarkable resemblance to this Eastern Spanish group, both generally and in detail, that some connection between the artists who made them seems probable—perhaps both were derived from the same late Palæolithic stock, the Bushman being a survival to our own day.

scholarly journals Validation of IMERG Precipitation in Africa

2017 ◽  
Vol 18 (10) ◽  
pp. 2817-2825 ◽  
Author(s):  
Amin K. Dezfuli ◽  
Charles M. Ichoku ◽  
George J. Huffman ◽  
Karen I. Mohr ◽  
John S. Selker ◽  
...  
Keyword(s):  
East Africa ◽  
Annual Cycle ◽  
Lake Victoria ◽  
Mountainous Regions ◽  
Meteorological Observatory ◽  
Precipitation Analysis ◽  
In Situ Observations ◽  
Short Rains ◽  
Good Agreement

Abstract Understanding of hydroclimatic processes in Africa has been hindered by the lack of in situ precipitation measurements. Satellite-based observations, in particular, the TRMM Multisatellite Precipitation Analysis (TMPA) have been pivotal to filling this void. The recently released Integrated Multisatellite Retrievals for GPM (IMERG) project aims to continue the legacy of its predecessor, TMPA, and provide higher-resolution data. Here, IMERG-V04A precipitation data are validated using in situ observations from the Trans-African Hydro-Meteorological Observatory (TAHMO) project. Various evaluation measures are examined over a select number of stations in West and East Africa. In addition, continent-wide comparisons are made between IMERG and TMPA. The results show that the performance of the satellite-based products varies by season, region, and the evaluation statistics. The precipitation diurnal cycle is relatively better captured by IMERG than TMPA. Both products exhibit a better agreement with gauge data in East Africa and humid West Africa than in the southern Sahel. However, a clear advantage for IMERG is not apparent in detecting the annual cycle. Although all gridded products used here reasonably capture the annual cycle, some differences are evident during the short rains in East Africa. Direct comparison between IMERG and TMPA over the entire continent reveals that the similarity between the two products is also regionally heterogeneous. Except for Zimbabwe and Madagascar, where both satellite-based observations present a good agreement, the two products generally have their largest differences over mountainous regions. IMERG seems to have achieved a reduction in the positive bias evident in TMPA over Lake Victoria.

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