SENSITIVITY OF VEGETATION (NDVI) TO CLIMATE OVER SOUTHERN AFRICA: RELATIONSHIPS WITH SUMMER RAINFALL AND OLR

1997 ◽  
Vol 79 (1) ◽  
pp. 52-60 ◽  
Author(s):  
M. P. GONDWE ◽  
M. R. JURY
Keyword(s):  
Southern Africa ◽  
Summer Rainfall

scholarly journals The Role of Mesoscale Convective Complexes in Southern Africa Summer Rainfall

2013 ◽  
Vol 26 (5) ◽  
pp. 1654-1668 ◽  
Author(s):  
R. C. Blamey ◽  
C. J. C. Reason
Keyword(s):  
South Africa ◽  
Southern Africa ◽  
Rainfall Variability ◽  
Warm Season ◽  
Tropical Rainfall Measuring Mission ◽  
Summer Rainfall ◽  
Spatial And Temporal Variability ◽  
Eastern Region ◽  
Southwest Indian Ocean ◽  
Mesoscale Convective

Abstract A combination of numerous factors, including geographic position, regional orography, and local sea surface temperatures, means that subtropical southern Africa experiences considerable spatial and temporal variability in rainfall and is prone to both frequent flooding and drought events. One system that may contribute to rainfall variability in the region is the mesoscale convective complex (MCC). In this study, Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) data is used to document the precipitation produced by MCCs over southern Africa for the 1998–2006 period. Most of the rainfall associated with MCCs is found to occur over central Mozambique, extending southward to eastern South Africa. High precipitation totals associated with these systems also occur over the neighboring southwest Indian Ocean, particularly off the northeast coast of South Africa. MCCs are found to contribute up to 20% of the total summer rainfall (November–March) in parts of the eastern region of southern Africa. If the month of March is excluded from the analysis, then the contribution increases up to 24%. In general, the MCC summer rainfall contribution for most of the eastern region is approximately between 8% and 16%. Over the western interior and Botswana and Namibia, the MCC contribution is much less (<6%). It is also evident that there is considerable interannual variability associated with the contribution that these systems make to the total warm season rainfall.

Elemental proxy evidence for late Quaternary palaeoenvironmental change in southern African sedimentary records: interpretation and applications

2021 ◽  
Author(s):  
M.S. Humphries
Keyword(s):  
Environmental Change ◽  
Southern Africa ◽  
Southern Oscillation ◽  
Late Quaternary ◽  
Rainfall Variability ◽  
Analytical Techniques ◽  
Summer Rainfall ◽  
Geochemical Data ◽  
Complex Nature ◽  
Cape Coast

Abstract Sediments are the most important source of Late Quaternary palaeoclimate information in southern Africa, but have been little studied from a geochemical perspective. However, recent advances in analytical techniques that allow rapid and near-continuous elemental records to be obtained from sedimentary sequences has resulted in the increasing use of elemental indicators for reconstructing climate. This paper explores the diverse information that can be acquired from the inorganic component of sediments and reviews some of the progress that has been made over the last two decades in interpreting the climatic history of southern Africa using elemental records. Despite the general scarcity of elemental records, excellent examples from the region exist, which provide some of the longest and most highly resolved sequences of environmental change currently available. Records from Tswaing crater and marine deposits on the southern KwaZulu-Natal coastline have provided rare glimpses into hydroclimate variability over the last 200 000 years, suggesting that summer rainfall in the region responded predominantly to insolation forcing on glacial-interglacial timescales. Over shorter timescales, lakes and wetlands found in the Wilderness embayment on the southern Cape coast and along the Maputaland coast in north-eastern South Africa have yielded highly-resolved elemental records of Holocene environmental change, providing insight into the changing interactions between tropical (e.g., El Niño-Southern Oscillation) and temperate (e.g., mid-latitude westerlies) climate systems affecting rainfall variability in the region. The examples discussed demonstrate the multiple environmental processes that can be inferred from elemental proxies and the unique insight this can provide in advancing our understanding of past climate change on different timescales. The interpretation of geochemical data can be complicated by the complex nature of sedimentary environments, various proxy assumptions and analytical challenges, and the reliability of sediment-based climate reconstructions is substantially enhanced through multi-proxy approaches.

scholarly journals Systematic Climate Model Rainfall Biases over Southern Africa: Links to Moisture Circulation and Topography

2018 ◽  
Vol 31 (18) ◽  
pp. 7533-7548 ◽  
Author(s):  
C. Munday ◽  
R. Washington
Keyword(s):  
Southern Africa ◽  
Climate Models ◽  
Climate Model ◽  
Regional Scale ◽  
Model Development ◽  
Coupled Model ◽  
Climate Science ◽  
Summer Rainfall ◽  
Southwest Indian Ocean ◽  
Low Level

An important challenge for climate science is to understand the regional circulation and rainfall response to global warming. Unfortunately, the climate models used to project future changes struggle to represent present-day rainfall and circulation, especially at a regional scale. This is the case in southern Africa, where models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) overestimate summer rainfall by as much as 300% compared to observations and tend to underestimate rainfall in Madagascar and the southwest Indian Ocean. In this paper, we explore the climate processes associated with the rainfall bias, with the aim of assessing the reliability of the CMIP5 ensemble and highlighting important areas for model development. We find that the high precipitation rates in models that are wet over southern Africa are associated with an anomalous northeasterly moisture transport (~10–30 g kg−1 s−1) that penetrates across the high topography of Tanzania and Malawi and into subtropical southern Africa. This transport occurs in preference to a southeasterly recurvature toward Madagascar that is seen in drier models and reanalysis data. We demonstrate that topographically related model biases in low-level flow are important for explaining the intermodel spread in rainfall; wetter models have a reduced tendency to block the oncoming northeasterly flow compared to dry models. The differences in low-level flow among models are related to upstream wind speed and model representation of topography, both of which should be foci for model development.

scholarly journals Die struktuur en moontlike aandrywingskragte van die 1991 - 1992 - droogte in Suidelike Afrika

1993 ◽  
Vol 12 (1) ◽  
pp. 8-16 ◽  
Author(s):  
M. R. Jury
Keyword(s):  
Indian Ocean ◽  
Southern Africa ◽  
Walker Circulation ◽  
Summer Rainfall ◽  
Sea Surface ◽  
Diagnostic Model ◽  
Sea Surface Temperatures ◽  
Moist Air ◽  
Atmospheric Processes ◽  
The Mean

A diagnostic model is used to investigate the underlying atmospheric processes that gave rise to the 1991-1992 drought over Southern Africa. The first indicator of the impending drought was a rise of more than 1 °C in the sea surface temperatures of the tropical part of the Southern Indian Ocean in the winter of 1991. This may have been instrumented in causing an anomaly in the mean Walker circulation to develop, through which the inflow of warm, moist air from the Mozambique Channel to the eastern escarpment of Southern Africa was inhibited, with a concurrent reduction in rainfall. It is concluded that the pattern and cycles of summer rainfall over Southern Africa are now sufficiently well understood to venture tentative predictions, but that increased co-operation between the meteorological bodies of Southern Africa will be required to achieve this.

The Influence on Summer Rainfall in the Lesotho Lowlands from Indian Ocean SSTs

2002 ◽  
Vol 33 (4) ◽  
pp. 305-318 ◽  
Author(s):  
Lars Hydén
Keyword(s):  
Indian Ocean ◽  
Southern Africa ◽  
Rainfall Variability ◽  
Austral Summer ◽  
Equatorial Indian Ocean ◽  
Summer Rainfall ◽  
Significant Negative Correlation ◽  
Annual Rainfall ◽  
Ocean Area ◽  
The Indian Ocean

Lesotho is located approximately at latitude 30 degrees south in the interior of Southern Africa. The mesoscale climate is complicated and governed by various weather systems. The inter-annual rainfall variability is great, resulting in low food security, since the growing of crops in the Lesotho Lowlands is almost exclusively rain-fed. Reliable forecasts of austral summer rainfall are thus valuable. Earlier research has shown that the sea surface temperatures (SST) in the Indian Ocean to some extent govern rainfall in Southern Africa. The research presented is part of an on-going project to find suitable oceanographic and meteorological predictors, which can be used in a forecast model for summer rainfall, to be developed later. The first part of this paper investigates the correlation between the average SSTs in the Equatorial Indian Ocean, the Central Indian Ocean, and the Agulhas Gyre, respectively, and rainfall two months later in the Lesotho Lowlands during early austral summer, October until December for the period 1949-1995. No significant correlations have been found, probably because the three ocean areas are too large. In the second part of this paper the monthly SST in 132 grid squares in the Indian Ocean were investigated and found to be correlated with rainfall in the Lesotho Lowlands two months later, October until March. Significant correlations have been found between the SSTs and certain ocean areas and December, January, and February rainfall, respectively. There is significant negative correlation between December rainfall and October SST in an ocean area between Kenya and Somalia across the Indian Ocean to Sumatra. In the area where the Somali Current flows there is also significant correlation between December SST and December rainfall. January rainfall is significantly negatively correlated with November SST in an ocean area, northeast of Madagascar. February rainfall is significantly, but weakly, negatively correlated with SST in a narrow north-south corridor in the Eastern Indian Ocean from the equator down to latitude 40 degrees south.

Studies in the genus Riccia (Marchantiales) from southern Africa. 25. A new species in subgenus Ricciella, section Ricciella

Bothalia ◽  
2001 ◽  
Vol 31 (2) ◽  
pp. 151-154 ◽  
Author(s):  
S. M. Perold
Keyword(s):  
New Species ◽  
Southern Africa ◽  
Summer Rainfall ◽  
Storage Tissue ◽  
Dorsal Epidermis ◽  
A New Species ◽  
Median Layer

Riccia sibayenii Perold is a new species, recently collected in Mpumalanga, near Sibayeni and has been named for this town, which is close to the Mozambique border and is in the summer rainfall area.  R. sibayenii is distinguished by lime- green, medium-sized to quite large thalli with a chlorophyllose dorsal epidermis, air pores that soon enlarge and lead into mostly 6-sided air chambers below; ventrally with a thin median layer of storage tissue; ventral scales absent and the rhizoids all smooth. The spores are winged and polar, the distal face completely or incompletely reticulate and the proxi­mal face ornamented with fine to coarse, sometimes spinose granules.

A taxonomic review of the dry-fruited species of Anemone (Ranunculaceae) in southern Africa

Bothalia ◽  
2013 ◽  
Vol 43 (1) ◽  
pp. 1-14 ◽  
Author(s):  
J. C. Manning ◽  
P. Goldblatt
Keyword(s):  
Southern Africa ◽  
Summer Rainfall ◽  
Cape Floristic Region ◽  
Taxonomic Review ◽  
Taxonomic History

The three dry-fruited species of Anemone sect. Pulsatilloides subsect. Alchemillifoliae (Ranunculaceae) from southern Africa are reviewed, with full descriptions and nomenclature, including complete synonomy, taxonomic history with nomenclatural corrections, ecological notes, and distribution. A. tenuifolia (L.f.) DC. from the Cape Floristic Region is segregated as ser. Pinnatifoliae from the two summer rainfall species, A. caffra (Eckl. Zeyh.) Harv. and A. fanninnii Harv. ex Masters, which remain in ser. Alchemillifoliae, emphasising the strong vegetative differences between the two series.

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