C.J.deW. Rautenbach

A hypothetical approach to determining the effect of palaeorotational rates on Earth's Neoproterozoic palaeoclimate

Abstract Revolving at a present rotation rate of approximately one revolution every 24 h, the Earth is regarded as a non-stationary sphere in space, covered with an extremely thin atmosphere in comparison with its radius. Apart from the frequency endorsed by the diurnal rotation rate, the Earth is also subject to other cycles on the seasonal and annual scales. Spatial and temporal climate variability are strongly influenced by these cycles. In this study the consequence of current and palaeorotational rates on the Earths climate is explored. This is achieved by comparing results from atmospheric general circulation model (AGCM) simulations with present-day and palaeorotational rates. An estimated Neoproterozoic (900 Ma) palaeorotational rate related to an 18.2-h diurnal cycle has been introduced. To conserve internal energy balances in the Earth–atmosphere system, and to avoid uncertainties concerning palaeocontinental and ocean distribution, the present land–sea–atmosphere configuration has been retained. As a result of these constraints, only deviations in the average of planetary scale atmospheric circulation patterns, such as the vertical profile of the zonal average of meridional and zonal wind fields, are explored. Results are consistent with previous findings, suggesting an equatorward latitudinal shift of planetary scale circulation cells, accompanied by reduced wind speed components throughout the atmosphere, when the 900 Ma palaeorotational rate is employed in the AGCM simulation.

The nature of rainfall in the main drainage sub-basins of Uganda

Abstract A study of rainfall trends and temporal variations within seven sub-basins of Uganda spanning from 1940 to 2009 has been made. Rainfall climatologies are constructed from observational data, using 36 station records which reflect hydroclimatic conditions. Long-term changes in rainfall characteristics were determined by non-parametric tests (Mann-Kendall and Sen’s T tests), coefficient of variation (CV), precipitation concentration index and drought severity index. Magnitude of change was estimated by applying Sen’s estimator of slope. Decadal variability of rainfall with marked seasonal cycles is evident. Temporal variability of drought patterns is detected. Variations in annual rainfall are low with no significant trends observed in the main drainage sub-basins. Significant trends occur in October, November, December and January. A noticeable decrease in the annual total rainfall was observed mostly in northwestern and southwestern sub-basins. Rainfall trend in the second normal of June–July–August (JJA) was decreasing in all the main drainage sub-basins. Editor Z.W. Kundzewicz; Associate editor S. Yue Citation Nsubuga, F.W.N., Botai, O.J., Olwoch, J.M., Rautenbach, C.J.deW., Bevis, Y., and Adetunji, A.O., 2014. The nature of rainfall in the main drainage sub-basins of Uganda. Hydrological Sciences Journal, 59 (2), 278–299.

Detecting changes in surface water area of Lake Kyoga sub-basin using remotely sensed imagery in a changing climate

Detection of changes in Earth surface features, for example lakes, is important for understanding the relationships between human and natural phenomena in order to manage better the increasingly scarce natural resources. This work presents a procedure of using modified normalised difference water index (MNDWI) to detect fluctuations of lake surface water area and relate it to a changing climate. The study used radiometrically and geometrically rectified Landsat images for 1986, 1995 and 2010 encompassing the Kyoga Basin lakes of Uganda, in order to investigate the changes in surface water area between the respective years. The standard precipitation index (SPI) and drought severity index (DSI) are applied to show the relationship between variability of surface water area and climate parameters. The present analysis reveals that surface water area fluctuation is linked to rainfall variability. In particular, Lake Kyoga sub-basin lakes experienced an increase in surface water area in 2010 compared to 1986. This work has important implications to water resources management for Lake Kyoga and could be vital to water resource managers across Ugandan lakes.

A micro-meteorological experiment in the atmospheric boundary layer in Highveld region

Meteorology of the planetary boundary layer (PBL) is to large extent determined by turbulent processes. Those processes and their interaction with surface properties are not well understood. The processes over heterogeneous land surfaces are understood even less. To progress in the understanding simultaneous observations with a network of meteorological stations are needed. A joint project between Norwegian and South African research foundations funded a micrometeorological experiment in the Highveld area of the South Africa (MMEH). The experiment has been organized to collect data from 5 automatic meteorological stations placed at 7 km to 23 km separation distances from each other. The data were collected continuously over 2 years. This paper presents the idea, the theoretical background and the organization of the MMEH.

Industrial development zone and South African environmental legal initiatives post-1994: a quest for sustainable industrial development

Many developing countries are currently undergoing increased industrialization, which has accelerated environmental degradation. This study aims to examine South Africas industrial development path as a socio-economic strategy pursued along the rill-lines of sustainable industrial development (SID) in view of the post-1994 environmental legislative initiatives. An exploratory review guided the study analysis. As industrial development zones (IDZs), environmental sustainability research is virtually non-existent, leading to the poor understanding of this programmes role in SID. This study reveals that the government political commitment, 1996 South Africas Constitution and National Environmental Act (No. 107 of 1998) are key pillars reconciling the environment and industrial development in diffusing apartheid legacies. Non-compliances re-occur in industries outside the IDZs due to shortage of environmental monitoring inspectors and government priorities changes. Therefore, there is need to ‘green’ IDZ stakeholders for proper environmental legislation implementation. Finally, the study highlights new potential directions for research into SID zoning.

CSIR-NLC mobile LIDAR for atmosphere remote sensing

A mobile LIDAR (LIght Detection And Ranging) system is being developed and employed for atmosphere remote sensing at the Council for Scientific and Industrial Research (CSIR) National Laser Centre (NLC), Pretoria (25.45 S; 28.16 E), South Africa. In this paper, we describe the results obtained using the CSIR-NLC mobile LIDAR in a 23 hour field campaign at the University of Pretoria.