Source profiling, source apportionment and cluster transport analysis to identify the sources of PM and the origin of air masses to an industrialised rural area in Limpopo

The Greater Tubatse Municipality in Limpopo is home to three ferrochrome smelters and over fifteen operational mines which are mining chromium, platinum or silica. Source apportionment in this study was performed by combining air mass back trajectories and receptor modelling. The particulate matter (PM) samples at six sites were collected using the University of North Carolina Passive Samplers. The monthly samples were collected for a period of 4-5 weeks, except for August-September and September-October 2015 where the samples were collected for up to 6 weeks. The sampling was carried out from July 2015 to June 2016. PM chemical analysis was performed using Computer Controlled Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (CCSEM-EDS). The PM chemical analysis indicated the presence of elements such as carbon (C), calcium (Ca), chromium (Cr), iron (Fe), aluminium (Al), silicon (Si), magnesium (Mg) and lead (Pb). All the six sites except site 1 exceeded the WHO annual guidelines for PM10 concentration of 20 μg/m3. The annual chromium concentrations exceeded the New Zealand limits of 0.0001 μg/m3 and 0.11μg/m3 Cr (VI) and Cr (III), respectively. The back trajectory clusters computed by the HYSPLIT model identified 5 transport clusters for each site. The main transport patterns were northerly to north-easterly, easterly to south-easterly, and south-westerly to north-westerly. The US EPA PMF model version 5.0 used in source profiling and source apportionment identified agriculture/wood combustion, coal combustion, crustal/road dust, ferrochrome smelters, and vehicle emissions as the main sources in the area. The source contributions varied across all sites indicating the existence of different microenvironments within the airshed and that the pollution can originate from either local or regional sources as indicated by back trajectory clusters

The development and production of GDP flash estimates in a newly industrialised country: the case of South Africa

The experience accumulated from the development and production of a flash estimate of GDP as an official statistic at Statistics South Africa (Stats SA) is presented and discussed. This experience could inform national statistical organisations operating under similar statistical production constraints in other newly industrialised countries or elsewhere. The use of the flash estimate as an early indicator of business cycle slowdowns and upturns is also presented to demonstrate one possible by-product use of the flash estimate

Evaluation of the use of moist potential vorticity and moist potential vorticity vector in describing annual cycles of rainfall over different regions in Tanzania

Please read abstract in the article.http://www.frontiersin.org/Earth_Scienceam2017Geography, Geoinformatics and Meteorolog

Evaluation of the use of moist potential vorticity and moist potential vorticity vector in describing annual cycles of rainfall over different regions in Tanzania

Please read abstract in the article.http://www.frontiersin.org/Earth_Scienceam2017Geography, Geoinformatics and Meteorolog

Assessment of the impacts of climate change on maize production in the Wami Ruvu basin of Tanzania

The IPCC assessment reports confirm that climate change will hit developing countries the hardest. Adaption is on the agenda of many countries around the world. However, before devising adaption strategies, it is crucial to assess and understand the impacts of climate change at regional and local scales. In this study, the impact of climate change on rain-fed maize (Zea mays) production in the Wami-Ruvu basin of Tanzania is assessed using process based crop model the Decision Support System for Agro-technological Transfer (DSSAT). The model was calibrated using detailed field and household survey information of (crop yields, soil and management data inputs). Daily minimum and maximum temperatures, rainfall and solar radiation for current climate condition (1971-2000) as well as future climate projections (2010-2039), (2040-2069) and (2070-2099) for two Representative Concentration Path ways (RCPs): RCP45 and RCP85 scenarios were used to drive the crop model. These data are derived from three high-resolution regional climate models (RCMs), used in the Coordinated Regional Climate Downscaling Experiment program (CORDEX). Impact of climate change on maize production is assessed by analyzing the changes in simulated maize yields for the period 2010-2039, 2040-2069 and 2070-2099 relative to baseline period 1971-2000. Projection results from different models showed that due to climate change, the length of growing season and future maize yields over Wami-Ruvu basin will decrease under both RCP4.5 and RCP8.5 at the current, mid and end of the centuries. However, the projected yields estimates and the length of growing season differ from model to model highlighting the uncertainties associated with the projections. Climate data from the ensemble average of five model members was constructed to address the issue of uncertainties from individual climate models and used to drive DSSAT. Results showed that due to climate change future maize yields over Wami-Ruvu basin will slightly increase relative to the baseline during current century under RCP 4.5 and RCP 8.5. Meanwhile, maize yields will decline in the mid and end centuries. The spatial distribution shows that more decline in maize yields are projected over lower altitude regions due to projected increase in temperatures and decreased rainfall in those areas. The eastern part of the basin will feature more decrease in maize yields, while central parts of the basin and the western side of the basin will experience increase in maize yields during current, mid and end centuries under RCP 4.5 and RCP 8.5. The main reason for decrease and increase maize yields is the projected increase in temperatures that will reduce the length of growing seasons and hence affecting maize productivity. It is therefore recommended that appropriate and adequate adaptation strategies need to be designed to help the communities adapt to the projected decrease in maize production.http://jwcc.iwaponline.com2017-06-30hb2017Geography, Geoinformatics and Meteorolog

Site characterisation : astronomical seeing from a turbulence-resolving model

A Lunar Laser Ranging (LLR) system is to form part of geodetic instrumentation to be located at a new fundamental space geodetic observatory for South Africa. For optimal efficiency, LLR requires optical resolution or so-called astronomical seeing conditions of ~1 arc-second in order to deliver usable ranging data. Site characterisation should include a description of astronomical seeing for various locations on-site and overall atmospheric conditions. Atmospheric turbulence degrades astronomical seeing. In-situ methods of determining astronomical seeing are difficult, time-consuming and costly. We propose the use of a turbulence-resolving model to determine and predict astronomical seeing at a site. Large Eddy Simulation NERSC (Nansen Environmental and Remote Sensing Centre) Improved Code (LESNIC) is a turbulence-resolving simulation code which models atmospheric turbulence. It has been used to compile a database of turbulence-resolving simulations, referred to as DATABASE64. This database consists of a collection of LESNIC runs for a stably stratified planetary boundary layer (SBL) over a homogeneous aerodynamically rough surface. Results from DATABASE64 for the nocturnal boundary layer are employed to render profiles of the vertical distribution of optical turbulence (CN 2 profiles). Seeing parameter values are also obtained by making use of DATABASE64 results. The CN 2 profiles and seeing parameter values obtained from DATABASE64 results are compared with general observational results that have been published in the literature. The values obtained are consistent with results from field campaigns as reported. Turbulence-resolving models, such as LESNIC, show potential for delivering and predicting profiles and parameters to characterise astronomical seeing, which are essential prerequisites for establishing an LLR system at the most suitable site and most suitable on-site location. A two-pronged approach is envisaged – in addition to modelling, quantitative seeing measurements obtained with an on-site seeing monitor will be used to verify and calibrate results produced by the LESNIC model.http://www.gssa.org.za/index.php?module=htmlpages&func=display&pid=5nf201

Links between observed micro-meteorological variability and land-use patterns in the highveld priority area of South Africa

Links between spatial and temporal variability of Planetary Boundary Layer meteorological quantities and existing land-use patterns are still poorly understood due to the non-linearity of air–land interaction processes. This study describes the results of a statistical analysis of meteorological observations collected by a network of ten Automatic Weather Stations. The stations were in operation in the highveld priority area of the Republic of South Africa during 2008–2010. The analysis revealed localization, enhancement and homogenization in the inter-station variability of observed meteorological quantities (temperature, relative humidity and wind speed) over diurnal and seasonal cycles. Enhancement of the meteorological spatial variability was found on a broad range of scales from 20 to 50 km during morning hours and in the dry winter season. These spatial scales are comparable to scales of observed land-use heterogeneity, which suggests links between atmospheric variability and land-use patterns through excitation of horizontal meso-scale circulations. Convective motions homogenized and synchronized meteorological variability during afternoon hours in the winter seasons, and during large parts of the day during the moist summer season. The analysis also revealed that turbulent convection overwhelms horizontal meso-scale circulations in the study area during extensive parts of the annual cycleThe authors would like to acknowledge the bilateral Norway–South Africa project 180343/S50 “Analysis and the Possibility for Control of Atmospheric Boundary Layer Processes to Facilitate Adaptation to Environmental Changes” co-funded by the South African National Research Foundation (NRF) and the Norwegian Research Council (NRC). A significant part of this work has been developed under the NRC project 191516/V30 “Planetary boundary layer feedback in the Earth's Climate System”, under the European Research Council Advanced Grant, FP7-IDEAS, 227915 “Atmospheric planetary boundary layers: physics, modeling and its role in the Earth system”, and under a grant from the Government of the Russian Federation (project code 11.G34.31.0048).http://link.springer.com/journal/703hb201

Nota técnica 2: An equal Variance Test

This article introduces (and hopes to encourage thereby) the econometrics practitioner to (use) a homoscedasticity test referred to in the field of statistics as the modified Levene test. Econometrics orthodoxy (from University to practice level) has focused mainly on three heteroscedasticity tests, namely the Goldfeld-Quandt (GQ), Breusch-Pagan-Godfrey (BPG), and the White (W) test. The difference between the aforementioned tests and the test elaborated on in this article is that the former are for regression whereas the latter is for ANOVA –analysis of variance– situations.Este artículo introduce (y espera animar por eso) al practicante de econometría a usar una prueba de homoscedasticidad, que se trata en el campo de estadísticas como una prueba de Levene modificada. La ortodoxia de econometría (en la educación Universitaria) se ha enfocado principalmente en tres pruebas de heterocedasticidad, los test de Goldfeld-Quandt (GQ), Breusch-pagano-Godfrey (BPG), y el test de White (W). La diferencia entre las pruebas mencionadas y la prueba elaborada en este artículo es que lo son para una regresión y el último considera situaciones ANOVA –análisis de varianza–

The Herfindahl-Hirschman Index as an official statistic of business concentration : challenges and solutions

Thesis (PhD)--Stellenbosch University, 2012.ENGLISH ABSTRACT: This dissertation examines the measurement of business concentration by the Herfindahl- Hirschman Index (HHI). In the course of the examination, a modification to this method of measurement of business concentration is proposed, in terms of which the accuracy of the conventional depiction of the HHI can be enhanced by a formulation involving the Gini index. Computational advantages in the use of this new method are identified, which reveal the Ginibased HHI to be an effective substitute for its regular counterpart. It is found that theoretically and in practice, the proposed new method has strengths that favour its usage. The practical advantages of employing this method are considered with a view to encouraging the measurement of business concentration using the Gini-based index of the HHI.AFRIKAANSE OPSOMMING: Hierdie verhandeling ondersoek die meting van sakekonsentrasie deur middel van die Herfindahl- Hirschman-indeks (HHI). ‘n Wysiging aan hierdie metode word voorgestel, deur middel waarvan die akkuraatheid van die konvensionele voorstelling van die HHI verhoog word, deur ‘n formulering wat die Gini-indeks betrek. Die berekeningsvoordele van hierdie nuwe metode word geïdentifiseer en dit word aangetoon dat die Gini-gebaseerde HHI ’n doeltreffende plaasvervanger vir sy meer bekende teenvoeter is. Daar word bevind dat die voorgestelde nuwe metode teoretiese en praktiese sterkpunte het wat die gebruik daarvan ondersteun. Die praktiese voordele van die voorgestelde metode word oorweeg met die oog op die aanmoediging van die gebruik van die Gini-gebaseerde HHI-indeks as maatstaf van sakekonsentrasie

An equal variance test

This article introduces (and hopes to encourage thereby) the econometrics practitioner to (use) a homoscedasticity test referred to in the field of statistics as the modified Levene test. Econometrics orthodoxy (from University to practice level) has focused mainly on three heteroscedasticity tests, namely the Goldfeld-Quandt (GQ), Breusch-Pagan-Godfrey (BPG), and the White (W) test. The difference between the aforementioned tests and the test elaborated on in this article is that the former are for regression whereas the latter is for ANOVA analysis of variance situations.Este artículo introduce (y espera animar por eso) al practicante de econometría a usar una prueba de homoscedasticidad, que se trata en el campo de estadísticas como una prueba de Levene modificada. La ortodoxia de econometría (en la educación Universitaria) se ha enfocado principalmente en tres pruebas de heterocedasticidad, los test de Goldfeld-Quandt (GQ), Breusch-pagano-Godfrey (BPG), y el test de White (W). La diferencia entre las pruebas mencionadas y la prueba elaborada en este artículo es que lo son para una regresión y el último considera situaciones ANOVA análisis de varianza