Climatic trends and soil moisture feedbacks over Zimbabwe

Includes bibliographical references (leaves 106-118). === The research focuses on an objective analysis of austral summer rainfall variability over Zimbabwe as well as characterization of rainfall patterns and frequency analysis over southern Africa region. A statistical analysis of historical trend...

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Main Author: Mdoka, Marshall Lison
Other Authors: Hewitson, Bruce
Format: Dissertation
Language:English
Published: University of Cape Town 2014
Subjects:
Online Access:http://hdl.handle.net/11427/4783
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spelling ndltd-netd.ac.za-oai-union.ndltd.org-uct-oai-localhost-11427-47832020-10-06T05:11:23Z Climatic trends and soil moisture feedbacks over Zimbabwe Mdoka, Marshall Lison Hewitson, Bruce Tadross, Mark Environmental and Geographical Science Includes bibliographical references (leaves 106-118). The research focuses on an objective analysis of austral summer rainfall variability over Zimbabwe as well as characterization of rainfall patterns and frequency analysis over southern Africa region. A statistical analysis of historical trends in climate extreme events is used and lays a foundation of projecting into future climates. A trend analysis done on rainfall patterns attained from SOMs approach compliments the RClimdex statistical approach and strengthens some of the historical trends findings on climate extremes. Thereafter, some exploratory research seeks to explain the trends observed using the land-atmosphere interactions and shows the response of rainfall to anomalous soil moisture conditions during an extreme wet and dry seasons using RegCM3. Finally, some radiation effects results are presented from these soil moisture perturbations experiments. Results show drying out patterns over the region from the historical records analysed. The trend analysis done with SOM arrays revealed a positive trend towards drier conditions and a negative trend for wet conditions. The climate extremes indices analysis complimented these findings as shown in the decrease in total precipitation and an increase in the number of dry spells. This is supported by the circulation patterns showing an increase in frequency of the 500hPa anticyclones and a decrease of low pressures. However, some high altitude stations showed an intensification of precipitation events. This would exacerbate need for proper planning of future water resource management and farming strategies. Soil moisture rainfall feedback mechanisms were not fully explored. However drier conditions experiments showed a stronger response to soil moisture perturbations than in wetter conditions experiments. No consistent response to soil moisture initialisation over southern Africa was found. The altitude does modulate these feedback mechanisms with low-lying areas depicting a stronger response. A better understanding of the observed rainfall patterns, historical climate trends and soil moisture-rainfall feedback mechanisms are essential for improved short-term and seasonal forecasting and will aid the generation of plausible climate change impact predictions. 2014-07-31T07:59:03Z 2014-07-31T07:59:03Z 2005 Master Thesis Masters MSc http://hdl.handle.net/11427/4783 eng application/pdf University of Cape Town Faculty of Science Department of Environmental and Geographical Science
collection NDLTD
language English
format Dissertation
sources NDLTD
topic Environmental and Geographical Science
spellingShingle Environmental and Geographical Science
Mdoka, Marshall Lison
Climatic trends and soil moisture feedbacks over Zimbabwe
description Includes bibliographical references (leaves 106-118). === The research focuses on an objective analysis of austral summer rainfall variability over Zimbabwe as well as characterization of rainfall patterns and frequency analysis over southern Africa region. A statistical analysis of historical trends in climate extreme events is used and lays a foundation of projecting into future climates. A trend analysis done on rainfall patterns attained from SOMs approach compliments the RClimdex statistical approach and strengthens some of the historical trends findings on climate extremes. Thereafter, some exploratory research seeks to explain the trends observed using the land-atmosphere interactions and shows the response of rainfall to anomalous soil moisture conditions during an extreme wet and dry seasons using RegCM3. Finally, some radiation effects results are presented from these soil moisture perturbations experiments. Results show drying out patterns over the region from the historical records analysed. The trend analysis done with SOM arrays revealed a positive trend towards drier conditions and a negative trend for wet conditions. The climate extremes indices analysis complimented these findings as shown in the decrease in total precipitation and an increase in the number of dry spells. This is supported by the circulation patterns showing an increase in frequency of the 500hPa anticyclones and a decrease of low pressures. However, some high altitude stations showed an intensification of precipitation events. This would exacerbate need for proper planning of future water resource management and farming strategies. Soil moisture rainfall feedback mechanisms were not fully explored. However drier conditions experiments showed a stronger response to soil moisture perturbations than in wetter conditions experiments. No consistent response to soil moisture initialisation over southern Africa was found. The altitude does modulate these feedback mechanisms with low-lying areas depicting a stronger response. A better understanding of the observed rainfall patterns, historical climate trends and soil moisture-rainfall feedback mechanisms are essential for improved short-term and seasonal forecasting and will aid the generation of plausible climate change impact predictions.
author2 Hewitson, Bruce
author_facet Hewitson, Bruce
Mdoka, Marshall Lison
author Mdoka, Marshall Lison
author_sort Mdoka, Marshall Lison
title Climatic trends and soil moisture feedbacks over Zimbabwe
title_short Climatic trends and soil moisture feedbacks over Zimbabwe
title_full Climatic trends and soil moisture feedbacks over Zimbabwe
title_fullStr Climatic trends and soil moisture feedbacks over Zimbabwe
title_full_unstemmed Climatic trends and soil moisture feedbacks over Zimbabwe
title_sort climatic trends and soil moisture feedbacks over zimbabwe
publisher University of Cape Town
publishDate 2014
url http://hdl.handle.net/11427/4783
work_keys_str_mv AT mdokamarshalllison climatictrendsandsoilmoisturefeedbacksoverzimbabwe
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