Event characteristics of intra-seasonal climate circulations

An analysis of rainfall characteristics over the summer rainfall areas of South Africa is done in order to find links between rainfall variability and the general circulation. Seasonal rainfall totals are clearly linked to significant rain days, indicating the importance of evaluating synoptic-scale event characteristics. Rank ordered rainfall characteristics reveal that normal rainfall may be considered as the middle three quintiles, with the outer quintiles representing wet and dry conditions. The general circulation in tenns of atmospheric state (humidity and temperature), moisture and heat transport, and energy exchange - with attention to tropical-extratropical cloud-bands, are central to wet seasons in South Africa. These are generally associated with deep convection that is driven by vertical instability. Transport of moisture into South Africa generally takes place from the east with the Indian Ocean being a major source of water vapour. Although important, fluctuations in moisture transport are not clearly associated with rainfall. This is because moisture is a necessary but not a sufficient condition for rainfall. Atmospheric dynamics producing rainfall are a combination of disturbances of mid-latitude and tropical origin. These disturbances often initiate the tropical-temperate cloud-band where eddy available potential energy, generated through surface heating over land, is converted to eddy kinetic energy. It is generally mid-latitude disturbances with stronger vertical shear that are associated with rainfall events. Increased baroclinic activity in the Southern Ocean south of South Africa, as such, is generally associated with dry seasons. During these seasons there is usually a greater amount of available potential energy which strengthens the southern branch of the Hadley Cell. The effect of this is to increase the strength of the subtropical jet through enhanced poleward flux of angular momentum. The resulting increase in baroclinicity in the South Atlantic Ocean then disrupts rainfall over South Africa through the advection of dry air from the west by the vertical-mean wind component. General circulation models are shown to capture inter-annual variability such that forecasts of regional rainfall, of useful skill at a seasonal scale, may be made. However, the skill level with regard to daily circulation, restricts their use to the large-scale circulation. Nonetheless, the analysis of rainfall and the links to large-scale circulation, discussed in the thesis, provide information to produce more skilful seasonal forecasts without having to model small-scale features directly. Such forecasts may also include additional information on rainfall characteristics, such as number of rain-days and length of dry spells

Course Manual Winter School on Structure and Functions of Marine Ecosystem: Fisheries

Marine ecosystems comprises of diverse organisms and their ambient abiotic components in varied relationships leading to an ecosystem functioning. These relationships provides the services that are essential for marine organisms to sustain in the nature. The studies examining the structure and functioning of these relationships remains unclear and hence understanding and modelling of the ecological functioning is imperative in the context of the threats different ecosystem components are facing. The relationship between marine population and their environment is complex and is subjected to fluctuations which affects the bottom level of an ecosystem pyramid to higher trophic levels. Understanding the energy flow within the marine ecosystems with the help of primary to secondary producers and secondary consumers are potentially important when assessing such states and changes in these environments. Many of the physiological changes are known to affect the key functional group, ie. the species or group of organisms, which play an important role in the health of the ecosystem. In marine environment, phytoplankton are the main functional forms which serves as the base of marine food web. Any change in the phytoplankton community structure may lead to alteration in the composition, size and structure of the entire ecosystem. Hence, it is critical to understand how these effects may scale up to population, communities, and entire marine ecosystem. Such changes are difficult to predict, particularly when more than one trophic level is affected. The identification and quantification of indicators of changes in ecosystem functioning and the knowledge base generated will provide a suitable way of bridging issues related to a specific ecosystem. New and meaningful indicators, derived from our current understanding of marine ecosystem functioning, can be used for assessing the impact of these changes and can be used as an aid in promoting responsible fisheries in marine ecosystems. Phytoplantkon is an indicator determining the colour of open Ocean. In recent years, new technologies have emerged which involves multidisciplinary activities including biogeochemistry and its dynamics affecting higher trophic levels including fishery. The winter school proposed will provide the insights into background required for such an approach involving teaching the theory, practical, analysis and interpretation techniques in understanding the structure and functioning of marine ecosystems from ground truth measurements as well as from satellite remote sensing data. This is organized with the full funding support from Indian council of Agricultural Research (ICAR) New Delhi and the 25 participants who are attending this programme has been selected after scrutiny of their applications based on their bio-data. The participants are from different States across Indian subcontinent covering north, east, west and south. They are serving as academicians such as Professors/ scientists and in similar posts. The training will be a feather in their career and will enable them to do their academic programmes in a better manner. Selected participants will be scrutinized initially to understand their knowledge level and classes will be oriented based on this. In addition, all of them will be provided with an e-manual based on the classes. All selected participants are provided with their travel and accommodation grants. The faculty include the scientists who developed this technology, those who are practicing it and few user groups who do their research in related areas. The programme is coordinated by the Fishery Resources Assessment Division of CMFRI. This programme will generate a team of elite academicians who can contribute to sustainable management of marine ecosystem and they will further contribute to capacity building in the sector by training many more interested researchers in the years to come

Agroforestry Opportunities for Enhancing Resilience to Climate Change in Rainfed Areas,

Not AvailableAgroforestry provides a unique opportunity to achieve the objectives of enhancing the productivity and improving the soil quality. Tree systems can also play an important role towards adapting to the climate variability and important carbon sinks which helps to decrease the pressure on natural forests. Realizing the importance of the agroforestry in meeting the twin objectives of mitigation and adaptation to climate change as well as making rainfed agriculture more climate resilient, the ICAR-CRIDA has taken up the challenge in pursuance of National Agroforestry Policy 2014, in preparing a book on Agroforestry Opportunities for Enhancing Resilience to Climate Change in Rainfed Areas at ICAR-CRIDA to sharpen the skills of all stakeholders at national, state and district level in rainfed areas to increase agricultural productivity in response to climate changeNot Availabl

A Dynamic Risk Management Framework for Water and Environmental Sustainability

The risks and vulnerabilities facing reservoir systems in river basins shift dynamically over time and space. These risks involve regime changes and shifts, throughout which one observes the transition of water availability from prolonged dry periods to prolonged wet periods. Ensuring reliability of water supply under these hydrological regime shifts involves understanding how these regime shifts can be identified, characterized, and quantified. This dissertation describes a dynamic risk management (DRM) framework for water management at the basin level whose main features are (1) a system of updating risk assessments and policy recommendations on a yearly basis, where the risk assessments themselves are multi-year projections for the purposes of long-term planning into the future, and (2) integration of water supply and water demand variables into a quantitative hydrological risk assessment and streamflow regime identification tool. The DRM framework expounded in this dissertation will be split into four parts. The first part is extending streamflow records using tree-ring chronology-based paleo-reconstruction techniques. Longer streamflow records have the advantage of containing more information about the past hydrological behavior than the much shorter observed records do. Chapter 2 details a novel streamflow reconstruction approach for river basins in which the streamflow gauges are organized as a network, in which one streamflow gauge feeds into another one downstream. The method is applied to reconstructing streamflow for eighteen streamflow gauges in the Upper Missouri River Basin (UMRB). The second part of the DRM system, discussed in chapter 3, introduces a set of metrics for identifying and quantifying hydrological regimes in streamflow records. The metrics developed here are applied to the streamflow reconstructions developed in chapter 2. A thorough analysis of the specific hydrological behavior identified along with a spatial analysis of the intensity of those hydrological phenomena as they appear in the UMRB, are presented. The third part of DRM is covered in Chapter 4, v which is a review of the entire history of the evolution of water policy and water consumption in the Delaware River Basin, specifically for the three reservoirs that serve New York City in this watershed, as a means of better understanding the demand side of water management and the factors that influence it. Finally, chapter 5 covers the fourth and final part of the DRM framework for the purposes of this dissertation, which is a constrained scenario-analysis model for determining the feasible demand space for future water management and water release policies. The constraints placed on this model are probabilistic constraints based on controlling the manifestation of risk factors to the reservoir system; namely, droughts and spills. The demand space is a set of water demand/release values that satisfy all constraints simultaneously while satisfying the needs of ecosystems and societies that demand on the water coming from the reservoir system

Climate change 2013: the physical science basis

This report argues that it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. This is an an unedited version of the Intergovernmental Panel on Climate Change\u27s Working Group I contribution to the Fifth Assessment Report following the release of its Summary for Policymakers on 27 September 2013.  The full Report is posted in the version distributed to governments on 7 June 2013 and accepted by Working Group I and the Panel on 27 September 2013. It includes the Technical Summary, 14 chapters and an Atlas of Global and Regional Climate Projections. Following copy-editing, layout, final checks for errors and adjustments for changes in the Summary for Policymakers, the full Report will be published online in January 2014 and in book form by Cambridge University Press a few months later

Southern African palaeoclimates and variability : the story from stalagmites, pollen and coral.

Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2005.Compared to extensive study in the northern hemisphere, very little is known of southern African palaeoclimates. This study aimed to extend understanding of the nature of and controls on southern African palaeoclimates of the last 40 000 years. Through a study of the approximately 20 000 year long Makapansgat and Wonderkrater palaeoclimatic records, and an extensive literature review of southern African palaeoclimatic studies, a number of common rainfall and temperature fluctuations were detected across the summer rainfall region. Based on these trends, general models of rainfall and temperature changes over time were developed for the region. The analysis of a coral core, derived from a Porites lutea head from Sodwana Bay, covering the last 116 years, indicated higher frequency climatic fluctuations over the last century. Climatic variability on the long- and short-term could then be related to known atmospheric processes through application of the Tyson (1986) model for southern Africa atmospheric circulation. North-south shifts in mean circulation dominate climatic variability in the region but there are also regular disturbances to this mean, such as in the form of the EI Nino - Southern Oscillation. The fluctuations seen in present and palaeoclimatic records are the result of a complex interaction between internal and external mechanisms of climate change. Wavelet analyses of recorded and proxy climatic datasets highlighted the cycles which dominate southern African climatic variability on timescales from years to millennia. The causes of these cycles were then assessed in the context of established solar, atmospheric and oceanic models. Wavelet analyses also provided an indication of frequency changes over time and were therefore useful for detecting climate change. An analysis of proxy and recorded climatic datasets for southern African rainfall over the last 100 years indicated a frequency modulation of the 18 year rainfall cycle, which was first described by Tyson (1971). This variation may be related to anthropogenic climate change. It became apparent from this study that there is a need for increased scientific interest in the palaeoclimatic trends of the region. The number of continuous, high-resolution datasets needs to be increased to allow for comparison and confirmation of various trends with records from sites across the globe. An understanding of the nature of regional and global teleconnections is essential before reliable climate change models can be established. There is also a need for further understanding of short-term southern African climate variability on inter-annual timescales.It is only once we have an understanding of the natural climatic variability of the region ,and its inherent cyclicity,that we can begin to distinguish the impact of anthropogenic activities on climate

Marine Ecosystems Challenges and Opportunities (MECOS 09) Book of Abstracts

Marine ecosystems contain several unique qualities that set them apart from other ecosystems. Of the 89 elements occurring in nature, the presence of 80 has been confirmed in seawater. It is perhaps true that the remaining 9 elements are also present, but in concentrations too small to be detected. This wide range of substances dissolved in seawater has placed the marine organisms in a more advantageous position than their freshwater counterparts. These elements provide the essential materials required for the synthesis of all the basic nourishments of the body including the skeletal support of marine animals. In the terrestrial ecosystems, the physical boundaries are well marked and environmental variabilities are rather wide. The terrestrial organisms and ecosystems have developed internal mechanisms to cope up with variabilities. In contrast, in the marine ecosystems, the physical variability is small and extends over very long time scales due to the large thermal capacity of the oceans and the long periods of exchange between deep and near shore waters. Consequently, the marine ecosystems are more vulnerable to large-scale environmental changes because they do not have the internal adaptability inherent in the terrestrial systems