Objective
To increase our understanding of the West African Monsoon and associated
precipition physics in addition to assessing the potential for cloud seeding
to enhance rainfall. Both Burkina Faso and Mali have recently implemented
additional infrastructure to conduct these studies and assessment. NCAR is
helping to support the operation of the infrastructure and conducting evalaution
and assessment studies on the potential for rainfall enhancement via cloud
seeding.
Description
Water stresses often occur in West Africa. Increasing demands for water require that the potential for enhancing the sources, storage, and recycling of freshwater be examined carefully. Also, destruction and loss of life due to severe weather, which is increasing with population growth and changing demographics, require that we examine ways to reduce these impacts. Recently, Mali and Burkina Faso have been conducting cloud seeding operations in hopes of augmenting precipitation to off-set the growing demands.
Understanding of the West African Monsoon and associated precipition physics is critical in assessing the potential for cloud seeding to enhance rainfall in this region of the world. In addition, there is evidence that human activities such as the emission of industrial air pollution can alter atmospheric processes on scales ranging from local precipitation patterns to global climate (NRC, 2003). Documentation of anthropogenic effects on the weather strengthens the physical basis for deliberate attempts to alter the weather. These inadvertent impacts on weather and climate require a concerted research effort.
1. Support Programme SAAGA to through development of their radar infrastructure.
2. To assist Mali and field personnel in conducting a feasibility study for rainfall enhancement via cloud seeding. The feasibility study will occur between end of July - September and include the latest technologies that have been developed in this field to conduct an airborne measurement program. The collaborative work will entail all necessary aspects of the project, including cloud physics and will build on the experience obtained in programs in other parts of the world.
RADAR
The use of radar in rainfall and cloud structure measurements has become an important tool over the past twenty years. Because meteorological radars provide a wealth of information about precipitating cloud systems it has also become essential to employ state-of-the-art software systems to display and analyze the data. While networks of weather radars are common in many western countries, large parts of Africa and other developing countries are currently not covered by weather radars. Recently, African countries have also started to acquire weather radars but in many cases lacked the infrastructure to maintain, calibrate the radars and interpret and analyze the data collected from these radars. Additional measurement capabilities in Burkina Faso, Mali and adjacent regions will fill an important gap in the observational area of the Sahel and adjacent regions. This region spans the transition zone between the Sahara and the Sahel, to the more wet tropical southern areas of West Africa. The additional observational capabilities in this region could help in understanding the interaction between the Saharan dust layer and the more tropical south, and the evolution of MCS's and CS's in this transition region and associated changes in rainfall patterns in the region. The Sahel region is currently experiencing a drought with decreasinh amounts of rainfall over the last few decades.
This website provides real-time displays from radars deployed in Burkina Faso and Mali. View radar information and data.
AIRCRAFT OBSERVATIONS
Of additional interest is the influence of aerosols and cloud microphysics (size and concentration of water droplets and ice particles inside clouds) on buoyancy, convergence, intensification of convection, and potential for enhancement of the natural precipitation. Aircraft operations are being conducted to assess the feasibility of any future precipitation enhancement potential in Mali clouds it is extremely important to obtain observations in a well-designed measurement program. No previous airborne aerosol and microphysical measurements have been conducted in Mali. The aerosol and microphysical measurements will determine the optimal seeding method that may have potential for enhancing precipitation in Mali. The potential for such manmade increases is strongly dependent on the natural microphysics and dynamics of the clouds that are being seeded. These factors can differ significantly from one geographical region to another, and even between seasons in the same region. In some instances, clouds may not be suitable for seeding, or the frequency of occurrence of suitable clouds may be too low to warrant the investment in a cloud seeding program. Both factors need to be evaluated in a climatological sense. It is therefore important to conduct preliminary studies on the microphysics and dynamics of the naturally forming clouds prior to commencing a larger experiment. It is also important to conduct hydrological studies relating rainfall with river flows and reservoir levels, and to determine hydrological regions where reservoir catchments are most efficient
REAL-TIME FORECASTING
Guidance for the aircraft observations is provided by the
radar network in Burkina Faso and Mali as well as a real-time
forecast model run at NCAR/RAL.
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