To extend the scientific evaluation of cloud seeding for the UAE, we have proposed to design and implement a randomized cloud seeding experiment during the summer season. The purpose is to statistically quantify the potential for cloud seeding to enhance rainfall, specifically over the UAE and Oman Mountains. The randomized seeding experiment will likely require two years to treat a sufficient number of cases, and requires close collaboration with Oman in operating the seeding experiment seamlessly across their border. Extending the operations area to include the mountain region between Al Ain and Muscat will improve the chances of quickly sampling sufficient cases for the randomized experiment.
To provide a statistical evaluation of the effect of seeding, we plan to modify the randomized seeding procedure previously used in Mexico and South Africa. The experimental unit will remain individual storms or cells, but changes will be made in how the response variables are analyzed, and techniques aimed at moving from storm-based results to possible area effects will be investigated.
The ultimate goal of all activities is to develop viable methods that will have a positive effect on the threatening water situation facing the UAE and Oman. Acceptable proof of positive seeding effects on storm-scale rainfall (as an experimental unit) is a prerequisite to showing higher area rainfall. The total seeding effect on all seeded storms' rainfall should quantitatively match the area effect. The studies will include the assessment of storm increases in rainfall on area rainfall and the resources necessary to implement an operational program that would have a substantial impact on area rainfall.
Numerical models will be used in the scientific evaluation of cloud and precipitation formation specific to the UAE and Oman regions. Improvements in the way that the Clark-Hall numerical cloud model simulates detailed microphysics has provided an opportunity to extend the studies of cloud processes initiated during the first two years to now for the first time being able to assess the impacts of hygroscopic seeding on microphysical and dynamical cloud processes from a modeling perspective. Additionally, boundary conditions defined by output from the MM5 meso-scale model should improve the simulations with the cloud-scale model. The main objectives of further modeling studies are:
- To simulate the formation of clouds over the complex terrain in these regions
- To study the effects of seeding on parameters not easily measured (such as dynamical aspects of cloud and precipitation formation) and over larger areas than a single storm.
While there have been significant improvements to the radar and raingauge networks throughout the UAE over the past few years, there is a growing awareness that additional rainguages and improved radar facilities are needed for statistical assessment of randomized seeding experiments. Part of NCAR's proposed follow-on work to continue the development of these technologies.
Current Radar and Rainguage observations From Department of Water Resources Studies - Office of His Highness the President