Background of Oman Trials
- Trials were carried out in the Hajar Mountains from 2013-2018; one of the most water-stressed / rainfall-stressed areas in the world
- ~20 Automatic Weather Stations were set up to monitor atmospheric conditions and collected daily measurements
- Array of ~200 rain gauges on a 10km grid to collect daily data
- Radiosonde data measured speed and direction of wind to help locate where systems had rainfall enhancement effect
- Trials utilized 12 devices over 6 years – with 3 generations of systems designed for improved ion generation and durability
- Randomized operating schedule was defined each year and system were switched on / off on designated operating days
- Total of 122,259 gauge-day and 740 days of data collected
- Daily footprint of each system is 30km wide and 70km long with analysis applied to positive gauge day rainfall in footprint
- Modelling used to estimate rainfall enhancements in footprints attributable to systems. Tests were not designed to optimize enhancement, but for statistical measurement
Historical Trial Results and Key Factors
- Analysis of the data collected in the trial shows that ionization led to a statistically significant enhancement in positive rainfall in gauges located up to 70 km downwind of the ionizers.
- A headline analysis specified prior to commencement of the trial resulted in an estimate of 16.23% enhancement relative to rainfall that would have fallen without any ionization, while a more sophisticated after the event analysis increased this estimate to 17.64% enhancement, but for statistical measurement.