The Met Office operates the Quantitative Volcanic Ash APIs in its role as the London Volcanic Ash Advisory Centre (VAAC), covering primarily Iceland and the North Atlantic.
Quantitative Volcanic Ash (QVA) forecasts provide higher resolution information on the location of ash in the atmosphere than the traditional volcanic ash advisory (VAA) products and unlike the VAA, also include ash concentration information. QVA also offers operators the opportunity to move away from the traditional ‘discernible ash’- based criteria for avoiding ash and instead use certified engine susceptibility volcanic ash exposure thresholds for flight route planning and in-flight re-planning.
Operators with approval and procedures/practices will be able to use QVA information to fly more efficient routes while maintaining safety in accordance with their safety management program.
The QVA information service comprises of three data sets at 0.25-degree horizontal resolution:
- The expected ash concentration as a gridded data set.
- The probability of the ash exceeding four different concentration thresholds (≥0.2mg/m3, ≥2mg/m3, ≥5mg/m3 and ≥10mg/m3) as a gridded data set.
- Features/objects in IWXXM format that show the expected ash areas for where ash exceeding the four concentration thresholds (≥0.2mg/m3, ≥2mg/m3, ≥5mg/m3 and ≥10mg/m3) is expected to occur.