The Impacts on Air Traffic of Volcanic Ash from the 2009 Mt. Redoubt Eruption

The March 2009 eruption of Mt. Redoubt created the potential for major problems for aviation due to the dispersion of volcanic ash. Mt. Redoubt, located 110 km west-southwest of Alaska Airlines hub Anchorage, last erupted in 1990 and caused an estimated $101 million cost to the aviation industry (Waythomas, 1998). It is important to assess the impacts on aviation so that valuable information may be obtained and used in developing better warning systems and handling situations associated with these impacts.

A study was performed to (1) determine the altitude of SO2 dispersion through analysis of synoptic meteorological conditions and satellite imagery and (2) investigate the reported impacts on aviation from the volcanic ash dispersion. To assess the altitude of SO2 dispersion, volcanic ash was tracked using OMI SO2 column measurements. The OMI satellite images were assimilated with CALIPSO backscatter profiles, geopotential height plots, and HYSPLIT forward model trajectories. To investigate the impacts on aviation, reports from airports and Volcanic Ash Advisories were also reviewed.

A complex dispersion of volcanic ash resulted from the eruption of Mt. Redoubt. The altitudes of ash dispersion were estimated on 23, 24, and 25 March 2009. On 23 March 2009, the majority of the ash plume remained at approximately 8 km, although reports indicate that the initial plume may have reached 18 km (60,000 ft). On 24 March 2009, most ash was entrained in a passing low pressure system at around 8 km. Some ash was detected by CALIPSO at higher altitudes (10 km and 16 km). Near Hudson Bay, atmospheric patterns suggest dispersion at approximately 3 km. On 25 March 2009, much of the ash plume remaining was detected at higher altitudes three days following the eruption. The stratospheric ash plume was located 14 km above mean sea level, as detected by CALIPSO. By the time the eruptions had subsided in April, Alaska Airlines had cancelled 295 flights and disrupted the flights of over 20,000 passengers.

This project supports Sub Goal 3A of the NASA Strategic Plan, “Study Earth from space to advance scientific understanding and meet societal needs.” Although the aviation industry was well prepared for the 2009 Mt. Redoubt eruption, preparatory measures need to be taken to prevent future volcanic ash encounters and reduce the economic impact from flight delays and cancellations. Improved forecast models and communication with pilots will mitigate the impacts from volcanic ash on aviation.