A Climatology of Volcanic Ash Dispersal from a Mount Rainier Eruption Using USGS Ash3D with NCEP–NCAR Reanalysis Data: Potential Impacts on Commercial Airspace

Mount Rainier, the tallest and most glaciated peak in the Cascade Mountain Range, has a history of violent eruptions. Due to the volcano’s geographic location, it poses a significant danger to inbound and outbound air traffic as well as any aircraft on the tarmac at any of the numerous airports in the vicinity of the Mount Rainier National Park. Two main air highways approaching and departing the Seattle-Tacoma International Airport (SeaTac) pass just north and south of the volcano’s summit respectively. The hazards to airplanes both in the air and on the ground should Mount Rainier erupt as well as the potential damage to the aviation industry as a whole would be significant. This study focuses on an ash climatology for Mount Rainier for all months of the year using the United States Geological Survey’s (USGS) web application Ash3D. Meteorological data used for this study are from NCEP/NCAR Reanalysis with 2.5-degree resolution for the calendar year 2010, and parameters specified for the volcanic eruption include duration (12 hours), plume height and erupted volume (identical to the May 1980 Mt. St. Helens eruption). The results provide probabilities for ash dispersal across major air highways as well as the wide geographical range of impacts for such an eruption.