ESRL Quarterly Newsletter - Summer 2010

Forecasting Ash

ESRL's FIM-Chem-Ash forecasts volcanic ash cloud in real time

In April and May, European authorities canceled more than 100,000 flights affecting 10 million passengers and costing the aviation industry billions in lost business due to the eruption of Icelandic volcano Eyjafjallajökull. NOAA established a volcanic ash forecast response effort aimed at improving international guidance. ESRL responded with a new forecasting model, the FIM-CHEM-Ash, that began producing experimental real-time volcanic ash forecasts in May. This is the first time that a global model has been run with in-line chemistry; with 17 aerosol and gas-phase tracer concentrations and four size bins of volcanic ash.

The model currently includes eruption data from Eyjafjallajökull and has cycled 14 aerosol concentration and three gas-phase prognostic variables since April 14, the start of the Icelandic volcano’s explosive eruption. Using the Global Forecast System for atmospheric initial conditions, the FIM-CHEM-Ash is run at 30-km resolution and maintains the aerosol/ash cycling with new five-day forecasts run on a daily basis. The inline treatment of chemistry and ash (interaction with other meteorological variables) within FIM-Chem-Ash will very likely provide a considerable improvement over current abilities to predict ash dispersion with regards to both accuracy and timeliness.

These new runs, though still under development and not considered official guidance, are an example of NOAA’s effort to help the international VAAC community as it continues to deal with new waves of dense volcanic ash in European airspaces and for future volcanic eruptions worldwide. There are nine VAACs: strategically located that were created when the International Civil Aviation Organization and other Aviation concerns recognized the need to keep aviators informed of volcanic hazards.

—Annie Reiser