Fronts and Atlantic Storm-Track Experiment

Fronts and Atlantic Storm-Track Experiment. It was a major international field campaign conducted from 1997 to 1998, focused on improving the understanding and prediction of extratropical cyclones and their associated weather fronts over the North Atlantic Ocean. The project aimed to address critical gaps in knowledge about the life cycle of storms that dominate the weather and climate of Western Europe and North America. Coordinated by a consortium including the Met Office and the National Center for Atmospheric Research, FASTEX represented a significant collaborative effort in atmospheric science.

Background and Objectives

The genesis of FASTEX lay in recognized deficiencies in the numerical weather prediction models of the late 20th century, particularly those operated by the European Centre for Medium-Range Weather Forecasts and the UK Meteorological Office. Scientists sought to better understand the rapid development phases of extratropical cyclones, a process known as cyclogenesis, and the detailed structure of cold fronts and warm fronts. A primary objective was to collect a comprehensive dataset to validate and improve theories on storm track dynamics and frontogenesis. The experiment specifically targeted the North Atlantic Ocean storm track, a key region influencing the climate of Northwest Europe, to enhance forecast skill for high-impact weather events affecting populated regions.

Field Campaign and Methodology

The intensive field phase occurred during the winter of 1997–1998, utilizing a formidable array of observational platforms. Research aircraft, including the National Center for Atmospheric Research's C-130 Hercules and the Met Office's C-130 Hercules, conducted targeted missions to sample the structure of developing storms. These were supplemented by dropsondes deployed from aircraft and enhanced measurements from a network of ocean weather ships and moored buoys. A key innovative aspect was the use of "adaptive" or "targeted" observations, where forecast models from the European Centre for Medium-Range Weather Forecasts guided aircraft into critical regions to reduce forecast uncertainty. Ground-based radar and lidar systems in locations like Ireland and the United Kingdom provided continuous monitoring of frontal systems as they made landfall.

Key Scientific Findings

FASTEX yielded transformative insights into the mesoscale structure of extratropical cyclones. Data analysis revealed the complex interplay between dry intrusions of stratospheric air and the intensification of cold fronts, leading to sharper frontal boundaries and more concentrated precipitation. The experiment provided definitive observations of sting jets, a mesoscale wind feature within certain severe cyclones that can cause significant surface damage. Findings greatly advanced the conceptual model of the Shapiro–Keyser cyclone, contrasting it with the classical Norwegian cyclone model. Furthermore, the collected data proved invaluable for testing and improving the parameterization schemes in global climate models used by institutions like the Hadley Centre for Climate Prediction and Research.

Impact and Legacy

The legacy of FASTEX is profound in both operational forecasting and atmospheric research. The methodologies for targeted observations pioneered during the campaign were directly adopted by major forecasting centers, including the European Centre for Medium-Range Weather Forecasts and the National Oceanic and Atmospheric Administration, improving the prediction of high-impact winter storms. The rich, high-quality dataset continues to be a benchmark for validating numerical weather prediction models and studying storm track variability. FASTEX also served as a direct prototype for subsequent major field campaigns, such as the North Atlantic Waveguide and Downstream Impact Experiment and the Observing System Research and Predictability Experiment, cementing its role in the evolution of modern dynamic meteorology.

Category:Atmospheric science Category:Meteorological field campaigns Category:1997 in science