COLD FOG AND COMPLEX TERRAIN

FOG IS THE SECOND-LEADING CAUSE OF AIRCRAFT ACCIDENTS AFTER STRONG WINDS.

Despite extensive research of high impact fog events, fog prediction remains challenging due to complex interactions between land surface, water, and atmosphere. Zhaoxia Pu, University of Utah professor of atmospheric sciences and Eric Pardyjak, professor of mechanical engineering, hope to change that through a field campaign and scientific research funded by a $1.17 million grant from the National Science Foundation, using Utah’s Heber Valley as the laboratory. Pu is on the National Oceanic and Atmospheric Administration (NOAA) Science Advisory Board and is an elected fellow of the American Meteorological and Royal Meteorological Societies.

On winter nights, cold air pools on the valley floor and creates favorable conditions for several forms of fog. By observing how these different kinds of fog form and dissipate, the researchers are continuing to learn about the meteorological conditions and physical processes governing the formation of fog to improve its prediction.

In addition to Pu and Pardyjak, the team for the field campaign includes scientists from the National Center for Atmospheric Research (NCAR) and Environment and Climate Change Canada as well as graduate and undergraduate students from atmospheric sciences and mechanical engineering at the U. From January 7 to February 24, 2022, this crew watched a network of sensors on the ground in Heber Valley along with comprehensive sets of instruments from the NCAR's Earth Observing Laboratory and satellite observations.

Since the field study, Pu and her colleagues have published findings contributing to The Cold Fog Amongst Complex Terrain (CFACT) project in a recent paper in the Bulletin of the American Meteorological Society. The CFACT project was conceived to investigate the life cycle of cold-fog events over complex terrain, improve microphysical parameterizations and visibility algorithms used in numerical weather prediction (NWP) models, and develop data assimilation and analysis methods for NWP models.

With over nine intensive observation periods (IOPs) that explored various mountainous weather and cold fog conditions, the CFACT field campaign collected an unprecedented, diverse, and extensive dataset. This dataset, complemented by model simulations, has been instrumental in studying the lifecycle of fog and the behavior of the stable boundary layer. More importantly, since Heber Valley is a small-scale valley, the observations provided critical high-resolution data to validate and improve current and next-generation NWP models.

Comprehensive studies are ongoing for an improved understanding of cold fog over complex terrain. The Department of Commerce and the NOAA announced in May that the U, under principal investigator Pu, will participate in a new multi-university consortium to improve weather forecasts using enhanced weather prediction systems recommended as part of President Biden's Investing in America agenda. Nearly seven million dollars from the Inflation Reduction Act will be used to establish the Consortium for Advanced Data Assimilation Research and Education, called CADRE. Other universities involved in the consortium include Howard University, Pennsylvania State University, the University of Maryland, University of Oklahoma, and Colorado State University. <

This augmented story is adapted by Lauren Wigod from an earlier announcement on this project by Paul Gabrielsen in @TheU.