Tuesday, 13 January 2009
Visibility Forecasting For Warm and Cold Fog Conditions Observed During FRAM Field Projects
Hall 5 (Phoenix Convention Center)
The main objective of this paper is to describe a research project on fog and visibility forecasting, and to summarize the results that have been obtained to date. The Fog Remote Sensing and Modeling (FRAM) project was designed to focus on 1) development of microphysical parameterizations for numerical model applications, 2) development of remote sensing methods for fog detection, 3) understanding instrument capabilities and limitations for observations of fog and related parameters, and 4) integration of model and observation data for developing nowcasting applications. The FRAM project was conducted over three regions of Canada and the U.S.A., including 1) Center for Atmospheric Research Experiments (CARE), Egbert, Ontario during 2005-2006 (FRAM-C), 2) Lunenburg, Nova Scotia during June 2006 and June 2007 (FRAM-L), and 3) U.S. Department Of Energy (DOE) ARM Climate Research Facility at Barrow, Alaska, US (FRAM-B) as part of the Indirect and Semi-Direct Aerosol Campaign (ISDAC) field program during April 2008. The FRAM-C was undertaken in a continental environment while FRAM-L was in a marine environment. The FRAM-B was undertaken to study ice fog conditions in a polar region. During each project, numerous in-situ measurements were obtained, including droplet and aerosol spectra, precipitation rate and amount, and visibility characteristics. Analyses of satellite microphysical retrievals and numerical model-based visibility parameterizations have been made. It is suggested that improved scientific understanding of fog formation can lead to better forecasting/nowcasting skills which will benefit both aviation and public forecasting programs.