Fog Nowcast


In 2006, a review of the potential offered by remote sensors was conducted at the Centre Nationale de Recherches Météorologiques of Météo-France. SODAR was identified as the single technique available that can detect in real-time the inversion at the top of the fog layer… 

Experiments conducted at CDG during the winter of 2008–2009 have proven that a SODAR can operate efficiently at an airport to provide reliable measurements of the thickness of fog layers. Using SODAR information, the COBEL-ISBA model improved its hits and misses on low-visibility forecasts. In particular, the time of fog dissipation is better predicted. (1)

Detection of the inversion layer is essential for fog forecast and fog nowcast. The ASI eSODAR windprofiler, while detecting atmospheric conditions real time, provides the location and relative strength of the inversion layer.  

The ASI windprofiler detects the thermal rise and the height of the inversion layer as it forms, providing the nowcast onset of fog conditions. The intensity of the layer is identified, providing the rate of fog formation, fog intensity levels, and the dissipation rate.

Regional MET systems can easily ingest this ASI eSODAR data to enhance the predictive forecast, including fog density and duration, greatly enhancing the regional grid for forecasting, especially dissipation timeframe.

Airport operations would more accurately determine both the onset, and demise of a fog event, invaluable to operations.  In many fog prone areas, the fog forecast/actual onset of fog, and onset/forecasted is around 50% accurate. When fog is forecasted, airlines must take on more fuel, reducing cargo capacity. When fog is not forecasted, the onset interrupts flight operations, including increased holding times, and diversions to other airports.

Defined forecasting, nowcasting, and dissipation, invaluable to airline flight operations and airport flow management… now available with the ASI eSODAR system.

(1) Use of a Sodar to Improve the Forecast of Fogs and Low Clouds on Airports, 2011 ALAIN DABAS,  SAMUEL REMY,  and THIERRY BERGOT