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A multi-disciplinary characterization and forecast of a unique fog event: microphysics measurements, mesoscale modeling and machine learning.
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  • Anton Gelman,
  • Ayala Ronen,
  • Pavel Kunin,
  • Tamir Tzadok,
  • Eyal Agassi,
  • Rong-Shyang Sheu,
  • Adam Pietrkowski,
  • Dorita Rostkier-Edelstein
Anton Gelman
Hebrew University of Jerusalem

Corresponding Author:[email protected]

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Ayala Ronen
Department of Environmental Physics, Israel Institute for Biological Research
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Pavel Kunin
Tel Aviv University
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Tamir Tzadok
Hebrew University of Jerusalem
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Eyal Agassi
Hebrew Unibersity of jerusalem
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Rong-Shyang Sheu
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Adam Pietrkowski
Forecasting Center
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Dorita Rostkier-Edelstein
Department of Environmental Physics, Environmental Sciences Division, IIBR
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We present a multidisciplinary study of the microphysics, mesoscale and synoptic conditions of a rare radiation-fog event in the central and southern regions of Israel during January 3-6, 2021. The fog developed during nighttime from south to central coastal areas and dissipated at morning. The synoptic conditions were dominated by Red Sea Troughs at the surface without cyclonic upper air circulation, suitable for radiation fog development. In-situ measurements were combined with satellite imagery, high resolution (1-km grid size) Weather Research and Forecast model (WRF) with Real-Time Four-Dimensional Data Assimilation (RTFDDA) forecasts and post-processing algorithms including machine learning (ML) to analyze this event and to evaluate its numerical forecasting. The micro-physical analysis involved measurements of droplet size distribution and visibility range, allowing the calculation of liquid-water content and effective diameter of fog droplets. The measured visibility range was 90 m. The droplet diameter main mode was 1-2 micrometers, followed by another one around 6 micrometers. Typical liquid-water content values were 0.01-0.025 g/m3. WRF-RTFDDA mesoscale forecasts, post-processed by simple thresholds-based and ML algorithms, largely succeeded in predicting the temporal and spatial development of the dense fog. They proved useful in distinguishing between near-surface fog and elevated fog/low clouds, a distinction not possible from satellite imagery only. Clear patches at coastal areas covered in part by urban landuse were observed both in satellite imagery and model forecasts. WRF-RTFDDA forecasts proved their usefulness in forecasting this massive fog and low clouds events and in providing alerts to operational users and field campaign deployments.
01 Mar 2024Submitted to ESS Open Archive
05 Mar 2024Published in ESS Open Archive