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Real-time forecast of dense fog events over Delhi: The performance of the wrf model during the wifex field campaign

Pithani, P and Ghude, SD and Jenamani, RK and Biswas, M and Naidu, CV and Debnath, S and Kulkarni, R and Dhangar, NG and Jena, C and Hazra, A and Phani, R and Mukhopadhyay, P and Prabhakaran, T and Nanjundiah, RS and Rajeevan, M (2020) Real-time forecast of dense fog events over Delhi: The performance of the wrf model during the wifex field campaign. In: Weather and Forecasting, 35 (2). pp. 739-756.

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Official URL: https://dx.doi.org/10.1175/WAF-D-19-0104.1


A Winter Fog Experiment (WiFEX) was conducted to study the genesis of fog formation between winters 2016�17 and 2017�18 at Indira Gandhi International Airport (IGIA), Delhi, India. To support the WiFEX field campaign, the Weather Research and Forecasting (WRF) Model was used to produce real-time forecasts at 2-km horizontal grid spacing. This paper summarizes the performance of the model forecasts for 43 very dense fog episodes (visibility, 200 m) and preliminary evaluation of the model against the observations. Similarly, near-surface liquid water content (LWC) from models and continuous visibility observations are used as a metric for model evaluation. Results show that the skill score is relatively promising for the hit rate with a value of 0.78, whereas the false alarm rate (0.19) and missing rate (0.32) are quite low. This indicates that the model has reasonable predictive accuracy, and the performance of the real-time forecast is better for both dense fog events and no-fog events. For success cases, the model accurately captured the near-surface meteorological conditions, particularly the low-level moisture, wind fields, and temperature inversion. In contrast, for failed cases, the WRF Model shows large error in near-surface relative humidity and temperature compared to the observations, although it captures temperature inversions reasonably well. Our results also suggest that the model is able to capture the variability in fog onset for consecutive fog events. Errors in near-surface variables during failed cases are found to be affected by the errors in the initial conditions taken from the Indian Institute of Tropical Meteorology Global Forecasting System (IITM-GFS) spectral model forecast. Further evaluation of the operational forecasts for dense fog cases indicates that the error in predicting fog onset stage is relatively large (mean error of 4 h) compared to the dissipation stage.

Item Type: Journal Article
Publication: Weather and Forecasting
Publisher: American Meteorological Society
Additional Information: The copyright of this article belongs to American Meteorological Society
Keywords: Atmospheric temperature; Climatology; Errors; Fog; Visibility, Horizontal grid spacing; International airport; Meteorological condition; Near-surface variables; Operational forecasts; Relative humidity and temperatures; Temperature inversions; Weather research and forecasting models, Weather forecasting, climate modeling; fog; performance assessment; real time; water content; weather forecasting; winter, Delhi; India
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 27 Aug 2020 05:39
Last Modified: 27 Aug 2020 05:39
URI: http://eprints.iisc.ac.in/id/eprint/66264

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