Characteristics of visibility for Chennai international airport

Abstract

Visibility at Chennai International Airport has shown a marked decline between 2016 and 2024, with a strong negative trend (R² = 0.89) linked to increasing weather disturbances and rising urban pollution. This reduction in visibility has contributed to more frequent flight delays, particularly during early morning hours (around 06:30–07:00 IST), when the lowest values are typically recorded in METAR. Seasonal analysis highlights November as the month with the poorest overall visibility, while the most severe reductions often below 1200 m and sometimes under 400 m occur in December through February. January records the highest frequency of extremely low visibility, including occurrences below 200 m. Fog typically begins near 03:30 IST and peaks around 07:00 IST, directly affecting early morning aviation operations. On average, fog occurs 5.2 days in January, 4.8 days in February, 3.9 days in December, and 3.1 days in March, with October–November adding another 3.2 days annually. Backward trajectory analysis suggests aerosol transport contributes to these conditions, reinforcing the role of both local pollution and regional atmospheric processes. The findings highlight an urgent need for stricter air-quality measures, improved airport infrastructure, and adaptive operational strategies to mitigate the growing challenges of low visibility.