Ground-zero met–ocean observations and attenuation of wind energy during cyclonic storm Hudhud

Abstract

Ocean–met observations from INCOIS real-time automatic weather station on-board a ship RV Kaustubh served as strong ground truth for satellite- and model derived forecasts during the very severe cyclonic storm Hudhud, which made a landfall at Visakhapatnam, India. The ship recorded maximum wind speed of 204 km/h (with a minimum central pressure of 945 hPa), which is the highest (lowest) ever instrumentally recorded value at a location on the Indian coastline during any cyclone. Though the global model forecasts of wind fields have shown good agreement inland, they failed in representing the reality along the coasts. Variation in wind energy from ocean towards inland suggests that it is attenuated exponentially inland (the maximum wind power density had reduced by 93,406 W/m² at Anakapalle (∼25 km) compared to the ocean and by 7022 W/m² at Chintapalle (∼100 km inland) compared to Anakapalle). The present study reinforces the significance of having realtime near-shore ocean–met observations, and their operational usage for evaluation (assimilation) of (into) ocean–met forecast models in real time.