Did Typhoon Haiyan have a new record-minimum pressure?
Hoarau, Karl ; Lander, Mark ; De Guzman, Rosalina ; Guard, Chip ; Barba, Rose
Année de publication
Since 12 October 1979, Typhoon Tip has officially remained the tropical cyclone associated with the lowest atmospheric pressure measured at sea level: 870hPa. The average winds over 1min were estimated at 165kn. On 7 November 2013, Typhoon Haiyan was the first cyclone to have been estimated at 170kn from satellite imagery. In the absence of aircraft reconnaissance, the minimum pressure has been estimated at 895hPa using the wind-pressure relationship. Using data observed at Guiuan meteorological station in the Philippines, we have estimated the minimum surface pressure in the eye of Haiyan. On the basis of the last pressure measurement of 910hPa at Guiuan, which was located at the outer edge of the eyewall, we estimated the pressure gradient for the 11km of the eyewall. This estimation was made using a comparison with the pressure gradient of the eyewall of two of the most intense tropical cyclones for which the pressures were precisely measured by aerial reconnaissance. During these airborne missions, Hurricane Patricia (23 October 2015), which formed in the eastern North Pacific, had a pressure of 879hPa, and Typhoon Megi (17 October 2010), which formed in the western North Pacific, had a pressure of 890hPa. At the time of the aircraft reconnaissance, the sustained winds of 180kn for Patricia (6h before the maximum wind of 185kn) and 160kn for Megi were comparable to the 170kn of Haiyan. Based on the pressure gradient calculated inside the eyewall of Patricia and Megi, we distinguished three scenarios for Haiyan. Each of them gives a minimum pressure at sea level below the 870hPa of Typhoon Tip, which was the world record holder.