Dual-aircraft investigation of the inner core of Hurricane Norbert. I: Kinematic structure

Two NOAA AOC WP-3D research aircraft were used to investigate air motions and physical processes in the eyewall region of Hurricane Norbert on September 24-25, 1984. The data obtained provide the first complete documentation of the 3D wind fields of the inner core of a hurricane on spatial scales of 10-25 km in the horizontal and 1 km in the vertical and temporal scales of 1-2 h. The wind was asymmetric, and the asymmetry varied with altitude. As altitude increased the location of the maximum tangential wind sloped upwind, from left of the storm track at 1-km altitude to right of the storm track above 3 km. The radial wind at 1-km altitude was inward in front of the storm and outward behind. This pattern in the radial flow reversed above 3-km altitude, with inflow at the rear of the storm and outflow in the front. The nature of the wind field asymmetry is investigated by partitioning the horizontal wind components into a horizontal mean wind, varying with altitude and a perturbation wind. (P.D.)