Revisiting estimation of TC winds from IR Imagery

Making sense of the data

Data and documentation• Flight-level data (1995-2012)• Estimates of tangential wind

at the 500km radius (GFS)• IR images (3-hourly here)• Best track (intensity, motion)• Methods to estimate surface

inflow angles• Methods to reduce winds

from flight-level to the surface

Analyses• Analyze aircraft data on a

polar grid, motion relative– Apply surface reduction– Decompose into wavenumber

0, 1, and 2

• Analyze IR images on a polar grid, motion relative– Decompose into 2-D principle

components

Method• Single-field principle component analysis (SFPCA; Bretherton

et al. 1992) applied to the amplitude and phase of the wind field– This relates intensity, latitude, translation speed, and the IR principle

components to the surface wind speeds

• Extrapolate the Amplitudes of wavenumbers through the 166km to 500km region of the vortex

• Apply inflow angles that are a function of translation speed, intensity, radius, and the radius of maximum wind (Zhang and Uhlhorn 2012)

Example Hurricane Ike 10 Sep 2008 18UTC

3-hourly wind estimates Ike 2008