Introduction – Airborne Measurements Print
To set the stage for introducing the UAV system, Figure 1 shows some examples of data taken from a NOAA P3 flight into Hurricane Isabel in the ONR CBLAST (Hurricanes) program. Figures 1a and 1b, show video stills of the sea surface at wind speeds of 23 m/s and 44.5 m/s, respectively. Note the qualitative differences in the whitecapping and foam.

Figure 1: a and b show images of  the sea surface at wind speeds of  23 m/s and 45 m/s, in Isabel. Note the extensive foam and streaks in b. Figure 1c shows the distribution of whitecap coverage, peaking in the right front quadrant, along with the wind speed contours. Figure 1d shows the whitecap coverage plotted against wind speed and compared with other data.  Figure 1e shows preliminary wave data taken from the P3 at 80 m altitude using a fixed laser altimeter without the lower frequency aircraft motion removed. Also shown is the wavenumber spectrum with a high wavenumber (surface wave) tail with a slope of -3.36.

Figure 1c shows the whitecap coverage as a function of position in the hurricane along with the contours of wind speed. Figure 1d shows historical data on whitecap coverage versus wind speed along with more recent measurements and the CBLAST data. Finally, Figure 1e shows LIDAR data measuring the range from the aircraft to the surface which includes the aircraft motion and the wave motion. The spectrum of these data shows low frequency motion dominated by the aircraft and higher frequencies dominated by the waves. Data like these can be measured from the UAV system described here.

scripps oceanography