Hurricane Jimena

Hurricane Jimena

The center of Hurricane Jimena was coming ashore over Baja California on September 2, 2009, when these images were taken. The top image is from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite. The lower image was made from data collected by a radar instrument flying on the Cloudsat satellite. Together, the images show the structure of the Category 1 hurricane shortly after it make landfall. The storm brought both damaging wind and drought-breaking rain to the peninsula.

As recently as the day before landfall, Jimena had been a strong Category 4 storm with sustained winds peaking at 250 kilometers per hour (155 miles per hour), according to the National Hurricane Center. Though the storm weakened significantly before making landfall, it retained the appearance of a strong storm, with well-organized bands of clouds and a near-circular shape. When the top image was taken at 1:55 p.m. Pacific Daylight Time, Jimena had sustained winds of 140 kilometers per hour (85 miles per hour) with stronger gusts.

The lower image provides a vertical profile of the storm. Cloudsat did not pass directly over Jimena’s eye, but its radar captured the cloud structure on the south side of the storm. The clouds in this section of the storm towered more than ten kilometers over sea level. Though the cloud heights are more or less uniform, small variations point to bands of thunderstorms within the hurricane.

Like a ground-based weather radar instrument, Cloudsat sees the structure of clouds by bouncing pulses of energy off cloud particles and recording the strength of the echo. Dense clouds will return a stronger echo, and higher clouds will return an echo more quickly. Cloudsat sees tiny particles of ice and water within clouds. It is 1,000 times more sensitive than ground-based weather radar instruments, which measure large drops of water (rain) within clouds.

NASA image created by Jesse Allen, using CloudSat FirstLook data provided courtesy of the CloudSat team at Colorado State University.

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