A pair of weather instruments built at NASA's Jet Propulsion Laboratory in Southern California captured images of Hurricane Franklin as the Category 4 storm moved off the East Coast of the United States on Aug. 29, 2023.

COWVR (short for Compact Ocean Wind Vector Radiometer) and TEMPEST (Temporal Experiment for Storms and Tropical Systems) observe the planet's atmosphere and surface from aboard the International Space Station, which passed in low Earth orbit over the storm at about 9:58 a.m. EDT.

This image combines microwave emissions measurements from both COWVR and TEMPEST. White sections indicate the presence of clouds. Green portions indicate rain. Yellow, red, and black indicate where air and water vapor were moving most vigorously. Franklin's center is seen about 700 miles (1,127 kilometers) east of Jacksonville, Florida, over the Atlantic Ocean.

Figure A shows Franklin with solely COWVR data, collected at 34 GHz. About the size of a minifridge, COWVR measures natural microwave emissions over the ocean. The magnitude of the emissions increases with the amount of rain in the atmosphere, and the strongest rain produces the strongest microwave emissions.

Figure A

Figures B and C show the storm in data collected by TEMPEST at 89 and 165 GHz, respectively. Comparable in size to a cereal box, TEMPEST tracks microwaves at shorter wavelength than COWVR does, allowing it to see ice particles within the hurricane's cloudy regions that are thrust into the upper atmosphere by the storm.

Figure B


Figure C

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COWVR's development was funded by the U.S. Space Force, and TEMPEST was developed with NASA funding. The U.S. Space Test Program-Houston 8 (STP-H8) is responsible for hosting the instruments on the space station under Space Force funding in partnership with NASA.