TMI Captures Ocean Reflection of Largest Recorded Solar Flare

TRMM TMI 11 GHz VPol Antnna Temperatures

On November 4, 2003, at approximately 19:47 UTC, the largest solar flare event ever recorded erupted. The extremely intense radiation coming from the flare saturated x-ray detectors for 11 minutes. The same hyper-accelerated solar electrons that are responsible for the x-ray burst also emit intense microwave radiation. This burst of solar microwaves, traveling from the sun to the Earth in 8 minutes, reflected off the ocean surface and was seen by the TRMM microwave imager (TMI). The radiation was so intense that it saturated the 11-GHz TMI channels.

Remote Sensing Systems (RSS) detected this event during a routine data quality check that revealed anomalous geophysical retrievals. RSS processes TMI data into a suite of ocean products, including ocean temperature, wind speed, atmospheric water vapor, cloud, and rain rates, for use in weather forecasting, climate modeling, and scientific research. The erroneous ocean retrievals were traced back to exceptionally high microwave radiances coming from the solar flare.

Imagine looking at the ocean on a sunny day. When you look at a certain angle, you see the sun’s reflection. This angle is the specular reflection angle. Occasionally the satellite’s viewing angle matches the specular reflection angle. Serendipitously, TMI was looking at the specular reflection of the sun at the time of the solar flare event. The 11-GHz solar reflection as seen by TMI increased more than 100-fold during the 11-minute flare.