Passive microwave images of tropical cyclones worldwide can now be viewed on the Web in near real time. Instant access can be obtained to any “live” tropical cyclone. The images show rainband and eye structure beneath higher cloud decks and can be used to infer intensity and storm position.

The images are available on the Web site of the U.S. Naval Research Laboratory's (NRL) Marine Meteorology Division (, select “tropical cyclones”). Because of the composite nature of the images, users can view unfamiliar Special Sensor Microwave Imager (SSM/I) images juxtaposed with much more familiar visible and IR images (see Figure 1). This juxtaposition allows a number of interpretations of storm structure that would not be possible using information from a single sensor alone. The ability to detect storm eyes from microwave images, and therefore fix storm position, is significant since cyclone eyes are often obscured by cirrus canopies on visible and IR images. Besides microwave, visible and IR images of tropical cyclones, the Web site also has charts giving official U.S. forecasts of the storm tracks and intensities (example in Figure 2).