Supertyphoon Pongsona Isotherms

The AIRS sounder reveals important new information to supplement the familiar overhead views of hurricanes that come from satellites. Here AIRS shows some of the internal temperature structure of Supertyphoon Pongsona just as it hit the island of Guam last December of 2002. Each of the colored surfaces represents a particular temperature, from red and warm near the surface to yellow and very cold near the top. Normally, these so-called isotherms would be much smoother and nearly horizontal. Here we see how the latent heat released in convective updrafts causes the isotherms to bulge upward. This bulging is even seen more than 50,000 feet above sea level. This relatively warm air cap above a hurricane has rarely been observed and can only be measured with an instrument like AIRS. As we zoom in on the lower 30,000 feet, the temperature structure becomes more striking. It is even possible to discern a dip in the center at the lowest level, where cooler and drier air descends and forms the often cloud free eye of a hurricane.