Joanne Simpson, widely recognized as a leader in the field of meteorlogy, and the first woman to earn a doctorate in meteorology passed away on March 4, 2010. She was a member of the U.S. National Academy of Engineering, a recipient of the Carl-Gustaf Rossby Award (the highest honor bestowed by the American Meteorological Society), a Guggenheim Fellowship, and served as President of the American Meteorological Society.
After completing a course at the University of Chicago with Herbert Riehl on tropical meteorology, she decided to concentrate on tropical cumulous clouds earned a Ph.D. working with Riehl as her advisor. Upon earning her Ph.D., she became an Assistant Professor of Physics at the Illinois Institute of Technology. During the summers, Simpson (now Joanne Malkus) traveled to Woods Hole Oceanographic Institute with her family to work on an exciting project involving tropical clouds. Simpson moved to the Woods Hole Oceanographic Institution after deciding to leave Chicago for a better place to raise her young children. There she began to develop a model of cumulus clouds and to take the first steps in demonstrating how important these clouds were in driving tropical circulations. There she established a new understanding in meteorology and understanding of hurricanes by showing that heat generated by the condensation of water within tall, anvil-shaped, cumulonimbus clouds called “hot towers” provided the energy needed to keep the Hadley circulation and the trade winds running. Although some doubted the hypothesis, the Tropical Rainfall Measuring Mission (TRMM) provided dramatic confirmation of hot towers in hurricanes when it collected data of Hurricane Bonnie on August 22, 1998. A column of intense rainfall rose to the astonishing altitude of 18,000 meters (59,000 feet). Simpson’s “hot-tower hypothesis” explained how hurricane are driven until they hit land, run into colder water, or encounter one of the other “hurricane enemies” such as wind shear that tears the warm core apart.
During the middle of her career Simpson conducted some unique “weather modification” experiments that continue to have an impact on meteorology today. After that period she came to NASA and in 1986, Simpson led the “study” science team for the proposed Tropical Rainfall Measuring Mission (TRMM), a satellite to carry the first space-based rain radar, which would measure rainfall across the tropics and subtropics. Between 1986 and launch in November 1997, She worked in close partnership with the project engineers, and recruited brilliant scientists to develop the data system.
Today TRMM is recognized as being instrumental for helping scientists learn how hurricanes start in the Atlantic Basin and in demonstrating how dust and smoke can drastically influence rainfall. But of all the results that came about from TRMM, the discovery that Simpson was most excited about occurred in 2002, on the fifth anniversary of the satellite’s launch.
By that time, TRMM had met or exceeded nearly all of its important goals. One of its goals, however, still remained, which was to measure from orbit the profile of latent heating released by tropical cloud systems. The ability to measure latent heat profiles over wide areas has long been on the wish list of the meteorological community. The difficulty has always been that latent heat cannot be measured directly. Today, scientists can accurately estimate latent heat in the tropics using a model based on TRMM rain profiles. Professor Robert Houze and Courtney Shumaker showed that for several different areas, the TRMM profiles and those profiles directly observed were in good agreement. Simpson’s early groundbreaking work on latent heating of the atmosphere had come full circle with TRMM’s many successes.
Simpson felt lucky to get into meteorology when she did and recognized that she was in the profession during a time when some of the biggest discoveries were made. She also felt that being the first woman in meteorology she carried a responsibility for the fate of other, younger women who wanted to be meteorologists and this pushed her to do her best. Later in her career she continued her work at the Goddard Space Flight center and became a widely recognized role model for women in meteorology.