The energy contained in the ocean (typically measured as heat) fuels hurricane formation, and understanding how much energy is available to hurricanes in the Atlantic basin has just improved through a new product developed by researchers at the University of Miami and implemented at NOAA. Traditionally, sea surface temperatures have been used to help predict hurricane intensification, but SSTs measure only the very upper skin of the ocean. Hurricanes, however, are able to extract heat energy from much deeper – it is believed that any depth of water with temperatures above 78 degrees F (26 C) can fuel hurricane intensification. By using data from the NOAA National Oceanographic Data Center’s World Ocean Atlas along with sea surface height measurements from the Jason satellites, the newly developed Ocean Heat Content product suite provides hurricane forecasters with more timely and accurate estimates of ocean heat energy.
The first image shows the depth of water with temperatures greater than or equal to 26 degrees C. Purplish colors indicate very deep pools of warm water. In 2005, it was these deep reserves of very warm Gulf of Mexico water that allowed for the development of Hurricanes Katrina, Rita, and Wilma in quick succession.
The second image shows how much energy is contained in those same areas. Deeper water with higher temperatures holds more total energy (measured in Joules per meter squared). Traditionally, it has been believed that 60 Joules of heat content are required for hurricane intensification, but recent research is showing that this threshold may be even lower. Just as important as understanding the areas of high heat content, areas with low heat content (where hurricanes will weaken) are also important measurements when trying to predict storm path and intensity (the latter being the much more difficult forecast challenge).