Sunday, July 26, 2015

Fewer but Stronger Global Tropical Cyclones (Hurricanes) Due to Ocean Warming

One of the most spectacular images ever captured of a tropical cyclone from space: Category 5 Super Typhoon Maysak as seen from the International Space Station at approximately 6 pm EDT Tuesday March 31, 2015 (just after dawn local time.) At the time, Mayask had top winds of 160 mph as estimated by the Joint Typhoon Warning Center, and a central pressure of 905 mb, as estimated by the Japan Meteorological Agency. Image has been brightened and flipped 180 degrees. (Image credit: Terry W. Virts.) Click to Enlarge.
Global ocean temperatures hit their warmest levels in recorded history last month.  Since hurricanes are heat engines which extract heat energy from the oceans and convert it to the kinetic energy of the storms' winds, we should be concerned about the potential for hurricanes to be stronger as a result of global warming.  Indeed, the observed 0.3°C (0.5°F) warming of Earth's oceans over the past 30 years has made more energy available to hurricanes, says a new study published in May in Nature Climate Change by Florida State hurricane scientist James Elsner and the deputy director of the National Typhoon Center in South Korea, Namyoung Kang.  The researchers found that this extra heat energy has led to a change in both the frequency and intensity of global tropical storms and hurricanes. 

Using a new mathematical framework to categorize all global tropical cyclones with wind speeds of at least 39 mph over the past 30 years, the authors showed that the observed warming of Earth's oceans during that time period has led to an average increase in wind speed of about 3 mph (1.3 m/s) for each storm--but there were 6.1 fewer named storms globally each year because of the warmer oceans.  A typical year has about 85 named storms globally, so this represents about a 7% decrease in the number of storms.

Read more at Fewer but Stronger Global Tropical Cyclones Due to Ocean Warming

No comments:

Post a Comment