70th Anniversary of seminal hurricane formation paper

In the summer 1948 edition of Geophysica journal, Eric Palmén published a seminal paper entitled “On the Formation and Structure of Tropical Hurricanes”.  In it he proposed that a tropical disturbance needed to be over sea surface temperature of at least 80℉ (26-27℃) in order to form into a tropical cyclone.  He imposed the tracks of tropical cyclones over a global map of sea surface temperature to illustrate his contention.  This temperature limit was cited in many subsequent papers published on tropical cyclone formation.

Figure showing sea surface temperatures and tropical cyclone tracks.

In addition to hurricane formation he attempted to sketch out the vertical structure of these storms.  He used radiosonde soundings taken in the vicinity of a 1947 hurricane while it was east of Florida.  He lacked any soundings within 125 miles (200 km) of the center so he used the eye sounding taken in a 1944 Tampa hurricane to represent the inner core.

Figure illustrating vertical thermal structure of a hurricane.

One feature of this early attempt to describe a hurricane’s anatomy is the eye being depicted as a large cone, spreading from tens of kilometers at the surface to nearly 300 km (190 miles) in radius at the tropopause.  It wasn’t until later high-altitude research flights into hurricanes that it was realized the hurricane eyewalls were far more vertical.

References

Palmén, E. H., 1948: On the formation and structure of tropical cyclones. Geophysica, 3, 26–38.