 The last two help determine whether or not a low pressure area is an extratropical cyclone, subtropical cyclone, or tropical cyclone.Christopher Landsea noted that the efforts to reanalyze the Atlantic hurricane database will not be able to recover observations of open ocean tropical cyclones that were just never taken.Researchers cannot assume that the Atlantic tropical cyclone database presents a complete depiction of frequency of events before the advent of satellite imagery in the mid-1960s.