It's a bit like digging for dinosaur bones.
Only in this archaeological excavation, researchers have so far uncovered 327 new tropical systems and revised the tracks or strengths of 453 more by poring through old ships reports and hand-drawn ocean maps.
This is the National Hurricane Center's project to reanalyze storm seasons from 1851 to 2000, to ensure tropical history is as accurate as possible. It's a herculean task because new meteorological techniques must be applied to dusty-old data, said Chris Landsea, the center's science and operations officer.
"We continue to discover new tropical storms that occurred over open ocean but weren't recognized as tropical storms at the time," he said. "We've removed nine systems from the database, which we determined were not in reality tropical storms."
The job isn't even half complete. Since starting the reanalysis project in 2000, Landsea and a team of researchers, usually university students, have scrutinized 60 seasons, from 1886 to 1945. They plan to reanalyze 90 more, including 35 before 1886 and 55 after 1945.
The team most recently examined the period from 1941 to 1945 and found four new tropical systems, including a hurricane. It also revised the intensity of three hurricanes.
Notable among them was a hurricane that slammed into Homestead in September 1945. It was upgraded from a Category 3 to Category 4 with sustained winds of 135 mph.
"It was amazing the similarities that hurricane had with Hurricane Andrew," Landsea said. "Both were very small and both tracked right over Miami-Dade County."
Another similarity: Ten years after it struck, Andrew also was upgraded from Category 4 to 5.
However, while Andrew demolished whole communities, the one 68 years ago did little damage to homes because so few people lived there then. However, it destroyed 25 blimps, more than 360 planes, 150 cars and a giant blimp hangar at what was then the Richmond Naval Air Station, near what is now Zoo Miami.
The reanalysis team also downgraded the 1944 Great Atlantic Hurricane from Category 3 to 2. That system struck New York and killed 390 along the East Coast.
And an October 1944 hurricane, which struck Cuba, killing 315 people, was upgraded from Category 3 to 4.
To study storms that popped up more than 60 years ago, before satellites and other sophisticated observation techniques, Landsea and his researchers largely resorted to a comprehensive ships report database, kept by the National Climatic Data Center, in Asheville, N.C.
The reports were filed by both commercial and military ships that either blundered into storms or skirted around them, recording atmospheric measurements, such as barometric pressure, along the way. But the reports were usually crude. For instance, wind speeds were estimated by the amount of white froth on waves, Landsea said.
The team also found hand-drawn storm-track maps, dug into hurricane center microfilm files and perused old weather record books.
Additionally, for the 1945 Homestead hurricane, the researchers were able to draw on military aircraft reconnaissance reports. At that time, planes were just beginning to fly into storms to get more accurate readings, said Chris Luckett, who took the lead role in studying that storm while interning at the hurricane center.
"Mainly from aircraft reconnaissance reports, we noticed the wind observations didn't really match," said Luckett, today a forecaster in Albuquerque, N.M. "We had to do a lot of research to find that information."
In all, the team scrutinized 52 storms in the early 1940s, which wasn't easy because it was during World War II, when few commercial ships took to the sea and many military ships destroyed their records.
Landsea said his research team is now in the process of reanalyzing storms from 1946 through 1959. He wants to make sure the entire hurricane database has been "homogenized" with modern-day techniques because emergency managers, insurance companies and other agencies count on it to be accurate.
But he noted the tropical record may never be complete.
"No way we can go back to 1943 and take a satellite image," he said. "So there are going to be storms that we missed."
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