As hurricane-forecasting techniques have improved, the loss of life due to severe storms has steadily declined. Nevertheless, researchers at the National Hurricane Center estimate that over the past five centuries, Atlantic hurricane fatalities have ranged from one-third to one-half million people, with a conservative 160,000 fatalities along coastal North and Central America due to storms this century. Beyond the cost in lives, the damage storms inflict has risen to billions of dollars. As a case in point, Hurricane Andrew made landfall in 1992 to the tune of $26.5 billion.
"Forecasters are getting better every single year at predicting a hurricane's track. But knowing what the actual intensity is going to be when it makes landfall and gauging how much rainfall it's going to dump are areas that still need a lot of work," said Robbie Hood, of NASA's Marshall Space Flight Center, Global Hydrology and Climate Center (GHCC) in Huntsville, Alabama. Hood was NASA's lead mission scientist on the Third Convection and Moisture Experiment (CAMEX-3) which included participants from six NASA field centers and seven universities.
"For instance, the Hurricane Center's statistics indicate that more people are killed from inland flooding and heavy rainfall in hurricane situations, than people who are actually killed along the coastline due to storm surges," Hood said. "That's because the message has gotten out. People know they need to evacuate and they know the tides are going to be high and storm surges are going to be significant, so officials are doing their jobs as far as evacuating folks, but inland flooding is still a tremendous problem," she said.
Aiming to push the envelope on hurricane forecasting, atmospheric researchers and crews flew instrumented aircraft directly into hurricanes. Depending on that day's mission, CAMEX-3 participants flew bow tie patterns over the eye of the storm, studied activities within the hurricane, or circled the storm, measuring its outside water vapor environment and other atmospheric conditions, up to eight hours at a stretch.
"We were trying to get a better three-dimensional picture of what a hurricane looks like in high detail," Hood said. CAMEX-3 followed two earlier CAMEX experiments completed in 1993 and 1995 that focused on detailed aspects of the hydrologic cycle. Each of the earlier CAMEX studies used prototype satellite instruments or instruments that mimicked existing satellite sensors. "Satellites monitor hurricanes too," Hood pointed out. "The differences are that most of the satellites only pass over once or twice a day, and the imagery that they collect is much coarser resolution because they're at higher altitude than our aircraft. We can fly lower and closer and see things in more detail.
"Aircraft instruments use the same remote sensing techniques, but provide more details of conditions," she said. "It's just like putting the hurricane under a microscope. You can look at something with your eye, but when you put it under a microscope you can see specifics." In addition to the immediate value of studies underway, collecting data by under-flying satellites with the same or comparable instruments allows scientists to calibrate and validate data taken from space. Such exercises in "ground truth" provide facts that, when compared to space imagery, allow scientists to better understand satellite signatures, and how comparable space sensors portray climate and surface features.
