LA JOLLA, Calif. (AFNS) -- Members of the 53rd Weather Reconnaissance Squadron "Hurricane Hunters" met with scientists from the University of California San Diego's Scripps Institution of Oceanography Nov. 29, 2017, to discuss plans for participating in atmospheric river reconnaissance missions in early 2018.
Dr. Fred "Marty" Ralph, Scripps Institution of Oceanography Center of Western Weather and Water Extremes researcher and director, leads a team of scientists that studies atmospheric rivers.
"Atmospheric rivers are essentially like rivers of water vapor in the sky," said Ralph. "If you think of a typical river on land, like the Mississippi River, you can image how much water the Mississippi River is carrying - it's a lot of water. A typical atmospheric river carries about 25 times the equivalent of a Mississippi River, but as water vapor rather than as liquid. And it does it in about a 500-mile-wide swath, and sometimes thousands of miles long, with winds from 50 knots up to hurricane force."
According to current scientific research, atmospheric rivers also act as a key component of the water supply on the U.S. West Coast - 30 to 50 percent of annual precipitation occurs within just a few atmospheric river events. As such, they have been shown to contribute to breaking more than 40 percent of California's droughts throughout history.
However, when the atmospheric rivers do make landfall they can lead to extensive flooding, which can in turn cause mudslides that may threaten both life and property. According to Ralph, one of the main reasons for studying these atmospheric rivers is to provide data that can be used to improve weather forecasts on the West Coast, which is important for improving reservoir operations that can supply water during droughts and control water levels during potential flood events.
Scripps researchers have been able to gather information closer to the coast and using satellite data over the Pacific Ocean, where these atmospheric rivers travel, but Ralph said there remain key observational gaps over the ocean, such as vertical profiles of wind and water vapor in atmospheric rivers.
This is where the Hurricane Hunters would come in.
Maj. Ashley Lundry, 53rd WRS aerial reconnaissance weather officer and chief scientific officer, said for missions into atmospheric rivers, Hurricane Hunters plan on having two aircrews flying these events simultaneously using their WC-130J Super Hercules, one from a location in Hawaii and another from the West Coast. An additional planning team would be located at the Scripps Institution of Oceanography to work directly with the scientific research team and National Weather Service on planning these missions.
"We could be dropping anywhere from 25 to 50 dropsondes per mission into an atmospheric river, and all of that data will be sent to the National Hurricane Center and then out to the public and ingested into forecast models," said Lundry. This same data also would be made available to Scripps researchers.
Lundry said both Hurricane Hunter planes would fly through the atmospheric river approximately 30,000 feet above the ocean to launch the dropsondes, where they would collect weather data such as air pressure, temperature, humidity, wind speed and direction, and global positioning system information. This data would be checked for accuracy by the weather officer on the aircraft and then sent to the National Hurricane Center. Normally for hurricane missions, 53rd WRS aircraft fly no higher than 10,000 feet through a storm.
The Hurricane Hunters took part in these data-collecting missions for the first time in February 2016, flying three missions that year. In 2018, they plan on flying six missions during two separate two-week intervals.
Ralph said the dropsondes would be very helpful for collecting wind data and determining a vertical profile for the water vapor in the low-level jet stream, something they are currently unable to do using only satellite data. Lundry also noted that the data gathered by the Hurricane Hunters at this level could help fill in those data-sparse areas of the Pacific, which would be crucial for improving the accuracy of forecast models.
These missions also represent a joint effort not only between Scripps researchers and the U.S. Air Force Reserve Command, but with the Sonoma County Water Agency and the California Department of Water Resources, as well as the U.S. Army Corps of Engineers, who operate many key reservoirs in the western U.S.
Lundry said these atmospheric river missions would provide the 53rd WRS with excellent training opportunities outside of the hurricane season, which runs from June 1 to Nov. 30 each year.
"We would be dropping up to 50 dropsondes a flight, so this is great training for the weather officer and the loadmaster dropsonde operator, especially for some of the junior members to get experience dropping the sondes and packaging the data at this high of a tempo," said Lundry, who added that for a hurricane flight the 53rd WRS aircrew can typically drop anywhere from 12 to 15 sondes. "It's a very busy time, especially when you have two aircraft in the system at the same time, but it looks to be a very rewarding and beneficial experience."