On Saturday, Air Force pilots in California will take off in a C-130J, a heavy plane similar to a cargo plane. They will fly out to sea and over atmospheric rivers that are expected to make landfall that day.
“Basically we’re flying aircraft that fly over the top of atmospheric rivers, and we’re dropping weather instruments into them called dropsondes,” said Lt. Ryan Rickert, a reconnaissance weather officer with the U.S. Air Force.
“They collect temperature, pressure, wind direction and wind speed – which is also important – and the moisture. And it’s an entire profile from where it’s launched from the aircraft, all the way to the surface of the ocean,” he said.
Atmospheric rivers are weather systems that can transmit a huge amount of airborne moisture to California, where it falls as precipitation. They bring up to 65% of California’s seasonal precipitation.
Rickert said the dropsondes that measure the atmospheric river look like cardboard cylinders. They’re equipped with a parachute to slow it down when they’re dropped from a plane at 30,000 feet.
“It falls to the ocean. The chutes come out and basically keeps it from flopping around in the atmosphere. So it’s falling in the correct position,” Rickert said.
Being able to better predict the development and movement of these rivers in the sky will help California’s water supply. Knowing how and when their rains will fall means being able to create reservoirs to store a lot more water.
The same kind of monitoring devices that are dropped from planes over the oceans are also released on land, fastened to weather balloons. Those instruments measure atmospheric rivers as they move over the land.
“We have been able to learn from that exactly how intense these storms are, how they’re oriented and how fast they’re moving,” said Anna Wilson, the atmospheric river reconnaissance coordinator for the Scripps Institution of Oceanography.
But she admits we’ve got a ways to go before we know how many atmospheric rivers a wet season may bring.
“I think right now we wish we were a lot better at that. And there is a lot of ongoing work with the California Department of Water Resources with Scripps, really trying to make that better,” Wilson said. “Because that knowledge would be incredible for the state to be able to have,”
