Issue 59: Atmospheric Rivers
January 19, 2023
In this week’s issue: Clouds clear after a torrent of atmospheric rivers bombard California; two rias glow in Spain; and grasses invade marshes in China.
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Feature Story: Atmospheric Rivers
California is left drenched, flooded, and perhaps a little hopeful after recurring atmospheric rivers pummeled the state for 2 weeks straight. The rains are a small reprieve for the area’s years-long drought. But the sheer volume of rainfall was much more than the parched landscape could handle. With a turn of the faucet, the state went from too dry to too wet in what’s called a “weather whiplash,” transforming the Golden State to shades of brown.
Despite its appearance as empty space, the atmosphere is actually fluid. And rivers can move through it as if on land. There are between 4–5 of these atmospheric rivers on Earth at any given time and they can hold up to 15 times the volume of the Mississippi River. But while they’re a normal part of the global weather system, having back-to-back-to-back-to-back-to-back-to-back-to-back-to-back events in just 2 weeks isn’t.
It can be difficult to photograph intense rainfall events as they happen. Rain comes from clouds, which get in between satellites and the ground, obscuring any observable changes as they happen in real time. It’s only until after the clouds have parted that the picture unfolds and the damage takes shape.
Satellites have been pivotal in forecasting the storms’ movements, monitoring conditions like soil wetness during the deluge, and assessing critical areas after the rivers passed through. Some areas in California have already received an amount of rainfall equivalent to what they get in a year. And the impacts are distinctly visible: from swelled rivers to rising reservoir levels.
The rain that bombarded California’s coast turned to snow as it reached the Sierra Nevada mountain range, boosting the snowpack to over twice the average for this time of year. Which is great news since it’s a critical supply to the state’s reservoirs (about 30%). It’s not enough to completely reverse years of intense drought, but it’s certainly a welcome start.
The price paid for the rainfall, however, is now being tallied — and it’s grim. The 24.5tn gallons of water that fell across California flooded communities, triggered mudslides, impaired infrastructure, took lives, and cost more than $1 billion in damages. And in the coming months questions about preparedness and water management will be front and center for the state.
The past three weeks have surprised many of those accustomed to California’s sunny dryness, even turning places like the waterfalls of Butte County into landscapes easily mistaken for Hawaii. But the transformation is indicative of a larger problem: retention. Like drinking from a hose, only some of the stream makes its way to where it matters. A lot of the water that has fallen in the past few weeks is flowing right back into the ocean and highlighting California’s need to work on its storage capabilities. Add it to the state’s growing laundry list of climate adaptation strategies.
California isn’t the only place inundated with water. The global hydrological system has spilled over in Western Australia too, where Tropical Cyclone Ellie and yet another La Niña year contributed to major flooding. The flow rate at Fitzroy River reached nearly three times its typical rate during floods, and the overflow is visibly seen by satellite.
Unfortunately, climate change is intensifying extreme rain events and disrupting communities to an unseen degree. There’s no ark that can save us. Just widespread preparedness.
What in the World: Glowing Rias
Today’s episode of Between Two Rias features Huelva in Andalusia, Spain. While browsing the country’s southern coast for plastic greenhouses last week, we spotted the port city surrounded by two colorful rias (drowned river valleys open to the sea). On some days their fractal-like tendrils take on striking colors. Have an idea what causes the color? Let us know!
And here’s the city on another recent day, with slightly more painterly tones.
Grass Invaders
The Spartina alterniflora grass species is engaged in a turf war in China’s coastal wetlands. The grass is invading marshes with the proficiency of their namesake Greek warriors. To address the threat to ecosystem health, researchers are using satellites to study the species’ life cycle and response to environmental factors in order to help manage the plant’s growth.
All imagery Ⓒ 2022 Planet Labs PBC
Editor: Ryder Kimball | Images: Robert Simmon, Max Borrmann, Julian Peschel, and Ryder Kimball
