Planet Earth

The Runoff From California's Storms Has Been so Intense It's Visible From Space

Dramatic satellite imagery reveals giant plumes of sediment clouding coastal waters in Southern California.

ImaGeo iconImaGeoBy Tom YulsmanJan 12, 2023 12:30 AM
Muddy Waters
An image acquired by the Sentinel-2 satellite on Jan. 6, 2023 reveals runoff of sediment into the sea along the California coast stretching from Oxnard to Santa Barbara. See the story below for a before-and-after animation. (Credit: Modified Copernicus Sentinel data processed by Tom Yulsman)

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As the relentless series of atmospheric river storms has battered California, some of the environmental impacts have become clearly visible from space.

You can see a vivid example in the image above, captured by the Sentinel-2 satellite on Jan. 6. It shows a portion of the Southern California coast stretching from Oxnard in the lower right corner to Santa Barbara at upper left. Rampaging streams and floodwaters have disgorged huge loads of sediment into the sea, staining large swaths of the near-shore waters in tones ranging from turquoise to orange.

To get a sense of what those waters would normally look like, check out this animation comparing the scene from Jan. 6 with an image captured by the satellite one year ago today:

A before and after animation of images acquired by the Sentinel 2 satellite. (Credit: Copernicus Sentinel image data; animation by Tom Yulsman)

The lack of sediments in coastal waters one year ago is obvious. But also note just how much greener the landscape is now. I don't think that's an illusion resulting from different lighting conditions between the two images. I checked something known as the NDVI, which is a way of assessing green vegetation in remote sensing images, and the greening looks very real.

Total rainfall for a large portion of California is plotted here for the 14-day period between Dec. 29, 2022 and Jan. 11, 2023. Along the Pacific coast, the map stretches from the Mexican border north to just beyond the Monterey Peninsula. (Credit: NOAA)

As the map above shows, the amount of rainfall that has fallen over this region, and other parts of California, truly is staggering. The mountains that stretch east-west along the coast in this part of the state have received some of the highest rainfall totals.

In just the first 11 days of January, one station in the mountains above Santa Barbara has recorded 26.15 inches of rain. That's more than 500 percent of its average precipitation for the entire water year (which runs from Oct. 1 to Sept. 30) — and 1,445 percent of the average rainfall for the month to date.

The storminess is not done yet. As the National Weather Service put it in a Tweet today, "A series of atmospheric rivers will continue to affect the western U.S., producing additional periods of heavy rain, snow, and flooding across California into next week."

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