The Big Storm: a satellite view of the channel In the three weeks following Christmas 2004, the South Coast was hit with a series of major winter storms delivering impressive amounts of rainfall in two distinct pulses: the first from Dec. 26 through Jan. 4 and, after a few days of sunshine, the second from Jan In Ojai, 10.4 inches were recorded during the first storm, and slightly more, 12.6 inches, in the second. By mid-January, a total of 28.8 inches had fallen since the beginning of the rainy season; a lot more than the annual average of 20.9 inches. In downtown Santa Barbara, totals were similar: 9.5 inches during each storm for a mid-January total of 24.4 inches (the annual Santa Barbara average is 18.1 inches). This kind of storm, very big storm, has large impacts on the Santa Barbara Channel. Vast amounts of debris and sediment, accumulated since the last big flood in 1998, were flushed into the ocean along with huge quantities of storm runoff. What are these impacts? How far to they reach? How long do they last? These are just a few of the many unanswered questions currently being studied by the Santa Barbara Channel Long Term Ecological Research Project (SBC-LTER) at UCSB. And it is thanks to this project that we have satellite images of the Santa Barbara Channel during these events. The images are from MODIS (can you say “Moderate Resolution Imaging Spectroradiometer”). This instrument is carried aboard two satellites named “Terra” and “Aqua.” Terra's orbit passes from north to south across the equator in the morning, while Aqua does the honors in the afternoon. Together they view the Earth's entire surface every one to two days, acquiring data in 36 groups of wavelengths. If you really want to know more you can check out these websites: modis.gsfc.nasa.gov and oceancolor.gsfc.nasa.gov One of the things MODIS does is measure the radiance leaving the surface of the ocean in a band of wave-lengths from 546 to 556 nanometers: a band that can detect sediment in water. Most of the wave bands MODIS measures are not in the visible spectrum, but this one is – think of it as a shade of green. In the images that follow, heavy sediment is indicated by the color brown. The colors are not real, rather they represent MODIS data, processed to remove sources of radiance not from the ocean surface, corrected for distortion and analyzed with various algorithms (think very complex equations) to produce a value that can be related to sediment intensity (don’t even think about asking what the units mean). The date and time of each image is on the top: year-month-day.hour.minute.

Just before Christmas, small plumes of sediment are flowing out of the mouth of the Santa Clara and Ventura rivers; by Christmas they extend further up the Ventura County coast line and out to sea.

By New Year’s Day a fringe of sediment rings the coast north and east of Pt. Conception, and extends out to the Channel Islands at the end of the second storm on January 12.

A week later, sediment is still found far out in the Santa Barbara channel. The sediment shown in these images is not the sand and gravel that settles to the bottom soon after leaving creek and river mouths, but fine silts and clays that remains in suspension long after entering the ocean.