Dust outbreak in California's Central Valley

By Jochen Kerkmann (Germany) and HansPeter Roesli (Switzerland)

Dust storms swept interior California on 11 October, shutting down highways and airports, and casting an eerie glow across an area that stretched from the Sacramento Valley to the Mojave Desert.

The dust was churned up by a low-pressure system known as an 'inside slider' that dropped down from the Pacific Northwest into California on the evening of 10 October and dug into Nevada's Great Basin the following day (see Figure 1).

The low-pressure system also brought snow to the Tahoe Basin, and caused winds that knocked over trees in the San Francisco Bay area.

Figure 2 shows a 12 hour animation of the dust outbreak in California. The low-level dust clouds appear in bright magenta colour. The dust appeared first in the southern Central Valley, then moved southward into the Mojave desert and further on into Nevada and Arizona.

Note the poor quality of the RGB images, i.e. the striping structure. This is due the problems with the cooling system of the ABI instrument, which was discovered during post-launch testing of the GOES-17 ABI instrument, see technical explanation below. Note: It is expected that GOES-17 (currently GOES-West) will soon be replaced by GOES-T (GOES-18), as soon as it becomes operational.

For comparison, Figure 3 shows the higher quality (no problems with the cooling system of the ABI) GOES-16 Dust RGB animation on early 12 October 2021. Dust can be seen over southern California, southern Nevada and western Arizona. In addition, a fire (hot spot) appears on the California coast, in the area of Santa Barbara. This fire, called the 'Alisal Fire', could be seen in this loop of GOES-16 Geocolor imagery (Source: RAMMB/CIRA). It is likely that the fire was intensified by the same strong northerly winds that caused the dust outbreak.

The dust outbreak could also be clearly seen on NOAA-20's VIIRS True Color RGB image (Figure 4).

This dust outbreak was just a few weeks after much of that same area had been smothered for most of the summer by smoke plumes from persistent, widespread wildfires, see Smoke plumes continue from Northern California wildfires (Source: CIMSS Satellite Blog) and California’s Dixie Fire Keeps on Growing (NASA Earth Observatory).

Technical explanation: According to NOAA, the loop heat pipe (LHP) subsystem, which transfers heat from the GOES-17 ABI electronics to the radiator, was not operating at its designed capacity. The consequence of this was that the ABI detectors could not be maintained at their intended temperatures under certain orbital conditions. Inadequate cooling of the infrared channels lead to partial loss of imagery during some of the overnight hours, before and after the vernal and autumnal equinoxes. Indeed, during some night hours during certain parts of the year, the sun heats up seven of the ABI detectors faster than they can be cooled. The detectors become warmer than they’re designed to operate, and they begin to radiate at temperatures closer to the wavelengths they’re attempting to detect from the Earth. Eventually, local emissions and dark current noise overwhelm the signal from the Earth, and the channels saturate, meaning a useful signal is not available.

Additional content

Dust storms shroud interior California amid high winds (SF Gate)
GOES-17 ABI performance (NOAA/NASA)