ACSPO Temperatures from VIIRS and GOES-R

September 6th, 2022 |
ACSPO Lake Surface Temperatures over Lake Superior, 0855 UTC on 6 September 2022, with and without Buoy observations (Click to enlarge)

Advanced Clear-Sky Processor for Ocean (ACSPO) temperatures over Lake Superior on 6 September, shown above, show a large area of surface temperature below 55oF (magenta and white in the enhancement) over central Lake Superior. Clear early-Autumn skies allowed for this mostly complete view of the Lake Surface. Although Lake Superior was quite cold with respect to normal in late June (see this graph), its surface waters are now very close to normal. Note how much warmer the northern end of Lake Michigan is! The yellow enhancement shows temperatures close to 70oF.


The animation below shows VIIRS ACSPO temperatures off the coast of Oregon from 3 separate overpasses. The strong north winds observed at the buoys strengthen oceanic upwelling, leading to the very cold ocean surface temperatures (51o – 52oF) along the Oregon coast.

ACSPO Sea Surface Temperatures along the Oregon Coast, 0855, 0948 and 1039 UTC on 6 September 2022, with Buoy observations (Click to enlarge)

GOES-R Satellites have level-2 Sea Surface Temperature products as well (link) that something like the ACSPO algorithm — albeit at lower spatial resolution. The toggle below compares the two products. VIIRS better captures the cold ribbon of water right along the coast. The GOES-R algorithm cloud mask at the time below is perhaps too stringent.

VIIRS and GOES-R ACSPO Sea Surface Temperatures, ca. 1000 UTC on 6 September 2022 (Click to enlarge)

On 4 September, strong nighttime radiation cooling led to the Lake Superior water temperatures being several degrees F warmer than the surface air temperatures at nearby inland locations (overnight minimum temperatures included 33ºF in far northern Wisconsin and 34ºF in Upper Michigan; note that the color scale used in the tweet below differs from the one above):

Labor Day Weekend Aurora Borealis via VIIRS Day Night Band

September 6th, 2022 |

The recent 3-day weekend was a 3-night extravaganza for Aurora enthusiasts with an active Aurora Borealis lighting up the sky for 3 nights in a row.  The VIIRS (Visible Infrared Imaging Radiometer Suite) Day Night Band Sensor flying on the Suomi-NPP and NOAA-20 polar-orbiting satellites captured stunning snapshots of the celestial phenomena during each North America overpass.  

NOAA-20 VIIRS DNB image acquired in the early hours (0954 UTC) of September 3rd, 2022
Suomi-NPP VIIRS DNB image acquired in the early hours (0904 UTC) of September 3rd, 2022

Auroras are visible signatures of disturbances in Earth’s magnetosphere that occur when the solar wind interacts with Earth’s magnetic field during geomagnetic storms and substorms. They typically flow between 100 to 500 km above Earth’s surface. Polar-orbiting satellites fly at an altitude of 824 km (512 miles) and are perfectly situated to observe and monitor the Aurora Borealis in the Northern Hemisphere or Aurora Australis in the Southern Hemisphere.

Suomi-NPP VIIRS DNB image acquired in the early hours (1027 UTC) of September 4th, 2022
Suomi-NPP VIIRS DNB image acquired in the early hours (0845 UTC) of September 4th, 2022
NOAA-20 VIIRS DNB image acquired in the early hours (0704 UTC) of September 4th, 2022
NOAA-20 VIIRS DNB image acquired in the early hours (0935 UTC) of September 4th, 2022
NOAA-20 VIIRS DNB image acquired in the early hours (0753 UTC) of September 4th, 2022
NOAA-20 VIIRS DNB image acquired in the early hours (0614 UTC) of September 4th, 2022

Uniquely sensitive to low levels of visible light at night, VIIRS Day Night Band is the only satellite sensor able to detect and display the Aurora. The DNB is sensitive to radiation in wavelengths between 0.5 – 0.9 µm, which covers much of the visible and some near-infrared wavelengths. The images appear monochromatic because they are a combination of all energy within the entire bandwidth, meaning we can’t separate out the “green” or “red” parts of the data to see vibrant colors that citizen science photographers capture from below. Thousands of Northern Lights pictures were shared on social media over the weekend. Here are just a few …

Suomi-NPP VIIRS DNB image acquired in the early hours (0826 UTC) of September 5th, 2022
NOAA-20 VIIRS DNB image acquired in the early hours (0733 UTC) of September 5th, 2022

Day Night Band images from North America satellite overpasses are available via the VIIRS Imagery Viewer , a 7-day archive — refreshed daily — for all 22 VIIRS channels, usually within 60 minutes of being acquired onboard the spacecraft. Current and archived VIIRS images over the continental USA are also available on the VIIRS TODAY website. As future JPSS VIIRS satellites join the fleet, that data will also be available on these sites.

Of note: the JPSS-2 (NOAA-21) satellite is scheduled for launch on November 1st, 2022.