MODIS Sea Surface Temperature product

An AWIPS image of the 1-km resolution MODIS Sea Surface Temperature (SST) product on 10 May 2012 (above) revealed that much of Lake Superior exhibited SST values in the 40s F (darker blue color enhancement), with the coldest SST value being 39.1 F off the coast of far northeastern Minnesota.

After several hours of daytime heating and generally light winds across the region, 1-km resolution GOES-13 0.63 µm visible channel images (below; click image to play animation) showed that a well-defined lake breeze boundary began to appear on the cumulus cloud field. Note that there was a similar lake breeze boundary seen surrounding Lake Nipigon in southern Ontario, Canada (where SST values were as low as 33.5 F).

GOES-13 0.63 µm visible channel images (click image to play animation)

A comparison of 1-km resolution MODIS visible channel, Land Surface Temperature (LST), and Normalized Difference Vegetation Index (NDVI) is shown below. LST values were generally in the 60s to 70s F surrounding Lake Superior, creating a large thermal contrast to the cold waters of the lake. To the northwest and southwest of Lake Superior, there were a number of areas exhibiting much warmer LST values (in the 80s  to around 90 F, darker red color enhancement) — and these areas of warmer LST values generally corresponded to features with a lower NDVI value. In particular, the large Pagami Creek wildfire burn scar (located east of Ely, Minnesota — station identifier KELO) had a maximum LST value of 96 F, with NDVI values less than 0.3 within the large burn scar.

MODIS 0.65 µm visible channel + Land Surface Temperature + Normalized Difference Vegetation Index

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GOES-12 Imager from 1045 UTC 9 May 2012 (click image to play animation of all bands)

GOES-M was launched in 2001 and as GOES-12 served as the operational GOES-East satellite from April 1, 2003 until April 14th, 2010, and has been serving recently as GOES-South America, providing Weather Services on that Continent with routine Imager and Sounder data.

Recently, the GOES-12 Imager has been experiencing ‘cycle slips‘, which manifest themselves in imagery as lines that are shifted, as shown in the loop above of the 5 Imager channels (Individual channels are here: 0.65 µm, 3.9 µm, 6.5 µm, 10.7 µm, 13.3 µm). Cycle slips occur as the satellite on-board software loses track of where the image mirror used to view the Earth is in its scan cycle. After the scan system initializes at the start of a scan cycle, the system expects consistent behavior, and no resources are allocated to track which cycle the mirror is in. Only increments are tracked. If the mirror is moving and a hiccup occurs, that anomaly (which is manifest as a shift in the center of the line) continues until the next system initialization.

The reason for the uptick in the number of Cycle Slips is unknown.

The images in this blog entry were generated using McIDAS-V.

(Update, 4 June 2012: An Imager Electronics Side Swap is scheduled for June 6, 2012, for GOES-12 (GOES-South America) based on the Manufacturer’s Recommendation as a potential remedy to mitigate the ongoing Cycle Slips. The side switch will be performed at 1615 UTC on 6 June 2012. The duplicate sensors that will now be used have not yet been used during GOES-12’s life. Because new sensors are being used, new look-up tables and calibration coefficients have been computed and are available here. Also, see page 29 in this pdf for more information on the two detector sets. Here is the notification of coming changes.)

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Suomi NPP VIIRS 0.7 µm Day/Night Band + 11.45 µm IR + "Fog/stratus product" images

An AWIPS comparison of Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB), 11.45 µm IR, and IR brightness temperature difference “Fog/stratus product” images at 06:51 UTC on 09 May 2012 (above) revealed several ribbons of the aurora borealis (which showed up as bright west-to-east oriented features on the DNB image over Ontario and Quebec, Canada). Note that there was no correlation between these bright DNB aurora features and any high cloud features on the 11.45 µm IR image, or  any low cloud or fog features on the legacy “fog/stratus product” image.

These aurora features would have been along the southern periphery of the auroral oval, which was expanding southward at that time  according to images from the Space Weather Prediction Center (below).

Space Weather Prediction Center auroral oval product images

Photos of the aurora borealis were taken from Upsala, Ontario — located approximately halfway between Thunder Bay (station identifier CYQT) and Dryden (station identifier CYHD) — and posted on Spaceweather.com. These photos were taken about an hour prior to the VIIRS images shown above.

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Suomi NPP VIIRS 0.7 µm Day/Night Band image + 11.45 µm IR image

A surface outflow boundary (resulting from a dissipating mesoscale convective system over southern Texas) created an undular bore that propagated southward and southwestward during the night-time hours on 07 May 2012. AWIPS comparisons of 1-km resolution Suomi NPP VIIRS 0.7 µm “Day/Night Band” images with the corresponding VIIRS 11.45 µm IR images at 07:27 UTC or 2:27 am local time (above) and also at 09:08 UTC or 4:08 am local time (below) demonstrated how the Day/Night Band imagery could be used to better visualize the individual cloud band structures of the bore. On the Day/Night Band images, cloud features could be seen due to moonlight illumination, and bright areas of city lights were also very prominent.

Suomi NPP VIIRS 0.7 µm Day/Night Band image + 11.45 µm IR image

This undular bore could also be seen on 4-km resolution GOES-13 10.7 µm IR images (below), although the individual cloud band features were not as well-defined due to the coarser spatial resolution. At Junction, Texas (station identifier KJCT), east-northeasterly winds gusted to 25 knots (29 mph) at 3:43 am local time as the bore passed.

GOES-13 10.7 µm IR images

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