Suomi NPP VIIRS 11.45 µm IR channel and 0.7 µm Day/Night Band images (with CG lightning strikes)

A night-time AWIPS image comparison of Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band data (above) showed a large mesoscale convective system (MCS) over the Gulf of Mexico at 07:08 UTC (2:08 AM local time) on 06 March 2014. On the IR image, brightness temperatures were as cold as -80º C on the far southern end of the storm, which had developed in the warm sector of a developing area of low pressure (surface frontal analysis). The Day/Night Band image revealed: (1) numerous bright west-to-east oriented “lightning streaks” caused by intense lightning activity illuminating the MCS cloud and cloud top — note that there were over 1300 cloud-to-ground (CG) lightning strikes detected in a 15-minute period, and (2) arc-shaped mesospheric airglow waves propagating northward and northeastward away from the region of vigorous overshooting tops at the southern end of the MCS.

A comparison of the 375-meter resolution Suomi NPP VIIRS 11.45 µm IR image with a 4-km resolution GOES-13 10.7 µm IR image (below) showed that the higher spatial resolution of the VIIRS data provided much clearer view of the various cloud structures along with a better depiction of the values of the cloud-top IR brightness temperatures.

Suomi NPP VIIRS 11.45 µm IR and GOES-13 10.7 µm IR channel images

GOES-13 10.7 µm IR channel images (click to play animation)

GOES-13 10.7 µm IR channel images (above; click image to play animation) showed the evolution of the MCS as it continued to move eastward toward Florida. A squall line developed along the leading edge of the MCS, which played a role in producing a few tornadoes and areas of damaging winds over the southern half of the Florida peninsula (below).

Plot of SPC storm reports

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

According to the 04 March 2014 Great Lakes Environmental Research Laboratory ice analysis, much of Lake Michigan had over 90% median ice concentration, with a total ice coverage of around 95%. However, AWIPS images of GOES-13 0.63 µm visible channel data on 05 March (above; click image to play animation) showed the effect of northerly winds on the ice , with large leads (cracks) opening up in the northern portion of the lake.

A comparison of AWIPS 0.64 µm visible channel and false-color Red/Green/Blue (RGB) images at 18:49 UTC (below) confirmed that most of Lake Michigan was cloud-free — snow and ice appear as varying shades of red on the RGB image, which supercooled water droplet clouds appear as shades of white.

Suomi NPP VIIRS 0.64 µm visible channel and False-color RGB images

A toggle between the 17:04 UTC Terra MODIS and 18:47 UTC Aqua MODIS true-color RGB images  from the SSEC MODIS Today site (below) showed the amount of ice motion within that 103 minute period of time.

Terra and Aqua MODIS true-color RGB images

===== 06 March Update =====

As winds changed to southerly and southwesterly in the wake of a retreating surface high pressure on 06 March, a corresponding change in Great Lakes ice motion was seen on GOES-13 0.63 µm visible channel images (below; click image to play animation).

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

15-meter resolution Landsat-8 0.59 µm panochromatic visible imagery viewed using the SSEC RealEarth web map server (below) offered a very detailed view of the Lake Superior ice in the vicinity of the Keweenaw Peninsula and Marquette  in the Upper Peninsula of Michigan.

Landsat-8 0.59 µm panochormatic visible channel image

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GOES-13 10.7 µm images (click to play animation)

Tests are underway this week to determine the impact of augmented GOES-13 (GOES-East) imager coverage. The animation above shows the coverage for routine scanning on 3 March 2014 between 1645 UTC and 1945 UTC. CONUS, Extended Northern Hemisphere and Full Disk images are included. The Optimized GOES-East schedule is available at this link. Note the presence of local solar RFI (radio frequency interference) in the 1645 UTC image; solar contamination resulted in no 1702 UTC image at all, as expected (link). Data at SSEC that are contaminated by solar RFI are typically replaced by data from CLASS, as times of local solar RFI in Madison, WI typically do not overlap with times of local solar RFI at Wallops Island, VA.

The difference in CONUS coverage is shown below in the toggle of the 1732 UTC image from 3 March and the 1730 UTC image from 4 March. The Optimized Image scan allows for more routine scanning of the Caribbean Sea, for example.

GOES-13 10.7 µm images at ~1730 UTC on 3 and 4 March (click to enlarge)

Side-by-side views of GOES-13 10.7 µm images. CONUS from 3 March, 1732 UTC (left) and Optimized CONUS from 4 March, 1730 UTC (right) (click to enlarge)

A side-by-side image of the regular and optimized CONUS scans is shown above. Note that the optimized scan has a slightly different time (Nominal times for each image are in the panel labels). Thus, batch jobs that access imagery by time must be altered. Side-by-side imagery for the entire test period is below. The 1645 UTC imagery should cover the same domain, but RFI interference is different on the two days. The test period ends before the 1902 UTC image. In the animation below, the CONUS images at half-past the hour show the increase in domain size.

Side-by-side views of GOES-13 10.7 µm images, 1645 UTC through 1902 UTC on March 3 2014 (Left, default schedule) and March 4, 2014 (right, optimized schedule). (click to animate)

Four-hour animation of Puerto Rico Regional Sector, 17-20 UTC on 4 March 2014 (click to enlarge)

As noted above, the optimized scan strategy significantly improves coverage in the Caribbean. In fact, the Puerto Rico Regional Sector is now almost completely covered. The animation above shows that sector for 2 hours with the expanded coverage during the test, and the subsequent two hours. Compare, for example, the 1830 UTC image, during the test, to the 1931 UTC image after the test (image toggle comparison).

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Suomi NPP VIIRS 0.64 µm visible channel and 0.7 µm Day/Night Band images

A comparison of AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel and 0.7 µm Day/Night Band (DNB) data (above) demonstrated the superior ability of the broadband spectral response of the DNB to detect the plumes of airborne aerosols which were being lofted by strong offshore winds in the southern Alaska Panhandle region on 01 March 2014.

These strong offshore winds were the result of the strong pressure gradient between a ridge of high pressure inland over Canada and a trough of low pressure located off the coast (below). The air was quite cold and dry across inland Canada (plot of minimum temperatures), and this air experienced further drying as it was forced through the various mountain passes and then descended toward the coast.

Suomi NPP VIIRS 0.7 µm Day/Night Band image with surface pressure and frontal analysis

McIDAS images of GOES-15 6.5 µm water vapor channel data (below; click image to play animation) showed a trend of strong middle-tropospheric drying during the day, as seen by the growth in areal coverage of the warmer (yellow-enhanced) region moving southwestward over the Alaska Panhandle region.

GOES-15 6.5 µm water vapor channel images (click to play animation)

It is interesting to note that the surface observations at Klawock, Alaska (below) included “Snow” as the wind speeds increased and the aerosol plume became evident on satellite imagery. However, given the relatively warm surface air temperatures and the very low dew points (along with the fact that the sky conditions were reported as “Clear” during the entire day), it is likely that automated sensors mistook the airborne aerosol particles as snow.

Time series of Klawock, Alaska surface observations

Klawock, Alaska surface observations

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