The launch of a SpaceX Falcon Heavy rocket from the NASA Kennedy Space Center in Florida occurred at 2235 UTC on 11 April 2019. Warm thermal signatures of pockets of air (which had been superheated by the booster rocket exhaust) were seen northeast of the launch site in GOES-16 (GOES-East) Low-level Water Vapor (7.3 µm), Mid-level Water Vapor (6.9 µm), Upper-level Water Vapor (6.2 µm) and Shortwave Infrared (3.9 µm) images (above). In addition, closer to the launch site a (thermally-cooler) signature of the lower-altitude rocket exhaust condensation plume was evident — for example, see an annotated comparison of the 2236 UTC images below (GOES-16 was scanning that exact location at 22:37:22 UTC, a little more than 2 minutes after launch).

Two portions of the lower-altitude rocket condensation plume — one moving northeastward, and one moving westward — were seen in higher-resolution GOES-16 “Red” Visible (0.64 µm) images (below).

The different directions of rocket condensation plume motion were due to directional shear of wind within the lowest 2 km or 6500 feet of the atmosphere, as shown in a plot of 00 UTC rawinsonde data from Cape Canaveral, Florida (below).

Similar signatures of other rocket launches have been seen using GOES-16 and GOES-17.

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Polar2Grid allows users to create true-color imagery from VIIRS (Visible Infrared Imaging Radiometer Suite) data from Suomi-NPP or NOAA-20. This tutorial will take you through the needed steps. Step one is to decide when you want the data; the ways to determine when a Polar Orbiter overflies a particular point are outlined in this blog post, that points to this website. For this blog post I’ve chosen Missouri. The image above shows a True-Color image over Missouri at about 19:42 UTC on 9 April 2019.

To create true-color imagery, Polar2Grid requires VIIRS M-Bands 3, 4 and 5 (Blue (0.48 µm), Green (0.55 µm) and Red (0.67 µm), respectively, all with 750-m resolution); click here for a list of all VIIRS bands). If the VIIRS I-Band 1 (at 0.64 µm) is present in the directory, then that image is used to sharpen the resultant image. Polar2Grid CREFL software also performs a simple atmospheric Rayleigh scattering removal; smoke and haze will still be apparent in the imagery, however.

To create the imagery above, first order the data from NOAA Class. (Steps to follow are shown here). Download the data into a unique directory. We are going to remap these data onto a map centered on Missouri, and for that to happen, Polar2Grid needs mapping parameters. These can be generated automatically with the p2_grid_helper.sh script that comes with Polar2Grid software. From the bin directory, I entered this command to put the grid parameters in a file .

/p2g_grid_helper.sh missouri -93.0 38.0 500 -500 2000 2000 > my_grids.txt

The line of data entered into that file is this:

missouri, proj4, +proj=lcc +datum=WGS84 +ellps=WGS84 +lat_0=38.000 +lat_1=38.000 +lon_0=-93.000 +units=m +no_defs, 2000, 2000, 500.000, -500.000, -99.055deg, 42.352deg

Now I’m ready to generate a true-color image (corrected ceflectance — crefl — imagery) with Polar2Grid, using this command:

./polar2grid.sh crefl gtiff –grid-configs /home/scottl/Polar2Grid/polar2grid_v_2_2_1/bin/my_grids.txt -g missouri -f /data-hdd/storage/Polar2GridData/09April/

The flags “–grid-configs <path to directory where file created by p2g_grid_help sits” and “-g map <name of map inside that file>” instruct to the Polar2Grid software to pull the mapping data for the defined grid out of the file. Otherwise, the data are in satellite projection. This polar2grid.sh invokation created a file named ‘j01_viirs_true_color_20190409_194226_missouri.tif’; I want to put a map on it so it is easier to georeference, and that is done using this shell in the Polar2Grid bin directory:

./add_coastlines.sh –add-borders –borders-resolution=f –borders-level=2 –borders-outline=’black’ j01_viirs_true_color_20190409_194226_missouri.tif

This adds a map to the image, then converts it to the png file (j01_viirs_true_color_20190409_194226_missouri.png) that is shown above.

After doing the same steps for a series of clear days in the midwest (09 March 2019, 15 March 2019, 21 March 2019, 26 March 2019, 31 March 2019), and annotating and concatenating the images in an animation, the greening up of Spring is apparent. See below.

Special shout-out to Dave Hoese, SSEC/CIMSS, for crafting software that is so easy to use to produce excellent satellite imagery.

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Strong winds — gusting as high as 77 mph in New Mexico and 88 mph in Texas — associated with a rapidly-intensifying midlatitude cyclone generated large plumes of blowing dust (originating from southeastern Arizona,southern New Mexico, northern Mexico and western Texas) on 10 April 2019. GOES-16 (GOES-East) Split Window (10.3-12.3 µm) images (above) helped to highlight the areas of blowing dust, which initially developed along and behind a cold front after 15 UTC.

GOES-16 Split Window images with hourly plots of surface wind barbs and gusts (above) showed the distribution of strong winds across the region, while plots of the surface visibility (below) showed decreases to 1/4 mile at Deming, New Mexico, 1/2 mile at Lubbock, Texas and 4 miles at Altus, Oklahoma.

GOES-16 True Color Red-Green-Blue (RGB) images (below; courtesy of Rick Kohrs, SSEC) depicted the blowing dust as shades of tan to light brown. Willcox Playa was the source of the dust plume coming from southeastern Arizona. Note that the dust plume emanating from White Sands, New Mexico was lighter in appearance compared to the other tan/brown-colored areas of blowing dust — this is due to the white gypsum sand that comprises the surface of White Sands National Monument.

250-meter resolution MODIS True Color RGB images from the MODIS Today site (below) provided a more detailed view of the plume streaming northeastward from its White Sands source. On the later Aqua image, dense tan-colored areas of blowing dust had developed below the thin higher-altitude veil of brighter gypsum aerosols that had earlier been lofted from White Sands.

A NOAA-20 True Color RGB image viewed using RealEarth is shown below. 19 UTC surface observations at 3 sites near White Sands included Las Cruces KLRU (visibility 3 miles, wind gusting to 46 knots), Alamogordo KALM (visibility 3 miles, wind gusting to 43 knots) and Ruidoso KSRR (visibility 5 miles, wind gusting to 55 knots). The strong winds and dense areas of blowing dust reducing surface visibility not only impacted ground transportation but also posed a hazard to aviation.

Dust and sandstorms create conditions of reduced visibility near the surface and like volcanic ash can create a hazard when ingested into engine intakes. In this case, the dust storm was widespread so the @NWSAWC issued a SIGMET for IFR conditions as a warning to pilots. pic.twitter.com/QOpe1pIs9b

— Scott Dennstaedt (@AvWxWorkshops) April 11, 2019

===== 11 April Update =====

In a larger-scale view of GOES-16 Split Window images (below), the yellow dust signature could be followed during the subsequent overnight hours and into the following day on 11 April, as the aerosols were being transported northeastward across the Upper Midwest. There were widespread reports and photos of dust residue on vehicles and tan/brown-colored snow in parts of Nebraska, Iowa, Minnesota and Wisconsin.

IDEA forward trajectories (below) — initialized from a cluster of elevated Aura OMI Aerosol Index points over Mexico, New Mexico and Texas — passed directly over areas of model-derived precipitation across the Upper Midwest, providing further support of precipitation scavenging of dust aerosols. Interestingly, a similar event of long range dust transport occurred on 10-11 April 2008.

HYSPLIT model 24-hour forward trajectories initialized at 3 locations — El Paso, Lubbock and Amarillo in Texas — showed a few of the likely dust transport pathways toward the Upper Midwest at 3 different levels (below).

GOES-16 True Color RGB images from the AOS site (below) showed that some clouds across the Upper Midwest exhibited a subtle light brown hue at times.

===== 12 April Update =====

GOES-16 Split Window (10.3-12.3 µm) images (above) showed that the yellow signature of dust aerosols aloft had wrapped all the way around the southern and eastern sectors of the occluded low on 12 April.

Ground-based lidar at the University of Wisconsin – Madison confirmed the presence of elevated levels of aerosol loading between the surface and 6 km.

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GOES-17 (GOES-West) Split Window (10.3-12.3 µm), Split Cloud Top Phase (11.2-8.4 µm) and “Red” Visible (0.64 µm) images (above) displayed a plume of blowing dust — whose source region was a dry lake bed along the California-Nevada border — which developed in advance of an approaching cold front (surface analyses) and moved northeastward across far southern Nevada on 09 April 2019. Wind gusts of 50-65 mph were reported across the region.

This dust plume was also apparent over far southern Nevada in GOES-17 True Color Red-Green-Blue (RGB) images from the AOS site (below).

There are 5 airports located in the Las Vegas Valley, and GOES-17 images showed that the dust plume passed directly over Henderson (KHND) — time series plots of surface data from these sites (below) indicated that visibility was reduced to 3 miles at Henderson, with visibilities dropping to 8-9 miles at McCarran International Airport (KLAS) and Nellis Air Force Base (KLSV). The visibility was not impacted at the North Las Vegas Airport (KVGT), with its more northwest location being farther from the dust plume.

A notable exception was the Boulder City Municipal Airport (KBVU), which was downwind of a smaller local point source of blowing dust (Mursha Reservoir, another dry lake bed to the southwest) — the visibility at KBVU was restricted to 2 miles at times. With the 2-km spatial resolution (at satellite nadir) of the GOES-17 Infrared spectral bands, there was not a signature of this smaller-scale Boulder City dust plume in the 10.3-12.3 µm and 11.2-8.4 µm Brightness Temperature Difference products — however, this hazy plume was evident in the 0.5-km resolution (at satellite nadir) Visible imagery.

A comparison of 1-km resolution NOAA-19 AVHRR Visible (0.63 µm), Shortwave Infrared (3.8 µm) and Split Window (10.8-12.0 µm) images (below) provided a detailed view of the primary dust plume — and also exhibited a subtle signature of the smaller plume that reduced visibility at Boulder City KBVU. The small dust aerosols act as efficient reflectors of incoming solar radiation, therefore appearing warmer (darker) on the Shortwave Infrared image.

The GOES-17 and NOAA-19 images also showed that the larger dust plume moved across a section of Interstate 15 between Sloan and Jean; traffic cameras showed significant reductions in visibility along I-15 near Primm (along the California/Nevada border).

Dust plume visible on @nevadadot cam blowing across I-15 near the NV/CA border! Be prepared for reduced visibility! #NVwx #CAwx pic.twitter.com/hkwlgp9IzJ

— NWS Las Vegas (@NWSVegas) April 9, 2019

#VegasWeather – it’s pretty bad out there in some areas. https://t.co/mdzeGNnMSL

— Clark County Nevada (@ClarkCountyNV) April 9, 2019

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