Geo2grid is a python-based software package that creates GeoTIFF imagery from native Himawari or GOES-16/GOES-17 imagery, as noted here. This blog post documents how to use the geo2grid software to create stereoscopic imagery, using either a Himawari-8/GOES-17 pairing, or a GOES-16/GOES-17 pairing. This requires first a remapping of the imagery to a fixed domain; when Geostationary Satellites aren’t separated by a great distance — for example when GOES-17 was in the test position and GOES-16 was at 75.2 — native projections can be used. That’s not the case with Satellites separated by 60 degrees of longitude.

Fortunately, geo2grid allows for a way to define a grid onto which the extracted data will be placed. The shell script command to create the map parameters is shown below:

$GEO2GRID_HOME/bin/p2g_grid_helper.sh G17H8Stereo -175.0 0.0 2000 -2000 1000 1000 > $GEO2GRID_HOME/mygrids.conf

I’m creating a map called ‘G17H8Stereo’ that is centered at 175 W and the Equator (Note: if you include a decimal point, you must include a digit afterwards. Some scripting languages fail to interpret ‘-175.’ correctly). The x-direction spacing is 2000 m (i.e., 2 km) and the y-direction spacing is also 2 km (that value is negative because point 1,1 is in the northwest corner). The grid size being created here is 1000×1000. If you were to look in the file created, mygrids.conf, you’d see a line looking like this:

G17H8Stereo, proj4, +proj=eqc +datum=WGS84 +ellps=WGS84 +lat_ts=0.00000 +lon_0=-175.00000 +units=m +no_defs, 1000, 1000, 2000.00000, -2000.00000, 176.01685deg, 8.98315deg

Note that the file name must have that “.conf” extension! The reading software expects it.

Data for both times (Full Disk imagery) has been downloaded and placed in directories.  This is HSD *.DAT files for Himawari-8 and netCDF Radiance files from CLASS for GOES-17.  This is a lot of data to move around.  The geo2grid invocation to create the True Color Imagery will look something like this for Himawari-8:

$GEO2GRID_HOME/bin/geo2grid.sh -r ahi_hsd -w geotiff –grid-configs $GEO2GRID_HOME/mygrids.conf -g G17H8Stereo –method nearest -f /data-ssd/CLASS/CSPPCheck/Stereo/H8/

The GOES-17 call will look like this:

$GEO2GRID_HOME/bin/geo2grid.sh -r abi_l1b -w geotiff –grid-configs $GEO2GRID_HOME/mygrids.conf -g G17H8Stereo –method nearest -f /data-ssd/CLASS/CSPPCheck/Stereo/

In both cases, –grid-configs is used to specify the grid to be used, with the -g tag naming the grid (the same name as used in the p2g_grid_helper.sh call above. The method of interpolation (the –method flag) is nearest neighbor, so a simple interpolation is used. Again, remember that those long dashes are really two short dashes.

Geo2grid does have built-in maps that you can use, and these are listed in the on-line documentation; you would include something like “-g lcc-aus” and that would put the data on a lambert conformal grid centered over Australia (not a useful grid for GOES-17, but very nice for Himawari-8 and for the coming GEOKOMPSAT-2!)

True Color imagery is created by these geo2grid.sh calls — and imagery for all 16 bands is created as well. (You can use the -c flag in geo2grid.sh to limit what is created if you wish). That imagery is shown above. If you cross your eyes and focus on the image that appears in the middle, it will be in three dimensions. Because this region is in the middle of the ocean, geo-location might be important, and the geo2grid script add_coastlines.sh is useful to add latitude/longitude lines.

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How will True Color appear in regions with land features as might occur with GOES-16 and GOES-17?  Halfway between GOES-16 (75.2) and GOES-17 (137.2) is 106 degrees W Longitude.  I’ll create a map centered at 35 N, 106 W (near Albuquerque) that is 1200×1200 (also 2 km resolution):

$GEO2GRID_HOME/bin/p2g_grid_helper.sh G16G17Stereo -106.0 35.0 2000 -2000 1200 1200

The output is placed in the same Mygrids.conf file (More than one map definition can appear in that csv file). AFter downloading the GOES16/GOES17 data, I invoked to geo2grid commands:

$GEO2GRID_HOME/bin/geo2grid.sh -r abi_l1b -w geotiff –grid-configs $GEO2GRID_HOME/mygrids.conf -g G16G17Stereo –method nearest -f /data-ssd/CLASS/CSPPCheck/Stereo/G16G17/G17/

$GEO2GRID_HOME/bin/geo2grid.sh -r abi_l1b -w geotiff –grid-configs $GEO2GRID_HOME/mygrids.conf -g G16G17Stereo –method nearest -f /data-ssd/CLASS/CSPPCheck/Stereo/G16G17/G16/

Use ImageMagick to put the images side-by-side

montage GOES-16_ABI_RadF_true_color_20190313_210036_G16G17Stereo.tif GOES-17_ABI_RadF_true_color_20190313_210038_G16G17Stereo.tif -tile 2×1 -geometry +0+0 GOES-16_GOES-17_ABI_RadF_true_color_20190313_210036_G16G17Stereo.png

The beautiful stereoscopic image below is created.

The mp4 animation below (click here for an animated gif) shows GOES-16 True Color imagery every 15 minutes (GOES-16 was in Mode 3 operations with 15-minute full-disks) from 1500 UTC to 2245 UTC. Imagery was created using geo2grid. The true-color imagery captures the dust that was kicked up by strong winds over Texas and New Mexico.

A similar animation made from GOES-17 from geo2grid is below. (Click here for an animated gif).

The GOES-16 and GOES-17 animations are combined into a true-color stereoscopic view of the strong cyclone below. The mp4 is below; click here for an animated gif.

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Very strong winds over the High Plains of Texas and New Mexico (associated with the extraordinary blizzard to the north) helped quickly spread a Grass Fire that developed over north Texas, north of Amarillo. (Tweet from NWS Amarillo is here). GOES-17’s Mesoscale Sector 1 was over the southern Plains, and viewed the fire development in 1-minute increments. The shortwave infrared (3.9 µm) imagery is shown in an mp4 animation above (Click here for an animated gif). Visible Imagery is shown below, and the smoke plume from the fire is difficult to see. (Click here for an animated gif). The fire first became apparent in the shortwave infrared imagery around 1837 UTC.

GOES-17 Fire Detection and Characterization Algorithm (FDCA) products (the Baseline Fire Product) are not yet available: distribution of these products has been delayed because of GOES-17’s Loop Heat Pipe problems (https://cimss.ssec.wisc.edu/satellite-blog/archives/29874; Blog Post 2). GOES-16 did view this fire, however, and are shown in the animation below. FDCA products are not produced for Mesoscale Domains, however, so only a CONUS product, available every 5 minutes is shown. The fire was first visually apparent in the Band 7 imagery at 1837 UTC (the fire is just northwest of a lake, and halfway between Stinett and Four Way on the map, and Fire Temperature was diagnosed starting at 1842 UTC. Note that the pixels from GOES-16, above the Equator at 75.2 Longitude are quite different from those from GOES-17, above the Equator at 137.2 W Longitude.

Both GOES-17 (and GOES-16) 3.9 µm Imagery could be used to monitor this event. GOES-16 Baseline Fire Detection products also viewed the fire, but these products are not produced for Mesoscale domains so only a 5-minute cadence is available.

Suomi NPP overflew the region after 2030 UTC on 13 March, and it provided a higher-resolution image of the fire than is available from GOES. The toggle below compares the shortwave infrared (3.9 µm), the snow/ice channel (1.61 µm) and the visible (0.64 µm) from VIIRS (the Visible Infrared Imaging Radiometer Suite). The shape of the fire is better defined in the VIIRS imagery. (A second fire is also apparent to the east). A useful strategy, if possible, is to use GOES-17 or GOES-16 to monitor the evolution of the storm, and to use VIIRS imagery from Suomi NPP and/or NOAA-20 to see details in the horizontal structure. This animation compares the fire views (at 2043 UTC) from Suomi NPP, GOES-16 and GOES-17.

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An unusually deep midlatitude cyclone — which easily met the criteria of a “bomb cyclone”, with its central pressure dropping 25 hPa in only 12 hours (surface analyses) — developed over the central US on 13 March 2019 (WPC storm summary). GOES-16 (GOES-East) Air Mass RGB images from the AOS site (above) showed the large size of the cloud shield — and the deeper red hues over the High Plains indicated the presence of ozone-rich air (from the stratosphere) within the atmospheric column as the tropopause descended. A preliminary new all-time low surface pressure of 975.1 hPa occurred at Pueblo, Colorado just after 13 UTC; to the east of Pueblo, a 970.4 hPa minimum pressure recorded at Lamar (plot) possibly set a new state record for Colorado.

On a map of NWS warnings/advisories valid at 14 UTC (below), Blizzard Warnings (red) extended from Colorado to the US/Canada border. South of the Blizzard Warnings, High Wind Warnings (brown) were in effect to the US/Mexico border.

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) displayed a hook-like signature resembling that of a sting jet, which developed over the Texas/Oklahoma Panhandle area after 11 UTC. At 14 UTC an interesting burst of surface wind gusts occurred at 3 sites — Burlington CO, Goodland KS and Colby KS — which may have been related to the downward transfer of momentum along the leading edge of the sting jet flow. The corresponding 7.3 µm Low-level Water Vapor animations are also available: GIF | MP4.

The MIMIC Total Precipitable Water product (below) showed the northward surge of moisture from the Gulf of Mexico.

During the afternoon hours, the strong surface winds began to create plumes of blowing dust across parts of southeastern New Mexico and western Texas — a blowing dust signature first became apparent on GOES-16 Split Window Difference imagery as plumes of yellow, but then became more obvious on “Red” Visible (0.64 µm) images as the afternoon forward scattering angle increased (below). Blowing dust reduced the surface visibility to 1-2 miles at Snyder (KSNK) and Lubbock (KLBB).

The blowing dust signature (lighter shades of brown) was also easily seen in late-afternoon GOES-16 True Color RGB images (below) — the dust plume reached southwestern Oklahoma by the end of the daytime hours, restricting the visibility to 5 miles at Frederick (KFDR). The blowing dust was also evident in True Color imagery from GOES-17, as seen here.

Not long after the cyclone reached its lowest analyzed surface pressure of 968 hPa at 18 UTC, an overpass of the Suomi NPP satellite around 19 UTC provided a swath of NUCAPS soundings covering much of the storm (below). The air was very dry and stable near the near the center of the surface low in eastern Colorado (TPW=0.29″, CAPE=0 J/kg), in western Texas (TPW=0.31″, CAPE=0 J/kg) and near the frontal triple point in southeastern Nebraska (TPW=0.30″, CAPE=0 Jkg) — and out ahead of the warm front, the air was moist but stable behind a line of thunderstorms in northeastern Arkansas (TPW=1.09″, CAPE=0 J/kg) but both moist and unstable in western Mississippi (TPW=1.36″, CAPE=3506 J/kg).

During the early stages of cyclone development, this system spawned severe thunderstorms that produced tornadoes, large hail and damaging winds across New Mexico and Texas (SPC storm reports) late in the day on 12 March. A GOES-17 (GOES-West) Mesoscale Domain Sector had been positioned over that region — which was helpful during a brief GOES-16 data outage — providing images at 1-minute intervals (below).

A Great Plains cyclone of historic proportions is now underway across the central U.S. Here’s the latest… pic.twitter.com/CLAsDmmOkZ

— NWS WPC (@NWSWPC) March 13, 2019

Powerful low in the Central Plains with widespread significant wind gusts. Over the past 24 hours, NWS offices logged about 350 wind gust reports of 50+ MPH, with a further 92 reports of damage. The most significant gusts (70+ MPH) generally in NE NM, TX Panhandle, E CO. pic.twitter.com/duCPfqdkII

— NWS WPC (@NWSWPC) March 14, 2019

===== 14 March Update =====

GOES-16 Mid-level Water Vapor (6.9 µm) images (above) showed the storm moving slowly northeastward across Kansas, Nebraska and Iowa on 14 March — with strong winds continuing north and west of the surface low, blizzard conditions persisted across much of the Midwest.

Farther to the east, severe thunderstorms produced large hail, damaging winds and tornadoes as far north as northern Illinois/Indiana/Ohio and southern Lower Michigan (SPC storm reports | NWS Detroit) — as shown with 1-minute Mesoscale Domain Sector GOES-16 Visible images (below). The corresponding GOES-16 Infrared image animation is available here; the coldest cloud-top infrared brightness temperatures were only in the -30 to -40ºC range

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GOES-16 (GOES-East) Near-Infrared “Snow/Ice” (1.61 µm) images (above) revealed a darkening signature resulting from a brief period of snow melt during the daytime hours on 12 March 2019. As a southerly flow of warm air (coupled with abundant solar insolation) began to melt the top surface of the deep snow cover, its “water to ice crystal” ratio increased — making it appear darker, since water is a stronger absorber of radiation at the 1.61 µm wavelength. The northward progression of this snow melt signature was most obvious across eastern South Dakota into eastern North Dakota and far western Minnesota, but was also evident in western parts of the Dakotas as well as downwind of the Turtle Mountains along the North Dakota / Manitoba border.

GOES-16 Snow/Ice images centered over the North Dakota / South Dakota / Minnesota border region (below) provided a closer view of the progressive northward darkening of this snow melt signature. Also of interest was a packet of standing waves to the lee (northeast) of the Coteau des Prairies — downsloping flow contributed to localized warming and melting at that location early in the day. The effect of the arrival of southwesterly downslope flow at Sisseton (located approximately midway between Browns Valley and Veblen) was very apparent in a time series of surface data. In contrast, the warm-up was much more gradual and the wind speeds significantly lighter not far to the west at Aberdeen.

An animation that cycles through GOES-16 Low-level Water Vapor (7.3 µm), “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice”  images is shown below — the standing waves were also evident in the Water Vapor imagery.

Hat tip to James Hyde for bringing this interesting signature to our attention.

Interesting satellite microphysics going on today on lee side of the Coteau de Prairie. Rotors coming off the Coteau I believe are mixing down warm air and melting the surface layer of the snow changing the reflective properties in Band 5. @CIMSS_Satellite @UWCIMSS @weatherdak pic.twitter.com/tL0SI51405

— James Hyde (@wxmeddler) March 12, 2019

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