16-Panel GOES-17 Full-Disk Advanced Baseline Imager (ABI) Imagery, 0010 – 2340 UTC on 14 April 2019 (Click to play mp4 animation)

Solar illumination of the GOES-17 Advanced Baseline Imagery (ABI) was at a maximum on 14 April, so that the effects of the Loop Heat Pipe that is not operating at its designed capacity (and therefore cannot keep the ABI detectors as cold as preferred) were at their worst. (This image of the predicted Focal Plane Temperature from this blog post shows the mid-April peak to be warmest). The animation above shows that only Band 14 (11.2 µm) was able to send a useable signal during the entire night. The Band 14 data are biased, however. The image below compares GOES-16 and GOES-17 temperatures over a region on the Equator (here, from the GOES-17 perspective, and here, from the GOES-16 perspective, from this website) equidistant between the two sub-satellite points (75.2º W for GOES-East, 137.2º W for GOES-West).  GOES-17 slowly cools relative to GOES-16 (assumed to be ‘truth’) before undergoing a series of cold/warm/cold oscillations relative to GOES-16.   So while a useful signal is preserved, algorithms that rely on threshold temperatures, or brightness temperature difference fields (such as the 3.9 µm – 11.2 µm Brightness Temperature Difference), would likely produce unexpected results.

 

Loop Heat Pipe issues should slowly subside over the coming weeks.  ‘Predictive Calibration’ is likely to be in place by the time the (Northern Hemisphere) Autumnal Equinox arrives.  This will extend the useful signal for the ABI channels.  One might even conclude that this current episode will have the worst impact on useable imagery from the ABI.

View only this post Read Less

An outbreak of severe weather began in eastern Texas on the morning of 13 April 2019, where thunderstorms produced hail up to 3.0 inches in diameter, tornadoes and damaging winds (SPC storm reports). 1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) showed the clusters of thunderstorms that developed as a surface low and associated frontal boundaries moved eastward (surface analyses). The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed numerous overshooting tops with infrared brightness temperatures as cold as -70 to -75ºC. In addition, the storm producing 3.0-inch hail and damaging winds at 1428 UTC exhibited an Above-Anvil Cirrus Plume (Visible/Infrared toggle).

A comparison of Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images at 1650 UTC is shown below.

Later in the day, the thunderstorms continued to produce a variety of severe weather as they moved eastward across Louisiana and Mississippi, as shown by GOES-16 Visible and Infrared images (below).

After sunset, the thunderstorms continued to move eastward, spreading more serve weather across Mississippi into Alabama and far southern Tennessee (below).

VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP (below) provided additional views of the storms as they were moving across Mississippi and Alabama. Several bright lightning streaks were evident on the Day/Night Band images. Note: the NOAA-20 image (downloaded and processed from the Direct Broadcast ground station at CIMSS) is incorrectly labeled as Suomi NPP.

On a NOAA-20 VIIRS Day/Night Band (0.7 µm) image at 0825 UTC (below), an impressively-long (~400 mile) dark “post-saturation recovery streak” extended southeastward from where the detector sensed an area of very intense/bright lightning activity northeast of Mobile, Alabama.

View only this post Read Less

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.

View only this post Read Less

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.

View only this post Read Less