GOES-16 Airmass RGB, 1400 UTC on 2 June 2020 to 1640 UTC on 3 June 2020

Severe weather occurred over the upper Midwest on 2 June 2020, and a derecho occurred over the mid-Atlantic States on 3 June 2020. These two events were linked, and the animation above shows the system moving and redeveloping from Minnesota on 2 June 202 eastward to Pennsylvania on 3 June 2020. How was this animation created?

geo2grid is a software packaged developed at CIMSS. It is designed to produce high-quality full-resolution imagery from archived (or real-time) GOES-16/GOES-17 Level-1b imagery. This blog post (a follow-up to this one) will outline how to use the software package to create imagery.  Note that geo2grid runs on CentOS6-compatible Linux.  There is no Windows version.  Here are the steps used to create the imagery above.

1. 1. geo2grid software can be downloaded as a g-zipped tarball from this link. (You may need to register — for free! — before downloading). Version 1.0.1 was released in March of 2020. You can also download documentation (always a good idea) as a pdf file from the download site, or you can access it online.  Once you have unzipped and untarred the software package, you’re ready to begin.  Your unix system must know where the software package sits, and that’s through this command: EXPORT GEO2GRID_HOME=/path/to/Geo2GridSoftwareLocation/
   2. Of course, you will also need data.  For Advanced Baseline Imager (ABI) data, geo2grid expects Radiance fields.  These can be accessed via NOAA CLASS, or via “The Cloud”, or from a GRB Receiving antenna.  (some data sources are listed here)  NOAA CLASS ABI L1b Radiances data (ordered under “GOES-R Series ABI Products (GRABIPRD) (partially restricted L1b and L2+ Data Products) ”  )  will have a file format that looks something like this:  OR_ABI-L1b-RadF-M6C08_G16_s20201542340169_e20201542349477_c20201542349544.nc ; that particular file listed is Full Disk (the ‘F’ in ‘RadF’) when GOES-16 was in Mode 6 (M6) scanning, and it contains Band 8 (C08);  the start time is Year 2020, Day 154 (June 2 2020) at 23:40:16.
   3. As noted in this blog post, you can specify which fraction of the domain to display. geo2grid also has a mapping routine if you want to define your own domain (i.e., not a satellite projection, or a subset of that satellite projection), and documentation is under ‘Utility Scripts’ at the geo2grid documentation site.  To define a domain near the Great Lakes, for example, I used this command:   $GEO2GRID_HOME/bin/p2g_grid_helper.sh PADERECHO -83.0 45.0 2000 -2000 1500 800 > $GEO2GRID_HOME/PADERECHO.conf ;  the shell scripts takes a grid name (PADERECHO in this case), a center longitude/latitude (83.0 degrees West, 45.0 Degrees North), x- and y- grid-spacing in meters (2 km for this case), and the number of points in the x- and y- directions.  These mapping instructions are placed in a configuration file;  cat $GEO2GRID_HOME/PADERECHO.conf will show this line in the file:  PADERECHO, proj4, +proj=lcc +datum=WGS84 +ellps=WGS84 +lat_0=45.00000 +lat_1=45.00000 +lon_0=-83.00000 +units=m +no_defs, 1500, 800, 2000.00000, -2000.00000, -104.24668deg, 50.40805deg .  It might take some trial and error using geo2grid to find the map domain that suits you best, but it is a simple matter to iterate to a solution.
   4. Next, run geo2grid.   The command I invoked (with small changes for each time) is here:  $GEO2GRID_HOME/bin/geo2grid.sh -r abi_l1b -w geotiff -p airmass -g PADERECHO --grid-configs $GEO2GRID_HOME/PADERECHO.conf --method nearest --cache-dir=$GEO2GRID_HOME/datacache/ -f /data-hdd/PADerecho/Day154/14/*1450*.nc   There are several flags included in this call, and they are explained in the documentation, but also here.
      • -r:  What kind of data are being read?  In this case, level-1b data from ABI
      • -w:  Output format (geotiff).  That is the only option for imagery
      • -p:  What imagery should be created?  In this case, airmass RGB.  To find out what can be computed given the data present, user the –list-products flag.  For the data I have downloaded, this returned C08, C10, C12, C13, C15, airmass:  I had downloaded to the specified directory the components necessary to compute the airmass RGB (plus band 15).  If you wanted to create imagery for all these channels in addition to the airmass RGB, -p airmass C08 C10 C12 C13 C15 would work.  (Note:  C15 is not actually needed in the computation of the airmass RGB).
      • -g:  to what grid should these data be interpolated?  The answer: the PADERECHO grid that is defined and specifed where –grid-configs points to:  $GEO2GRID_HOME/PADERECHO.conf;
      • –method:  what interpolation method should be used?  For this case, nearest neighbor is specified.
      • –cache-dir:  This is used to speed processing.  If you have multiple files being interpolated to the same grid, it speeds things to save the interpolation methods/points.  You have to specify the directory where this file will sit.
      • -f:  Where do the Radiance files sit?  In this example I have placed different times in separate directories.  I haven’t yet figured out how to use Geo2Grid that points to a directory where multiple times sit.
   5. geo2grid includes scripts (“add_coastlines.sh“;  for full documentation, see the ‘Utility Scripts’ section in the geo2grid documentation)  that will add maps to the imagery.  $GEO2GRID_HOME/bin/add_coastlines.sh --add-coastlines --coastlines-resolution=h --coastlines-level=4 GOES-16_ABI_RadF_airmass_20200602_152017_PADERECHO.tif  This command invoked only a few of the mapping additions, as described below.  For a full list, refer to the documentation.
      1. –add-coastlines ;  as you might expect this flag adds coastlines.  In the animation above, you’ll see that the coastlines include lakes.  You can also add borders, grids (lat/lon lines) and other features.
      2. –coastline-resolution=h ; I have asked for high resolution.
      3. –coastlines-level=4 ; This is the default level of detail in the lines.
      4. The .tif is the geotiff created from Geo2Grid.  When add_coastlines.sh is finished, the filename GOES-16_ABI_RadF_airmass_20200602_152017_PADERECHO.png is created.
   6. geo2grid does not annotate imagery.  I use ImageMagick for that.  (something like this:  convert GOES-16_ABI_RadF_airmass_20200603_163017_PADERECHO.png -gravity Northeast -fill white -pointsize 32 -annotate +8+40 "3 June 2020 1630 UTC" GOES-16_ABI_RadF_airmass_20200603_163017_PADERECHOannotate.png )

A challenge in scripting geo2grid is that the start time of the files is not constant.  For example, on 2 June, the 15:20 image starts at 15:20:17.1 (as shown above, the file name includes 152017) ; the 17:20 image starts at 17:20:16.9 and the created filenames include 172016.

The completed animation is shown above.

View only this post Read Less

GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images covering the 26-hour period from 1801 UTC on 03 June to 1956 UTC on 04 June 2020 (above) featured the merger of 2 Mesoscale Convective Systems over northwestern Missouri (beginning around 06 UTC). An animation of radar reflectivity is available here (credit: Pete Pokrandt, AOS).

To all of you asking us what this means/is. We basically have a back-building Mesoscale Convective System (MCS) from the east running into a forward propagating MCS from the west. It’s not out of the realm of possibility, but for us on shift we’ve never witnessed it in real-time. https://t.co/AIBLTz0cul

— NWS Kansas City (@NWSKansasCity) June 4, 2020

1-minute Mesoscale Domain Sector GOES-16 Infrared images from 0200-0800 UTC (below) include time-matched plots of SPC Storm Reports. Cloud-top infrared brightness temperatures reached -80ºC (violet pixels) around the time of the MCS merger.

With ample illumination from the Moon — in the Waxing Gibbous phase, at 93% of Full — a Suomi NPP VIIRS Day/Night Band (0.7 µm) image (below) shortly after the MCS merger revealed cloud-top gravity waves propagating outward from the center of the storm (along with numerous clusters of bright white pixels, highlighting areas of intense lightning activity):

As the merged MCS dissipated during the day on 04 June, a Mesoscale Convective Vortex became evident on GOES-16 “Red” Visible (0.64 µm) images (below), which then moved across southeastern Missouri, far southern Illinois and western Kentucky (helping to initiate new convective activity).

View only this post Read Less

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images with time-matched plots of SPC Storm Reports (above) displayed a fast-moving derecho which moved southeastward across Pennsylvania and New Jersey on 03 June 2020. Winds gusted as high as 83 mph in Pennsylvania (at 1535 UTC)  and 93 mph in New Jersey (at 1719 UTC).

A sequence of GOES-16 Visible images – with and without an overlay of GLM Flash Extent Density – and “Clean” Infrared Window (10.35 µm) images (below) showed modest lightning activity and pulsing overshooting tops with cloud-top infrared brightness temperatures as cold as -75ºC (darker red enhancement).

View only this post Read Less

Severe weather occurred over Minnesota and Wisconsin on 2 June 2020, and the storms developed in clear skies. This allowed GOES-16 Derived Stability Indices (a clear-sky product) to provide information on the near-storm environment. The animation above combines GOES-16 Clean Window infrared (10.3 µm) imagery (where clouds exist) with Convective Available Potential Energy (CAPE) estimated from GOES-16 Advanced Baseline Imager channel information (that adjusts an initial field created using GFS data); this Baseline product (and others including all-sky products) can be found online here).  Strong convection over Minnesota at this time was supported in part by instability diagnosed to its south.

Note how, south of the main convection, a second line of convection initiated over southern Minnesota at around 2030 UTC, along the northern edge of the diagnosed CAPE maximum.  When do you think lightning initiated with this second line of convection? What imagery/products will help in that assessment?

The 4-panel animation, below, shows the initiation of convection in the southern line, from 2031 to 2101 UTC.  The developing convection is fairly bright in the Snow/Ice channel initially, consistent with the presence of clouds made up of water droplets.  The Cloud Phase product shows water (or supercooled water) at these times, and the Day Cloud Phase Distinction color of the clouds is mostly greenish.

As glaciation occurs, the clouds in the Snow/Ice channel become darker:  ice absorbs (rather than reflects) energy at 1.61 µm so less is detected by the satellite.  The change in the 1.61 µm channel reduces the amount of blue in the Day Cloud Phase Distinction RGB (so pixels acquire a yellow or red hue), and the Cloud Phase product also detects mixed phase and ice clouds.  Once the glaciation has occurred, lightning production is more likely, and at 2101 UTC, the GLM detects lightning activity.  (Here is the 2101 UTC Day Cloud Phase Distinction image without GLM overlain; here are toggles between 2056 and 2101 UTC without and with GLM overlain;  a toggle between the 2056 and 2101 UTC Cloud Phase product is here; ice is present at 2056 UTC (and actually at 2051 UTC!) but more widespread at 2101 UTC). Of course, a 1-minute mesoscale sector could give even better temporal resolution of cloud phase changes than CONUS scans’ 5-minute time steps.

NOAA-20 overflew this region shortly after noon on 2 June, and the thermodynamic information from the infrared and microwave sounder instruments on board can be used to diagnose instability. The toggle below compares the total totals index computed from gridded NUCAPS data with the GOES-16 clear-sky estimates of CAPE.

Both measures of instability agree that the region of instability is narrow, and that its axis extends from central Wisconsin west-southwestward to southwest Minnesota and southeast South Dakota.

Gridded NUCAPS fields are created from soundings that may or may not have converged (that is, from points displayed in AWIPS as green — infrared and microwave retrievals converged), yellow (infrared retrieval failed, microwave retrieval converged) or red (infrared and microwave retrievals failed)).  The image below shows surface observations with the G16 Clean Window (10.3 µm) overlain with NUCAPS Sounding Points (This figure shows the total totals index overlain with the NUCAPS sounding points).  As expected because of the clear skies, most of the NUCAPS Soundings south of the convection show both infrared and microwave retrieval convergence: dots are green.

NUCAPS data that is gridded can include effects that are related to how well (or how poorly) a NUCAPS sounding observes and estimates the boundary layer. The sounding below is from a ‘green’ point in extreme south-central Minnesota (to the northeast of the observation plotted at Spencer Iowa). Surface dewpoints are observed in the mid-60s; however, the original NUCAPS sounding, shown below, shows a dewpoint near 60. When the lower-tropospheric dewpoints values are increased towards more representative values, estimated MLCAPE and MUCAPE as reported in the NSharp readout in AWIPS increase as well, from 2466 to 3404, and from 2635 to 3630, respectively. When using gridded NUCAPS estimates of thermodynamic variables that include surface or near-surface variables, consider just how well the NUCAPS soundings can observe that part of the troposphere.

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images with time-matched plots of SPC Storm Reports (above) showed the development of these storms during the 1700-0112 UTC period.

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images (below) revealed pulsing overshooting tops which exhibited cloud-top infrared brightness temperatures in the -70 to -79ºC range (darker black to brighter shades of white). Evidence of Above-Anvil Cirrus Plumes (reference | VISIT training) was seen in the Visible and Infrared imagery.

View only this post Read Less