Using Polar2Grid software to display historical MODIS data

May 19th, 2020 |

Terra MODIS Bands 2 (0.86 µm), 6 (1.62 µm) and 26 (1.38 µm) from 28 January 2004 (Click to enlarge)

The satellites Terra (launched in 1999) and Aqua (launched in 2002) both carry the Moderate-Resolution Imaging Spectroradiometer (MODIS) instrument, an imager with 26 channels at wavelengths that range from 0.41 µm to 14.1 µm. There are simple ways to create useful imagery with this historical data with Polar2Grid software that was developed at CIMSS as part of the Community Satellite Software Package (CSPP). This blog post will show you how to create imagery as shown above (0.86 µm, 1.62 µm and 1.38 µm) over Mt. Everest on 28 January 2004.  (Similar imagery from 29 January 2004:  0.86 µm, 1.62 µm, 1.38 µm, or toggles between 28/29 January at 0.86 µm, 1.62 µm and 1.38 µm)

The self-contained Polar2Grid software package can be downloaded from this link. (You may have to register your email address before accessing the site; registration is free). Once on the website, scroll down to find “Polar2Grid V2.3 Reprojection Software for Linux” (note that the version number will occasionally increment!) and download the gzipped tarfile. You should also download the documentation (it’s a pdf file) at that site. This will tell you what to do before you can successfully run the software: for example, the POLAR2GRID_HOME variable must be set:
export POLAR2GRID_HOME=/path/to/softwarebundle.

Next, order archived MODIS data. These data are available at the NASA LAADS (Level-1 and Atmosphere Archive and Distribution System) DAAC (Distributed Active Archive Center) at this link. If you click on ‘Find Data’ at that website, a long list of possible products will be displayed. MODIS data that are compatible with Polar2Grid are Level 1b Calibrated Radiances: MOD02 files, and for this example I chose 1-km and half-kilometer resolution (that is, MOD021KM, MOD02HKM). Geolocation files (MOD03) must also be selected.

Polar2Grid includes software to create a grid onto which the data will be projected; for the example above, I first ran the Polar2Grid script ./p2g_grid_helper.sh asia 87.0 28.0 500 -500 6000 6000 > myasiagrids.txt.

This creates a grid centered at 28 N, 87 E (west longitudes are negative) with a 500-m grid spacing in both x- and y-directions; the grid has a size of 6000×6000. If you don’t create a grid, the satellite data are placed on the native satellite grid, a grid that changes from day to day for a polar orbiter.

Once the MODIS data has been placed on your local machine, you are ready to use Polar2Grid to query what products can be created using this command

./polar2grid.sh modis gtiff --list-products -f /data-hdd/AckFriendData/MODIS/MOD02_03/day028/;

the -f flag identifies the directory holding the MODIS data and modis gtiff identifies the data type and output files to be created. The result of this is a (sometimes lengthy) list of products that can be created given the input. The following command creates geotiff:

./polar2grid.sh modis gtiff -p vis02 vis06 vis26 --grid-configs /home/scottl/Polar2Grid/polar2grid_v_2_3/bin/myasiagrids.txt -g asia -f /data-hdd/AckFriendData/MODIS/MOD02_03/day028/

This command creates Bands 2, 6 and 26 GeoTiffs, and the data are placed on the ‘asia’ grid defined above (and placed in the myasiagrids.txt file). The grids created do not have georeferencing embedded within the image; that is added with the add_coastlines shell script:
./add_coastlines.sh --add-grid --add-borders --borders-resolution=f --borders-outline='red' terra_modis_vis06_20040129_031000_asia.tif

The add-grid flag inserts lat/lon lines; add-borders includes country borders (with the outline color defined, and the resolution specified; for more control flags, refer to the documentation).

Other CIMSS blog posts that discuss Polar2Grid software are here , here and here.

Outbreak of severe thunderstorms across the Deep South

April 12th, 2020 |

GOES-16 "Red" Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

A major outbreak of severe thunderstorms (SPC Storm Reports) occurred across the Deep South on 12 April 2020. 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development and propagation of deep convection during the 1200-2359 UTC period. The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images are shown below.

GOES-16

GOES-16 “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

Some of the strongest long-track tornadoes occurred in southern Mississippi — a closer view of GOES-16 Visible, Infrared and Visible/Infrared Sandwich Red-Green-Blue (RGB) images (below) revealed the pulsing nature of overshooting tops — which exhibited cloud-top infrared brightness temperatures as cold as -77ºC at 2038-2039 UTC, about 35 minutes prior to the destructive tornado that moved through Bassfield — and well defined “enhanced-v” signatures were apparent in the Infrared and RGB imagery, with that signature’s warm wake immediate downwind (east) of the overshooting tops indicating the likely presence of Above-Anvil Cirrus Plumes.

GOES-16 "Red" Visible (0.64 µm ), "Clean" Infrared Window (10.35 µm), and Visible/Infrared Sandwich RGB images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm ), “Clean” Infrared Window (10.35 µm) and Visible/Infrared Sandwich RGB images [click to play animation | MP4]

GOES-16 "Red" Visible (0.64 µm) images, with time-matched SPC Storm Reports plotted in red [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images, with time-matched SPC Storm Reports plotted in red [click to play animation | MP4]

1-minute GOES-16 Visible images (above) and Infrared images (below) include plots of time-matched SPC Storm Reports.

GOES-16 "Clean" Infrared Window (10.35 µm) images, with time-matched SPC Storm Reports plotted in cyan [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with time-matched SPC Storm Reports plotted in cyan [click to play animation | MP4]

NOAA/CIMSS ProbSevere is a tool that could have been used during this outbreak to identify which radar cells were most likely to produce severe weather.  The image below, from here, shows the reports of severe weather, the warning polygons, and ProbSevere locations (a closer view of the Mississippi tornadoes can be seen here).

Severe weather reports from 12 April 2020 (Green: Hail; Blue: Wind; Red: Tornado), NWS Warning Polygons and ProbSevere locations (plotted as boxes when ProbSevere exceeded 50% (Click to enlarge)

===== 14 April Update =====

GOES-16

GOES-16 “Red” Visible (0.64 µm) and Normalized Difference Vegetation Index images [click to enlarge]

Southwest-to-northeast oriented tornado damage paths in southern Mississippi were evident in a toggle between GOES-16 Visible and Normalized Difference Vegetation Index (NDVI) images (above). NDVI values within the damage path were generally 0.6, compared to 0.7-0.8 in adjacent areas. According the the NWS Jackson storm survey, the maximum path width of the longest-track (~67 mile) EF-4 tornado that began near Bassfield was about 2 miles — the widest ever measured in Mississippi, and one of the widest tornado damage paths ever measured in the US.

In a toggle between Aqua MODIS NDVI and Land Surface Temperature (LST) images (below), LST values were 5-10ºF warmer — low 80s F, darker shades of red —  within the tornado damage path, compared to areas adjacent to the path.

Aqua MODIS Normalized Difference Vegetation Index and Land Surface Temperature images [click to enlarge]

Aqua MODIS Normalized Difference Vegetation Index and Land Surface Temperature images [click to enlarge]

The tornado damage paths were also apparent in a comparison of before (26 March) and after (14 April) Aqua MODIS True Color RGB images (below) from the MODIS Today site. Note that 2 smoke plumes were seen on the 26 March image.

Aqua MODIS True Color RGB images from 26 March and 14 April [click to enlarge]

Aqua MODIS True Color RGB images from 26 March and 14 April [click to enlarge]

True and False-color imagery from NOAA-20 (from this (temporary) website) also show the damage path.

True- and False-Color imagery from the afternoon NOAA-20 overpass on 14 April 2020 (Click to enlarge)

NOAA-20 True Color RGB imagery of the Mississippi EF-4 tornado damage path that had a maximum with of 2 miles is shown below, using RealEarth.

NOAA-20 VIIRS True Color RGB image, including county outlines and map labels [click to enlarge]

NOAA-20 VIIRS True Color RGB image, including county outlines and map labels [click to enlarge]

Experimental: The VIIRS Today website

April 8th, 2020 |

NOAA-20 VIIRS Day Night Band over the western United States, ~0900 UTC on 8 April 2020 (Click to enlarge)

CIMSS has long hosted the popular site ‘MODIS Today‘ that allows easy access to full-resolution imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board Terra (launched in 1999 and still producing imagery) and Aqua (launched in 2002 and still producing imagery). That site remains active and allows access to imagery back to 2007.

Ongoing work at CIMSS means a similar site for VIIRS imagery will soon be available, allowing access to full-resolution VIIRS imagery. For example, the Day-Night Band image above, during the Full Moon on 8 April 2020, is presented in one region of the USA — the Pacific Northwest just after 0900 UTC, on a clear night. The image below shows the midwestern United States at around 0700 UTC. (Reminder:  NOAA-20 Orbits can be viewed here).

Stay tuned!

NOAA-20 VIIRS Day Night Band over the midwestern United States, ~0700 UTC on 8 April 2020 (Click to enlarge)

Wildfire in the Oklahoma Panhandle

March 7th, 2020 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Power (bottom left) and Fire Temperature (bottom right) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images along with 5-minute Fire Power and Fire Temperature products (which are components of the GOES Fire Detection and Characterization Algorithm (SHyMet | ATBD) showed the rapid northeastward run (as fast as 103 feet per minute) of the 13,000 acre “Beaver Fire” (also known as the “412 Fire”) in the Oklahoma Panhandle on 07 March 2020. An elevated thermal signature on Shortwave Infrared imagery first began to appear southwest of Beaver, OK around 1546 UTC  — and 3.9 µm infrared brightness temperatures eventually peaked around 139ºC. Maximum Fire Power and Fire Temperature values exceeded 3100 MW and 2900 K, respectively. Fire Warnings were issued, with residents of Beaver and Forgan being advised to evacuate as the fire rapidly approached. In Visible imagery, the dark signature of a long, narrow vegetation burn scar was evident — and pyrocumulus clouds were seen developing over the fire.


Extreme fire behavior was aided by anomalously-strong winds across the southern Plains. The peak wind gust at Beaver, Oklahoma was 46 mph; south of the fire, surface winds were gusting to 43 mph at Perryton (in far the northern Texas Panhandle), and west of the fire winds gusted to 42 mph at Guymon (in the Oklahoma Panhandle). A large-scale animation of 1-minute GOES-16 Visible images from the AOS site (below) indicated that the smoke plume was transported northeastward across Kansas and eventually moved over south-central Nebraska. Smoke reduced the surface visibility to 6 miles at Dodge City as it moved across southwestern Kansas.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Shortwave Infrared images from MODIS (3.7 µm) and VIIRS (3.74 µm) (below) displayed three snapshots of the 10-15 mile long thermal anomaly (elongated cluster of black pixels) associated with the wildfire.

Shortwave Infrared images from MODIS (3.7 µm) and VIIRS (3.74 µm) [click to enlarge]

Shortwave Infrared images from MODIS (3.7 µm) and VIIRS (3.74 µm) [click to enlarge]

===== 08 March Update =====

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 0857 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 0857 UTC [click to enlarge]

During the subsequent overnight hours, a comparison of NOAA-20 VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 0857 UTC or 3:57 am local time (above) revealed the dark southwest-to-northeast oriented burn scar, with isolated small fires still burning along the northwestern periphery of the burn scar. Note: the NOAA-20 images are incorrectly labelled as Suomi NPP.

===== 09 March Update =====

GOES-16 Land Surface Temperature product and

GOES-16 Land Surface Temperature product and “Red” Visible (0.64 µm) image [click to enlarge]

A toggle between a GOES-16 Land Surface Temperature product and the corresponding Visible image (above) showed the fire burn scar at 2101 UTC on 09 March. Land Surface Temperature values were 10ºF warmer within the burn scar (middle 80s F, shades of yellow to orange) compared to areas immediately adjacent to the burn feature.