VIIRS views of the surface and atmosphere, late September 2020 version

September 24th, 2020 |

VIIRS True-Color imagery on 02 and 22 September 2020 (Click to enlarge). Data from the VIIRS Today website

VIIRS True-Color imagery taken from the VIIRS Today website, above, shows the reddening/yellowing of trees over the upper midwest between 2 September and 22 September 2020. The inexorable slip into autumn and winter is ongoing.

Early in the morning on 24 September, Direct Broadcast NOAA-20 data downloaded at CIMSS and processed with CSPP showed an extensive aurora over much of Canada. (These data are available from the Direct Broadcast ftp site: link; direct link to the NOAA-20 data used below: link — note that this direct link is ephemeral and will disappear after about a week). The Day Night Band imagery is toggled with 11.45 µm infrared imagery.

NOAA-20 remapped VIIRS Day Night Band visible (0.7 µm) imagery and infrared 11.45 µm imagery, 0804 UTC on 24 September 2020

ACSPO Lake Surface Temperatures over the Great Lakes

September 23rd, 2020 |

Great Lakes lake surface temperatures, 0735 UTC on 23 September 2020, as well as zoomed-in views of the individual lakes (Click to animate)

Suomi-NPP’s descending pass at ~0730 UTC (shown here, from this site), had an ideal path — moving south from far eastern Upper Michigan to western Lower Michigan — to view all five Great Lakes.  Sprawling High Pressure and the attendant clear skies meant that a good basin wide view of the lake temperatures was observed, as shown above. (DB imagery from this pass is also available for a short time at the CIMSS DB ftp site) These ACSPO (Advanced Clear-Sky Processor for Ocean) SST fields are available to NWS offices via LDM fields. The default color bar in AWIPS has been changed so that only temperatures between 45º F and 70º F are shown

Lake Temperatures in the imagery above range, for Lake Superior from 47.5º (east of Minnesota) to 66º (just off southwest Upper Michigan); for Lake Michigan from 57º (east of Sheboygan WI) to 67º (mid-lake, east of Chicago); for Lake Huron from 55º (in northwestern Georgian Bay and also northwestern Lake Huron) to 65º (far southern Lake Huron); for Lake Erie from 63º (western Lake Erie) to 69º (central Lake Erie); for Lake Ontario from 62º (western Lake Ontario) to 67º (eastern Lake Ontario).

This view of the Great Lakes from early in September (also from the CIMSS DB site, processed with CSPP), shows — with a color bar that ranges from 41ºF to 86ºF — much warmer water, especially in Lake Superior where the coolest mid-lake temperatures were in the mid-50s. Storms and vertical mixing since early September have cooled the surface waters. GLERL has a website that shows modeled lake surface temperatures, accessible here.

Hurricane Teddy and wildfire smoke

September 22nd, 2020 |

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 (GOES-East) True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) revealed that the large circulation of Hurricane Teddy (downgraded from a Category 2 to a Category 1 storm at 18 UTC) was drawing hazy filaments of smoke — likely originating from wildfires in the western US — southward from eastern Canada and New England, carrying it across the far western Atlantic Ocean on 22 September 2020. Also of interest (early in the animation) were the narrow fingers of river valley fog across parts of New York, Pennsylvania, Maryland, West Virginia and Virginia.

Although the size of Teddy’s cloud shield was still fairly large, a DMSP-17 SSMIS Microwave (85 GHz) image at 2217 UTC from the CIMSS Tropical Cyclones site (below) showed that no organized core of deep convection remained as the storm began to move across colder waters (Sea Surface Temperature | Ocean Heat Content) and encounter a more hostile environment of increasing deep-layer wind shear.

DMSP-17 SSMIS Microwave (85 GHz) image at 2217 UTC [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 2217 UTC [click to enlarge]

GOES-16 CIMSS Natural Color RGB images, with and without an overlay of Aerosol Optical Depth [click to play animation | MP4]

GOES-16 CIMSS Natural Color RGB images, with and without an overlay of Aerosol Optical Depth [click to play animation | MP4]

A larger-scale view of GOES-16 CIMSS Natural Color RGB images — with and without an overlay of Aerosol Optical Depth (above) showed that an elongated plume of smoke stretched westward from New York and Pennsylvania to parts of Wisconsin, Illinois and Iowa. Upward-looking lidar data from the University of Wisconsin – Madison (below) depicted a thick layer of smoke between altitudes of 2-6 km.

Plots of lidar backscatter and depolarization from 12 UTC o n 22 September to 00 UTC on 23 September [click to enlarge]

Plots of lidar backscatter (top) and depolarization (bottom) from 12 UTC on 22 September to 00 UTC on 23 September [click to enlarge]

Medicane Ionas after Greece

September 21st, 2020 |

VIIRS Daily True-Color images, 18-21 September 2020 (Click to animate)

What did the Medicane that hit Greece do afterwards?  VIIRS True-color imagery, above, taken from the NASA WorldView site, show an intact feature moving along the northern coast of Africa on 20-21 September towards the Nile Delta.  The amount of cloudiness is in general declining as it moves into a drier environment.  Total Precipitable Water (TPW) from the MIMIC website shows the general drying surrounding the storm.

MIMIC hourly estimates of Total Precipitable Water from 00 UTC on 17 September to 14 UTC on 21 September 2020 (Click to animate)


Rick Kohrs, SSEC/CIMSS, supplied the True-Color multi-day animation from Meteosat-11 imagery below. (Updated on 23 September to include date annotations)

Meteorsat-11 True-Color Imagery over the Mediterranean sea, 15-21 September 2020 (Click to animate)