Blowing dust across the Canary Islands and Atlantic Ocean

February 23rd, 2020 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with plots of hourly surface reports [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the onset of a 2-day event of dense plumes of blowing sand/dust (known locally as a Calima) — with Western Sahara and Morocco being the primary source regions — which moved across the Canary Islands and the adjacent East Atlantic Ocean on 22 February 2020. Along the coast of Morocco, surface visibility was reduced to 1/8 mile at Tan-Tan (GMAT); over the Canary Islands, visibility dropped to 1/4 mile at Gran Canaria (GCLP).

GOES-16 Dust Red-Green-Blue (RGB) images spanning the period 0800 UTC on 22 February to 2100 UTC on 23 February (below) provided a continuous day/night visualization of the first dust plume (shades of pink/magenta). During the day on 23 February, a second dust plume could be seen emerging from below a patch of mid/high-altitude clouds. The RGB images were created using Geo2Grid.

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

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

VIIRS True Color RGB images from Suomi NPP and NOAA-20 as viewed using RealEarth (below) revealed orographic waves in the airborne sand/dust downwind (northwest) of some of the Canary Islands on 23 February.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

This sand/dust was being lofted by anomalously strong lower-tropospheric winds — which were up to 5 standard deviations above the mean at the 925 hPa pressure level (below).

925 hPa wind speed anomaly during the period 00 UTC on 22 February to 00 UTC on 24 February [click to enlarge]

925 hPa wind speed anomaly during the period 00 UTC on 22 February to 00 UTC on 24 February [click to enlarge]

===== 24 February Update =====

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

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

GOES-16 Dust RGB images on 24 February (above) showed the second major pulse of sand/dust curling around the northern periphery of the offshore cutoff low pressure system. Toward the end of the animation, another minor pulse could be seen streaming northwestward off the coast of Western Sahara. A longer Dust RGB animation from 08 UTC on 22 February to 18 UTC on 24 February is available here.

In addition to the Dust RGB, signatures of the airborne sand/dust were also evident in GOES-16 Split Window Difference (10.3-12.3 µm) and Split Cloud Top Phase (11.2-8.4 µm) imagery (below). This arises from the fact that silicates (sand/dust particles) have different energy absorption characteristics at varying wavelengths.

GOES-16 Dust RGB, Split Window Difference (10.3-12.3 µm) and Split Cloud Top Phase (11.2-8.4 µm) [click to play animation | MP4]

GOES-16 Dust RGB, Split Window Difference (10.3-12.3 µm) and Split Cloud Top Phase (11.2-8.4 µm) images [click to play animation | MP4]

A comparison of TROPOMI Aerosol Index, TROPOMI Aerosol layer height (meters), Meteosat-11 Natural Color RGB and Meteosat-11 Dust RGB images at 1515 UTC is shown below (credit: Bob Carp, SSEC). Note that the height of the center of the aerosol layer near the western tip of the plume was generally in the 500-1000 meter range (shades of blue to cyan).

Panel 1: TROPOMI Aerosol Index Panel 2: TROPOMI Aerosol layer height (meters) Panel 3: Meteosat-11 Natural Color RGB Panel 4: Meteosat-11 Dust RGB [click to enlarge]

TROPOMI Aerosol Index (top left), TROPOMI Aerosol layer height in meters (top right), Meteosat-11 Natural Color RGB (bottom left) and Meteosat-11 Dust RGB (bottom right) [click to enlarge]

GOES-16 Split Window Difference image, with plots of available NUCAPS profile points [click to enlarge]

GOES-16 Split Window Difference (10.3-12.3 µm) image, with plots of available NUCAPS profile points [click to enlarge]

A GOES-16 Split Window Difference (10.3-12.3 µm) image with plots of available NUCAPS profile points at 1600 UTC (above) denoted the locations of a sequence of 9 consecutive north-to-south sounding points through the western tip of the dust plume. Profiles of NUCAPS temperature and dew point data for those 9 points are shown below — the strong temperature inversion and dry air below 1 km at Points 6, 7 and 8 showed the presence of this dry, dust-laden air (and the Total Precipitable Water value dropped to a minimum value of 0.34 inch at Point 7).

Profiles of NUCAPS temperature and dew point data for Points 1-9 [click to enlarge]

Profiles of NUCAPS temperature and dew point data for Points 1-9 [click to enlarge]

Eruption of the Whakaari volcano on White Island, New Zealand

December 9th, 2019 |

“Red” Visible (0.64 µm) images from Himawari-8 (left) and GOES-17 (right) [click to play animation | MP4]

A brief eruption of the Whakaari volcano on White Island, New Zealand occurred around 0110 UTC on 09 December 2019 — “Red” Visible (0.64 µm) images from JMA Himawari-8 and GOES-17 (GOES-West) showed the small volcanic cloud as it fanned out east of the island (above).

A signature of the volcanic cloud was also seen in VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP, as viewed using RealEarth (below). The cloud exhibited a rather warm infrared brightness temperature, since the Wellington VAAC only estimated the maximum height to be

VIIRS True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

The volcanic plume contained elevated levels of SO2 which drifted south-southeastward, as seen in a McIDAS-V image of Sentinel-5 TROPOMI Vertical Column SO2 at 0206 UTC (below).

Sentinel-5 TROPOMI Vertical Column SO2 (credit: Bob Carp, SSEC) [click to enlarge]

Sentinel-5 TROPOMI Vertical Column SO2 (credit: Bob Carp, SSEC) [click to enlarge]

Bush fires in eastern Australia

November 8th, 2019 |

JMA Himawari-8 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and Longwave Infrared Window (10.4 µm) imagery (below) showed the evolution of smoke plumes, hot 3.9 µm fire thermal anomalies (red pixels) and cloud-top infrared brightness temperatures of isolated pyrocumulus associated with bush fires that were burning in far eastern parts of New South Wales and Queensland, Australia from 1900 UTC on 07 November to 0800 UTC on 08 November 2019. With strong northwesterly surface winds, many of the fire thermal anomalies exhibited rapid southeastward runs toward the coast. That region of Australia had just experienced severe to record 3-month rainfall deficiencies — which included the driest October on record for the southern third of the country.

Himawari-8

Himawari-8 “Red” Visible (0.64 µm) images, with hourly plots of surface reports [click to play animation | MP4]

Himawari-8 Shortwave Infrared (3.9 µm) images, with hourly plots of surface reports [click to play animation | MP4]

Himawari-8 Shortwave Infrared (3.9 µm) images, with hourly plots of surface reports [click to play animation | MP4]

Himawari-8 Longwave Infrared Window (10.4 µm) images, with hourly plots of surface reports [click to play animation | MP4]

Himawari-8 Longwave Infrared Window (10.4 µm) images, with hourly plots of surface reports [click to play animation | MP4]

Himawari-8 True Color Red-Green-Blue (RGB) images created using McIDAS-V (below) provided another view of the dense smoke plumes from 0000-0610 UTC. Toward the end of the animation — in the upper left portion of the satellite scene — plumes of blowing dust could be seen moving eastward from farther inland.

Himawari-8 True Color RGB images (credit: Bob Carp, SSEC) [click to play animation | MP4]

Himawari-8 True Color RGB images (credit: Bob Carp, SSEC) [click to play animation | MP4]

A combination of Suomi NPP VIIRS True Color RGB and Shortwave Infrared (4.1 µm) imagery at 0328 UTC (below) revealed hot thermal signatures of the fires (yellow to red enhancement) at the source of the smoke plumes.

Suomi NPP VIIRS True Color RGB + Shortwave Infrared (4.1 µm) imagery at 0328 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB + Shortwave Infrared (4.1 µm) imagery at 0328 UTC (credit: Bob Carp, SSEC) [click to enlarge]

A toggle between a Suomi NPP VIIRS True Color RGB image and a display of Sentinel-5 TROPOMI Tropospheric Vertical Column NO2 (below) indicated high NO2 concentrations immediately downwind of these fires.

Suomi NPP VIIRS True Color RGB image + TROPOMI Tropospheric Vertical Column NO2 [click to enlarge]

Suomi NPP VIIRS True Color RGB image + Sentinel-5 TROPOMI Tropospheric Vertical Column NO2 (credit: Bob Carp, SSEC) [click to enlarge]

The dense smoke plumes were also evident in a sequence of 3 VIIRS True Color RGB images from NOAA-20 and Suomi NPP, as visualized using RealEarth (below).

NOAA-20 and Suomi NPP VIIRS True Color RGB images [click to enlarge]

VIIRS True Color RGB images from NOAA-20 and Suomi NPP [click to enlarge]

Smoke reduced the surface visibility to 3 miles or less at Grafton (YGFN) from 03-05 UTC (below).

Time series of surface report data from Grafton, New South Wales [click to enlarge]

Time series of surface report data from Grafton, New South Wales [click to enlarge]


Rope cloud in the East Pacific Ocean

January 16th, 2019 |
GOES-17

GOES-17 “Red” Visible (0.64 µm) image, with an overlay of the 12 UTC surface analysis [click to enlarge]

* GOES-17 images shown here are preliminary and non-operational *

An 1802 UTC GOES-17 “Red” Visible (0.64 µm) image with an overlay of the 12 UTC surface analysis (above) revealed a well-defined rope cloud which stretched for nearly 1000 miles, marking the cold front position at the time of the image. Rope clouds can therefore be used to diagnose the exact location of the leading edge of a cold frontal boundary between times when surface analyses are available. In this case, the cold front was associated with a Hurricane Force low over the East Pacific Ocean on 16 January 2019 (surface analyses).

GOES-17 "Red" Visible (0.64 µm) images [click to play animation]

GOES-17 “Red” Visible (0.64 µm) images [click to play animation]

An animation of GOES-17 Visible images is shown above, with a zoomed-in version closer to the rope cloud displayed below.

GOES-17 "Red" Visible (0.64 µm) images [click to play animation]

GOES-17 “Red” Visible (0.64 µm) images [click to play animation]

An even closer look (below) showed that the rope cloud was only about 2-3 miles wide.

GOES-17 "Red" Visible (0.64 µm) images [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) images [click to enlarge]

When the 18 UTC surface analysis later became available, a close-up comparison with the 1802 UTC GOES-17 Visible image (below) indicated that the northern portion of the cold front (as indicated by the rope cloud) was slightly ahead of — and the southern portion slightly behind — the smoothed cold frontal position of the surface analysis product.

1802 UTC GOES-17 "Red" Visible (0.64 µm) image, with an overlay of the 18 UTC surface analysis [click to enlarge]

1802 UTC GOES-17 “Red” Visible (0.64 µm) image, with an overlay of the 18 UTC surface analysis [click to enlarge]

NOAA-15 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images at 1617 UTC [click to enlarge]

NOAA-15 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images at 1617 UTC [click to enlarge]

1-km resolution AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images of the rope cloud were captured by NOAA-15 at 1617 UTC (above) and by NOAA-18 at 1710 UTC (below). Along the northeastern portion of the rope cloud, there were a few convective clouds which exhibited cloud-top infrared brightness temperatures as cold as -55 to -60ºC (darker shades of red) and were tall enough to be casting shadows due to the low morning sun angle.

NOAA-18 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images [click to enlarge]

NOAA-18 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images at 1710 UTC [click to enlarge]


===== 17 January Update =====

GOES-17 True Color RGB images [click to play animation | MP4]

GOES-17 True Color RGB images [click to play animation | MP4]

On the following day, another rope cloud (one that was more fractured) was seen moving across Hawai’i as a cold front passed the island of Kaua’i — the southeastward progression of the rope cloud was evident on GOES-17 True Color Red-Green-Blue (RGB) images (above)  from the UW AOS site.

Surface observations plotted on GOES-17 Visible images (below) showed the wind shift from southwest to north as the cold front moved through Lihue on Kauwa’i around 00 UTC.

GOES-17

GOES-17 “Red” Visible (0.64 µm) images, with plots of surface reports [click to play animation | MP4]

===== 18 January Update =====

Suomi NPP VIIRS Day/Night Band (0.7 µm) image, with and without buoy observations [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image, with and without buoy observations [click to enlarge]

Not all rope clouds are associated with cold fronts; with ample illumination from the Moon — in the Waxing Gibbous phase, at 90% of Full — a Suomi NPP VIIRS Day/Night Band (0.7 µm) image (above) provided a “visible image at night” of a rope cloud in the northern Gulf of Mexico which highlighted a surface wind shift axis.

A sequence of VIIRS Day/Night Band images from NOAA-20 and Suomi NPP (below) showed the movement of the rope cloud during a time span of about 1.5 hours.

NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]