Saharan Air Layer dust over the Gulf of Mexico

June 21st, 2014
GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 0.63 µm visible channel images (click to play animation)

McIDAS images of GOES-13 0.63 µm visible channel data on 20 June 2014 (above; click image to play animation; also available as an MP4 movie file) and on 21 June 2014 (below; click image to play animation; also available as an MP4 animation file) revealed the hazy signature of a veil of Saharan Air Layer (SAL) dust aloft over much of the southern and western portions of the Gulf of Mexico.

GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 0.63 µm visible channel images (click to play animation)

The hazy dust signature also showed up well in Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images, as visualized using the SSEC RealEarth web map server (below).

Suomi NPP VIIRS true-color RGB images

Suomi NPP VIIRS true-color RGB images

The SAL tracking product showed the strong pulse of SAL dust emerging from the African continent on 10 June, then moving rapidly westward across the Atlantic Ocean and over the Caribbean Sea by 17 June (below; click image to play animation).

Meteosat-10 Saharan Air Layer tracking product (click to play animation)

Meteosat-10 Saharan Air Layer tracking product (click to play animation)

Thunderstorms producing very large hail near Paris, France

June 9th, 2014
Meteosat-10 0.7 µm visible channel images (click to play animation)

Meteosat-10 0.7 µm visible channel images (click to play animation)

Severe thunderstorms developed over parts of France on 09 June 2014, some of which produced very large hail (photos). EUMETSAT Meteosat-10 1-km resolution 0.7 µm visible channel images (above; click image to play animation; also available as an MP4 movie file) and 3-km resolution 10.8 µm IR channel images (below; click image to play animation; also available as an MP4 movie file) revealed some interesting details in the thunderstorm structure: a narrow flanking line was seen on the visible imagery, and the storms exhibited well-defined “enhanced-V” signatures and thermal couplets on the IR imagery. For reference, the asterisk marks the location of the Charles De Gaulle Airport in Paris.

Meteosat-10 10.8 µm IR channel images (click to play animation)

Meteosat-10 10.8 µm IR channel images (click to play animation)

The Suomi NPP satellite overpass of the region occurred around 12:15 UTC, allowing the VIIRS instrument to provide a 375-meter resolution true-color Red/Green/Blue (RGB) image of the developing thunderstorms (below, visualized using the SSEC RealEarth web map server).

Suomi NPP VIIRS true-color RGB image

Suomi NPP VIIRS true-color RGB image

von Kármán vortex street downwind of Madeira Island

May 1st, 2014
Meteosat-10 0.75 µm visible channel image (click to play animation)

Meteosat-10 0.75 µm visible channel image (click to play animation)

McIDAS images of EUMETSAT Meteosat-10 0.75 µm visible channel data (above; click image to play animation) showed a beautiful example of a von Kármán vortex street downwind of Madeira Island on 01 May 2014. Northeasterly winds in the marine boundary layer were perturbed by the topography of the island, whose highest point rises to an elevation of 1,862 m (6,109 ft) above sea level. Note how some of the downwind vortices rotate in a clockwise direction, while other rotate counterclockwise.

Mesovortices within a mid-latitude cyclone

February 25th, 2014
Meteosat-10 0.75 µm visible channel and 10.8 µm IR channel images (click to play animation)

Meteosat-10 0.75 µm visible channel and 10.8 µm IR channel images (click to play animation)

Twitter follower @PedroCFernandez alerted us to an interesting case of mesovortices (original Spanish language blog post | Google translate version) which developed within the circulation of a strong mid-latitude cyclone over the northeastern Atlantic Ocean (moving toward the British Isles) on 24-25 February 2014. McIDAS images of EUMETSAT Meteosat-10 daytime 0.75 µm high resolution visible channel and night-time 10.8 µm IR channel data (above; click to play animation) revealed the series of mesovortices that spun up along the “bent-back” occluded frontal boundary (surface analyses); this storm was producing hurricane force winds during the 12-18 UTC period on 24 February, according to the NWS Ocean Prediction Center. Mesovortex cloud-top IR brightness temperatures were around -40º C (green color enhancement), indicating significant vertical development of the cloud structure associated with these features.

Meteosat-10 0.75 µm visible channel and 10.8 µm IR channel images at 18:00 UTC

Meteosat-10 0.75 µm visible channel and 10.8 µm IR channel images at 18:00 UTC

A comparison of the 18:00 UTC Meteosat-10 visible and IR images (above) showed two well-developed mesovortices at that time: #1, located southwest of the storm center, and #2, located west of the storm center;  a new mesovortex #3 was just in the process of forming to the northwest of the storm center (below).

Meteosat-10 10.8 µm IR channel image at 18:00 UTC

Meteosat-10 10.8 µm IR channel image at 18:00 UTC