Large mesoscale convective system over Argentina

February 7th, 2012 |
GOES-12 10.7 µm IR channel images (click image to play animation)

GOES-12 10.7 µm IR channel images (click image to play animation)

McIDAS images of 4-km resolution GOES-12 10.7 µm IR channel data (above; click image to play animation) showed the development of a very large mesoscale convective system (MCS) over Argentina on 07 February 2012. A number of smaller, discrete thunderstorms initially began to develop around 14:45 UTC, which then eventually merged into a large MCS having large areas which exhibited cloud top IR brightness temperatures of -80 C and colder (purple color enhancement). Multiple “enhanced-v” storm top signatures could be seen at various times, which is a satellite signature of thunderstorms that are capable of producing either tornadoes, large hail, or damaging winds.

Much more detail in the cloud top IR brightness temperature structure can be seen in a 375-meter resolution Suomi NPP VIIRS 11.45 µm image at 18:21 UTC (below). The coldest VIIRS IR brightness temperatures sensed was -96 C (darker violet color enhancement) — much colder than the -77 C seen on the corresponding 18:15 UTC GOES-12 IR image. The black striping seen along the right side of the image is an artifact of the side-to-side scan strategy of the VIIRS instrument; software to remove these artifacts and create a smoother-looking image is under development.

Suomi NPP VIIRS 11.45 µm IR image

Suomi NPP VIIRS 11.45 µm IR image

Large outbreak of Saharan dust over the eastern Atlantic Ocean

February 7th, 2012 |
EUMETSAT Meteosat-9 0.635 µm visible channel images (click image to play animation)

EUMETSAT Meteosat-9 0.635 µm visible channel images (click image to play animation)

McIDAS images of EUMETSAT Metosat-9 0.635 µm visible channel images (above; click image to play animation) showed a very large outbreak of airborne Saharan dust streaming off the continent of Africa and moving west-southwestward out over the adjacent waters of the eastern Atlantic Ocean on 07 February 2012. In addition, a pair of long von Karman vortex streets can be seen moving southwestward from the Cape Verde islands.

While the viewing angle was more extreme, the Saharan dust could also be seen on GOES-13 0.63 µm visible channel images (below).

GOES-13 0.63 µm visible channel images + surface reports

GOES-13 0.63 µm visible channel images + surface reports

The emergence of this Saharan dust over water can be seen to occur around 00:00 UTC on 06 February on the Meteosat-9 Saharan Air Layer tracking product (below).

EUMETSAT Meteosat-9 Saharan Air Layer tracking product

EUMETSAT Meteosat-9 Saharan Air Layer tracking product