Archive for June, 2009

Airborne Saharan dust over the North Atlantic Ocean

Tuesday, June 30th, 2009
Meteosat-9 visible image

Meteosat-9 visible image

A Meteosat-9 visible image at 18:00 UTC (above) showed the presence of a great deal of airborne Saharan dust over the North Atlantic Ocean on 30 June 2009. Due to a favorable forward scattering angle, this dust appeared as a large “hazy” feature between Africa and South America. Also note the well-defined “comma cloud” signature of a strong mid-latitude cyclone off the southeastern coast of South America.

The Meteosat-9 Saharan Air Layer (SAL) tracking product from the CIMSS Tropical Cyclones site (below) displayed a strong signal (darker red colors) of this latest pulse of thick dust beginning to move westward off the coast of western Africa on 30 June.

Meteosat-9 Saharan Air Layer product

Meteosat-9 Saharan Air Layer product

This pulse of dust was also apparent on Meteosat-9 Red/Green/Blue (RGB) aerosol tracking product images (below), showing up as a brighter pink feature to the north of a large Mesoscale Convective System that was moving westward across western Africa during the 28-30 June period.

Meteosat-9 RGB aerosol tracking images

Meteosat-9 RGB aerosol tracking images

===== 02 JULY UPDATE =====

After the initial pulse of Saharan dust was seen to move off the west coast of Africa around the end of June, another strong pulse of blowing sand/dust (the brighter pink features) was seen to develop inland over northwestern Africa (across parts of Algeria, Niger, and Mali) during the 01-02 July period (below), with some of this dust reaching the coast on 02 July.

Meteosat-9 RGB aerosol tracking product images

Meteosat-9 RGB aerosol tracking product images

Yemenia Airways Flight 626 crash

Monday, June 29th, 2009
Meteosat-7 IR images

Meteosat-7 IR images

Yemenia Airways Flight 626 departed from Sana in Yemen and crashed after an aborted landing attempt at Moroni in the Comoros Islands off the east coast of Africa on 29 June 2009. Meteosat-7 11.5 µm IR images (above) showed that there was a strong southerly flow over the region on that day, in the wake of a cold frontal passage. Meteosat-7 IR cloud drift winds from the CIMSS Tropical Cyclones site (below) showed that winds were generally in the 20-30 knot range over the region at the time of the crash.

Meteosat-7 IR cloud drift winds

Meteosat-7 IR cloud-tracked winds

These wind speeds are consistent with the surface METAR reports at Moroni Hahaya International Airport:

FMCH 292200Z 18022G33KT 9999 FEW020 24/17 Q1018 NOSIG=
FMCH 292300Z 21025G35KT 9999 FEW020 25/16 Q1017 TEMPO 18015G30KT=
FMCH 300000Z 21025G35KT 9999 FEW020 25/17 Q1016 TEMPO 19014KT=

Moroni Hahaya International Airport surface meteorogram

Moroni Hahaya International Airport surface meteorogram

For additional information, see Yemenia Flight 626: A detailed meteorological analysis by Tim Vasquez.