Airborne Saharan dust over the North Atlantic Ocean

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

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 ┬Ám 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.

GOES-O (GOES-14) launched!

June 27th, 2009
GOES-12 visible images

GOES-12 visible images

The GOES-O satellite was launched at 22:51 UTC on 27 June 2009 from Cape Canaveral, Florida (station identifier XMR). GOES-12 visible images (above) showed a portion of the rocket plume on the 23:02 UTC image (some ground-based photos of the launch are available here).

This satellite will become GOES-14 after the hand-off from NASA to NOAA, and will then undergo a Post Launch Test (PLT) during the July-December 2009 period — the first GOES-14 visible images should be made available on 27 July, with the first InfraRed images available in mid-August. CIMSS has calculated the weighting functions for the GOES-14 imager and sounder channels as well as the spectral response functions and Planck function constants for GOES-O…and CIMSS will also contribute to the NOAA Science Test portion of the PLT in November/December 2009.

Convective initiation along an outflow boundary

June 25th, 2009
GOES-12 visible images

GOES-12 visible images

GOES-12 visible images (above) showed a nice example of convective initiation along an outflow boundary from thunderstorms a few hours earlier across northeastern Iowa on 25 June 2009. This new convection that developed along the outflow boundary produced hail of 1.5 inch in diameter and damaging winds in extreme northern Illinois (just south of the Wisconsin border) during the 20:42 -21:02 UTC period.

A comparison of AWIPS images of the MODIS visible channel and a Red/Green/Blue (RGB) composite using MODIS bands 01/07/31 (below) showed the value of the false-color RGB imagery to help highlight the darker green patch of wet ground produced by heavy rainfall from the initial area of thunderstorms. Ice crystal clouds appear as varying shades of pink in the RGB image, which also helps to identify growing areas of cumulus clouds that have glaciated.

The next generation of AWIPS (AWIPS2) should offer NWS forecasters the ability to create and display this type of 24-bit RGB imagery (which is not possible using the 8-bit graphics capability of the current AWIPS system).

MODIS visible + false-color RGB image

MODIS visible + false-color RGB image