Fader comparison of ASADA Smoke Product and Visible Image
Residents in northeastern Argentina reported "blue rain" on 02 September 1998. A recent press release (24 October) by Argentine government scientists revealed that the "blue rain" was caused by ash associated with fire activity in Bolivia and Brazil.
The NOAA Geostationary Operational Environmental Satellite (GOES)-8 experimental Automated Smoke/Aerosol Detection Algorithm (ASADA) products and visible imagery (above) were processed by the CIMSS Biomass Burning Monitoring Program. These images show the southward movement of a large smoke pall over central South America from 30 August to 02 September 1998. Smoke associated with fire activity extended over nearly 5 million square kilometers. Wind streamlines at 700 millibars (about 3.0 km in altitude) indicate that an anticyclone was in place over southeastern Brazil during this period. Northerly flow along the western periphery of this anticyclone helped to advect the smoke southward from Brazil into Bolivia, Paraguay, and eventually northern Argentina. Convection over northeastern Argentina on 02 September produced rain that appeared blue in color, due to the large amount of airborne smoke and ash particulate that was scavenged by the precipitation.
The GOES-8 Automated Biomass Burning Alogorithm (ABBA) derived fire product indicated that thousands of fires were burning throughout Brazil, Bolivia, Paraguay, and Northern Argentina during the last week of August and the first week of September. On 01 September 1998, the GOES ABBA detected over 2400 fires at 1745 UTC as seen in the 4-panel (below), which displays the locations of fires observed in the GOES-8 imagery at 1145, 1445, 1745, and 2045 UTC. A plot of 48-hour backward trajectories calculated using the NOAA Air Resources Lab HYsplit model shows that air parcels arriving over northeastern Argentina originated 2 days earlier over regions of fire activity and smoke as seen on the ABBA and ASADA products.