Wildfire near Lake Okeechobee in Florida

May 30th, 2007 |

GOES + MODIS shortwave IR images

Hot spots on GOES-12 3.9µm and MODIS 3.7µm IR imagery (above) indicated the presence of several wildfires near the northwestern shoreline of Lake Okeechobee in southern Florida on 30 May 2007. The fires were hot enough to saturate the shortwave IR detectors on GOES-12, causing the hottest brightness temperatures (normally appearing as black pixels) to “roll over” and show up as “cold” (white) pixels. An Aqua MODIS true color image (below) showed a smoke plume extending westward from the fires, with the smoke reaching the Gulf Coast of Florida. That region continued to experience extreme drought conditions — in fact, the water levels for the lake set an all time record low (note how much the lake water had receded from the southern, western, and northwestern portion of Okeechobee in the MODIS true color image).

MODIS true color image

TD Alvin and TS Barbara

May 30th, 2007 |


An AWIPS image of the GOES 10.7µm InfraRed (IR) channel (above) shows Tropical Depression Alvin (left) and Tropical Storm Barbara (right) on 30 May 2007 — both disturbances were located near the Intertropical Convergence Zone (ITCZ) over the Eastern Pacific Ocean. The morning NHC discussion pointed out that only twice before (in 1956 and 1984) have there been two named Eastern Pacific basin storms in the month of May. An animation of GOES-12 IR imagery with a different color enhancement (below) indicates that the cold cloud top temperatures (red to white enhancement) associated with Tropical Storm Barbara were increasing in areal coverage during the morning hours.

GOES-12 IR animation

The NHC discussion also made reference to the CIMSS Advanced Dvorak Technique or ADT (below) in their decision to upgrade Tropical Depression Barbara to a Tropical Storm.

CIMSS Advanced Dvorak Technique

Satellite-based Flash Flood Warning

May 29th, 2007 |

GOES-11 10.7µm IR image

GOES-11 10.7µm InfraRed (IR) images (above; Java animation) showed an area of strong thunderstorms (exhibiting cold brightness temperatures of -70 to -80º C, black to white enhancement) expanding eastward toward the islands of American Samoa in the South Pacific Ocean on 28-29 May 2007. The motion of these storms on satellite imagery prompted the issuance of a Flash Flood Warning for the islands of Tutuila, Aunuu, and Manua at 02:54 UTC on 29 May (3:54 PM on 28 May, local time). It is important to note that there is no radar in that particular region, making satellite imagery the only forecasting tool for such hazards — however, GOES-11 Southern Hemisphere sector imagery (below) is only available over that region 2-3 times per hour.

GOES-11 Southern Hemisphere sector

The moon on GOES-12 images

May 24th, 2007 |

GOES-12 visible image

The moon was observed adjacent to the Earth’s limb on the GOES-12 imagery at 11:15 UTC on 24 May 2007. Some of the large-scale features of the moon’s surface could be seen in the GOES-12 visible channel image (above), while the other 4 InfraRed (IR) channels (below) revealed a “banded” pattern of brightness temperatures resulting from the large thermal gradient between the very hot sunlit portion of the moon (where temperatures can reach +110º C / +230º F) and the very cold “dark” side of the moon (where temperatures can fall to -180º C / -292º F).

GOES-12 imager channels 1-6