Thermal Data was Used to Direct Firefighting Efforts

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Thermal imagery collected by EarthData helped firefighters to detect fires at Ground Zero. Aerial flights ran thermal sensors at dawn in order to avoid false positive readings by ground areas heated in the sun, according to Logan. The imagery showed where fires were and helped firefighters to get a clearer picture of where fires were spreading or receding. Digital orthophotography was taken later in the day. (source)


Firefighting teams identified the lack of absolute temperature data as a significant limitation of the thermal datasets initially available to response teams. The sequence of temperature readings on the top row of Figure 3, were acquired by EarthData between 18th-22nd October, using the FLIR thermal imagining device. They are overlaid here with the aerial orthophotography from October 7th. Notably, the thermal data are calibrated to record temperature in degrees Fahrenheit, thereby addressing the limitations of relative magnitudes acquired using the Raytheon sensor. The red areas correspond with temperatures exceeding 125F and the yellow class equates with temperatures from 75F to 125F . Values < 75F are omitted.


The "hot spots", where intensely burning debris generated temperatures in excess of 1,300 degrees Fahrenheit, posed a significant danger to relief workers. NASA had an instrument that could provide information that would be useful to emergency responders. NASA's Airborne Visible Infrared Imaging Spectrometer [AVIRIS (AVIRIS)] science instrument was capiable of providing data that could be used to filter smoke and locate extreme hot spots. (source)


EarthData_FLIR_changes.jpg

The sequence of temperature readings on the top row of were acquired by EarthData between 18th-22nd October, using the FLIR thermal imagining device. They are overlaid here with the aerial orthophotography from October 7th. Notably, the thermal data are calibrated to record temperature in degrees Fahrenheit, thereby addressing the limitations of relative magnitudes acquired using the Raytheon sensor. The red areas correspond with temperatures exceeding 125F and the yellow class equates with temperatures from 75F to 125F . Values < 75oF are omitted.

Sensor: FLIR ThermaCAM SC2000 (source)

An overlay of the above image from 09-18-01 with the [ AVIRIS_09-18-01_image_with_hot_zones_labeled.jpg corresponding AVIRIS image from 09-18-01] is available in gimp(xcf) format here: http://s3.amazonaws.com/nasathermalimages/public/images/09-18-01_FLIR_overlay_with-09-18-01_AVIRIS_and_visible_background_from_10-07-01.xcf


The potential for explosions was always present at the site. In one case, a fuel tank with tens of thousands of gallons of diesel fuel was buried seven stories below ground. With smoldering fires, a rupture could have been disastrous. Once workers located the tank, it was safely emptied, and the fuel was removed from the site. (source)


NVIS_SWIR_Graph_Sep27_vs_Oct2_from_s59ec61u.pdf_800px.jpg

[NVIS Sensor Suite NVIS] HSI 0.4-2.4 microns, 384 bands spectrum of a single hot spot from September 27th and again on October 2nd. There is a significant reduction at SWIR wavelengths compared to the near infrared bands less than 1 micron. This is indicative of significant cooling of the hot spot. This is one area where the NYC Fire Department was dumping a lot of foam for fire suppression. (source)

[AVIRIS Spot G Compare this graph to AVIRIS data acquired on 09-16-01]

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