[ Updated Feb 2017 – new info below indicates a water vapor cloud. ]
An anomaly visible on satellite thermal images from March 8, 2014 may indicate a large hydrocarbon plume that could help narrow the search area for missing flight MH370 in the Southern Indian Ocean.
Visible on two passes of the NASA Aqua/MODIS and Terra/Modis satellites, the isolated dark cloud is moving northeast with normal clouds in the area, but has some peculiarities that set it apart.
The thermal images come from sensor band 31 of the satellites, which corresponds to 11 microns (10.780 – 11.280 um). This is near the spectral minimum of atmospheric water vapor absorption, but liquid water absorption remains high. The 11 micron range is associated with the greenhouse effect, where thermal radiation from the earth’s surface can be blocked by carbon dioxide, but also more strongly by hydrocarbon gases like methane. Fuel vapor detectors typically operate in the nearer thermal infrared band around 3.3 micron, and dramatic demonstrations of FLIR thermal imaging cameras tuned for that band show the high sensitivity. MODIS does record a 3.6 micron band at lower resolution, which could be useful for further analysis.
It appears quite possible that a plume of hydrocarbon vapors or combustion residue could be detected by its blockage of 11 micron radiation from the earth.
The images can be explored with this preselected hyperlink to the NASA Worldview satellite image server: https://goo.gl/5wO2Zb
The first appearance of the dense cloud is at 04:46:30 UTC Mar 8 2014 on Aqua/MODIS, using the “Brightness Temperature (Band 31-Day)” selection. Its location at that time is S39.47 E90.45 (about 4:26:30 after expected impact). It is about 30×10 km in size.
The second appearance is on Terra/MODIS day pass at 07:23:00 and location S37.8 E92.93 with a diminished size of about 10×10 km.
The cloud has moved 284 km NE from bearing 228.5 at an estimated wind speed of 109 km/hr = 59 knots.
This implies that a plume would have reached to a high altitude jetstream. This is not far fetched. Volcanic ash plumes are known to reach beyond 60,000 ft within 10 minutes of eruption. [A revised estimate using the Nullschool weather model puts the cloud altitude near 10,000 ft based on the wind speed.]
What sets this cloud apart from other dense clouds found in the area is that they are rarely isolated, and they all have a high humidity that causes a bright reflectance at shorter infrared wavelengths. Exploring the online images in visible bands available also reveals that the clouds appear nearly transparent in true color mode. Comparing visible to thermal images for the first detection, the images are precisely aligned elsewhere, but there appears to be a disturbance in the clouds just west of the thermal locus.
The direction of elongation provides another clue. Other clouds are elongated in the travel direction of the high altitude wind. Our cloud is traveling NE but is denser on its western edge and tapers to the east, even as the cloud is dissipating in the second capture. This would likely be caused by surface winds elongating a plume eastward from a source until it reached higher altitude winds and got carried along intact.
Extrapolating from these images implies that the impact site would be at least 50-100 km west of a 228.5 bearing pointing into the jetstream wind. The distance along that bearing would depend on the amount of time taken for the plume to develop and rise to high altitude.
The first detection is about 4:27 after expected 7th arc impact timing. The plume could not have traveled further than about 450 km in that time, possibly even half that distance.
The previous hydroacoustic map released may now be useful, with the prominent candidate on at S41 E88. The distance from the first plume candidate detection to the DotAuto map candidate is 310 km on bearing 239, which puts it about 100 km west of the 228.5 wind movement line. The high altitude travel time to that location would be 310 km / 109 kmph = 2.844 hr = 2:51. That would allow nearly two hours for the plume to develop along 30 km eastward and then reach altitude.
Unfortunately, the upper wind direction is running nearly parallel to the 7th arc, so there is no intersection. The search path would be about 250 km from the arc in the expected source area. The width of the search path would be dependent on the low altitude wind speed and the rate of rise of the proposed plume. It is a relatively small and narrow area compared to the expanse already searched.
A .kml map overlay is available for download showing the key markers. The NASA server can also snapshot a downloadable .kmz image overlay of the area.
Feb 2017 Update – Thermal Plume showing before 0000 UTC
The MODIS satellites in low orbit pass over any particular spot on the earth infrequently, obtaining good resolution images. A geostationary satellite instead is parked over the equator at a particular longitude and can scan more frequently. The Meteosat-7 satellite at E57 over the Indian Ocean produces a complete scan of the entire hemisphere every 30 minutes, using additional thermal and infrared bands.
15 hours of Meteosat-7 imaging of the SIO area in IR, WaterVapor, and Visible bands
The image sequence shows snapshots from Mar 7 2200 UTC through Mar 8 1300 UTC. The fifth frame would be at 0000 UTC on Mar 8. Stepping frame by frame, it can be seen at the center of the image that the plume likely formed from an existing water vapor formation. The surrounding vapor clouds are receding while this one is forming, but it is very close to the most dense portion of the receding cloud before it reforms.
There are two other brief plumes that appear along the 7th arc, but they both are visibly forming just before 0000 UTC. Another linear formation of clouds with increasing size that was interesting on the MODIS images also existed before 0000 UTC.
This appears to rule out the thermal formation as a hydrocarbon plume from an impact, and more likely a dense cloud of water vapor.