MODIS true color and false color images

A comparison of 250-meter resolution MODIS true color and false color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) showed a large fire (perhaps a prescribed burn?) in a remote area of the Red Lake Indian Reservation, just to the west of the Upper and Lower Red Lakes in far northern Minnesota on 26 March 2010. On the false color RGB image, the fire hot spot shows up as a large bright red feature — note the rapid increase in areal coverage of the burn area between the time of the 17:04 UTC Terra satellite overpass and the 18:50 UTC Aqua satellite overpass. The still-frozen lakes appear as varying shades of cyan, while unfrozen bodies of water show up as a much darker blue color. On the true color RGB image, the hazy-looking smoke plume can be seen drifting northward (advected by surface winds from the south that were gusting as high as 29 knots).

MODIS 3.7 µm, POES AVHRR 3.7 µm, and GOES-12 3.9 µm shortwave IR images

AWIPS images of the 1-km resolution MODIS 3.7 µm, the 1-km resolution POES AVHRR 3.7 µm, and the 4-km resolution GOES-12 3.9 µm shortwave IR channel data (above) shows some important differences in both the location of the hottest pixels (GOES-12 has the fire located farther to the west, in far eastern Pennington county) as well as the intensity of the hot spots: the 18:42 UTC MODIS image registered a maximum IR brightness temperature value of 46.5º C, and the 18:48 UTC POES AVHRR image registered a value as high as 54.5º C. At that same time, the cursor readout for the 18:45 UTC GOES-12 image read “NO DATA” — thus demonstrating the value of the 1-km resolution MODIS and POES AVHRR imagery for identifying the exact location of the hottest portion of the fire.

An animation of the 4-km resolution GOES-12 3.9 µm shortwave IR images (below) did show that the fire hot spot was gradually growing in size, and briefly began to exhibit IR brightness temperature values as high as 37.5º C at 17:45 UTC and 48.0º C at 18:15 UTC — but then the fire intensity exceeded the AWIPS temperature threshold and “NO DATA” was indicated by the AWIPS cursor readout before the fire hot spot eventually became obscured by a dense cirrus cloud canopy drifting overhead from the southwest..

GOES-12 3.9 µm shortwave IR images

The shortwave IR channels on the ABI instrument aboard the GOES-R satellite will have a spatial resolution of 2 km, which should produce images that more closely resemble the 1-km resolution MODIS and POES AVHRR images shown above (further enhancing our fire detection capabilities in the future).

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NOAA-19 AVHRR 3.7 µm shortwave IR image

The Eyjafjallajökull volcano in southern Iceland (which had last erupted in the 1820s) experienced a minor eruption on 21 March 2010. An AVHRR 3.7 µm shortwave IR image from the polar-orbiting NOAA-19 satellite (above) showed evidence of a “hot spot” (black to yellow pixels) due to the resulting lava flows.

According to the London VAAC, the volcanic eruption did not produce significant volcanic ash above the 5000 foot level:

FVXX01 EGRR 211458
VA ADVISORY
DTG: 20100321/1200Z
VAAC: LONDON
VOLCANO: EYJAFJOLL
PSN: N6339 W01926
AREA: ICELAND
SUMMIT ELEV: 1000M
ADVISORY NR: 2010/006
INFO SOURCE: ICELAND MET OFFICE
AVIATION COLOUR CODE: UNKNOWN
ERUPTION DETAILS: ERUPTION CONTINUES
OBS VA DTG: 21/1200Z
OBS VA CLD: SFC/FL050 N6331 W01923-N6559 W02252-N6559 W03252-N6047 W03823-N6017 W0342 -N6331 W01923
FCST VA CLD +6HR: 21/1800Z SFC/FL050 N6331 W01919-N6705 W02525-N6704 W03621-N5801 W04323-N5633 W03545-N6143 W03035-N6331 W01919
FCST VA CLD +12HR: 22/0000Z SFC/FL050 N6331 W01903-N6750 W02833-N6750 W03955-N6131 W04520-N5435 W04459-N5501 W03207-N5954 W03105-N6331 W01903
FCST VA CLD +18HR: 22/0600Z SFC/FL050 N6342 W01929-N6838 W03232-N6808 W04515-N5426 W04601-N5202 W03737-N5644 W02954-N6143 W03247-N6342 W01929
RMK: THIS ADVISORY SUPERCEDES ADVISORY 2010/005. VOLCANIC ASH NOT ABOVE FL050, ERUPTION MAINLY LAVA
NXT ADVISORY: 20100321/1800Z=

Aqua MODIS 3.7 µm shortwave IR image

The minor volcanic eruptions continued for several days; meteorological clouds often obscured Iceland during that time, but on 24 March an overpass of NASA’s Aqua satellite allowed another view of the lava flow “hot spot” (red pixels) on a 1-km resolution MODIS 3.7 µm shortwave IR image (above). The maximum IR brightness temperatures within the red pixel area were 330 K. Additional photos and video have been posted by the Icelandic Met Office.

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GOES-12 0.65 µm visible images

McIDAS images of the GOES-12 0.65 µm visible channel data (above) revealed a large hazy aerosol plume that was moving off the Northeast US and drifting out over the adjacent waters of the Atlantic Ocean on 19 March 2010. This aerosol plume exhibited Aerosol Optical Depth (AOD) values of 0.6 and higher on the GOES Aerosol/Smoke Product (GASP) on the IDEA site. Real-time GASP images are also available from the NOAA/NESDIS/SSD/OSDPD site.

A MODIS true color Red/Green/Blue (RGB) image from the SSEC MODIS Direct Broadcast site (below) showed a better view of the varying structure and optical thickness of the aerosol plume.

MODIS true color Red/Green/Blue (RGB) image

An AWIPS image of the MODIS 0.65 µm visible channel data with an overlay of ECMWF 805-500 hPa layer winds (below) shows that the hazy aerosol plume was being advected eastward by a predominantly westerly flow within that layer.

MODIS 0.65 µm visible image + ECMWF 850-500 hPa layer winds

Model output from the Realtime Air Quality Modeling System (RAQMS) shows the mixing ratio of surface sulfate or SO4 (below) — this demonstrates the increase in SO4 levels over the northeastern US during the 17-19 March period, with a forecast that then advects the high levels of SO4 eastward out over the Atlantic.

RAQMS surface sulfate (SO4) mixing ratio

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Saint Patrick’s Day over the Midwest was unusually clear, affording great images of the Great Lakes from the MODIS instrument aboard the Terra and Aqua satellites. The loop above includes the Visible imagery, the cirrus detection channel (1.38 micrometers), the snow-ice detection channel (2.1 micrometers), the derived lake-surface temperatures and the normalized difference vegetation index (NDVI).

Close-up views of the individual lake basins: Ontario, Erie, Michigan-Huron and Superior show mostly uniform surface temperatures in the upper 30s (Fahrenheit) as is normal in early Spring. There are warm thermal plumes in Lake Erie, however, emerging from Sandusky Bay and from the Maumee River at Toledo. MODIS-derived Lake surface temperatures in those regions are in the upper 40s. (True-color imagery for that time (here) show great turbidity over Lake Erie; perhaps the warm temperatures are a result of enhanced run-off from the Maumee and Sandusky Rivers) Temperatures over Lake Michigan are slightly warmer in the middle of the lake — near 40 F — than along the perimeter where lake temperatures are still in the mid-30s. This might be a signature of recently melted near-shore ice.

High-resolution imagery such as these will be routinely available when GOES-R is launched and becomes the operational GOES satellite over the United States.

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