MODIS 3.7 µm shortwave IR, 11.0 µm IR, and Land Surface Temperature product

As noted on the AccuWeather WeatherMatrix blog, some locations in far eastern Colorado and far western Kansas experienced a “heat burst” as dry convection passed across the region overnight. AWIPS images of the 04:35 UTC (10:35 pm local time) MODIS 3.7 µm shortwave IR, MODIS 11.0 µm IR, and MODIS Land Surface Temperature (LST) product (above) revealed the isolated pocket of warm temperatures (darker orange color enhancement: as high as 24º C / 75.2º F on the shortwave IR image, 21.5º C / 70.7º F on the IR image, and 25.4º C / 78.7º F on the LST product) just northwest of Burlington, Colorado (station identifier KITR), in the wake of the passing convection (which exhibited cloud top IR brightness temperatures as cold as -36º C, darker blue color enhancement). Around the time of the MODIS images, the surface air temperature at Burlington had abruptly risen to 89º F / 32º C with wind gusts to 53 knots (61 mph).

A comparison of the 1-km resolution MODIS 11.0 µm IR image with the corresponding 4-km resolution GOES-13 10.7 µm R image (below) demonstrated the dramatic improvement in feature detection with higher spatial resolution. Parallax error associated with the high viewing angle of the geostationary GOES-13 satellite was also obvious in the image comparison.

MODIS 11.0 µm IR and GOES-13 10.7 µm IR images

An animation of the GOES-13 10.7 µm IR images (below) showed the warm heat burst signature (the pocket of darker orange colors) migrating eastward into western Kansas, where the surface air temperature at Goodland (station identifier KGLD) later rose to 92º F / 33º C at 06:00 UTC (Midnight local time). Note that there no cloud-to-ground lightning strikes associated with the convection that produced the heat burst.

GOES-13 10.7 µm IR images

The heat burst signature was even evident on the 10-km resolution GOES-13 sounder Skin Temperature derived product image (below), with a maximum skin temperature value of 21.5º C / 70.7º F just to the northwest of Burlington, Colorado at 05:00 UTC (11:00 pm local time).

GOES-13 sounder Skin Temperature derived product image

Another example of a heat burst signature on satellite imagery can be seen in this case at Amarillo, Texas in June 2002.

View only this post Read Less

MODIS 0.65 µm visible, 3.7 µm shortwave IR, and 11.0 µm IR images

Winds gusting in excess of 50 mph across parts of eastern Idaho on 05 September 2010 created a plume of blowing dust which could be seen on AWIPS images of the MODIS 0.65 µm visible channel, the MODIS 3.7 µm shortwave IR channel, and the MODIS 11.0 µm IR channel data (above). The blowing dust plume appeared as a slightly brighter, hazy-looking feature on the MODIS visible image, but showed up as a darker feature on the MODIS shortwave IR image due to solar reflection off the small dust particles. There were also no extremely hot pixels (yellow to orange color enhancement) seen at the point source of the plume, ruling out the likelihood that this was smoke from a fire. On the IR image, the dust plume was about 10-15º C colder (lighter gray enhancement) than the surrounding warm land surfaces.

The blowing dust plume was even more apparent on 250-meter resolution Terra and Aqua MODIS true color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above), displayed using Google Earth. The tan color of the dust plume made it easy to distinguish from the brighter white meteorological clouds in the area. This blowing dust restricted visibility to less than 1/3 of a mile along Interstate 15 near Hamer, Idaho (Local Storm Report).

Terra and Aqua MODIS true color RGB images (displayed using Google Earth)

View only this post Read Less

GOES-13 6.5 µm water vapor images (with surface fronts analyses)

AWIPS images of the GOES-13 6.5 µm water vapor channel data (above) showed Hurricane / Tropical Storm Earl as it moved inland across the Canadian Maritime provinces on 04 September – 05 September 2010. However, at the same time a large mid-latitude cyclone was intensifying over far western Quebec — and the water vapor imagery began to display what appeared to be a warm conveyor belt signature (below) that stretched northwestward across Quebec and over Hudson Bay. It was somewhat surprising to see such a warm conveyor belt signature develop so close to the proximity of the back edge of the cloud shield of Earl.

GOES-13 water vapor image (with surface front analysis)

The GFS40 model winds within the 315-325 K isentropic layer (below) indicated that there was a strong 60-knot jet moving across the region where the warm conveyor belt signature formed on the water vapor imagery.

GOES-13 water vapor image + GFS 315-325 K layer winds

A pair of 1-km resolution MODIS 6.7 µm water vapor images (below) showed greater detail of the structure of the warm conveyor belt signature as it was forming.

MODIS 6.7 µm water vapor images

A sequence of four 1-km resolution POES AVHRR 10.8 µm IR images (below) showed the banding structure that was forming within the conveyor belt feature.

AVHRR 10.8 µm IR images

View only this post Read Less

MODIS Sea Surface Temperature product + RTG_SST Hi-Res model analysis

The image comparison above shows “before” and “after” views of the axis of the Gulf Stream off the southeast coast of the US. The “before” view is the Sea Surface Temperatue (SST) analysis from the RTG_SST High Resolution model at 00:00 UTC on 02 September 2010 (before Hurricane Earl arrived) — the axis of the Gulf Stream can be taken to be the wide  ribbon of SST values of 84º F and warmer.

The “after” view is an AWIPS image of the 1-km resolution MODIS Sea Surface Temperature product at 16:03 UTC on 03 September 2010 (after Hurricane Earl had passed). One can see the effect that Hurricane Earl had on the axis of the Gulf Stream, with warm and cold eddies of water — the red colors on the MODIS image are SST values in the middle 80s F, while the blue colors are SST values in the upper 70s F.

Terra and Aqua MODIS true color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) showed Hurricane Earl moving along the East Coast of the US on 03 September. Note the increased amount of sediment flowing off the coast of North Carolina and South Carolina, due to heavy rainfall and strong offshore winds.

Terra and Aqua MODIS true color RGB images (displayed using Google Earth)

View only this post Read Less