GOES-13 10.7 µm IR images

GOES-13 10.7 µm IR images from the CIMSS Tropical Cyclones site (above) showed increasing convective banding within the eastern semicircle of Tropical Storm Nate as the system was undergong a period of intensification on 10 September 2011.

Deep layer wind shear was light over the region (below), which was a factor that aided in the intensification of the tropical cyclone.

GOES-13 IR image + 200-850 hPa deep layer wind shear product

A TRMM 85 GHz microwave image from 16:12 UTC (below) showed the band of deep convection withn the southeastern quadrant of Nate.

TRMM 85 GHz microwave image

The GOES-13 satellite had been placed into Super Rapid Scan Operations (SRSO), providing bursts of 1-minute interval imagery. A sample of GOES-13 0.63 µm visible channel SRSO images (below; click image to play animation) showed the development of the convective bands wrapping around the center of the tropical cyclone. Early in the animation, you can also see the hazy appearance of the water to the east of Nate (off the west coast of the Yucatan Peninsula of Mexico) — this enhanced turbidity was the result of persistent strong southerly winds across those waters as Nate developed and moved very slowly across the region.

GOES-13 0.65 µm visible channel SRSO images (click image to play animation)

View only this post Read Less

Comparison of 8-day average MODIS SST (left) and 07 September MODIS SST (right)

A comparison of the MODIS 8-day average Sea Surface Temperature (SST) ending on 06 September 2011 (above, left) with the MODIS SST product on 07 September 2011 (above, right) revealed a dramatic cooling of the near-shore waters just off the east coastline of Lake Michigan. Persistent strong northerly daytime winds (gusting in the 20-30 mph range) induced an upwelling of colder water from below the surface, with 07 September values as cold as 6.8ºC (44ºF) at one location (Latitude/Longitude 43.63 North/81.96 West) — compared to the previous 8-day average SST of 22.8ºC (73ºF) at that same location. Unfortunately, the MODIS Cloud Mask that is applied to the SST product mistakenly identifies the strongest SST gradient as a cloud, and blanks out the SST product along the far western fringe of the ribbon of colder water.

AWIPS images of MODIS 0.65 µm visible channel and 11.0 µm IR channel data (below) showed greater detail in the ribbon of colder waters, with a series of eddies forming along the northern edge of the feature. Since no Cloud Mask is applied to the IR image, the full westward extent of the cold water feature can be seen.

MODIS 0.65 µm visible channel and 11.0 µm IR channel images

A sequence of four MODIS 11.0 µm IR images (below) shows the evolution of the eddy features along the western edge of the cold water. Note that the land surfaces exhibit cool IR brightness temperatures (blue to cyan color enhancement) on the first 2 night-time images (03:10 UTC and 07:21 UTC, or 10:10 pm and 2:21 am local time), but on the 2 daytime images (16:45 UTC and 18:27 UTC, or 11:45 am and 1:27 pm local time) urban areas and regions with less dense vegetation heat up and exhibit much warmer IR brightness temperatures (orange to red color enhancement). However, the Lake Michigan IR brightness temperatures generally remain constant during this time period.

MODIS 11.0 µm IR images

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations. Currently there are 49 NWS offices receiving MODIS imagery and products from CIMSS. In addition, the VISIT training lesson “MODIS Products in AWIPS” is available to help users understand these products and their applications to weather analysis and forecasting.

View only this post Read Less

GOES-13 3.9 µm shortwave IR channel + 0.63 µm visible channel images

McIDAS images of GOES-13 3.9 µm shortwave IR and 0.63 µm visible channel data (above; click image to play animation) showed the fire hot spot (dark black pixels) and large smoke plume associated with the Bastrop County fire complex in eastern Texas on 04 September 2011. This fire went on to set a record for the highest number of homes damaged (over 500) by a single fire in Texas history.

A comparison of AWIPS images of 1-km resolution POES AVHRR 0.63 µm visible channel and 3.74 µm shortwave IR channel data (below) showed finer detail in the location of the individual fire hot spots (black to red to yellow color enhancement).

POES AVHRR 0.63 µm visible channel + 3.74 µm shortwave IR channel images

On the following day (05 September), the number of fires quickly grew to over 60 — a number of very large smoke plumes could be seen growing on GOES-13 0.63 µm visible channel images (below; click image to play animation). The thick smoke was causing air quality problems at a number of locations. Strong northerly winds around the circulation of the remnants of Tropical Storm Lee helped to create an environment that allowed many of the fires to quickly burn out of control.

GOES-13 0.63 µm visible channel images (click image to play animation)

The location of many of the larger fire hot spots (black to yellow to red color enhancement) could be seen on a comparison of GOES-15 and GOES-13 3.9 µm shortwave IR images (below; click image to play animation).

GOES-15 and GOES-13 3.9 µm shortwave IR images (click image to play animation)

View only this post Read Less

GOES-15 10.7 µm IR images (click image to play animation)

McIDAS images of 4-km resolution GOES-15 10.7 µm IR data (above; click image to play animation) showed the transition of Tropical Depression #13 into Tropical Storm Lee in the northern Gulf of Mexico on 02 September 2011. Deep convection persisted within the eastern semi-circle of the system, with large areas exhibiting cloud top IR brightness temperatures of -80º C and colder (violet color enhancement) prior to Lee reaching tropical storm intensity.

A comparison of AWIPS images of 1-km resolution POES AVHRR 0.63 µm visible channel and 10.8 µm IR channel data (below) revealed a few vigorous overshooting tops embedded within the convective region, with one feature located southeast of the circulation center having an IR brightness temperature value of -93º C (darker violet color enhancement).

POES AVHRR 0.63 µm visible channel and 10.8 µm IR channel images

About 2 hours later, a similar comparison of 1-km resolution MODIS 0.65 µm visible channel and 11.0 µm IR channel images (below) showed overshooting tops with IR brightness temperatures as cold as -89º C.

MODIS 0.65 µm visible channel and 11.0 µm IR channel images

===== 03 SEPTEMBER UPDATE =====

GOES-13 0.63 µm visible channel images (click image to play animation)

GOES-13 0.63 µm visible channel images (above; click image to play animation; also available as a QuickTime movie) revealed a curious “dual-vortex” structure to Tropical Storm Lee early in the day on 03 September 2011, with convective bursts developing in the vicinity of each of the two vortices. Later in the day, it appears that these dual vortices merged into a single vortex, as the center of Lee approachd the coast of Louisiana.

A comparison of 1-km resolution MODIS 6.7 µm and 4-km resolution GOES-13 6.5 µm water vapor images (below) showed that a significant tongue of dry continental air was being drawn into the western portion of the circulation of Lee.

MODIS 6.7 µm and GOES-13 6.5 µm water vapor channel images

View only this post Read Less