Strong convection in the Gulf of Mexico

March 28th, 2011 |
GOES-13 10.7 µm IR images (click image to play animation)

GOES-13 10.7 µm IR images (click image to play animation)

AWIPS images of GOES-13 10.7 µm IR data (above; click image to play animation) showed the development of two strong Mesoscale Convective Systems over the Gulf of Mexico on 28 March 2011. These storms prompted  the Storm Prediction Center to issue Severe Thunderstorm Watch #70 and #71 for the threat of  strong winds and large hail — however, no reports of severe weather were received from these particular storms.

The MODIS Sea Surface Temperature (SST) product from the previous day (below) revealed that the northern edge of the Gulf of Mexico Loop Current (warmer SST values in the upper 70s to around 80º F, red color enhancement) was located near the areas of development of these two Mesoscale Convective Systems — raising the question as to the role that this warmer water may have played in their initiation. In addition, an overlay of the High Resolution Real-Time Global Sea Surface Temperature (RTG_SST_HR) model SST failed to capture the warmer tongue of SSTs located to the east of the main core of the Loop Current.  MODIS SST values were 2-3 degrees F warmer than the model SST values in the eastern warm tongue feature — and 3-4 degrees F cooler within the main core of the Loop Current.

MODIS SST product + RGT_SST_HR model SST analysis

MODIS SST product + RGT_SST_HR model SST analysis

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MODIS SST product + MODIS 11.0 µm IR images

MODIS SST product + MODIS 11.0 µm IR images

A comparison of the MODIS SST product with MODIS 11.0 µm IR images of the first MCS (above) along with a similar comparison of the MODIS SST with a combination of MODIS 11.0 µm IR and POES AVHRR 10.8 µm IR images (below) showed the development of each MCS in the general proximity of the areas of warmer SST values associated with the Loop Current.

MODIS SST + MODIS 11.0 µm IR + POES AVHRR 10.8 µm IR images

MODIS SST + MODIS 11.0 µm IR + POES AVHRR 10.8 µm IR images

A comparison of a 4-km resolution GOES-13 10.7 µm image with the corresponding 1-km resolution POES AVHRR image (below) demonstrated the value of higher spatial resolution for locating the colder cloud top IR brightness temperatures associated with overshooting tops of intense deep convection. The coldest IR temperature on the GOES-13 image was -71º C, compared to -80º C on the POES AVHRR image.

GOES 10.7 µm IR image + POES AVHRR 10.8 µm IR image

GOES 10.7 µm IR image + POES AVHRR 10.8 µm IR image

CIMSS participation in GOES-R Proving Ground activities includes making a variety of  MODIS and POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations.

Fires burning across eastern Oklahoma

March 23rd, 2011 |
GOES-13 3.9 µm shortwave IR images (click image to play animation)

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

AWIPS images of 4-km resolution GOES-13 3.9 µm shortwave IR data (above; click image to play animation) displayed a number of “hot spots” (black to red to yellow  color enhancement) associated with fires that were burning across much of eastern Oklahoma on 23 March 2011. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode to monitor severe convection in the eastern US, providing images as frequently as every 5-10 minutes.

The corresponding 1-km resolution GOES-13 6.3 µm visible channel images (below; click image to play animation) showed the development of a few long southeastward-drifting smoke plumes emanating from some of the larger fires.

 

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

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

A comparison of the 4-km resolution GOES-13 3.9 µm shortwave IR image with the corresponding 1-km resolution POES AVHRR 3.7 µm shortwave IR image (below) demonstrates the advantage of higher spatial resolution for determining the exact location of the hottest fire pixels, as well as for the detection of many of the smaller fires.

GOES-13 3.9 µm shortwave IR image + POES AVHRR 3.7 µm shortwave IR image

GOES-13 3.9 µm shortwave IR image + POES AVHRR 3.7 µm shortwave IR image

These samples of images at both higher temporal resolution and at higher spatial resolution offer a glimpse of the types of improvements that will be available with the ABI instrument on the future GOES-R satellite. CIMSS participation in GOES-R Proving Ground activities includes making a variety of POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations.

“Plume of unknown etiology” moving over Alaska

March 17th, 2011 |
GOES-11 0.65 µm visible channel images (click image to play animation)

GOES-11 0.65 µm visible channel images (click image to play animation)

McIDAS images of GOES-11 0.65 µm visible channel data (above; click image to play animation) showed an interesting “dark plume” feature that was moving in an arc from far northeastern Russia, across the East Siberian Sea and Chukchi Sea, and finally over far northwestern Alaska on 16 March – 17 March 2011.

When viewed from a more western angle using MTSAT-2 0.73 µm visible channel images (below; click image to play animation), the plume feature (which can be seen moving over far northwestern Alaska in the upper right portion of the images) also exhibited a darker appearance, similar to that seen on the GOES-11 visible imagery. This darker appearance was due to backward scattering of light from the particles within the plume.

 

MTSAT-2 0.73 µm visible channel images (click image to play animation)

MTSAT-2 0.73 µm visible channel images (click image to play animation)

AWIPS images of POES AVHRR 0.86 µm visible channel data (below) provided more of a “direct view from above”,  and revealed that the main body of the plume was basically transparent (allowing details of the sea ice to be seen through the plume).  However, the plume edges appeared to have some vertical structure, being thick enough to cast shadows onto the sea ice below.

POES AVHRR 0.86 µm visible channel images

POES AVHRR 0.86 µm visible channel images

It is interesting to note that this plume feature did not exhibit any notable signature on POES AVHRR 12.0 µm IR images (below).

POES AVHRR 12.0 µm IR images

POES AVHRR 12.0 µm IR images

A series of MODIS true color Red/Green/Blue (RGB) images (below; courtesy of the GINA, University of Alaska) again showed the transparent nature of the main body of the plume feature, except for the thicker edges which  were casting shadows.

MODIS true color Red/Green/Blue (RGB) images (courtesy of University of Alaska, GINA)

MODIS true color Red/Green/Blue (RGB) images (courtesy of University of Alaska, GINA)

Could this feature have been an aged volcanic plume that was being transported aloft over the Arctic? AWIPS images of the MODIS Volcanic Ash Mass Loading product (below) did display a few isolated very small patches exhibiting 1-10 tons per square kilometer of loading at 04:44 UTC on 17 March, but there was no temporal continuity when examining the Ash Mass Loading product before or after this particular time.

MODIS Volcanic Ash Mass Loading product

MODIS Volcanic Ash Mass Loading product

Volcanic Ash Height product

Volcanic Ash Height product

The corresponding MODIS Volcanic Ash Height product (above) indicated that these features were located at an altitude of 3-4 km, while the MODIS Ash Mass Effective Particle Radius product (below) showed values in the 3-5 µm range.

Volcanic Ash Particle Effective Radius product

Volcanic Ash Particle Effective Radius product

However, rather than an aged volcanic ash plume, a more plausible explanation of the feature seen on satellite imagery is the long-range transport of smoke and pollution from industrial sources in northeastern China. A calculation of 96-hour backward trajectories using the NOAA ARL HYSPLIT model (below) indicated that air parcels arriving at 3 points along the plume at an altitude of 6-km had originated within the boundary layer over northeastern China on 13 March. MODIS images showing the thick haze over that region can be found on the US Air Quality “Smog Blog”.

NOAA ARL HYSPLIT back trajectories arriving at  the 4km, 6km, and 8km altitudes

NOAA ARL HYSPLIT back trajectories arriving at the 4km, 6km, and 8km altitudes

Widespread fire activity in Oklahoma

March 11th, 2011 |
POES AVHRR 0.63 µm visible image + POES AVHRR 3.7 µm shortwave IR image

POES AVHRR 0.63 µm visible image + POES AVHRR 3.7 µm shortwave IR image

AWIPS images of 1-km resolution POES AVHRR 0.63 µm visible and POES AVHRR 3.7 µm shortwave IR data (above) showed a large number of IR “hot spots” (black to red to yellow color enhancement) due to widespread fire activity across southeastern Oklahoma on 10 March 2011. One well-defined smoke plume could be sen streaming southeastward ffrom one of the larger fires.

On the following day (11 March 2011), the POES AVHRR 3.7 µm shortwave IR image again displayed a large number of fire hot spots over that same region.

POES AVHRR 3.7 µm shortwave IR image

POES AVHRR 3.7 µm shortwave IR image

CIMSS participation in GOES-R Proving Ground activities includes making a variety of POES AVHRR images and products available for National Weather Service offices to add to their local AWIPS workstations.