GOES-13 10.7 µm IR images

AWIPS images of 4-km resolution GOES-13 10.7 µm IR channel data (above) showed a large convective complex that developed over extreme eastern Colorado and then tracked eastward across Kansas and Nebraska during the pre-daylight hours on 15 September 2010. According to the SPC Storm Reports, this severe convection produced a few tornadoes, hail up to 1.75 inch in diameter, and surface winds gusts as high as 78 mph across Kansas.

A comparison of the 1-km resolution POES AVHRR 10.8 µm IR image with the corresponding 4-km resolution GOES-13 10.7 µm IR image (below) demonstrates the improved ability to detect such mesoscale storm top features as overshooting tops and packets of concentric gravity waves. At that particular time, the coldest AVHRR IR brightness temperature was -80º C, compared to -71º C on the GOES-13 IR image. The parallax error associated with geostationary satellite imagery was also apparent, with the slight northwestward shift of the location of the features on the GOES-13 image.

POES AVHRR 10.8 µm and GOES-13 10.7 µm IR images

The AHPS 24-hour total precipitation analysis (below) indicated a large swath of substantial rainfall was produced by this convective system, which included amounts in excess of 4 inches in northern Kansas.

24-hour precipitation (ending at 12 UTC on 15 September 2010)

At 19:48 UTC, AWIPS images of 1-km resolution MODIS 0.65 µm visible channel and 3.7 µm shortwave IR data (below) revealed the very large swath of wet ground (as indicated by the lighter shades of gray on the shortwave IR image); however, little evidence of this wet ground could be seen on the visible image.

MODIS 0.65 µm visible channel and 3.7 µm shortwave IR images

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MODIS 3. µm shortwave IR image + METAR surface reports

Looking at plots of the surface METAR data (above) and the daily maximum temperatures (below), the large area of wet ground appeared to be holding surface air temperatures down a few degrees compared to adjacent sites across the region.

MODIS 3.7 µm shortwave IR image + daily maximum temperatures for 15 September

On a side note, it is interesting to point out that smoke from wildfires burning in the western US was concentrated along and just ahead of the cold frontal boundary that was moving across Nebraska – this was seen very clearly on a MODIS Red/Green/Blue (RGB) true color image from the SSEC MODIS Today site (below).

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

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Atlantic Basin GOES-13 IR images

GOES-13 10.7 µm IR images (above) showed 3 tropical cyclones in the Atlantic Basin on 14 September 2010: from left to right, Tropical Storm Karl, Hurricane Igor, and Hurricane Julia. Real-time visible and IR images covering the Tropical Atlantic are available from NOAA/NESDIS/OSDPD/SSD.

A comparison of geostationary-orbiting satellite IR images and polar-orbiting microwave images (from the CIMSS Tropical Cyclones site) for each of the 3 tropical cyclones are shown below. Note that there is a 1-2 hour difference between the IR images and the microwave images — however, these comparisons show the utility of the microwave images for showing tropical cyclone structures that are often masked by the cold convective cloud shield.

Tropical Storm Karl: geostationary IR image + polar microwave image

Hurricane Igor: geostationary IR image + polar microwave image

Hurricane Julia: geostationary IR image + polar microwave image

An AWIPS image of EUMETSAT METOP Advanced Scatterometer (ASCAT) winds (below) indicated surface winds as high as 63 knots near the center of Hurricane Igor at 13:28 UTC; however, ASCAT winds are known to have a low speed bias (which increases as winds get to higher speeds).

EUMETSAT METOP ASCAT winds

As part of the GOES-15 Post Launch Science Test, the satellite was placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5 minutes during the day. The evolution of the eye of Hurricane Igor is seen on GOES-15 0.63 µm visible channel images (below; also available as a QuickTime movie) — note the occasional presence of small mesovortices within the eye region.

GOES-15 0.63 µm visible channel images

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GOES-15 0.63 µm visible images (Super Rapid Scan Operations)

As part of the GOES-15 Post Launch Science Test, the satellite was placed into Super Rapid Scan Operations (SRSO) mode on 13 September 2010, providing images as frequently as every 1 minute during the day. GOES-15 0.63 µm visible channel images (above; also available as a QuickTime movie) showed the well-defined eye of Hurricane Igor, with SRSO images during a 4 hour period (from 16:39 – 20:39 UTC). The visible images were brightened a bit after 19:26 UTC to help detect the presence of any mesoscale vortices within the eye.

A comparison of 1-minute interval GOES-15 SRSO images with the normal operational 15-minute interval GOES-13 visible images (below) clearly demonstrates the advantage of higher temporal resolution for monitoring the evolution of the eye structure of the hurricane (courtesy of Tim Schmit, NOAA/ASPB).

GOES-15 1-minute visible images (left) and GOES-13 15-minute visible images (right)

While Hurricane Igor maintained a Category 4 intensity for more than 24 hours, an SSMI/S 85 GHz microwave brightness temperature image from the CIMSS Tropical Cyclones site (below) suggested that the storm might be entering an eyewall replacement cycle (ERC) late in the day on 13 September, which would signal a likely decrease of the storm’s intensity during the ERC process.

SSMI/S 85 GHz microwave brightness temperature image

A large eye was also evident on GOES-13 10.7 µm IR imagery (below).

GOES-13 10.7 µm IR images

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SSMI/S 85 GHz microwave brightness temperature image

An SSMI/S 85 GHz microwave brightness temperature image from the CIMSS Tropical Cyclones site (above) displayed a well-defined eyewall structure associated with Hurricane Igor ar 11:32 UTC on 12 September 2010.

GOES-13 1-km resolution 0.63 µm visible channel images (below) showed an improving appearance to the eye of Igor during the morning hours.

GOES-13 0.63 µm visible channel images

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GOES-13 10.7 µm IR images

Igor rapidly intensified into a Category 4 hurricane later in the day. GOES-13 4-km resolution 10.7 µm IR images (above) displayed a well-defined eye, while a plot of the CIMSS Advanced Dvorak Technique (below) showed the trend of rapid intensification.

Plot of the CIMSS Advanced Dvorak Technique (ADT)

1-km resolution GOES-13 0.63 µm visible channel images (below) showed a fairly nice eye structure during the daytime hours.

GOES-13 0.63 µm visible channel images

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