GOES-14, which was launched on 27 June and is now undergoing post-launch check-out, is over the Equator at 90 degrees W longitude, whereas GOES-12, the operational GOES-East, is over the Equator at 75 W Longitude. The two satellites give slightly different views of Hurricane Bill, and stereoscopy can be used to view the visible imagery, allowing three dimensions to be perceived. This is done by crossing your eyes to produce three images; when the middle image comes into focus, three dimensions can be perceived.

In this case, stereoscopy shows vertical structure to the clouds, and also the presence of cirrus over the Hurricane eye.

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Super Rapid Scan Operations are called on GOES-East or GOES-West when meteorologists want to investigate phenomena that occur over very short timescales. Typically, SRSO imagery is taken every minute. However, gaps exist because of responsibilities to other regions. For example, when the National Hurricane Center requested SRSO observations of Hurricane Bill, satellite imagery was still required to observe tornadic thunderstorms over the upper midwest, and to fulfill international treaty obligations to provide full disk imagery every three hours. GOES-R, scheduled for launch in 2015, will have enhanced observational capabilities, enabling SRSO and full-disk scanning simultaneously. Indeed, ABI on GOES-R will scan a full disk image every 15 minutes, a CONUS image every 5 minutes, and a 1000×1000 km area every 30 seconds, simultaneously.

In the case of Hurricane Bill, the SRSO helped define the small cloud vortices within the hurricane eye, as seen in the image above. These vortices have been observed in previous hurricanes as well — mostly notably in Hurricane Isable in 2003. The SRSO visible loop is here (Warning: 25 M animated gif) and the SRSO color enhanced infrared loop is here. IR Brightness temperatures within the eye are in the 290-300 K range, somewhat cooler than the sea surface temperature in this region. The small vortices within the eye are low clouds.

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GOES-12 IR images

Bill became the first Atlantic hurricane of the 2009   season  on 17 August 2009. GOES-12 IR images from the CIMSS Tropical Cyclones site (above) displayed a canopy of very cold cloud tops around the center of the hurricane. The CIMSS satellite-derived wind shear product indicated that the storm environment was characterized by low shear, allowing intensification to progress.

A comparison of a 10:15 UTC GOES-12 IR image with a DMSP SSM/IS 85 GHz microwave image from a couple of hours earlier (below) showed a well-organized banding structure beneath the central dense overcast of cold cloud tops.

GOES-12 IR image + SSM/IS microwave image

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GOES-12 IR images

GOES-12 IR images from the CIMSS Tropical Cyclones site (above) showed that Tropical Storm Claudette intensified fairly quickly during the morning hours on 16 August 2009, with the areal coverage of cold cloud tops increasing rapidly during the 09-15 UTC time period. A DMSP SSM/IS 85 GHz microwave image at 13:02 UTC (below) revealed the formation of convectiove banding within the eastern semicircle of the storm.

DMSP SSM/I microwave image

While there was a report of 40 knot winds from a Carnival Cruise Line vessel to the northeast of the center of Claudette (below), this wind report was probably not representative of the winds at the surface (due to the large size of the ship and the height of the wind measuring equipment).

GOES-12 visible image with ship reports

AWIPS images of the MODIS 11.0 µm IR channel (below) revealed cloud top brightness temperatures as cold as -76º C (lighter red color enhancement) south of the center of Claudette during the late morning and early afternoon hours.

MODIS 11.0 µm IR images

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