GOES-11 SRSO visible images

GOES-11 continued in Super Rapid Scan Operations (SRSO) mode on 11 September 2008, with visible imagery (above) showing additional convective bursts around the eye of the storm.

GOES-12 water vapor channel imagery (below) revealed an interesting series of middle- to upper-tropospheric “gravity waves” propagating radially outward away from Ike, moving inland over the Gulf Coast states.

GOES-12 water vapor images

A comparison of AWIPS MODIS images on 12 September 2008 (below) displayed Category 2 Hurricane Ike as the large storm approached the Texas coast. MODIS IR cloud top brightness temperatures at 16:58 UTC were as cold as -84º C (purple enhancement).

AWIPS images of the MODIS visible, IR, cirrus, and water vapor channels

An oblique view of a MODIS true color image using Google Earth (below; courtesy of Liam Gumley, CIMSS) shows that the clouds associated with Hurricane Ike covered a good deal of the Gulf of Mexico on 12 September.

MODIS true color image (viewed using Google Earth)

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GOES-11 SRSO visible images

The GOES-11 (GOES-West) satellite was placed into Super Rapid Scan Operations (SRSO) mode on 10 September 2008, allowing imagery at 1-minute intervals to monitor Hurricane Ike in the Gulf of Mexico. Using the visible channel imagery (above; QuickTime animation), the large satellite viewing angle from GOES-West positioned over the Pacific Ocean (the satellite zenith angle is approximately 66 degrees for features over the Gulf of Mexico) allowed for an interesting “oblique view” of convective bursts developing around the core of Hurricane Ike.

GOES-11 10.7 µm IR imagery (below; QuickTime animation) revealed a band of very cold cloud top temperatures — colder than -80º C (purple colors) — in the northeastern quadrant of Hurricane Ike early in the day. The minimum cloud top brightness temperature value of -83º C was seen at 12:49 and 13:19 UTC. During the course of the day, Hurricane Ike re-intensified into a Category 2 storm as it moved over a high Ocean Heat Content area in the eastern Gulf of Mexico.

GOES-11 SRSO IR images

A plot of NOAA aircraft reconnaissance data from the CIMSS Tropical Cyclones site (below) showed that Ike was a rather large hurricane, with tropical storm force winds extending  a significant distance away from the eye. TRMM/TMI (Tropical Rainfall Measuring Mission Microwave Imager) data indicated that Ike possessed a double eyewall structure, with a small inner eye within a very large outer eyewall.

GOES-12 IR image + NOAA aircraft reconnaissance data

A sequence of AWIPS images of the 1-km resolution MODIS 11.0 µm IR channel data (below) showed that Hurricane Ike remained very well organized even after its encounter with the island of Cuba.

AWIPS images of the MODIS 11.0 µm IR channel

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CIMSS Envrionmental Steering product

Jason Dunion (formerly at CIMSS, now at the NOAA/AOML Hurricane Research Division) penned an excellent summary of the utility of the CIMSS Environmental Steering (or Deep Layer Mean Wind) product that is available on the CIMSS Tropical Cyclones site. Satellite-derived Atmospheric Motion Vectors produced at CIMSS are in important inputs to these environmental steering flow products. With Hurricane Gustav, Tropical Storm Hanna, Hurricane Ike, and Tropical Storm Josephine all in the Atlantic basin, Jason noted the following interactions between the steering flow patterns and the motion of those 4 tropical cyclones during the first few days of September 2008:

03 September:
– Gustav has made landfall and helps build ridge #1 to its east
– big ridge #2 is located north-northeast of Ike

04 September:
– gigantic low over Canadian Maritimes lifts out;
– ridge #1 slides to the east, ridge #2 slides to the west

Late 04 September to early 05 September:
– ridge #1 & ridge #2 link to form a sprawling ridge to the north of Ike
– Ike is stuck in northwesterly steering flow until that “ridge linking”, and then starts a turn to the west

05 September:
– ridge #1 and ridge #2 consolidates and parks to the north-northwest of Ike; Ike then quickly comes into a southwesterly steering flow
– Hanna is forced “up the alley” between ridge #1/#2 and a trough approaching from the west
– Josephine is pushed to the northwest by the deep flow (shallow Deep Layer Mean is more of a west-southwesterly flow); Josephine then deteriorates as southwesterly  wind shear increases

The corresponding 3-hourly images of the AWIPS Northern Hemisphere water vapor channel composite are shown below, covering the period 01-05 September 2008.

AWIPS Northern Hemisphere water vapor composite images

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GOES-13 10.7 µm IR images

Rapid Scan Operations (RSO) images of the GOES-13 10.7 µm IR channel (above) showed some interesting evolution of Tropical Storm Hanna on 05 September 2008. Strong bursts of convection were seen to develop near the center of Hanna, with periods of cloud top temperatures colder than -80º C (purple colors).

A comparison of AWIPS images of the 1-km resolution MODIS 11.0 µm IR and the 4-km resolution GOES-12 10.7 µm IR channel data (below) indicated that the coldest cloud top temperatures were -89º C with MODIS and -78º C with GOES.

AWIPS images of the MODIS 11.0 µm IR + GOES-12 10.7 µm IR chanels

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