CIMSS Environmental Steering product

September 5th, 2008 |
CIMSS Envrionmental Steering product

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

AWIPS Northern Hemisphere water vapor composite images

Tropical Storm Hanna

September 5th, 2008 |
GOES-13 10.7 µm IR images

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.

MODIS 11.0 µm IR + GOES-12 10.7 µm IR images

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