GOES-13 10.7 µm IR imagery

Tropical Storm Earl formed in the eastern Atlantic Ocean on 25 August 2010. GOES-13 10.7 µm IR images from the CIMSS Tropical Cyclones site (above) revealed a well-defined circulation, with the development of convective clusters and curved bands.

The environment around Earl was one that exhibited low values of 200-850 hPa deep layer wind shear (below), which was favorable for further intensification of the tropical cyclone.

GOES-13 IR image + 200-850 hPa Deep Layer Wind Shear product

View only this post Read Less

Visible and infrared GOES-11 imagery over the eastern Pacific Ocean have indicated a persistent southwestward-moving cloud edge during the past several days. The visible image, above, from 1830 UTC on 25 August, shows a distinct cloud edge arcing from northwest to southeast. What is the history of this feature? The visible imagery loop below, showing 1800 UTC images over the course of 4 days, show that the feature likely has its roots in dry air exiting the North American continent. A loop of 11-micron imagery from GOES-11 every two hours (here) shows the steady progression of the feature, and the persistent sharpness of the edge. Brightness temperatures of the clouds are steady near 287-288 K; brightness temperatures in the clear region are 290-291 K.

View only this post Read Less

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

As part of its NOAA post Launch Science Test, the GOES-15 satellite was placed into Super Rapid Scan Operations (SRSO) mode on 24 August 2010, providing images at 1-minute intervals to monitor Hurricane Danielle. McIDAS images of GOES-15 0.63 µm visible channel data (above) did show some interesting convective development associated with Danielle, but no eye was apparent.

While Danielle had intensified into a Category 2 hurricane during the preceding overnight hours, a collapse in both intensity and in satellite appearance began during the daylight hours. AWIPS images of the CIMSS MIMIC Total Precipitable Water (TPW) product (below) did show that some dry air became entrained into the southern and eastern quadrants of Danielle, but fairly far from the center of the tropical cyclone.

MIMIC Total Precipitable Water (TPW) product

In addition to the entrainment of dry air, there was also a change from light easterly wind shear on 23 August to light northwesterly wind shear on 24 August, as seen on images from the CIMSS Tropical Cyclones site (below). It is unclear to what degree either of these factors played in the decrease in intensity  of Hurricane Danielle (which was actually downgraded to a Tropical Storm later in the day)..

GOES-15 IR image with Deep Layer Shear overlay + 85 GHz microwave image + MIMIC TPW

There was an 8-hour gap in SRSO imagery due to a GOES-15 satellite maneuver, but once the 1-minute interval imagery resumed, it almost appeared as though Danielle was trying to form a more organized convective eyewall later during the day (below).

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

View only this post Read Less

GOES-13 10.7 µm IR images

McIDAS images of GOES-13 10.7 µm IR data (above) revealed a classic convective burst signature as Tropical Storm Danielle began to intensity over the middle Atlantic Ocean on 23 August 2010. The coldest cloud top IR brightness temperature during this time period was -90º C at 07:15 UTC.

UPDATE: Danielle continued to intensify during the day, becoming the second hurricane of the 2010 Atlantic Basin Season. Images from the CIMSS Tropical Cyclones site (below) showed that Danielle continued to exhibit a large, cold Central Dense Overcast (CDO) on IR imagery, with a number of overshooting tops being indicated on the IR/Water Vapor difference product. However, a well-defined closed eyewall structure could be seen on SSMI/S-16 microwave imagery.

GOES-13 IR image + GOES-13 IR/Water Vapor difference product + SSMI/S-16 microwave image

The CIMSS Deep Layer (200-850 hPa) Wind Shear product (below) showed that Danielle was within (and moving into) a very low shear environment, which was a favorable factor for further intensification. The nearly circular CDO was characteristic of tropical cyclones that are located within such a low shear environment.

GOES-13 IR image + Deep Layer Wind Shear product

View only this post Read Less