Ghost Eye
Posted by JAC on 9/21/2009, 7:24 am
 A curious image artifact was noted on MTSAT-1R 3.75 m shortwave IR imagery, in the form of a very cold "false eye" appearing just to the right of the actual eye of Typhoon Choi-Wan (17W) in the western North Pacific Ocean. The "ghost" of the eye exhibited a satellite radiance of zero (very cold, appearing bright white on the image), and was offset from the true eye by 16 pixels in the horizontal and 1-2 pixels in the vertical. This false eye was most apparent on MTSAT-1R imagery during the local night-time hours, as was seen on 16 September 2009 at 14:30 UTC (above).  A similar (but less obvious) image artifact could be seen on a night-time shortwave IR image over China (below) - there was a bright white "ghost" of the warm area between the two colder cloud features, offset to the east by 16 pixels with a vertical displacement of 1-2 pixels.  The exact cause of these image artifacts is not known; however, since the MTSAT-1R satellite scans from left to right using a Charge-Coupled Device (CCD) array, the satellite sensor may be overcompensating for the CCD "quantum wells" losing more charge faster than expected, subtracting more of a bias than it should (this could also be a side-effect of sensor aging). Instrument crosstalk could be another source of this type of image anomaly. Kudos to Chris Schmidt at CIMSS for creating and analyzing these MTSAT-1R images, and supplying the explanations of possible causes of such an image artifact. |
35
In this thread:
Choi-Wan Stats: ACE = 19.75 - JAC, 9/21/2009, 7:08 am
- Ridin the waves at the Banzai Pipeline - JAC, 9/24/2009, 8:42 am
- CIMSS Blog - JAC, 9/21/2009, 7:28 am
Post A Reply
This thread has been archived and can no longer receive replies.