ATS department ESS department

Research - Clouds & Contrails - Jet Contrails

Radiative Effects of Jet Contrails
This study supported by NASA has the following objectives:
1. To develop an automated technique in order to detect jet contrails from satellite imagery.
2. To estimate their global frequency of occurrence and their radiatve impact.

Automatic contrail detection is of major importance in the study of the atmospheric effects of aviation. Due to large volume of satellite imagery, selected contrail images for study by hand is impractical and highly subject to human error. It is far better to have a system in place that will automatically evaluate an image to determine 1) whether it contains contrails, and 2) where the contrails are located. Results show that it is possible to automatically detect and locate contrails in AVHRR imagery with a high degree of confidence.

1. Create a channel 4-5 difference image
2. Clasification of pixels into ridges. (Algorithm examines a 6X6 group of pixels into horizontal , vertical, and diagonal ridges).
3. Hough Transform
4. Contrail segmentation

Future plans:
1. Estimating the radiative impact of jet contrails
2. Estimating the difference in microphysical properties between jet contrails and thin cirrus clouds.
3. Global survey of jet contrail using AVHRR data.

Weiss, . M., S. A. Christopher, and R. M. Welch, 1996: Automatic Contrail Detection and Segmentation. submitted to IEE Transcations on Geoscience and Remote Sensing.
Engelstad, M., S. K. Sengupta, T. Lee, and R. M. Welch, 1992: Automated detection of jet contrails using the AVHRR split window. Int. J. Rem. Sens., 13(8), 1391-1412.