Operational detection of contrails from NOAA-AVHRR-data

This paper describes a fully automated scheme that allows for the detection of contrails using the infrared channels of the Advanced Very High Resolution Radiometer (AVHRR). The presented algorithm is adjusted to have a low rate of misdetection in spite of the low contrail detection efficiency resulting from this tuning. A time-series and regional patterns of contrail cloudiness over Central and Western Europe are derived. Daily analysis of noon scenes in 1996 indicates that the average of daytime contrail coverage over Central Europe was 0.5% +/- 0.25 with regional maxima of 1.2%. Comparing noon and midnight scenes shows that night-time contrail coverage, which is especially effective in greenhouse forcing, is approximately one-third of that of daytime.