A MODIS-based contrail climatology of coverage and cloud properties

Accurate measurements of contrail coverage are essential for accurate estimates of global contrail radiative forcing. Nearly all estimates of global radiative forcing from line-shaped contrails use estimates of regional contrail coverage derived from satellite imagery. Although several studies of regional contrail coverage are available, no comprehensive study of the coverage of both the conterminous United States (CONUS) and Europe using the same satellite dataset has been produced. Estimates of contrail coverage over both regions from current numerical models show considerable uncertainty, and research programs including the Aviation-Climate Change Research Initiative (ACCRI) have recognized the need to develop a global climatology of line-shaped contrails from a homogeneous set of satellite data to reduce this model uncertainty.

We use an automated contrail detection algorithm (CDA) to determine the coverage of line-shaped persistent contrails over the CONUS and European regions. The contrail detection algorithm is a modification of the Mannstein et al. (1999) method, and uses several channels from the Terra and Aqua MODerate-resolution Imaging Spectroradiometers (MODIS) to reduce the occurrence of false positive detections. In addition, we will develop improved narrowband-broadband (NB-BB) conversion functions to estimate contrail radiative forcing from high-resolution spectral radiance data. We will apply the revised algorithms and standard cloud retrieval techniques to several months of MODIS data over the two aviation-intense regions to provide a more homogeneous, accurate, and statistically significant dataset for model validation and analysis of contrails.