A diagnostic study of the global distribution of contrails Part I: Present day climate

Abstract

The global distribution of contrail formation potential and contrail cloud coverage are estimated using meteorological analyses of temperature and humidity (ECMWF reanalyses) and an aircraft fuel inventory. A large potential for contrail formation is found in the upper troposphere, in particular in the tropics, but also at mid-latitudes. The global potential contrail coverage is calculated to be 16%. The actual contrail coverage is proportional to the product of the potential coverage and the fuel consumption of 1991/92 air traffic. The actual global contrail coverage is 0.09%, however, the pattern of main air routes show up in the geographical distribution of contrail coverage with maximum values of more than 5%. Regionally, contrail coverage shows a distinct annual cycle, with larger values in winter than in summer, in the mid-latitudes. The result is only weakly sensitive to the propulsion efficiency of aircraft, but strongly sensitive to aircraft flight altitude.