Is there a trend in cirrus cloud cover due to aircraft traffic?

[摘要] Trends in cirrus cloud cover have been estimated based on 16 years of datafrom ISCCP (International Satellite Cloud Climatology Project). The resultshave been spatially correlated with aircraft density data to determine thechanges in cirrus cloud cover due to aircraft traffic. The correlations areonly moderate, as many other factors have also contributed to changes incirrus. Still we regard the results to be indicative of an impact ofaircraft on cirrus amount. The main emphasis of our study is on the areacovered by the METEOSAT satellite to avoid trends in the ISCCP dataresulting from changing satellite viewing geometry. In Europe, which iswithin the METEOSAT region, we find indications of a trend of about 1-2%cloud cover per decade due to aircraft, in reasonable agreement withprevious studies. The positive trend in cirrus in areas of high aircrafttraffic contrasts with a general negative trend in cirrus. Extrapolation intime to cover the entire period of aircraft operations and in space to coverthe global scale yields a mean estimate of 0.03 Wm^-2 (lower limit 0.01,upper limit 0.08 Wm^-2) for the radiative forcing due to aircraftinduced cirrus. The mean is close to the value given by IPCC (1999) as anupper limit.

[学科分类] 大气科学