Surface temperature impacts of jet contrail outbreaks and their forecasting applications for two sub-regions of the Continental United States

The artificial cloudiness, or “contrail cirrus,” that results from multiple jet contrails (“clear-sky outbreaks”) can last for several hours, altering the radiation budget, and thereby potentially, surface temperatures. An extensive database of satellite-derived outbreaks over two sub-regions of the continental United States– the South and the Midwest –for two mid-season months (January, April) of 2008 and 2009 was used to determine the impact of contrail outbreaks on the diurnal temperature range (DTR). This was achieved by comparing the departures from the long-term normal at stations overlain by outbreaks with those at adjacent stations having similar synoptic meteorological and land surface conditions, but not experiencing contrail cloudiness. The results at the South stations during January, and the Midwest stations in April, both indicate a statistically significant suppression of DTR at contrail outbreak stations versus adjacent non-outbreak stations. A synoptic climatology (i.e., composite average) of upper troposphere variables (temperature, specific humidity, horizontal winds, and vertical lapse rate) for these longer-lasting jet contrail outbreaks links the impacts of contrail outbreaks with the conditions favorable for their formation. Specifically, enhanced gradients of specific humidity and temperature, as well as greater wind shear- conditions symptomatic of a baroclinic environment- characterized the formation of longer-lived outbreaks. The synoptic climatology also was the basis for successful prediction and retrodiction (hindcasting) of contrail outbreak cases through the use of reanalysis and forecast model data.