Evaluating the Significance of the Contrail Effect on Diurnal Temperature Range Using the Eyjafjallajökull Eruption‐Related Flight Disruption

• Published in: Geophysical research letters 2018-12, Vol.45 (23), p.13,090-13,098
• Main Authors: Sandhu, Ajvir S., Baldini, James U. L.
• Format: Article
• Language: English
• Subjects: Anomalies; anthropogenic; Atmospheric conditions; Aviation; climate; climate change; Contrail effects; Contrails; Daily temperature range; Daily temperatures; Disruption; Evolution; Flight; Groundings; High temperature; Low temperature; Meteorological data; Migration; Removal; Stations; Temperature; temperature change; Temperature data; Temperature effects; Volcanic eruptions; Weather; Weather effects; Weather stations
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2018GL080899

Meteorological data collected during the post‐9/11 flight grounding in the United States suggested that the removal of contrails increased diurnal temperature range (DTR), but subsequent research has contested this result. The 2010 Eyjafjallajökull eruption resulted in a 97% flight cancelation rate across the UK, offering another rare opportunity to compare DTR under contrail‐free skies against those with contrails. Temperature data from 199 UK meteorological stations indicate that a +3.4 °C DTR anomaly occurred during the grounding interval across the region previously affected by the highest flight densities, substantially larger than the +1.1 °C anomaly previously observed but smaller than other DTR anomalies (up to ~ +6 °C) that were independent of the grounding. Although the observed DTR anomalies are largely attributable to weather system migration, a contribution of up to +1 °C from contrail absence appears reconcilable with both the observed time evolution in DTR during the Eyjafjallajökull grounding period and previous results. Plain Language Summary Due to permanent and near‐constant aviation activity, directly comparing atmospheric conditions underneath skies with and without contrails under equivalent ambient conditions is difficult. Previous research used the post‐9/11 flight groundings in 2001 to detect a contrail effect on diurnal temperature range across the United States. The removal of contrails was found to have increased daytime high temperatures and decreased nighttime low temperatures. However, subsequent research challenged this result and the overall effect of contrails on weather remains unclear. Here we use a very high density network of meteorological stations across the United Kingdom to assess the importance of contrails on diurnal temperature range during a more recent flight grounding following the Eyjafjallajökull volcanic eruption of 2010. We find that subtle, but substantial, temperature shifts related to contrails may have been overprinted by larger shifts in weather systems passing over the United Kingdom. Key Points Weather largely controlled diurnal temperature range variations during the 2010 Eyjafjallajökull eruption‐related UK flight disruption Evidence is consistent with a ~1.1 °C contrail effect on DTR in high flight density region Using rare observational data, this study broadly corroborates previous estimates of the contrail effect on DTR