Record-breaking rain falls at Greenland summit controlled by warm moist-air intrusion

On 14 August 2021, rain fell on the peak of Greenland for the first time on record. The atmospheric circulation and water vapour transport responsible for the rain were investigated. A high-pressure ridge favoured southwesterly advection of warm and moist air, the intrusion of which contributed to the rainfall. At the same time, Summit station observed above-freezing temperatures, which was the third time in a decade, after summers 2012 and 2019. The previous two warm events also included influxes of moisture, but no rainfall. Comparison between them and the 2021 event show different atmospheric pressure fields and water vapour transports. In 2021, the moisture from the southwest ascended the sloping ice sheet, whereas in the prior events moisture was transported from the southeast in smaller amounts. The sufficient supply of warm and moist air was the key factor in the 2021 rain event.

Automated summary

On 14 August 2021, rain was recorded for the first time on the peak of Greenland. The rain was caused by the advection of warm and moist air from the southwest brought by a high-pressure ridge. Unlike the previous warm events in 2012 and 2019, the 2021 event had a different atmospheric pressure field and moisture transport pattern, with moisture ascending from the southwest. The presence of sufficient warm and moist air was the key factor in the 2021 rain event.