Unusual warm conditions in the Arctic Ocean
1 December 2016
GHRSST Science Team member Jacob Hoeyer from DMI reports on the unusual warm conditions in the Arctic Ocean:
An average air temperature of -10 °C in the Arctic sounds like cold conditions, but actually, it is 15 to 20 °C warmer in the Arctic than normal for this time of the year (late 2016). The warm atmosphere is caused by advection of warm air from the south but it is also related to an unusually warm ocean, which is up to 5 °C warmer than normal. This means that the sea ice in the Arctic is surrounded by a warm ocean, which delays the sea ice formation as the ocean has to be cooled before the sea ice can form.
In normal years, we would see the Kara Sea and Chukchi Sea covered by ice but large areas with open waters are seen in these regions. Considering the time of the year, we are observing a record low sea ice extent.
The figures below shows the warm conditions in the ocean and atmosphere and the resulting slow sea ice formation. Figure 1 is a map of SST anomalies in the Arctic showing the very warm ocean temperatures; these conditions have persisted for several months. The figure is from the DMI OI global Level 4 SST analysis. The climatology is the monthly Pathfinder climatology from 1985 to 2001 interpolated to the exact day.
Figure 2 plots the daily mean T2m air temperature from NWP models north of the 80th northern latitude and shows exceptional warm weather conditions with an average temperature more than 20 °C warmer than normal for this time of the year.
The warm ocean and atmosphere cause a delay in the sea ice formation. The sea ice extent is currently below what was observed at the same time in 2012, which was the all-time low. Figure 3 shows the last 4 years’ sea ice extent and the climatology derived from the OSI-SAF sea ice concentration products.
You can follow the evolution of the Arctic conditions at:
DMI Arctic level 4 SST anomaly:
Average air temperature anomalies for > 80 deg lat:
Sea ice extent:
Høyer, J. L., Le Borgne, P., & Eastwood, S. (2014). A bias correction method for Arctic satellite sea surface temperature observations. Remote Sensing of Environment, 146, 201-213.
Tonboe, R. T., Eastwood, S., Lavergne, T., Sørensen, A. M., Rathmann, N., Dybkjær, G., Pedersen, L. T., Høyer, J. L., and Kern, S.: The EUMETSAT sea ice concentration climate data record, The Cryosphere, 10, 2275-2290, doi:10.5194/tc-10-2275-2016, 2016.