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Carried out in the framework of the APPLICATE project, a new study by scientists at the Alfred Wegener Institute recently published in the journal Geophysical Research Letters investigates the impact of lower latitudes’ climate on the Arctic troposphere for both winter and summer months. The analysis has been performed by looking at numerical experiments with the ECMWF atmospheric model in which several variables were relaxed towards the ERA Interim reanalysis in the midlatitudes and tropics. In the model, the Arctic has been left free to develop its own weather in response to this forcing.

The results suggest that the lower latitudes constrain the atmospheric circulation in the Arctic regions mainly during winter, while the summer state is mostly determined by internal drivers. During the winter months, the west Arctic sector is mainly influenced by the atmospheric state in the tropics.

The midlatitudes play a central role in setting the Arctic weather in the east Arctic sector. When it comes to Arctic surface warming, the lower latitudes seem to account for a relatively small portion of the Arctic surface warming during winter. This points to the local sea ice feedback for being responsible for the recently observed winter warming events, which could then be amplified by local radiation feedbacks in the lower Arctic troposphere.

The interaction between the atmospheric circulation and the sea ice over the Arctic Ocean is key to understanding the Arctic surface climate change.

The full open-access paper can be found at:

DJF SAT/T850/Z500 trends 1990-2013

Ye, K. & Jung, T. (2019). How strong is influence of the tropics and midlatitudes on the Arctic Atmospheric circulation and climate change? Geophysical Research Letters, 46.