Co-varying temperatures at 200 hPa over the Earth’s three poles

The Earth’s three poles, the North Pole, South Pole, and Third Pole (i.e., the Tibetan Plateau and its surroundings), hold the largest amount of fresh water on Earth as glaciers, sea ice, and snow. They are sensitive to climate change. However, the linkages between climate variations of the three poles, particularly between the South Pole and Third Pole, remain largely unknown. The temperatures at 200 hPa over the three poles are the highest in the summer and are less affected by surface conditions, which could reflect large-scale dynamic linkages. Temperatures at 200 hPa peak the three poles during their respective hemispheric summer and exhibit in-phase variations on interdecadal timescales (10-100 years). The 200 hPa temperatures over the North Pole and South Pole were significantly correlated with the Brewer-Dobson circulation (BDC), which transports stratospheric ozone poleward, heating the air at 200 hPa. Tropopause warming over the Third Pole was found to enhance the poleward BDC, particularly to the South Pole, linking the Third Pole’s climate to the other two poles. Additionally, the Interdecadal Pacific Oscillation (IPO) also exhibits links with the 200 hPa temperatures of the three poles.