How an ocean thousands of miles away dictates rainfall on the Tibetan Plateau

At the bottom of the heart of Central Asia, the Kunlun mountains form a vital barrier in the north of the Tibetan plateau. Their precipitation is a lifeline, supplying the oases and rivers of the Arid Basin de Tarim. While scientists have mapped the basic climatic patterns of the region, a question remained: what motivates the big oscillations from year to year in summer precipitation here?

The answer, according to a new study in Climate dynamiccomes from an unexpected source: the North Atlantic Ocean.

Research reveals that the abnormal dipole scheme of sea surface temperature in the North Atlantic affects summer precipitation on the northern slope of the Tibetan plateau through atmospheric teleconnexion processes.

“On the northern slope of the Tibetan plateau, annual precipitation is dominated by summer precipitation, with interannual variability representing most of the changes,” said the first author Shijie Tang, a doctorate. Student at the Institute of Atmospheric Physics, Academy of Chinese Sciences.

“We found that the horizontal convergence of water vapor – in particular associated with the abnormal winds of the South – plays the main role in the regulation of the variability of summer precipitation on the northern slope of the Tibetan plateau.”

A more in-depth analysis reveals that the dipole of the temperature of the northern Atlantic of the Atlantic of the Atlantic influences the tropospheric circulation through abnormal heat flows, triggering Rossby waves which propagate towards the east along the “Western-Western-North European Way”. These waves induce anticyclonic circulation and abnormal southern winds above the Kunlun mountains and the surroundings, thus improving the transport of water vapor and ultimately modifying the summer precipitation patterns.

The corresponding author, Tianjun Zhou, noted that research provides a new framework to understand the variability of precipitation by connecting Ocean-Atmosphere remote interactions to local water processes, considerably improving the potential for climate risk management in the region.