Warming of the upper ocean in the equatorial Pacific, a key oceanographic region in Earth’s climate system, is likely to make the East Asian monsoon season wetter, according to a study co-authored by a Rutgers researcher. .
Recent increases in the heat content of the ocean, where energy is absorbed by the waters, have been implicated in the intensification of tropical storms that draw their energy from the ocean surface. However, the link between warming oceans and precipitation on land is less clear. A study published in Nature provides insight into this link.
“Our study suggests that variations in the thermal structure of the ocean affect moisture supply, latent heat and what happens when they reach land,” said Yair Rosenthal, a professor of marine and coastal sciences in the School of Arts and Sciences at Rutgers and School. of Environmental and Biological Sciences.
Rosenthal said that changes in the latitudinal temperature gradient, the difference in sea surface temperature between low and high latitudes, not only control how the upper part of the equatorial ocean absorbs energy, but also how winds transport moisture. from the ocean to the land.
The study, led by Zhimin Jian of Tongji University in China, found that over the past 360,000 years, increases in monsoon rainfall in eastern China correlated with increases in the heat content of the Indus Warm Pool. -Pacific, a region where sea surface temperatures are maintained. above ~82°F throughout the year, likely due to increased transport of moisture and latent heat absorbed in water vapor from the ocean to the continent.
According to the study, changes in the upper ocean’s heat content follow changes in Earth’s orbit that occur approximately every 23,000 years and change the distribution of incoming solar radiation at each latitude.
Using two species of foraminifera, calcareous marine organisms, one that lives on the surface and the other that lives approximately 200 meters below the sea surface, the scientists pieced together how the upper thermal structure of the ocean gets its heat and Energy. They compared their results with climate model simulations and reconstructions of monsoon precipitation in eastern China over the same period.
The coupling of ocean heat content and monsoon variations, both coordinated by changes in insolation on astronomical time scales, is critical for regulating global hydroclimate, the researchers said.
Coauthors include Zhimin Jian, Yue Wang, Haowen Dang, Zhongfang Liu, Haiyan Jin, Liming Ye, Xingxing Wang of Tongji University; Mahyar Mohtadi of the University of Bremen; David Lea of the University of California, Santa Barbara; and Wolfgang Kuhnt of Christian-Albrechts University.