Journal Highlights

Could Stratospheric Ozone Depletion Make Hadley Cells Expand?

From Research Spotlights—

Convection-driven Hadley cells are expanding poleward. Scientists now may have uncovered part of the reason why.

In 1735, meteorologist George Hadley shook up his field by proposing a novel model of global atmospheric circulation, since named the Hadley cell, in which warm air rises at the equator and heads toward the poles, before cooling and sinking back toward the Earth’s surface at midlatitudes. Over time, especially within the past few decades, these large-scale circulation patterns have been visibly widening, for reasons unknown to scientists. 

The southernmost edges of the Hadley cell in the Southern Hemisphere are defined by the set of points where sea level pressure is highest. Using a technique called optimal fingerprinting analysis, Kim et al. compared a series of model simulations to examine long-term observed changes in these edges during the austral summers (December through February) of 1979–2009. They found that the southernmost edges of the Hadley cell over the Atlantic and Indian oceans have been expanding farther poleward during this period. 

While examining causes of these trends, the researchers detected within the models strong signals of anthropogenic forcing, or human activities such as industry and agriculture, which has ultimately led to increases in greenhouse gases. Specifically, the models showed a link between the expansion of Hadley cells and the depletion of, stratospheric ozone. Ozone depletion can lead to “holes” in the ozone, like the one detected over Antarctica in 1985. This would induce cooler conditions over Antarctica, shifting the lower-latitide circulation system poleward—including Hadley cells. 

This newfound knowledge provides an important link in the chain for scientists seeking to understand the Earth’s evolving climate. The authors note that the correlation they uncovered needs to be fleshed out with causes that pinpoint exactly how ozone depletion leads to Hadley cell expansion, and what the future holds for Hadley cells if ozone does or does not recover.  

-- Sarah Witman, Freelance Writer,

Recent Highlights Across AGU Publications Earth & Space Science News

View more Earth and space science news from Eos

Download the App

New Android App Available!

Google Play Store Logo

Download the Geophysical Research Letters app from the Google Play Store

iOS App for iPad or iPhone


Download the Geophysical Research Letters app from the Apple store

AGU Career Center

AGU Unlocked

Featured Special Collection

First Results from NASA's Magnetospheric Multiscale (MMS) Mission

The Magnetospheric Multiscale (MMS) mission has been performing particle and electromagnetic field measurements in the near-Earth environment since its launch in March 2015. Thanks to data with unprecedented time resolution on four identical spacecraft in a close tetrahedron configuration (down to 10 km), MMS science goals are to probe and understand the electron-scale physics involved in the magnetic reconnection process. This collection provides a selection of key results obtained during the first phase of the mission at the dayside magnetopause. It includes new observations of the geometry and variability of the reconnection process, the detailed dynamics of particles, fields and waves in the vicinity of the reconnection region, the observation of small-scale signatures at current sheets formed in the magnetosheath, in Kevlin-Helmholtz vortices, or flux transfer events, as well as other small-scale features which are by-products of magnetic reconnection or not. These results open a new window for our understanding of magnetic reconnection in space, with direct and numerous implications for astrophysical and laboratory plasmas.