Widening and weakening of the Hadley circulation under global warming

Abstract

The Hadley circulation is one of the most important atmospheric circulations. Widening of the Hadley circulation has drawn extensive studies in the past decade. The key concern is that widening of the Hadley circulation would cause poleward shift of the subtropical dry zone. Various metrics have been applied to measure the widening of the tropics. What are responsible for the observed widening trends of the Hadley circulation? How anthropogenic and natural forcings caused the widening? How the widening results in regional climatic effects? These are the major questions in studing the widening of the Hadley circulation. While both observations and simulations all show widening of the Hadley circulation in the past few decades, there are no general agreements of changes in the strength of the Hadley circulation. Although some reanalysis datasets show strengthening of the Hadley circulation, it was shown that the strengthening trend could be artificial, and simulations show weakening of the Hadley circulation for global greenhouse warming. In the present paper, we shall briefly review the major progresses of studies in trends in width and strength of the Hadley circulation. We address answers to these questions, clarify inconsistent results, and propose ideas for future studies.

Surface and tropospheric ozone trends in the Southern Hemisphere since 1990: possible linkages to poleward expansion of the Hadley circulation

“…Expansion rates of approximately 0.5°-1.0°latitude decade À1 since 1979 have been identified from a variety of metrics and datasets [34]. Robust expansion of the SHHC has been reported and is likely driven by Antarctic stratosphere ozone depletion and tropospheric greenhouse gas forcing [35][36][37][38][39] but also affected by natural climate variability [40]. In Fig.…”

Analysis and quantification of ENSO-linked changes in the tropical Atlantic cloud vertical distribution using 14 years of MODIS observations

“…Moreover, a weakening of the Atlantic Hadley and Walker circulations and an eastward shift of the latter (Philander, 1989;Klein et al, 1999;Wang, 2006) are associated with higher Pacific SSTs. Furthermore, a reduction in equatorial Atlantic rainfall (Saravanan and Chang, 2000;Chiang and Sobel, 2002), a lagged SST increase caused by a warmer troposphere, and reduced latent and sensible heat losses due to weaker trade winds and a reduction in cloudiness (Curtis and Hastenrath, 1995;Enfield and Mayer, 1997;Klein et al, 1999;Saravanan and Chang, 2000;Huang, 2002) were found during El Niño. The reduction in cloudiness leads to changes in radiation fluxes due to higher absorption of solar radiation by the ocean, which in turn increases the mean tropical Atlantic SST (Curtis and Hastenrath, 1995;Klein et al, 1999), strengthening the positive SST feedback between the Pacific and the Atlantic.…”

Hydrologic Resilience from Summertime Fog and Recharge: A Case Study for Coho Salmon Recovery Planning

“…The interannual coastal fog frequency is closely tied to the relative latitudinal location of the descending branch of the Hadley cell that generates the Pacific high-pressure zone. Black carbon and tropospheric ozone effects have been associated with the poleward widening of the descending branch of the Hadley circulation (Hu et al 2018), which would increase summertime FLCC in northern California. Black carbon and tropospheric ozone effects have been associated with the poleward widening of the descending branch of the Hadley circulation (Hu et al 2018), which would increase summertime FLCC in northern California.…”

“…When the high-pressure zone moves north, more fog is observed along the California coast, when it moves south less fog is observed (Johnstone and Dawson 2010). Black carbon and tropospheric ozone effects have been associated with the poleward widening of the descending branch of the Hadley circulation (Hu et al 2018), which would increase summertime FLCC in northern California. The uncertainty associated with feedbacks complicates the picture.…”