DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Tropical Expansion Driven by Poleward Advancing Midlatitude Meridional Temperature Gradients

Journal Article · · Journal of Geophysical Research: Atmospheres

An abundance of evidence indicates that the tropics are expanding under climate change. Despite many attempts to decipher the cause, the underlying dynamical mechanism driving tropical expansion is still not entirely clear. Here, based on observations, multi-model simulations from the Coupled Model Intercomparison Project phase 5 (CMIP5) and purposefully designed numerical experiments, the variations and trends of the tropical width are explored from a regional perspective. We find that the width of the tropics closely follows the meridional displacement of subtropical front. In a warming climate, the subtropical ocean experiences more surface warming because of the mean Ekman convergence of the anomalously warm water. The enhanced subtropical warming, which is independent of the natural climate oscillations, such as the Pacific Decadal Oscillation, leads to poleward advance of subtropical front and drives the tropical expansion. Our results, supported by both observations and model simulations, imply that global warming may have already significantly contributed to the ongoing expanding tropics, especially over the ocean dominant Southern Hemisphere.

Research Organization:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE; German Research Foundation (DFG)
Grant/Contract Number:
AC05-76RL01830; BMBF 01LP1607A
OSTI ID:
1650188
Alternate ID(s):
OSTI ID: 1650189; OSTI ID: 1668287
Report Number(s):
PNNL-SA-152257
Journal Information:
Journal of Geophysical Research: Atmospheres, Vol. 125, Issue 16; ISSN 2169-897X
Publisher:
American Geophysical UnionCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 29 works
Citation information provided by
Web of Science

References (68)

Significance of a Midlatitude SST Frontal Zone in the Formation of a Storm Track and an Eddy-Driven Westerly Jet* journal April 2010
Widening of the Hadley Cell from Last Glacial Maximum to Future Climate journal December 2017
Regional changes in the annual mean Hadley circulation in recent decades journal July 2014
The interplay of internal and forced modes of Hadley Cell expansion: lessons from the global warming hiatus journal September 2017
The global climatology of an interannually varying air–sea flux data set journal August 2008
Formation of Jets by Baroclinic Instability on Gas Planet Atmospheres journal September 2007
The Storm-Track Response to Idealized SST Perturbations in an Aquaplanet GCM journal September 2008
Which way will the circulation shift in a changing climate? Possible nonlinearity of extratropical cloud feedbacks journal August 2016
The Transient Circulation Response to Radiative Forcings and Sea Surface Warming* journal December 2014
A new global reconstruction of temperature changes at the Last Glacial Maximum journal January 2013
Southeast Australia Autumn Rainfall Reduction: A Climate-Change-Induced Poleward Shift of Ocean–Atmosphere Circulation journal January 2013
Enhanced Mid-Latitude Tropospheric Warming in Satellite Measurements journal May 2006
Cooling of the Arctic and Antarctic Polar Stratospheres due to Ozone Depletion journal May 1999
Migration of the subtropical front as a modulator of glacial climate journal July 2009
Last Glacial Maximum sea surface temperature and sea-ice extent in the Pacific sector of the Southern Ocean journal August 2016
An Overview of CMIP5 and the Experiment Design journal April 2012
Poleward expansion of the hadley circulation in CMIP5 simulations journal April 2013
Enhanced Mid-Latitude Meridional Heat Imbalance Induced by the Ocean journal November 2019
Signatures of the Antarctic ozone hole in Southern Hemisphere surface climate change journal October 2011
Re-examining tropical expansion journal August 2018
Regional and Seasonal Characteristics of the Recent Expansion of the Tropics journal September 2018
The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model journal January 2014
Observed poleward expansion of the Hadley circulation since 1979 journal January 2007
Using aquaplanets to understand the robust responses of comprehensive climate models to forcing journal May 2014
Regional characteristics of tropical expansion and the role of climate variability: REGIONAL TROPICAL EXPANSION journal July 2015
The Role of Poleward-Intensifying Winds on Southern Ocean Warming journal November 2007
Evidence for climate change in the satellite cloud record journal July 2016
Testing Latitudinally Dependent Explanations of the Circulation Response to Increased CO 2 Using Aquaplanet Models journal September 2018
The response of midlatitude jets to increased CO 2 : Distinguishing the roles of sea surface temperature and direct radiative forcing : Response of jets to increased CO2 journal October 2014
Attribution of the local Hadley cell widening in the Southern Hemisphere journal January 2017
Phase Speed Spectra and the Latitude of Surface Westerlies: Interannual Variability and Global Warming Trend journal November 2008
Widening of the tropical belt in a changing climate journal December 2007
Responses of the Hadley Circulation to Regional Sea Surface Temperature Changes journal December 2019
A consistent poleward shift of the storm tracks in simulations of 21st century climate: POLEWARD SHIFT OF THE STORM TRACKS journal September 2005
Poleward Shift of the Major Ocean Gyres Detected in a Warming Climate journal March 2020
Strong Dynamical Modulation of the Cooling of the Polar Stratosphere Associated with the Antarctic Ozone Hole journal January 2012
Response of the Zonal Mean Atmospheric Circulation to El Niño versus Global Warming journal November 2008
Revisiting the Relationship among Metrics of Tropical Expansion journal September 2018
The Role of Ocean–Atmosphere Coupling in the Zonal-Mean Atmospheric Response to Arctic Sea Ice Loss journal March 2015
Regional Widening of Tropical Overturning: Forced Change, Natural Variability, and Recent Trends journal June 2019
Sea-surface temperature and sea ice distribution of the Southern Ocean at the EPILOG Last Glacial Maximum—a circum-Antarctic view based on siliceous microfossil records journal April 2005
The mystery of the expanding tropics journal February 2016
Distinct modes of East Asian Winter Monsoon documented by a southern Red Sea coral record journal March 2014
Stratospheric Ozone Depletion: The Main Driver of Twentieth-Century Atmospheric Circulation Changes in the Southern Hemisphere journal February 2011
A Reanalysis of Ocean Climate Using Simple Ocean Data Assimilation (SODA) journal August 2008
A Pacific Interdecadal Climate Oscillation with Impacts on Salmon Production journal June 1997
Hadley Cell Widening: Model Simulations versus Observations journal May 2009
Understanding Hadley Cell Expansion versus Contraction: Insights from Simplified Models and Implications for Recent Observations journal June 2013
Breaking down the tropospheric circulation response by forcing journal December 2011
Recent Northern Hemisphere tropical expansion primarily driven by black carbon and tropospheric ozone journal May 2012
Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica journal June 1999
Historical trends in the jet streams journal January 2008
Sensitivities of zonal mean atmospheric circulation to SST warming in an aqua-planet model: CIRCULATION RESPONSE TO SST WARMING journal June 2010
Natural variations of tropical width and recent trends: Natural Variations of Tropical Width journal April 2017
Effects of the PDO Phase on the Tropical Belt Width journal May 2012
Recent Tropical Expansion: Natural Variability or Forced Response? journal March 2019
Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century journal January 2003
Twenty-First-Century Multimodel Subtropical Precipitation Declines Are Mostly Midlatitude Shifts journal June 2012
The Role of Natural Climate Variability in Recent Tropical Expansion journal August 2017
Plastic Pollution in the World's Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea journal December 2014
Intensification and poleward shift of subtropical western boundary currents in a warming climate: INTENSIFICATION AND POLEWARD SHIFT OF WBCs journal July 2016
Width of the Hadley cell in simple and comprehensive general circulation models journal January 2007
Measurements of the movement of the jet streams at mid-latitudes, in the Northern and Southern Hemispheres, 1979 to 2010 journal January 2012
Expansion of the Hadley cell under global warming journal January 2007
On the Role of Radiative Processes in Stratosphere–Troposphere Coupling journal August 2009
Widening and weakening of the Hadley circulation under global warming journal May 2018
Ocean circulation in a warming climate journal January 2008
Changes in extratropical storm track cloudiness 1983–2008: observational support for a poleward shift journal April 2011

Figures / Tables (14)