Southward shift of the Intertropical Convergence Zone due to Northern Hemisphere cooling at the Oligocene-Miocene boundary

Geology ◽  
2014 ◽  
Vol 42 (8) ◽  
pp. 667-670 ◽  
Author(s):  
K. Hyeong ◽  
J. Lee ◽  
I. Seo ◽  
M. J. Lee ◽  
C. M. Yoo ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Intertropical Convergence Zone ◽  
Convergence Zone ◽  
Southward Shift

scholarly journals AMO Forcing of Multidecadal Pacific ITCZ Variability

2018 ◽  
Vol 31 (14) ◽  
pp. 5749-5764 ◽  
Author(s):  
Aaron F. Z. Levine ◽  
Dargan M. W. Frierson ◽  
Michael J. McPhaden
Keyword(s):  
Northern Hemisphere ◽  
Climate Model ◽  
Atlantic Multidecadal Oscillation ◽  
Intertropical Convergence Zone ◽  
Hadley Cell ◽  
Convergence Zone ◽  
Proxy Record ◽  
Temperature And Precipitation ◽  
The Pacific ◽  
The Impact

The Atlantic multidecadal oscillation (AMO) has been shown to play a major role in the multidecadal variability of the Northern Hemisphere, impacting temperature and precipitation, including intertropical convergence zone (ITCZ)-driven precipitation across Africa and South America. Studies into the location of the intertropical convergence zone have suggested that it resides in the warmer hemisphere, with the poleward branch of the Hadley cell acting to transport energy from the warmer hemisphere to the cooler one. Given the impact of the Atlantic multidecadal oscillation on Northern Hemisphere temperatures, we expect the Atlantic multidecadal oscillation to have an impact on the location of the intertropical convergence zone. We find that the positive phase of the Atlantic multidecadal oscillation warms the Northern Hemisphere, resulting in a northward shift of the intertropical convergence zone, which is evident in the Pacific climate proxy record. Using a coupled climate model, we further find that the shift in the intertropical convergence zone is consistent with the surface energy imbalance generated by the Atlantic multidecadal oscillation. In this model, the Pacific changes are driven in large part by the warming of the tropical Atlantic and not the extratropical Atlantic.

scholarly journals Tropical rainfall patterns driven by reduced sea ice in high boreal latitudes

2018 ◽  
Vol 11 (1) ◽  
pp. 74-85
Author(s):  
Isimar de Azevedo Santos ◽  
Maria Gertrudes Alvarez Justi da Silva ◽  
Alfredo Silveira da Silva ◽  
Otto Corrêa Rotunno Filho
Keyword(s):  
Sea Ice ◽  
Northern Hemisphere ◽  
General Circulation ◽  
Regional Distribution ◽  
Vertical Motion ◽  
Circulation Model ◽  
Intertropical Convergence Zone ◽  
Convergence Zone ◽  
Intergovernmental Panel ◽  
Tropical Rainfall

Abstract Satellite data enabled the Intergovernmental Panel on Climate Change (IPCC), through Report V, to indicate that the regional distribution of sea ice has been reducing in the Northern hemisphere high latitudes. This study assimilated that reduction into a general circulation model of intermediate complexity to simulate the tropical rainfall response. The Northern hemisphere tropospheric wind field simulations presented a clear similarity to the Northern Annular Mode negative phase. In particular, the meridional wind anomalies of the Northern hemisphere Ferrel cell suggest that the energy upsurge due to the boreal sea ice decrease results in an increase in the amplitude of the Rossby waves, thus connecting the polar zone to the tropics. The 500 hPa vertical motion and the rainfall distribution in the tropical belt simulations show a southward displacement of the Atlantic Intertropical Convergence Zone and also the South Atlantic Convergence Zone. Although several studies indicate the Intertropical Convergence Zone is shifted towards the hemisphere most heated by climatic variations, the apparent disagreement with our results can be understood by considering that some continental sectors in the Northern Hemisphere mid-latitudes have shown cooling in recent years, probably in response to the boreal sea ice decrease.

OH measurement near the Intertropical Convergence Zone in the Pacific

1987 ◽  
Vol 92 (D2) ◽  
pp. 2020 ◽  
Author(s):  
L. I. Davis ◽  
John V. James ◽  
Charles C. Wang ◽  
Chuan Guo ◽  
Peter T. Morris ◽  
...  
Keyword(s):  
Intertropical Convergence Zone ◽  
Convergence Zone ◽  
The Pacific

scholarly journals Dynamics of the Intertropical Convergence Zone of the East Pacific

2006 ◽  
Vol 63 (2) ◽  
pp. 582-597 ◽  
Author(s):  
David J. Raymond ◽  
Christopher S. Bretherton ◽  
John Molinari
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Deep Convection ◽  
Intertropical Convergence Zone ◽  
Surface Fluxes ◽  
Balance Model ◽  
Convergence Zone ◽  
East Pacific ◽  
Layer Flow ◽  
Sst Gradient

Abstract The dynamical factors controlling the mean state and variability of the east Pacific intertropical convergence zone (ITCZ) and the associated cross-equatorial boundary layer flow are investigated using observations from the East Pacific Investigation of Climate (EPIC2001) project. The tropical east Pacific exhibits a southerly boundary layer flow that terminates in the ITCZ. This flow is induced by the strong meridional sea surface temperature (SST) gradient in the region. Away from the equator and from deep convection, it is reasonably well described on a day-to-day basis by an extended Ekman balance model. Variability in the strength and northward extent of this flow is caused by variations in free-tropospheric pressure gradients that either reinforce or oppose the pressure gradient associated with the SST gradient. These free-tropospheric gradients are caused by easterly waves, tropical cyclones, and the Madden–Julian oscillation. Convergence in the boundary layer flow is often assumed to be responsible for destabilizing the atmosphere to deep convection. An alternative hypothesis is that enhanced total surface heat fluxes associated with high SSTs and strong winds act to produce the necessary destabilization. Analysis of the moist entropy budget of the planetary boundary layer shows that, on average, surface fluxes generate over twice the destabilization produced by boundary layer convergence in the east Pacific ITCZ.

The Intertropical Convergence Zone

2013 ◽  
pp. 35-46
Author(s):  
T. N. Krishnamurti ◽  
Lydia Stefanova ◽  
Vasubandhu Misra
Keyword(s):  
Intertropical Convergence Zone ◽  
Convergence Zone
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