Energetic constraints on the width of the intertropical convergence zone

Michael Patrick Byrne, Tapio Schneider

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)

Abstract

The intertropical convergence zone (ITCZ) has been the focus of considerable research in recent years, with much of this work concerned with how the latitude of maximum tropical precipitation responds to natural climate variability and to radiative forcing. The width of the ITCZ, however, has received little attention despite its importance for regional climate and for understanding the general circulation of the atmosphere. This paper investigates the ITCZ width in simulations with an idealized general circulation model over a wide range of climates. The ITCZ, defined as the tropical region where there is time-mean ascent, displays rich behavior as the climate varies, widening with warming in cool climates, narrowing in temperate climates, and maintaining a relatively constant width in hot climates. The mass and energy budgets of the Hadley circulation are used to derive expressions for the area of the ITCZ relative to the area of the neighboring descent region, and for the sensitivity of the ITCZ area to changes in climate. The ITCZ width depends primarily on four quantities: the net energy input to the tropical atmosphere, the advection of moist static energy by the Hadley circulation, the transport of moist static energy by transient eddies, and the gross moist stability. Different processes are important for the ITCZ width in different climates, with changes in gross moist stability generally having a weak influence relative to the other processes. The results are likely to be useful for analyzing the ITCZ width in complex climate models and for understanding past and future climate change in the tropics.
Original languageEnglish
Pages (from-to)4709-4721
Number of pages13
JournalJournal of Climate
Volume29
Issue number13
Early online date14 Jun 2016
DOIs
Publication statusPublished - Jul 2016

Keywords

  • Geographic location/entity
  • Intertropical convergence zone
  • Circulation/dynamics
  • Atmospheric circulation
  • Hadley circulation
  • Physical meterology and climatology
  • Climate change
  • Energy budget/balance
  • Models and modeling
  • Climate models

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