The Relative Humidity in an Isentropic Advection–Condensation Model: Limited Poleward Influence and Properties of Subtropical Minima

O’Gorman, Paul A.; Lamquin, Nicolas; Schneider, Tapio; Singh, Martin S.

doi:10.1175/jas-d-11-067.1

Cited by 16 publications

(27 citation statements)

References 33 publications

(35 reference statements)

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“…This accompanies an increase in tropopause height and Hadley circulation width (cf. Schneider et al 2010;O'Gorman et al 2011;Levine and Schneider 2011). At the same time, the precipitation maximum ( Fig.…”

Section: A Global Warmingmentioning

confidence: 80%

“…With the idealized GCM, we can investigate separately the effects of tropical energy input changes and cross-equatorial energy flux changes, effects that usually occur together during ENSO or global warming. Our GCM is that of O'Gorman and Schneider (2008), which is similar to that used in Frierson et al (2006) and Frierson (2007). The GCM uses a twostream radiation scheme without clouds or aerosols, and the lower boundary consists of a slab ocean.…”

Section: Gcm Simulationsmentioning

confidence: 99%

“…However, closure approximations for fluxes of latent energy (water vapor) must take into account that moist air parcels from the subtropical boundary layer are transported upward and poleward, losing moisture along the way through cooling, condensation, and precipitation. The vertical structure of the flux must be considered, which can lead to a nonlocal dependence of water vapor fluxes, for example, on a subtropical specific humidity (Pierrehumbert 2002;Caballero and Langen 2005;O'Gorman and Schneider 2006;Pierrehumbert et al 2007;O'Gorman and Schneider 2008;O'Gorman et al 2011;Caballero and Hanley 2012).…”

Section: A Atmospheric Eddy Energy Fluxesmentioning

confidence: 99%

“…The GCM has a simplified representation of the hydrological cycle and radiative transfer (Frierson et al 2006;O'Gorman and Schneider 2008). It only takes into account the liquid-vapor phase transition, it has no ice phase, and the latent heat of evaporation is fixed at L y 5 2.5 3 10 6 J kg…”

Section: Description Of Gcm and Simulationsmentioning

confidence: 99%

“…Moist convection is parameterized by a simplified quasi-equilibrium scheme that relaxes temperatures to a moist adiabat and specific humidity to a profile with a fixed reference relative humidity of 70% (O'Gorman and Schneider 2008;Frierson 2007). Large-scale condensation is parameterized so that relative humidity on the grid scale does not exceed 100%.…”

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confidence: 99%

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Energetic Constraints on the Position of the Intertropical Convergence Zone

2014

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The intertropical convergence zone (ITCZ) can shift meridionally on seasonal and longer time scales. Previous studies have shown that the latitude of the ITCZ is negatively correlated with cross-equatorial atmospheric energy transport. For example, the ITCZ shifts southward as the Northern Hemisphere cools and the northward cross-equatorial energy transport strengthens in response. It has remained unclear what controls the sensitivity of the ITCZ position to cross-equatorial energy transport and what other factors may lead to shifts of the ITCZ position. Here it is shown that the sensitivity of the ITCZ position to crossequatorial energy transport depends on the net energy input to the equatorial atmosphere: the net radiative energy input minus any energy uptake by the oceans. Changes in this energy input can also lead to ITCZ shifts. The cross-equatorial energy transport is related through a series of approximations to interhemispheric asymmetries in the near-surface temperature distribution. The resulting theory of the ITCZ position is tested in idealized general circulation model simulations with a slab ocean as lower boundary condition. In the simulations, cross-equatorial energy transport increases under global warming (primarily because extratropical latent energy fluxes strengthen), and this shifts the ITCZ poleward. The ITCZ shifts equatorward if primarily the tropics warm in response to an increased net energy input to the equatorial atmosphere. The results have implications for explaining the varied response of the ITCZ to global or primarily tropical changes in the atmospheric energy balance, such as those that occur under global warming or El Niño.

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Section: A Global Warmingmentioning

confidence: 80%

Section: Gcm Simulationsmentioning

confidence: 99%

Section: A Atmospheric Eddy Energy Fluxesmentioning

confidence: 99%

Section: Description Of Gcm and Simulationsmentioning

confidence: 99%

mentioning

confidence: 99%

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Energetic Constraints on the Position of the Intertropical Convergence Zone

2014

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Long temporal autocorrelations in tropical precipitation data and spike train prototypes

Abbott

Stechmann

Neelin

2016

Geophysical Research Letters

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Temporal precipitation autocorrelations drop slower than exponentially at long lags, and there is a range from tens to thousands of minutes where it is relevant to ask if a scale‐free process might underlie the long autocorrelations. A simple stochastic model in which precipitation appears as variable‐length spikes provides a reasonable prototype for this behavior. In both observations and the model, separating the component of the autocorrelation within wet events from the interevent contribution suggests long autocorrelation behavior is primarily associated with the latter. When precipitation spikes are short compared to dry events, a true power law is obtained with analytical exponent −0.5 and precipitation autocorrelation is determined by dry‐spell model parameters. In more realistic cases, wet‐spell termination is also important. Although a variety of apparent power law exponents can be obtained for different parameters, the fundamental long‐lag process appears to be that of the interevent correlation.

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