On Moist Potential Temperatures and Their Ability to Characterize Differences in the Properties of Air Parcels

Marquet, Pascal; Stevens, Björn

doi:10.1175/jas-d-21-0095.1

Cited by 3 publications

(1 citation statement)

References 42 publications

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“…Recently, it has been shown that the entropy potential temperature, θ s , (potential temperature that has the same conservative properties as the moist entropy; see Marquet (2011) and Marquet and Geleyn (2013)) can be used to distinguish between the shallow convection regime and the stratocumulus regime (Marquet & Bechtold, 2020; Marquet & Stevens, 2021).…”

Section: The 2te Scheme Coupled To the Apdf Methodsmentioning

confidence: 99%

The Two‐Energies Turbulence Scheme Coupled to the Assumed PDF Method

Ďurán

Sakradzija

Schmidli

2022

J Adv Model Earth Syst

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In previous papers (Bašták Ďurán et al., 2014(Bašták Ďurán et al., , 2018 the authors derived a turbulence scheme based on two prognostic turbulence energies with the aim to parameterize turbulence and clouds in the atmospheric boundary layer (ABL) in a unified way.The two-energy (2TE) approach originates in the work of S. S. Zilitinkevich et al. (2007) and S. Zilitinkevich et al. (2008, who proposed the usage of two turbulence energies in the stable boundary layer. In Bašták Ďurán et al. (2018), this work is extended to all atmospheric stabilities in the framework of Bašták Ďurán et al. (2014). The influence of moisture on turbulence mixing is also accounted for. The fundamental difference between the two-energy scheme and turbulence schemes with only one prognostic turbulence energy, the

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Section: The 2te Scheme Coupled To the Apdf Methodsmentioning

confidence: 99%

The Two‐Energies Turbulence Scheme Coupled to the Assumed PDF Method

Ďurán

Sakradzija

Schmidli

2022

J Adv Model Earth Syst

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On the thermodynamic invariance of fine‐grain and coarse‐grain fluid models

Dubos

2024

Quart J Royal Meteoro Soc

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Thermodynamics is an essential ingredient of fine‐grain and coarse‐grain models of oceanic and atmospheric flows. Thermodynamic functions and conservative variables, for a given set of observable quantities such as pressure, temperature, and composition, may be defined up to a certain degree of arbitrariness, in the sense that the predictions of the fine‐grain model are insensitive to, for example, some reference enthalpies, entropies, or pressures. Since the compressible Navier–Stokes model, regarded as a “mother” fine‐grain model, is invariant with respect to arbitrary changes in reference enthalpies and entropies, restricted only by phase change, any coarse‐grain model obtained from it, even conceptually, must be invariant at least to the same extent. A framework is devised that enables the systematic examination of this invariance. It is found that the dependence of usual conservative variables on a reference pressure propagates to their fluxes and gradients, and to downgradient closures based on them. To resolve this issue, it is shown how to construct invariant “reduced” gradients and fluxes of enthalpy and entropy. Closure relationships between such “reduced” fluxes and gradients are then guaranteed to be invariant. More work is required to address the invariance of more sophisticated closures, especially shallow and deep convective closures.

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A colorful look at climate sensitivity

Stevens,

Kluft

2023

Atmos. Chem. Phys.

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Abstract. The radiative response to warming and to changing concentrations of CO2 is studied in spectral space. If, at a particular wavenumber, the emission temperature of the constituent controlling the emission to space does not change its emission temperature, as is the case when water vapor adopts a fixed relative humidity in the troposphere or for CO2 emissions in the stratosphere, spectral emissions become independent of surface temperature, giving rise to the idea of spectral masking. This way of thinking allows one to derive simple, physically informative, and surprisingly accurate expressions for the clear-sky radiative forcing, the radiative response to warming, and hence climate sensitivity. Extending these concepts to include the effects of clouds leads to the expectation that (i) clouds dampen the clear-sky response to forcing; (ii) diminutive clouds near the surface, which are often thought to be unimportant, may be effective at enhancing the clear-sky sensitivity over deep moist tropical boundary layers; (iii) even small changes in high clouds over deep moist regions in the tropics make these regions radiatively more responsive to warming than previously believed; and (iv) spectral masking by clouds may contribute substantially to polar amplification. The analysis demonstrates that the net effect of clouds on warming is ambiguous, if not moderating, justifying the assertion that the clear-sky (fixed relative humidity) climate sensitivity – which, after accounting for surface albedo feedbacks, we estimate to be about 3 K – provides a reasonable prior for Bayesian updates accounting for how clouds are distributed, how they might change, and deviations associated with changes in relative humidity with temperature. These effects are best assessed by quantifying the distribution of clouds and water vapor and how they change in temperature rather than geographic space.

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On Moist Potential Temperatures and Their Ability to Characterize Differences in the Properties of Air Parcels

Cited by 3 publications

References 42 publications

The Two‐Energies Turbulence Scheme Coupled to the Assumed PDF Method

The Two‐Energies Turbulence Scheme Coupled to the Assumed PDF Method

On the thermodynamic invariance of fine‐grain and coarse‐grain fluid models

A colorful look at climate sensitivity

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