The mixed-phase version of moist-air entropy

TL;DR

This paper derives a new mixed-phase moist-air entropy potential temperature $ heta_s$ that accounts for coexistence of liquid water and ice, enhancing the understanding of atmospheric parcels with mixed-phase conditions.

Contribution

It introduces a mixed-phase version of $ heta_s$, extending previous models to include coexistence of liquid water and ice in moist-air entropy calculations.

Findings

The new $ heta_s$ effectively describes mixed-phase atmospheric conditions.

Application to high-latitude profiles shows improved representation of moist-air entropy.

Results suggest better modeling of clouds with liquid and ice coexistence.

Abstract

The aim of this note is to derive the mixed-phase version of the moist-air entropy potential temperature $\theta_s$ derived in Marquet (2011). This mixed-phase version is suitable to describe parcels where liquid water and ice are allowed to coexist, with possible under- or super-saturations, with possible supercooled water and with possible different temperatures for dry air and water vapour, on the one hand, condensed water and ice, on the other hand. The impact of this new mixed-phase version for $\theta_s$ are evaluated by using high latitudes, SHEBA/FIRE-ACE vertical profiles depicted in Figure 7 of Morisson et al. (2011).