A summary of several meteorological properties of the moist-air entropy variables $\theta_s$ and $PV(\theta_s)$

The aim of this note is to describe several meteorological properties shown in a conference talk (Marquet, January 2022) for the moist-air specific entropy, the associated potential temperature ($\theta_s$) defined in Marquet (2011) and the associated potential vorticity $PV(\theta_s)$ defined in Marquet (2014), with in particular regions of negative values of $PV(\theta_s)$ close to the cold fronts that seems to indicate regions of symmetric instability.Comment: 43 pages, 20 figures. Workshop for Forecasting and Modelling, 24th of January, 2022. M\'et\'eo-France, Toulouse, Franc