EUCLIPSE First Period Report

D3.4 and D3.5 Equilibrium Solutions of SCMs for boundary layer clouds and
identification and comparison of the key quantities used in ESM parameterization
schemes that control the cloud properties (Month 30).
KNMI (Sara Dal Gesso) has been working on generalizing the equilibrium cases of
CGILS for the equilibrium stratocumulus and shallow cumulus case. This
generalisation is accomplished by varying the strength of the inversion jumps and
investigating how the equilibrium solutions of the atmospheric state depend on this.
φ ∈ θ , between 3000
These inversion jumps are represented as the difference of { }
m and the sea surface, where θl denotes the potential liquid water temperature and qt
denotes the total water specific humidity. The reason for this is that the inversion
strength is an important parameter that largely determines the cloud amount of the
equilibrium solution. As an example we show in Figure 15 for a SCM version of EC-
Earth how the liquid water path of the equilibrium solutions varies with the inversion
strength.
Figure 15: The liquid water path(left panel) and the cloud fraction (right panel) for 100
equilibrium runswith a SCM version of EC-Earth are shown in which the inversion
strengths of the humidity and the temperature is varied. The S11 and the S12 case are
indicated as special cases.
It can be seen in Figure 15 that if the temperature jump is decreased the cloud
fraction and the liquid water path is decreasing and a transition from Stratocumulus to
cumulus can be observed. Such a result can be viewed as fingerprint of which
boundary clouds a parameterization scheme produces as a function the inversion
strength. This exercise will be repeated for all SCM version of the ESMs that
participate within EUCLIPSE and benchmarked with LES results that can serve as a
benchmark. Also the sensitivity for the used entrainment formulation will be
addressed as well as the response of an increased SST thereby generalizing the CGILS
philosophy to a more complete phase space.
D3.6 Compilation of ESM results at selected grid points (Month 18).
All the ESMs have implemented the appropriate software to have dedicated output at
selected grid points in all the present and future climate ESM runs described in WP1.
l qt
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