Therefore, there is a spread in LWPs among systems with the same κ.

A cooler and moister free troposphere also allows the turbulent boundary layer air parcels to overshoot to a higher height, leading to a higher cloud top. For the three cases with the same κ, cooler and moister free-tropospheric air leads to a cooler and moister boundary layer through entrainment, hence a lower cloud base. Results indicate that the thermodynamic properties of the free-tropospheric air are important. One of the three cases even has larger LWP than the base case, which is not expected by the CTEI theory. The LWPs of these three cases are also compared with the base case where κ is smaller. It is found that the spread of liquid water path (LWP) among the three cases is large. By employing large-eddy simulations coupled with bin microphysics, this study investigates the characteristics of three nocturnal nonprecipitating MSc systems with the same κ but different free-tropospheric conditions. Notice that if boundary layer temperature and humidity remain the same, a given κ can correspond to different combinations of free-tropospheric temperature and humidity. Marine stratocumulus (MSc) cloud amount can decrease with an increase in the cloud-top instability parameter κ, based on the cloud-top entrainment instability (CTEI) theory.

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