A new approach for entrainment rate estimation in cumulus clouds
Authors
Chunsong Lu — Nanjing University of Information Science and Technology
Yangang Liu — Brookhaven National Laboratory
Seong Soo Yum — Yonsei University
Shengjie Niu — Nanjing University of Information Science and Technology
Satoshi Endo — Brookhaven National Laboratory
Category
Cloud Properties
Description
Figure 1. Comparison of the vertical profile of entrainment rate (λp) obtained using the new approach and the result from a traditional approach with different liquid water mixing ratio thresholds. The uncertainties are also shown.
A new approach is presented to estimate entrainment rate in cumulus clouds with aircraft measurements. The new approach is directly derived from the definition of fractional entrainment rate and relates it to cloud-clear air mixing fraction and height above cloud base. The results derived from the new approach compare favorably with those obtained with a commonly used approach and have smaller uncertainties (Figure 1). This new approach has several advantages: it eliminates the need for in-cloud measurements of temperature and water vapor content, which are often problematic in current aircraft observations; it has the potential for straightforwardly connecting the estimation of entrainment rate and the microphysical effects of entrainment-mixing processes; and it also has the potential for developing a remote sensing technique to infer entrainment rate.
