Advances in Atmospheric Sciences

, Volume 22, Issue 1, pp 114–121 | Cite as

Parameterization for the depth of the entrainment zone above the convectively mixed layer

  • Sun Jianning
  • Jiang Weimei
  • Chen Ziyun
  • Yuan Renmin


It has been noted that when the convective Richardson numberRi* is used to characterize the depth of the entrainment zone, various parameterization schemes can be obtained. This situation is often attributed to the invalidity of parcel theory. However, evidence shows that the convective Richardson numberRi* might be an improper characteristic scaling parameter for the entrainment process. An attempt to use an innovative parameter to parameterize the entrainment-zone thickness has been made in this paper. Based on the examination of the data of water-tank experiments and atmospheric measurements, it is found that the total lapse rate of potential temperature across the entrainment zone is proportional to that of the capping inversion layer. Inserting this relationship into the so-called parcel theory, it thus gives a new parameterization scheme for the depth of the entrainment zone. This scheme includes the lapse rate of the capping inversion layer that plays an important role in the entrainment process. Its physical representation is reasonable. The new scheme gives a better ordering of the data measured in both water-tank and atmosphere as compared with the traditional method usingRi*. These indicate that the parcel theory can describe the entrainment process suitably and that the new parameter is better thanRi*.

Key words

convectively mixed layer the depth of the entrainment zone capping inversion layer parameterization scheme parcel theory 


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Copyright information

© Advances in Atmospheric Sciences 2005

Authors and Affiliations

  • Sun Jianning
    • 1
  • Jiang Weimei
    • 1
  • Chen Ziyun
    • 1
  • Yuan Renmin
    • 2
  1. 1.Department of Atmospheric SciencesNanjing UniversityNanjing
  2. 2.Department of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei

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