Parametric representation of heat and moisture fluxes in cloud-topped mixed layers

Richard S. Penc, Bruce A Albrecht

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Aircraft measurements were made from the NCAR Electra in stratus and stratocumulus clouds off the coast of California in June 1976. Several types of cloud conditions were observed, including (1) a broken layer less than 100 m thick, capped by an inversion at ~1000 m, (2) a broken stratocumulus layer ~300 m thick with an inversion at ~500 m, and (3) a 'solid' stratocumulus layer ~250 m thick with an inversion at ~500 m. Although these observations indicate that a variety of cloud conditions may exist in mixed layers, simple one-dimensional mixed-layer models implicitly assume a solid cloud layer with no unsaturated region within the cloud. In order to generalize these simple models, a parametric representation of the heat and moisture fluxes is considered. In this scheme, the fluxes are parameterized in terms of the product of a cloud mass flux and the characteristic difference between the thermodynamic properties of an updraft-downdraft circulation. This representation allows for an explicit representation of the buoyancy flux when the downdraft has no liquid water. Data collected during these flights were used to calculate heat and moisture fluxes and to obtain the mean difference in the thermodynamic properties of the updrafts and downdrafts at a given level. The mass flux was calculated using updraft-downdraft differences and the fluxes. The mass fluxes obtained using various thermodynamic quantities are examined for consistency. The vertical distribution of the mass flux is determined. These results indicate that a mass flux formulation could prove to be useful in modeling applications where cloud conditions may vary between solid and broken.

Original languageEnglish (US)
Pages (from-to)225-248
Number of pages24
JournalBoundary-Layer Meteorology
Volume38
Issue number3
DOIs
StatePublished - Feb 1987
Externally publishedYes

Fingerprint

moisture flux
mixed layer
heat flux
stratocumulus
updraft
thermodynamic property
stratus
airborne survey
buoyancy
vertical distribution
thermodynamics
flight
liquid
coast
modeling
inversion

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Parametric representation of heat and moisture fluxes in cloud-topped mixed layers. / Penc, Richard S.; Albrecht, Bruce A.

In: Boundary-Layer Meteorology, Vol. 38, No. 3, 02.1987, p. 225-248.

Research output: Contribution to journalArticle

Penc, Richard S. ; Albrecht, Bruce A. / Parametric representation of heat and moisture fluxes in cloud-topped mixed layers. In: Boundary-Layer Meteorology. 1987 ; Vol. 38, No. 3. pp. 225-248.
@article{7b349ae9a0d64e8dbe44378028c483ea,
title = "Parametric representation of heat and moisture fluxes in cloud-topped mixed layers",
abstract = "Aircraft measurements were made from the NCAR Electra in stratus and stratocumulus clouds off the coast of California in June 1976. Several types of cloud conditions were observed, including (1) a broken layer less than 100 m thick, capped by an inversion at ~1000 m, (2) a broken stratocumulus layer ~300 m thick with an inversion at ~500 m, and (3) a 'solid' stratocumulus layer ~250 m thick with an inversion at ~500 m. Although these observations indicate that a variety of cloud conditions may exist in mixed layers, simple one-dimensional mixed-layer models implicitly assume a solid cloud layer with no unsaturated region within the cloud. In order to generalize these simple models, a parametric representation of the heat and moisture fluxes is considered. In this scheme, the fluxes are parameterized in terms of the product of a cloud mass flux and the characteristic difference between the thermodynamic properties of an updraft-downdraft circulation. This representation allows for an explicit representation of the buoyancy flux when the downdraft has no liquid water. Data collected during these flights were used to calculate heat and moisture fluxes and to obtain the mean difference in the thermodynamic properties of the updrafts and downdrafts at a given level. The mass flux was calculated using updraft-downdraft differences and the fluxes. The mass fluxes obtained using various thermodynamic quantities are examined for consistency. The vertical distribution of the mass flux is determined. These results indicate that a mass flux formulation could prove to be useful in modeling applications where cloud conditions may vary between solid and broken.",
author = "Penc, {Richard S.} and Albrecht, {Bruce A}",
year = "1987",
month = "2",
doi = "10.1007/BF00122446",
language = "English (US)",
volume = "38",
pages = "225--248",
journal = "Boundary-Layer Meteorology",
issn = "0006-8314",
publisher = "Springer Netherlands",
number = "3",

}

TY - JOUR

T1 - Parametric representation of heat and moisture fluxes in cloud-topped mixed layers

AU - Penc, Richard S.

AU - Albrecht, Bruce A

PY - 1987/2

Y1 - 1987/2

N2 - Aircraft measurements were made from the NCAR Electra in stratus and stratocumulus clouds off the coast of California in June 1976. Several types of cloud conditions were observed, including (1) a broken layer less than 100 m thick, capped by an inversion at ~1000 m, (2) a broken stratocumulus layer ~300 m thick with an inversion at ~500 m, and (3) a 'solid' stratocumulus layer ~250 m thick with an inversion at ~500 m. Although these observations indicate that a variety of cloud conditions may exist in mixed layers, simple one-dimensional mixed-layer models implicitly assume a solid cloud layer with no unsaturated region within the cloud. In order to generalize these simple models, a parametric representation of the heat and moisture fluxes is considered. In this scheme, the fluxes are parameterized in terms of the product of a cloud mass flux and the characteristic difference between the thermodynamic properties of an updraft-downdraft circulation. This representation allows for an explicit representation of the buoyancy flux when the downdraft has no liquid water. Data collected during these flights were used to calculate heat and moisture fluxes and to obtain the mean difference in the thermodynamic properties of the updrafts and downdrafts at a given level. The mass flux was calculated using updraft-downdraft differences and the fluxes. The mass fluxes obtained using various thermodynamic quantities are examined for consistency. The vertical distribution of the mass flux is determined. These results indicate that a mass flux formulation could prove to be useful in modeling applications where cloud conditions may vary between solid and broken.

AB - Aircraft measurements were made from the NCAR Electra in stratus and stratocumulus clouds off the coast of California in June 1976. Several types of cloud conditions were observed, including (1) a broken layer less than 100 m thick, capped by an inversion at ~1000 m, (2) a broken stratocumulus layer ~300 m thick with an inversion at ~500 m, and (3) a 'solid' stratocumulus layer ~250 m thick with an inversion at ~500 m. Although these observations indicate that a variety of cloud conditions may exist in mixed layers, simple one-dimensional mixed-layer models implicitly assume a solid cloud layer with no unsaturated region within the cloud. In order to generalize these simple models, a parametric representation of the heat and moisture fluxes is considered. In this scheme, the fluxes are parameterized in terms of the product of a cloud mass flux and the characteristic difference between the thermodynamic properties of an updraft-downdraft circulation. This representation allows for an explicit representation of the buoyancy flux when the downdraft has no liquid water. Data collected during these flights were used to calculate heat and moisture fluxes and to obtain the mean difference in the thermodynamic properties of the updrafts and downdrafts at a given level. The mass flux was calculated using updraft-downdraft differences and the fluxes. The mass fluxes obtained using various thermodynamic quantities are examined for consistency. The vertical distribution of the mass flux is determined. These results indicate that a mass flux formulation could prove to be useful in modeling applications where cloud conditions may vary between solid and broken.

UR - http://www.scopus.com/inward/record.url?scp=0023519796&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023519796&partnerID=8YFLogxK

U2 - 10.1007/BF00122446

DO - 10.1007/BF00122446

M3 - Article

AN - SCOPUS:0023519796

VL - 38

SP - 225

EP - 248

JO - Boundary-Layer Meteorology

JF - Boundary-Layer Meteorology

SN - 0006-8314

IS - 3

ER -