Direct sampling of entrainment events in a marine stratocumulus layer

Journal Article · Tue Jun 15 04:00:00 EDT 1993 · Journal of the Atmospheric Sciences; (United States)

DOI:https://doi.org/10.1175/1520-0469(1993)050<1734:DSOEEI>2.0.CO;2· OSTI ID:6018519

Khalsa, S J ^[1]

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1. Univ. of Colorado, Boulder (United States)

Entrainment mixing and the stability of a marine stratocumulus layer are investigated using aircraft data gathered during the FIRE (First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment) marine stratocumulus experiment. Direct measurement of entrainment events is accomplished through conditional sampling based on ozone mixing ratio. This enables the identification of evaporatively cooled, negatively buoyant events that could otherwise only be inferred by thermodynamic jump conditions at cloud top. Evidence for evaporation cooling within entrainment events is obtained with aerosol and cloud droplet spectra. An increase in the entrainment of dry air into the cloud layer due to sinking of negatively buoyant downdrafts is offset by an increased flux of moisture through cloud base. The positive flux of moisture at cloud base is driven, in part, by the sinking of evaporatively cooled parcels through the entire cloud layer. Despite a minimum in buoyancy flux near cloud base, the cloud layer was not decoupled from the subcloud layer. 35 refs., 8 figs., 9 tabs.

• OSTI ID: 6018519
• Journal Information: Journal of the Atmospheric Sciences; (United States), Journal Name: Journal of the Atmospheric Sciences; (United States) Vol. 50:12; ISSN 0022-4928; ISSN JAHSAK
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110
540120* -- Environment
Atmospheric-- Chemicals Monitoring &amp; Transport-- (1990-)
BOUNDARY LAYERS
CLIMATIC CHANGE
CLOUDS
EARTH ATMOSPHERE
EVAPORATION
GREENHOUSE EFFECT
GREENHOUSE GASES
HUMIDITY
LAYERS
OZONE
PHASE TRANSFORMATIONS
REMOTE SENSING
TEMPERATURE INVERSIONS
TEMPERATURE MEASUREMENT