Stratocumulus cloud evolution

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:467674

Yang, X; Rogers, D P; Norris, P M ^[1]; Johnson, D W; Martin, G M ^[2]

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1. Scripps Institution of Oceanography, La Jolla, CA (United States)
2. Defense Research Agency, Farnborough (United Kingdom)

The structure and evolution of the extra-tropical marine atmospheric boundary layer (MABL) depends largely on the variability of stratus and stratocumulus clouds. The typical boundary-layer is capped by a temperature inversion that limits exchange with the free atmosphere. Cloud-top is usually coincident with the base of the inversion. Stratus clouds are generally associated with a well-mixed MABL, whereas daytime observations of stratocumulus-topped boundary-layers indicate that the cloud and subcloud layers are often decoupled due to shortwave radiative heating of the cloud layer. In this case the surface-based mixed layer is separated from the base of the stratocumulus (Sc) by a layer that is stable to dry turbulent mixing. This is sometimes referred to as the transition layer. Often cumulus clouds (Cu) develop in the transition layer. The cumulus tops may remain below the Sc base or they may penetrate into the Sc layer and occasionally through the capping temperature inversion. While this cloud structure is characteristic of the daytime MABL, it may persist at night also. The Cu play an important role in connecting the mixed layer to the Sc layer. If the Cu are active they transport water vapor from the sea surface that maintains the Sc against the dissipating effects of shortwave heating. The Cu, however, are very sensitive to small changes in the heat and moisture in the boundary-layer and are transient features. Here the authors discuss the effect of these small Cu on the turbulent structure of the MABL.

• Sponsoring Organization: Office of Naval Research, Washington, DC (United States)
• OSTI ID: 467674
• Report Number(s): CONF-9409461--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AMBIENT TEMPERATURE
ATMOSPHERIC CIRCULATION
CLIMATIC CHANGE
CLOUDS
ENVIRONMENTAL TRANSPORT
HEAT FLUX
TURBULENCE