Vertical coupling of the stratocumulus boundary layer by penetrating cumulus
- National Center for Atmospheric Research, Boulder, CO (United States)
During the Atlantic Stratocumulus Transition Experiment (ASTEX), small cumulus clouds that penetrate through the stratocumulus sheets were observed frequently. Radar observations show that the reflectivity cores in the penetrating cumuli are generally 1--2 km in diameter with a much larger enhanced patch of stratocumulus approximately 15--20 km across, whereas visual estimates of the diameter of the cumuli are generally in the neighborhood of several kilometers. In this study, the authors analyze measurements made on 10 June 1992 from the NCAR Electra aircraft. They are particularly interested in the role penetrating cumuli play in transporting moisture and other scalar between the sea surface and the top of the boundary layer, which is directly related to the important practical question of whether or not the penetrating cumuli tend to break up or dissipate the overlying stratocumulus cloud and aid the transition from a stratocumulus to a cumulus boundary layer. Large variations in temperature, specific humidity, and ozone are observed on both in-cloud legs. The differences between the maximum and minimum values of potential temperature, specific humidity, and ozone on these legs are around 1.1 deg, 1.4 g kg{sup {minus}1}, and 7 ppbv, respectively. To the authors` knowledge, such substantial horizontal variations of scalar variables have never been reported before in stratocumulus-topped boundary layers over the ocean. Close inspections of the time series indicate that the highest temperature and moisture and the lowest ozone concentration are found in the Cu region on both legs.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States)
- OSTI ID:
- 467671
- Report Number(s):
- CONF-9409461-; TRN: IM9721%%99
- Resource Relation:
- Conference: 2. International conference on air-sea interaction and on meterology and oceanography of the coastal zone, Lisbon (Portugal), 22-27 Sep 1994; Other Information: PBD: [1994]; Related Information: Is Part Of Second international conference on air-sea interaction and on meteorology and oceanography of the coastal zone; PB: 343 p.
- Country of Publication:
- United States
- Language:
- English
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