Modeling of a tropical squall line in two dimensions: Sensivity to radiation and comparison with a midlatitude case

Journal Article · Fri Sep 01 04:00:00 EDT 1995 · Journal of the Atmospheric Sciences

OSTI ID:113774

Hung-Neng, S C; Bradley, M M ^[1]; Fu, Qiang ^[2]; Molenkamp, C R ^[1]

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1. Lawrence Livermore National Lab., CA (United States)
2. Univ. of Utah, Salt Lake City, UT (United States)

A two-dimensional cloud model is used to study a tropical oceanic squall-line system. The influence of the microphysics treatment on cloud radiative properties and the sensitivity of this simulated system to radiation is also investigated. The major conclusions are as follows: (1) The simulated tropical squall-line system replicates many observed features. A transition zone in the simulated multicellular storm is primarily caused by the jetlike wind profile, while it is due to longwave radiation in the midlatitude system. (2) The effect of a jetlike wind profile is to weaken/strengthen the convective/anvil portion of the simulated system, which leads to an overall decrease of total surface precipitation by 17%. (3) The moisture budgets indicate that tropical deep convection serves as a more efficient engine, pumping low-level moisture upward to form the upper-level anvil cloud, than its midlatitude counterpart although the convective instability is lower in the tropical environment. (4) Microphysical production is the primary source of the water budget ({similar_to}3/5) in the simulated tropical anvil, and the rest ({similar_to}2/5) is contributed by horizontal transport of hydrometeors from deep convection. (5) The simulated tropical oceanic anvil has a stronger shortwave radiative forcing than the midlatitude continental anvil, although they have comparable longwave forcings. (6) The small difference in total precipitation of the simulated system caused by different radiation transfer schemes appears to justify the assumption of using a bulk parameterization for cloud radiative properties. (7) Comparisons of water budgets and cloud radiative properties between simulated tropical and midlatitude anvils suggest the need to parameterize the tilting structure of mesoscale convective systems for improving the representation of cloud processes in general circulation models. 81 refs., 15 figs., 5 tabs.

• OSTI ID: 113774
• Journal Information: Journal of the Atmospheric Sciences, Journal Name: Journal of the Atmospheric Sciences Journal Issue: 17 Vol. 52; ISSN 0022-4928; ISSN JAHSAK
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
ATMOSPHERIC CIRCULATION
BOUNDARY LAYERS
EARTH ATMOSPHERE
MATHEMATICAL MODELS
STORMS
TROPICAL REGIONS
WIND