A preliminary study of the tropical water cycle and its sensitivity to surface warming

Journal Article · Thu Jul 01 04:00:00 UTC 1993 · Bulletin of the American Meteorological Society; (United States)

DOI:https://doi.org/10.1175/1520-0477(1993)074<1313:APSOTT>2.0.CO;2· OSTI ID:5824148

Lau, K M; Tao, W K ^[1]; Sui, C H

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1. Goddard Space Flight Center, Greenbelt, MD (United States)

This paper presents preliminary findings of an investigation of the water budget of tropical cumulus convection using the Goddard Cumulus Ensemble Model (GCEM). Results of an experiment designed to obtain a [open quotes]fingerprint[close quotes] in the tropical hydrologic cycle in response to surface warming are also presented. The ensemble mean water budget shows the distribution of water vapor and cloud water in tropical atmosphere is maintained as a result of a balance between moisture convergence and condensation and reevaporation by various microphysical species within the cumulus clusters. Under radiative convective equilibrium conditions, 66% of the precipitation reached the ground comes from the convective region and 34% from the stratiform region. Water vapor is increased throughout the troposphere with the surplus largest near the surface and decreases monotonically up to 10 km. The percentage increase in water vapor is largest near 8 to 16 km. As a result of the warming, the freezing level in clouds is elevated resulting in a large increase (decrease) in cloud water just above (below) 5 km. As with water vapor, the fractional increase in cloud water and cloudiness amount is largest at the upper troposphere. The results on changes in temperature and water vapor induced by surface warming are in agreement with those from general circulation models that use crude cumulus parameterization. This is consistent with previous findings that equilibrium water vapor distribution is a strong function of temperature. In an open domain such as the tropical convective environment, with a specified climatological vertical velocity, the ratio of increased precipitation to increased surface evaporation due to a 2[degrees]C surface warming is approximately 5. The climate implication of these changes is also discussed. 25 refs., 8 figs.

• OSTI ID: 5824148
• Journal Information: Bulletin of the American Meteorological Society; (United States), Journal Name: Bulletin of the American Meteorological Society; (United States) Vol. 74:7; ISSN 0003-0007; ISSN BAMIAT
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
540120 -- Environment
Atmospheric-- Chemicals Monitoring &amp; Transport-- (1990-)
AIR-WATER INTERACTIONS
ATMOSPHERIC CIRCULATION
ATMOSPHERIC PRECIPITATIONS
CLIMATES
CLOUDS
CONVECTION
EARTH ATMOSPHERE
ENERGY TRANSFER
FLUIDS
GASES
GENERAL CIRCULATION MODELS
HEAT TRANSFER
HYDROLOGY
MASS TRANSFER
MATHEMATICAL MODELS
METEOROLOGY
RAIN
TROPICAL REGIONS
TROPOSPHERE
VAPORS
WATER VAPOR