Tropical cloud feedbacks and natural variability of climate

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Journal of Climate; (United States)

DOI:https://doi.org/10.1175/1520-0442(1994)007<1388:TCFANV>2.0.CO;2· OSTI ID:6795348

Miller, R L; Del Genio, A D ^[1]

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1. NASA Goddard Institute for Space Studies, New York, NY (United States)

Simulations of natural variability by two GCMs are examined. One GCM is a sector model, allowing relatively rapid integration without simplification of the model physics, which would potentially exclude mechanisms of variability. Two mechanisms are found in which tropical surface temperature and SST vary on interannual and longer timescales. Both are related to changes in cloud cover that modulate SST through the surface radiative flux. Over the equatorial ocean, SST and surface temperature vary on an interannual timescale, which is determined by the magnitude of the associated cloud cover anomalies. Over the subtropical ocean, variations in low cloud cover drive SST variations. In the sector model, the variability has no preferred timescale, but instead is characterized by a [open quotes]red[close quotes] spectrum with increasing power at longer periods. In the terrestrial GCM, SST variability associated with low cloud anomalies has a decadal timescale and is the dominant form of global temperature variability. Both GCMs are coupled to a mixed layer ocean model, where dynamical heat transports are prescribed, thus filtering out ENSO and thermohaline circulation variability. The occurrence of variability in the absence of dynamical ocean feedbacks suggests that climatic variability on long timescales can arise from atmospheric processes alone. 28 refs., 13 figs., 2 tabs.

• OSTI ID: 6795348
• Journal Information: Journal of Climate; (United States), Journal Name: Journal of Climate; (United States) Vol. 7:9; ISSN JLCLEL; ISSN 0894-8755
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
ANNUAL VARIATIONS
ATMOSPHERIC CIRCULATION
CLIMATES
CLOUD COVER
COMPARATIVE EVALUATIONS
EVALUATION
GENERAL CIRCULATION MODELS
MATHEMATICAL MODELS
OCEANIC CIRCULATION
SEAS
SURFACE WATERS
TEMPERATURE MEASUREMENT
TROPICAL REGIONS
VARIATIONS