Publication Abstracts

Tselioudis 1992

Tselioudis, G., 1992: Global Patterns of Cloud Optical Thickness Variation with Temperature and the Implication for Climate Change. Ph.D. thesis. Columbia University.

This thesis present a correlative analysis of cloud optical thickness and cloud temperature in large space and time scales. The analysis is designed to document and explain the patterns of cloud optical thickness variation with temperature, and to produce an understanding of cloud optical property feedbacks on climate change.

The results of the global correlations between cloud optical thickness and temperature are presented in Cahpter I. The analysis focuses on low clouds to limit variations in cloud vertical extent, particle size and water phase. Coherent patterns of change are observed on several time and space scales. On the planetary and the seasonal scales, clouds in the colder latitudes and seasons are found to be optically thicker than clouds in the warmer latitudes and seasons. The seasonal, latitudinal, and day-to-day variations of this relation show that in cold continental clouds optical thickness increases with temperature consistent with the temperature variation of the adiabatic cloud water content, but in warm continental and in most maritime clouds optical thickness decreases with temperature.

In Chapter II, a number of cases are presented that attempt to identify the cloud parameters responsible for the optical thickness changes and to resolve the atmospheric processes that produce those changes. It is found that the temperature variation of low cloud optical thickness primarily reflect changes in the liquid water content of the clouds, and that changes in cloud particle size and vertical extent play a secondary role. In continental clouds, the optical thickness-temperature relation changes from a positive to a negative slope at the same temperature range that the percentage of precipitating clouds shows a marked increase. It is proposed that an increase in the efficiency of formation of warm rain at higher temperatures relative to condensation, raises the probability of occurrence of optically thin clouds at warmer temperature and produces the observed negative optical thickness slopes.

In Chapter III, a two dimensional radiative convective model is used to estimate the magnitude and sign of the feedback that the observed cloud optical thickness changes would produce in a climate warming scenario. A positive feedback is derived that increases the predicted 2×CO2 warming by 1.5°C in the subtropics and by 0.5°C in the midlatitudes of the Northern Hemisphere. The latitudinal contrast in the strength of the feedback acts to negate the high latitude amplification of the greenhouse warming.

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BibTeX Citation

@phdthesis{ts05000n,
  author={Tselioudis, G.},
  title={Global Patterns of Cloud Optical Thickness Variation with Temperature and the Implication for Climate Change},
  year={1992},
  school={Columbia University},
  address={New York, N.Y.},
}

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RIS Citation

TY  - THES
ID  - ts05000n
AU  - Tselioudis, G.
PY  - 1992
BT  - Global Patterns of Cloud Optical Thickness Variation with Temperature and the Implication for Climate Change
PB  - Columbia University
CY  - New York, N.Y.
ER  -

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