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  • Author or Editor: H. Nüzhet Dalfes x
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Mete Tayanç, Mehmet Karaca, and H. Nüzhet Dalfes

Abstract

The March 1987 blizzard over the eastern Mediterranean and Balkan regions is investigated. Northern Hemispheric and regional 250- and 850-hPa geopotential heights illustrate the formation of blocking over northern Europe and cyclogenesis over the considered area. The 850-hPa analyses and National Centers for Environmental Prediction Eta model simulations are in good agreement. Temporal analyses of temperature and precipitation fields show that a cold air surge over the region resulted in a decrease in the daily temperatures of up to 15°C and a heavy accumulation of snow in the early days of the storm. Spatial analyses of the precipitation field reveal that the most snowfall-affected regions were northwestern Turkey and the Balkan countries.

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H. Nuzhet Dalfes, S. H. Schneider, and Starley L. Thompson

Abstract

A zonally averaged energy balance climate model is used to generate zonal temperature variability through fluctuating meridional energy transports. In the base model, stochastic transport fluctuations are introduced by multiplying the eddy diffusion coefficients by Gaussian random deviates. For eddy coefficient variability of 50%, the base model generates an interannual temperature variability of 0.03 K for the global temperature, and 0.04 and 0.05 K for the Northern and Southern Hemispheric temperatures, respectively. The sensitivity to modeling assumptions of the model generated variability and its meridional distribution are investigated through a series of numerical experiments. For the range studied, the temperature variability level generated is linearly related to the transport variability level introduced. Switching from the multiplicative noise model of the base to an additive noise model results in an increase in the level of model generated temperature variability and a change in the shape of variance spectra of temperature anomaly time series. These model results are compared with a time series of central England temperatures as well as GCM generated climate variability. Because the level of variability is so dependent on the form of stochastic forcing parameterization, we conclude that great caution is needed before ascribing physical reality to such stochastic fluctuations.

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