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An Empirical Approach for Estimating Macroturbulent Heat Transport Conditional upon the Mean State

An Empirical Approach for Estimating Macroturbulent Heat Transport Conditional upon the Mean State A stochastic specification for monthly mean wintertime eddy heat transport conditional upon the monthly mean circulation is proposed. The approach is based on an analog technique. The nearest neighbor for the monthly mean streamfunction (at 850 and 300 hPa) is searched for in a library composed of monthly data of a 1268-yr control simulation with a coupled ocean–atmosphere model. To reduce the degrees of freedom a limited area (the North Atlantic sector) is used for the analog specification. The monthly means of northward transient eddy flux of temperature (at 750 hPa) are simulated as a function of these analogues. The stochastic model is applied to 300 years of a paleosimulation (last interglacial maximum around 125 kyr BP). The level of variability of the eddy heat flux is reproduced by the analog estimator, as well as the link between monthly mean circulation and synoptic-scale variability. The changed boundary conditions (solar radiation and CO 2 level) cause the Eemian variability to be significantly reduced compared to the control simulation. Although analogues are not a very good predictor of heat fluxes for individual months, they turn out to be excellent predictors of the distribution (or at least the variance) of heat fluxes in an anomalous climate. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of the Atmospheric Sciences American Meteorological Society

An Empirical Approach for Estimating Macroturbulent Heat Transport Conditional upon the Mean State

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Publisher
American Meteorological Society
Copyright
Copyright © 1998 American Meteorological Society
ISSN
1520-0469
DOI
10.1175/1520-0469(1999)056<2070:AEAFEM>2.0.CO;2
Publisher site
See Article on Publisher Site

Abstract

A stochastic specification for monthly mean wintertime eddy heat transport conditional upon the monthly mean circulation is proposed. The approach is based on an analog technique. The nearest neighbor for the monthly mean streamfunction (at 850 and 300 hPa) is searched for in a library composed of monthly data of a 1268-yr control simulation with a coupled ocean–atmosphere model. To reduce the degrees of freedom a limited area (the North Atlantic sector) is used for the analog specification. The monthly means of northward transient eddy flux of temperature (at 750 hPa) are simulated as a function of these analogues. The stochastic model is applied to 300 years of a paleosimulation (last interglacial maximum around 125 kyr BP). The level of variability of the eddy heat flux is reproduced by the analog estimator, as well as the link between monthly mean circulation and synoptic-scale variability. The changed boundary conditions (solar radiation and CO 2 level) cause the Eemian variability to be significantly reduced compared to the control simulation. Although analogues are not a very good predictor of heat fluxes for individual months, they turn out to be excellent predictors of the distribution (or at least the variance) of heat fluxes in an anomalous climate.

Journal

Journal of the Atmospheric SciencesAmerican Meteorological Society

Published: Jan 14, 1998

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