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Influence of Midlatitude Thermal Anomalies on the Circulation of an Idealized Moist Model

Abstract:

Observational evidence suggests that midlatitude surface thermal variability is transported poleward along the warm conveyor belt of extratropical weather systems and can influence the temperature of the arctic midtroposphere on intraseasonal timescales. This linkage can be understood through the analysis of moist potential temperature in the atmosphere, since this variable is conserved under moist adiabatic motion (including condensation).

Understanding this linkage and its sensitivity to the location of the surface perturbation is complicated in the observations because of the complex and seasonally varying nature of the atmospheric processes involved; therefore we use an idealised moist model with simple surface perturbations to study the circulation impacts and the connection to the arctic mid-troposphere.

We find that the zonal mean moist potential temperature response approximately follows the moist isentropic surfaces from the unperturbed control integration, that the polar midtroposphere shows a heat and moisture anomaly 10-20 days after the surface perturbation is switched on, and that the response is strongest when the perturbation is located in the midlatitudes. The data is further analysed by calculating the heatfluxes, in a moist isentropic framework and it is shown that the changes in the heatflux are most sensitive to changes in the eddy covariance.

Abstract:
Observational evidence suggests that midlatitude surface thermal variability is transported poleward along the warm conveyor belt of extratropical weather systems and can influence the temperature of the arctic midtroposphere on intraseasonal timescales. This linkage can be understood through the analysis of moist potential temperature in the atmosphere, since this variable is conserved under moist adiabatic motion (including condensation).
Understanding this linkage and its sensitivity to the location of the surface perturbation is complicated in the observations because of the complex and seasonally varying nature of the atmospheric processes involved; therefore we use an idealised moist model with simple surface perturbations to study the circulation impacts and the connection to the arctic mid-troposphere.
We find that the zonal mean moist potential temperature response approximately follows the moist isentropic surfaces from the unperturbed control integration, that the polar midtroposphere shows a heat and moisture anomaly 10-20 days after the surface perturbation is switched on, and that the response is strongest when the perturbation is located in the midlatitudes. The data is further analysed by calculating the heatfluxes, in a moist isentropic framework and it is shown that the changes in the heatflux are most sensitive to changes in the eddy covariance. evidence suggests that midlatitude surface thermal variability is transported poleward along the warm conveyor belt of extratropical weather systems and can influence the temperature of the arctic midtroposphere on intraseasonal timescales. This linkage can be understood through the analysis of moist potential temperature in the atmosphere, since this variable is conserved under moist adiabatic motion (including condensation).
Understanding this linkage and its sensitivity to the location of the surface perturbation is complicated in the observations because of the complex and seasonally varying nature of the atmospheric processes involved; therefore we use an idealised moist model with simple surface perturbations to study the circulation impacts and the connection to the arctic mid-troposphere.
We find that the zonal mean moist potential temperature response approximately follows the moist isentropic surfaces from the unperturbed control integration, that the polar midtroposphere shows a heat and moisture anomaly 10-20 days after the surface perturbation is switched on, and that the response is strongest when the perturbation is located in the midlatitudes. The data is further analysed by calculating the heatfluxes, in a moist isentropic framework and it is shown that the changes in the heatflux are most sensitive to changes in the eddy covariance.