Τομέας Φυσικής ΕφαρμογώνLibrary of the School of Science
Σοφιανός Σαράντης Λέκτορας (Επιβλέπων) , Κάλλος Γεώργιος Επικ. Καθηγ. ,Ιακωβίδης Κωνσταντίνος Επικ. Καθηγ.
Μελέτη των δομών της θαλάσσιας κυκλοφορίας και των λύσεων Goldsbrough - Stommel κάτω από την επίδραση της εξάτμισης, με αριθμητικές προσομοιώσεις
The present diplomatic work aims to study the development of the structure
and intensity of the Goldsbrough – Stommel circulation. Goldsbrough showed that
the freshwater flow between the atmosphere and the ocean causes large scale
circulation. Later Stommel completed the theory of Goldsbrough as he added the
idea of planetary divergence and the westward intensification and that is why
the movement caused by evaporation or rainfall christened Goldsbrough – Stommel
circulation. To simulate such a movement used numerical model it is necessary
to use numerical model in which the surface boundary condition of virtual salt
flux has been replaced by the condition of real freshwater flux so it is not
zero the vertical velocity at the surface of the sea.
For the study of Goldsbrough – Stommel circulation the numerical model
POM (Princeton Ocean Model) has been used after after some modifications
to an “ideal” ocean basin. For the simulation closed boundary conditions has
been used. At the center of the ocean surface there was an area, with a disc
shape, in which evaporation took place. The experiments which were made to
study the Goldsbrough – Stommel circulation was conducted at “f –plane” and “β-
plane” to an ocean with stable stratification. There were also experiments with
virtual salt flux and latent heat flux for the same type of evaporation.
Finally sensitivity experiments were carried out to simulate Goldsbrough -
Stommel circulation for a different type of stratification.
The results of the experiments showed the barotropic type nature of
Goldsbrough - Stommel circulation and the phenomenon of the westward
intensification. There were obvious differences in the structure of the
circulations which were simulated by virtual salt flux and latent heat flux as
well as was baroclinic character. The calculation of the energy contribution of
Goldsbrough – Stommel circulation in general circulation caused by evaporation
at "β-plane" and "f-plane" was done and it has been pointed out the mechanism
of the dissipation of kinetic energy in western boundary seconded by the area
of the disturbance in the form long Rossby wave, but also the mechanisms of
baroclinic instability developed in the area of the disturbance. Also the
results of the experiments for different stratification (sensitivity
experiments) showed differences in the development of kinetic energy due to
the effect of different baroclinic flow patterns. Finally the numeric model POM
has been used after modifications to simulate the Goldsbrough – Stommel
circulation at the Mediterranean region and the energy contribution of the G –
S gyres to the overall movement of the region was 0.1%. The Goldsbrough –
Stommel circulation , despite the small contribution to the energy balance of
the region , gives rise to significant flow patterns which can alter the
general circulation of the region.
Goldsbrough - Stommel circulation, Evaporation minus Precipitation, Real freshwater flux, Virtual salt flux, Westward intensification
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