The Amazon river breeze and the local boundary layer: II. Linear analysis and modelling |
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Authors: | Amauri Pereira De Oliveira David R Fitzjarrald |
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Institution: | (1) Departmento de Ciencias Atmosféricas, Instituto Astronômico e Geofísco, Universidade de São Paulo, Brazil;(2) Atmospheric Sciences Research Center, State University of New York, 12205 Albany, USA |
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Abstract: | Observed boundary-layer circulations close to the confluence of the Negro and Solimões rivers near Manaus in the Brazilian equatorial Amazon forest were presented in Part I. These are shown through linear analysis and second-order turbulence modelling to be aspects of a river breeze superimposed on the basic flow. Linear analysis is presented to estimate the spatial structure and intensity of a breeze induced by a river with width and thermal contrast similar to that observed in the central Amazon. It is found that observed thermal contrasts are sufficient to produce a river breeze that can be perceived more than 20 km inland daily. A one-dimensional second-order closure model is used to show that observed nocturnal low-level wind maxima and diurnal surface wind rotation are aspects of a river breeze interacting with the seasonally-varying mean flow. At night, partial decoupling of the surface from the lower atmosphere allows the land breeze to be expressed as a low-level wind maximum. During the day, convective mixing communicates upper level winds to the surface during rapid morning boundary-layer growth. Rotation of the surface wind follows as the river breeze circulation is then superimposed. |
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