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Spatial patterns of nocturnal surface-to-atmosphere decoupling over the Amazon

Otávio C Acevedo, UFSM, otavio@smail.ufsm.br
Osvaldo L L Moraes, UFSM, moraes@mail1.ufsm.br (Presenting)
David R Fitzjarrald, SUNY, fitz@asrc.cestm.albany.edu
Ricardo K Sakai, SUNY, sakai@asrc.cestm.albany.edu
Mathew Czikowski, SUNY, matt@asrc.cestm.albany.edu

At nighttime, when there is enough surface cooling, often the surface layer decouples from the upper atmosphere. In this case, surface processes, such as ecosystem respiration, water evaporation or dew deposition, accumulate on a very shallow layer, near the surface. Regional surface fluxes are seriously affected in these conditions, as decoupling is a highly localized process. The average fluxes over a given area, important for the surface parameterization of weather and climate numeric models depend on an accurate knowledge of the temporal and spatial patterns of surface decoupling. Observations carried out during LBA indicate that, over deforested regions in the Amazon, there is large nighttime radiative loss, leading to strongly stable temperature stratification, and significant nighttime decoupling. In the present study, we use 7 years of data collected by 9 meteorological stations scattered over the confluence region of the Amazon and Tapajós rivers to infer decoupling occurrence and how it is affected by land use type (forested or clear) and proximity to the rivers. The impact of surface heterogeneity on average regional fluxes is then estimated. Focus is given to the importance of the deforestation and its spatial patterns on the average surface-to atmosphere exchange.

Science Theme:  LC (Land Use and Land Cover Change)

Presentation Type:  Poster

Abstract ID: 108

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