Atmospheric surface layer characteristics of turbulence above the Pantanal wetland regarding the similarity theory

Abstract

In this manuscript, some micrometeorological characteristics of the Pantanal are presented. This region, one of the greatest wetlands in the world, is located in the central western part of South America. It has very peculiar environmental and ecological characteristics, a great biodiversity and an irregular hydrological cycle, which often presents floods during the wet season and droughts and fires during the dry season. The experimental data were collected in a meteorological tower during the Interdisciplinary Pantanal Experiment (IPE-1), on April–May 1998. This was a transition period between the wet and the dry season, which a shallow water layer was present at several parts of the experimental field, even around the 25 m-height extended meteorological tower. The surface energy budget components associated with the existence of the shallow water layer, its diurnal variability and some turbulent variables related to the surface–atmosphere turbulent exchange processes were investigated. Eddy-correlation and variance methods have been used to estimate turbulent fluxes and to study the validity of the Monin–Obukhov similarity theory for the Pantanal region. A mixed layer slab model has been used to estimate the height of the turbulent mixing-layer and to provide useful information to test the validity of general relationships concerning horizontal wind velocity variances above Pantanal. In general, the dimensionless relationships between turbulent variables and scaling parameters agree well with the ones found in the literature. Some aspects regarding the heat storage in the shallow water layer present interesting information about its role in the surface–atmosphere energy exchanges processes along the day.