Pablo E. S. Oliveira

The Influence of Submeso Processes on Stable Boundary Layer Similarity Relationships

AbstractPrevious observational studies in the stable boundary layer diverge appreciably on the values of dimensionless ratios between turbulence-related quantities and on their stability dependence. In the present study, the hypothesis that such variability is caused by the influence of locally dependent nonturbulent processes, referred to as submeso, is tested and confirmed. This is done using six datasets collected at sites with different surface coverage. The time-scale dependence of wind components and temperature fluctuations is presented using the multiresolution decomposition, which allows the identification of the turbulence and submeso contributions to spectra and cospectra. In the submeso range, the spectra of turbulence kinetic energy range increases exponentially with time scale. The exponent decreases with the magnitude of the turbulent fluctuations at a similar manner at all sites. This fact is used to determine the smaller time scale with relevant influence of submeso processes and a ratio ...

Nocturnal Intermittent Coupling Between the Interior of a Pine Forest and the Air Above It

A 1-year set of measurements of CO2 and energy turbulent fluxes above and within a 25-m pine forest in southern Brazil is analyzed. The study focuses on the coupling state between two levels and its impact on flux determination by the eddy-covariance method. The turbulent series are split in their typical temporal scales using the multiresolution decomposition, a method that allows proper identification of the time scales of the turbulent events. Initially, four case studies are presented: a continually turbulent, a continually calm, a calm then turbulent, and an intermittent night. During transitions from calm to turbulent, large scalar fluxes of opposing signs occur at both levels, suggesting the transference of air accumulated in the canopy during the stagnant period both upwards and downwards. Average fluxes are shown for the entire period as a function of turbulence intensity and a canopy Richardson number, used as an indicator of the canopy coupling state. Above the canopy, CO2 and sensible heat fluxes decrease in magnitude both at the neutral and at the very stable limit, while below the canopy they increase monotonically with the canopy Richardson number. Latent heat fluxes decrease at both levels as the canopy air becomes more stable. The average temporal scales of the turbulent fluxes at both levels approach each other in neutral conditions, indicating that the levels are coupled in that case. Average CO2 fluxes during turbulent periods that succeed very calm ones are appreciably larger than the overall average above the canopy and smaller than the average or negative within the canopy, indicating that the transfer of air accumulated during calm portions at later turbulent intervals affects the flux average. The implications of this process for mean flux determination are discussed.

Monitoring the micrometeorology of a coastal site next to a thermal power plant from the surface to 140 m

AbstractA 140-m micrometeorological tower has been operating since August 2016 at 4 km from the coastline and 250 m from a thermal power plant that releases heat from its 20-m stacks in southeaster...

ESTUDO DA TURBULÊNCIA ATMOSFÉRICA NOTURNA SOBRE COXILHAS (ESTÂNCIA). PARTE 2: RESULTADOS PRELIMINARES

Uma campanha micrometeorologica foi conduzida nos meses de agosto e setembro de 2013 com o objetivo de identificar padroes de variabilidade espacial de variaveis meteorologicas em noites de pouco vento, em escalas horizontais de centenas de metros. Neste trabalho, alguns resultados preliminares sao apresentados.

Quasi-Experimental Determination of Turbulent Dispersion Parameters for Different Stability Conditions from a Tall Micrometeorological Tower

AbstractTurbulent wind data measured by sonic anemometers installed at various heights on a 140-m-tall micrometeorological tower located at a coastal site are used to obtain vertical profiles of th...

ANALISYS OF ATMOSPHERIC TURBULENCE IN THE NOCTURNAL BOUNDARY LAYER OVER THE AMAZON RAIN FOREST

In this study, turbulence data taken in different vertical levels in the Amazon rain forest are analyzed for two distinct nights: a night characterized by intense turbulent mixing, and a night which turbulence was intermittent. This is done using the multiresolution decomposition, which allows the identification of the turbulence and submeso contributions to spectra and cospectra.

COMPARATIVE ANALYSIS OF WATER AND THERMAL REGIME OF TWO EXPERIMENTAL SITES IN PAMPA

In the last 15-20 years has greatly increased research on the problem of climate change, necessitating a demand for reliable measurements of absorption and emission of carbon dioxide, methane, as well as the impact on water resources. In the biome Pampa are the largest continuous natural field extensions, requiring a monitoring of water and temperature regime on the ground. The water content of the soil has spatial and temporal variability affecting many hydrological processes and determining this is needed since the soil store and provide the water and nutrients for the plants, thus involving relationships water-soil-plant-atmosphere. In this work, we compared the water content behavior of the soil at depths of 10, 30 and 50 cm, the temperature of the soil at depths of 5, 15 and 30 cm, heat flux in soil installed 10 cm deep and the thermal conductivity was determined in two experimental sites in the Pampa biome, for the period 01.01.2015 to 06.31.2015. It was found that there are differences between the sites in the capacity to retain moisture in the soil and in the ability to store energy in the soil for the study period.

INVESTIGAÇÕES SOBRE O VENTO NORTE NA REGIÃO CENTRAL DO RIO GRANDE DO SUL UTILIZANDO UMA MICRO-REDE DE ESTAÇÕES METEOROLÓGICAS

The North Wind, a phenomenon characterized by intense winds in the central region of Rio Grande do Sul state, Brazil, was investigated using data from a meteorological stations’ micro-web.

QUANTIFICAÇÃO DA INTERMITÊNCIA NA CAMADA LIMITE ESTÁVEL EM UM SÍTIO EXPERIMENTAL NA FLORESTA AMAZÔNICA

O proposito do presente trabalho e utilizar um metodo de determinacao de intermitencia e quantificar como esta afeta as series de temperatura e CO 2 . Tais analises sao feitas para um sitio especifico na regiao Amazonica.

MODELANDO O ESCOAMENTO ATMOSFÉRICO NOTURNO EM UMA REGIÃO DE FLORESTA

Neste trabalho, um modelo simplificado e utilizado para simular o comportamento da turbulencia na camada limite noturna em uma regiao de floresta. Apesar das simplificacoes inicialmente impostas, o modelo e capaz de reproduzir alguns aspectos do escoamento atmosferico, em condicoes estaveis, tais como o acoplamento atmosferico e a intermitencia.