Franciano Scremin Puhales

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 ...

Derivation of third-order vertical velocity turbulence moment in the convective boundary layer from large eddy simulation data: an application to the dispersion modeling

A new formulation for the vertical turbulent velocity third statistical moment in a convective boundary layer is proposed. The parameterization is based directly on the definition of this higher order moment, with velocity skewness and variance being calculated from large eddy simulation data. The formulation, included in a Lagrangian stochastic dispersion model, has been tested and compared with expressions for the third moment obtained from experimental data and reported in the literature, using concentration data from field experiments. The application of a statistical evaluation shows that the proposed parameterization has one of the best overall adjustments to the data.

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...

Evaluation of Nocturnal Temperature Forecasts Provided by the Weather Research and Forecast Model for Different Stability Regimes and Terrain Characteristics

The quality of nocturnal temperature forecasts made by the Weather Research and Forecast (WRF) numerical model is evaluated. The model was run for all July 2012 nights, and temperature fields compared to hourly observations made at 26 weather stations in southern Brazil. Four different planetary boundary-layer (PBL) schemes are considered: Bougeault–Lacarrere (BouLac), Quasi-Normal Scale Elimination (QNSE), Yonsei University (YSU) and Mellor–Yamada–Janjic (MYJ). Additional simulations to assess the role of higher horizontal and vertical resolutions were performed using the MYJ scheme. All schemes, except BouLac, underestimated the 2-m temperature, and in all cases the temperature bias is dependent on wind speed. At high wind speeds, all schemes exhibit a cold bias, which is greater for those that yield lower nocturnal surface-layer turbulent intensity. The elevation difference between each station and the model nearest grid point

MULTI-LAYER ATMOSPHERIC ANALYSIS DURING SNOW EPISODES IN SOUTHERN BRAZIL

H_{\textit{station}} -H_{\textit{gridpoint}}

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

Hstation-Hgridpoint is highly correlated with the temperature simulation error. We found that a consistent cold bias is restricted to conditions with low-level clouds. We concluded that one possible means of improving nocturnal temperature forecast is to use parametrization schemes that allow for higher turbulent intensity in near-neutral conditions. The results indicate that this improvement would partially counteract the misrepresentation of the low-level cloud cover. In most stable cases, a post-processing algorithm based on terrain characteristics may improve the forecasts.

APPLICATION OF THE HILBERT-HUANG TRANSFORM IN VELOCITY DATA MEASURED IN WIND TUNNEL

Wind power is currently one of the sources of electricity the fastest growing worldwide. However, especially in Brazil, it is still very difficult to locate areas with reliable winds for the implementation of a wind farm, because there is not enough data density that guarante the wind farm efficiency. Thus, the development of models that simulate wind conditions are extremely important for studies and research in this area. In this way, weather reanalysis data can be used as input into high-resolution regional models, for example. Therefore, this work presents a study comparing two sets of weather Reanalysis of wind data - ERA-Interim and CFSR - with measured data from automated weather stations of the National Institute of Meteorology in the Rio Grande do Sul state in order to obtain the coefficient correlation of data from reanalysis with data measured for each measurement point and for every season. For better visualization of the correlation results, it is also built contour maps with correlation coefficient where can be seeing that the best performance of the CFSR reanalysis.

EVALUATION OF DIFFERENT BOUNDARY LAYER SCHEMES FOR FOG EVENTS SIMULATION AND FORECASTING IN RIO GRANDE DO SUL

A climatology for thickness, temperature, absolute and relative humidities, and vertically-integrated water vapor is presented for a number of distinct atmospheric layers during snow episodes reported in Southern Brazil from January 1979 to March 2011, totaling 64 events. Data from “The Climate Forecast System Reanalysis” (CFSR) were used in the analysis of aforementioned variables for the following atmospheric layers: 850-1000 hPa, 7001000 hPa, 500-1000 hPa, and 700-850 hPa. The snow episodes were subdivided into three sets according to the local surface elevation. The thicknesses of the atmospheric layers found for the snow events in southern Brazil were considerably deeper than the corresponding ones documented in the literature for North America. In addition, analysis of the vertical distribution of water vapor, temperature and relative humidity in the lower troposphere indicated that the atmospheric layer with favorable conditions to snow production is relatively shallow, being below 850hPa. Moreover, the threshold value of thickness for the 850-1000h Palayer during snow occurrence in southern Brazil was around 133 dam, being considerably higher than its counterpart value documented for North America, highlighting the role played by the local topography in setting the conditions that are favorable for snow occurrence in Brazil.