Otto Corrêa Rotunno Filho

Urban climate and clues of heat island events in the metropolitan area of Rio de Janeiro

This paper aims to map the thermal field in the metropolitan region of Rio de Janeiro (MARJ) considering the atmospheric characteristics and the land use that contribute to understanding the urban heat island. Three thermal maps are defined through the use of Landsat5-TM satellite images for three winter events chosen for the decades of 1980, 1990, and 2000, respectively. The results reveal a concentration of warmer cores in urban central areas as well as some local warmer areas in suburban region. Sites with lower temperatures correspond to vegetated areas which are away from the central part of the MARJ, including points of suburban areas. This work emphasizes the importance of the combined analysis of surface temperature with land use and atmospheric conditions, depicting a distinct pattern of heat islands for tropical climate.

A comparison of experimental energy balance components data and SEBAL model results in Dourados, Brazil

The understanding of surface energy flux is important as regards weather and climate models. Therefore, analysis of remotely sensed data, estimation of surface energy balance components (fluxes), validating experiments and results are discussed in this work. Data extracted from NOAA–AVHRR (National Oceanic and Atmospheric Administration–Advanced Very High Resolution Radiometer) satellite images were used to estimate the fluxes based on the SEBAL (Surface Energy Balance for Land) algorithm, as suggested by Bastiaanssen [Bastiaanssen, W.G.M., 1995, Regionalization of surface flux densites and moisture indicators in composite terrain. PhD thesis, Wageningen Agricultural University, The Netherlands.] To validate the results, one wide-ranging field experiment was organized near Dourados, municipality in the Brazilian state of Mato Grosso do Sul, during the summer of 1999. The experiment involved simultaneous taking of satellite images and in-situ measurements. SEBAL results are shown and discussed. The obtained average errors are less than 4%, 6% and 7% for net surface radiation, surface heat and latent flux estimations, respectively, as compared to the in-situ measurements.

Evaluation of six empirical evapotranspiration equations - case study: Campos dos Goytacazes/RJ

The evapotranspiration is a component of the water balance constituting a major challenge in its quantification. The complex physical processes involved in its effective determination on a large scale have spurred scientists to often make use of empirical equations, which have inherent limitations with regard to their applicability as descriptors of the evapotranspiration behavior in different regions across the world. This study was performed for the Campos dos Goytacazes region, in Rio de Janeiro state. It is proposed to investigate and to evaluate the performance of six empirical equations in contrast to FAO56-Penman-Monteith equation. The results indicated that the differences observed between the values obtained using the empirical models applied in this study and the values calculated by the FAO56-Penman-Monteith equation were greater than 10%, which means an error of about 0.5 mm.day-1.

Sharing the knowledge generated during a Water Resources project

This article focuses on the generation of knowledge chains as a way of retaining the knowledge generated during the execution of a water resources project. To create new chains we are making use of the knowledge stored in project tasks, and the ontology technology. The ontology concepts associated with a task are converted into knowledge units, which are filled with all the information related to it. The ontology structure will be used to create the sequence of the knowledge chain that includes the units created. The new chain will be presented and must be validated by the author to be added to the environment knowledge chains base.

Estudo da poluição pontual e difusa na bacia de contribuição do reservatório da usina hidrelétrica de Funil utilizando modelagem espacialmente distribuída em Sistema de Informação Geográfica

Este estudo avaliou o potencial poluidor da bacia de contribuicao do reservatorio de Funil (BCRF), localizado na bacia hidrografica do rio Paraiba do Sul, considerando a geracao da carga de nutrientes, nitrogenio (N) e fosforo (P), por fontes pontuais e difusas, a partir de uma modelagem distribuida utilizando Sistema de Informacao Geografica (SIG). As cargas e concentracoes medias anuais desses nutrientes foram geradas a partir do acoplamento de equacoes empiricas, em SIG, considerando informacoes espaciais de uso e cobertura do solo, populacao residente na bacia e vazao media anual de longo periodo, obtida por equacoes do tipo chuva vazao. Os resultados indicaram que 80% da carga total de nitrogenio foram provenientes de fontes pontuais e 20% de fontes difusas, enquanto que, da carga total de fosforo, 89,1% foram originadas de fontes pontuais e 10,9% de fontes difusas. As concentracoes de nutrientes estimadas pelo modelo empirico apresentaram bons ajustes em relacao aos valores observados de fosforo e de nitrogenio no rio Paraiba do Sul, com R²=0,96 (p<0,01) e R²=0,70 (p<0,01), respectivamente. Dessa forma, o modelo foi capaz de detectar, de forma significativa, a tendencia das variacoes nas concentracoes de nutrientes ao longo de diferentes trechos da BCRF.

Evaluation of atmospheric thermodynamics and dynamics during heavy-rainfall and no-rainfall events in the metropolitan area of Rio de Janeiro, Brazil

Local prediction of thunderstorms is one of the most challenging tasks in weather forecasting due to their high spatiotemporal variability. An improved understanding of such meteorological phenomena, therefore, requires high-frequency measurements along the vertical profile of the atmosphere of interest. In this context, the evaluation of thermodynamic and dynamic parameters obtained from radiosondes to identify atmospheric conditions favorable to thunderstorm and heavy-rainfall development emerges as a valuable tool for investigations of thunderstorms. In this context, four radiosondes were launched to collect a data set for the area of interest at the sub-daily scale (12 UTC, 16 UTC, 18 UTC, and 00 UTC). The collection period encompassed two dates—November 29 and December 12, 2016—chosen specifically due to the existence of heavy-rainfall warnings in the forecast for the Metropolitan Area of Rio de Janeiro, Brazil (“MARJ”) for those days. However, heavy rainfall was registered only for December 12 and not for November 29 (which led us to explore this contrast with the announced rainfall forecasts). Sub-daily radiosonde data showed a clear decrease in atmospheric instability in the early afternoon on November 29. On the other hand, an opposite scenario occurred on December 12, which saw an expressive increase in thermodynamic instability during the day. The meteorological modeling approach used also revealed that the vertical coupling of low-level moisture flux convergence centers and upper-level mass flux divergence centers worked as a dynamic trigger for the thunderstorm and heavy-rainfall developments that took place on December 12, 2016.

A Hydrophysical Database to Develop Pedotransfer Functions for Brazilian Soils: Challenges and Perspectives

Access to soil hydrological data is vital for hydrology projects and for supporting decision-making in issues related to the availability of food and water and the forecasting of phenomena related to geomechanics. Brazil is a country of continental dimensions and has accumulated a significant body of soil information, holding a prominent position in tropical soil science. Nevertheless, a database with hydrophysical information on Brazilian soils has not been compiled so far, whereas much information is registered and analyzed. In this study we discuss the potential for the development of a Brazilian hydrophysical database and pedotransfer functions (PTFs). We present on metadata the measurement methods of soil hydrophysical attributes and the characteristics of the sites where these soil properties were determined. Statistical analyses were performed to characterize the dataset according to the metadata-based data structure. A total of 8,983 datasets contains soil water retention information associated with physical or chemical properties. Besides these, 1,253 datasets with data on saturated hydraulic conductivity coupled with water retention information are also available. The results of this study suggest that it is possible to develop a representative hydrophysical database for Brazilian soils that covers most of Brazil’s federative states, with a substantial volume of data and homogeneous with respect to the methods of measuring soil properties. This creates excellent prospects for PTFs development, especially for estimating water retention, at a national scale. The challenge in the development of the Brazilian soil hydrophysical database is the refinement of the dataset model that can encompass the wide range of available information and can provide answers to queries of interest to different types of users of soil information. Considering the size of the Brazilian territory, it would be of interest that the database development become a joint effort of government agencies, universities and commercial enterprises.

Monitoring Drought in Brazil by Remote Sensing

Drought is a natural phenomena responsible for significant socioeconomic and environmental damage worldwide. Remote sensing techniques can provide high resolution and multitemporal images for drought monitoring and warning systems. In this review, we depict drought definition and its different types and we also demonstrate a set of sensors for global terrestrial monitoring and how they contribute for mapping hydrological variables. Finally, we present a practical example on the use of remote sensing technologies to detect and quantify a recent drought event in Brazil during 2012–2015. Soil moisture data derived from Advanced Microwave Scanning Radiometer (AMSR), vegetation index from Moderate Resolution Imaging Spectroradiometer (MODIS), and total water storage retrieved from Gravimetry Recovery and Climate Experiment (GRACE) was used to estimate impacted areas and region-specific water deficits over Southeastern and Northeastern Brazil. Drought has impacted significantly all of the three remotely sensed variables mentioned above in different degrees for the two studied regions. It was also observed that a positive correlation between monthly time series of GRACE and 16 reservoirs located within Southeastern Brazil varied from 0.42 to 0.82. Differences are mainly explained by reservoir sizes and proximity to the drought nucleus.

Algorithms implementation for land surface temperature estimation based on Landsat data as an indicator of urban heat island

This paper presents a proposal for estimating land surface temperature (LST) for the metropolitan area of Rio de Janeiro (MARJ), Brazil, based on Landsat 5 and 7 data from 1984 to 2010. The main objective is to emphasize the need for greater accuracy in urban heat island studies, overlooking a series of essential steps to retrieve LST as close as possible to the true, including cloud masking techniques, atmospheric correction and surface emissivity.

An empirical study on groupware support for water resources ontology integration

In this paper we discuss groupware support for ontology integration and present an experiment carried out with a group of specialists in the Water Resources domain and in Ontology Engineering. The main goals of this experiment are to create, in a collaborative way, a well-formed ontology for a Water Resources domain and evaluate the ontology integration process. The motivation of our work came from the development of knowledge management and information systems for the hydrological domain, where ontologies can be used as a broker between heterogeneous systems, to facilitate tasks inter-mediation and to help in knowledge storage, being used to publish semantic enriched documents. Since the development of a great ontology has a high cost, ontology re-use becomes an important activity; and consequently, so does the integration process. For this reason, tool support is essential.