Navegando por Assunto "Tempestades"

Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Condições termodinâmicas de eventos de precipitação extrema em Belém-PA durante a estação chuvosa
(2012-07) TAVARES, João Paulo Nardin; MOTA, Maria Aurora Santos da
The thermodynamic conditions from any region are very important to the development of the deep, moist convection, mainly in the tropical region. Therefore, the aim of this work was to understand and characterize the role of atmospheric thermodynamic conditions during extreme rainfall events in the rainy season, in Belém (PA, Brazil). The results show that the extreme rainfall, in their majority (56%) present a pre-storm environment with strong instability, indicated by the CAPE high values (above 1000 J/kg) and meaningful values of the instability indexes. There was, however, events with low values of CAPE in the 1200 UTC sounding at the day of the event, but larger values in the day before, which indicates that the rain in question may have begun in the early hours and have last for several hours, crossing the time of the sounding, explaining the decrease of this parameter. The K, TT and LI instability indexes showed a close representation of the environment, predicting storms with heavy rainfall with 74% of correct identification, if taken into account the events on which all indexes showed the same indication of strong instability. Therefore, thermodynamic conditions of strong instability may lead to storms, but are not the only responsible factors for convective storms with extreme rainfall
Acesso aberto (Open Access)
Electric systems failures produced by CG lightning in Eastern Amazonia
(Universidade Federal do Pará, 2014-12) SANTOS, Ana Paula Paes dos; SOUZA, José Ricardo Santos de; SOUZA, Everaldo Barreiros de; CARMO, Alexandre Melo Casseb do; RIBEIRO, Wanda Maria do Nascimento
Operational records of power outages of the electric energy distribution systems in eastern Amazonia presented a large number of events attributed to lightning strikes, during the 2006 to 2009 period. The regional electricity concessionary data were compared to actual lightning observations made by SIPAM’s LDN system, over two areas where operational sub systems of transmission lines are installed. Statistical relations were drawn between the monthly lightning occurrence density and the number of power outages of the electric systems for both areas studied. The results showed that, although with some delays between these variables peaks, the number of power disruptions has a tendency to follow the behavior of the lightning occurrence densities variations. The numerical correlations were positive and may be useful to the transmission lines maintenance crews at least for the Belém-Castanhal electricity distribution sub system. Evidence was found, that the SST’s over certain areas of the Pacific and Atlantic Oceans, influence convection over the area of interest, and may help to prognosticate the periods of intense electric storms, requiring repair readiness for the regional electric systems.
Acesso aberto (Open Access)
Lightning and precipitation produced by severe weather systems over Belém, Brazil
(2014-12) RIBEIRO, Wanda Maria do Nascimento; SOUZA, José Ricardo Santos de; LOPES, Marcio Nirlando Gomes; CÂMARA, Renata Kelen Cardoso; ROCHA, Edson José Paulino da; ALMEIDA, Arthur da Costa
CG Lightning flashes events monitored by a LDN of the Amazon Protection System, which included 12 LPATS IV VAISALA sensors distributed over eastern Amazonia, were analyzed during four severe rainstorm occurrences in Belem-PA-Brazil, in the 2006-2007 period. These selected case studies referred to rainfall events, which produced more than 25 mm/hour, or more than 40 mm/ 2 hours of precipitation rate totals, registered by a tipping bucket automatic high-resolution rain gauge, located at 1º 47' 53" S and 48º 30' 16" W. Centered at this location, a 30 ,10 and 5 km radius circles were drawn by means of a geographic information system, and the data from lightning occurrences within this larger area, were set apart for analysis. During these severe storms the CG lightning events, occurred almost randomly over the surrounding defined circle, previously covered by mesoscale convective systems, for all cases studied. This work also showed that the interaction between large-scale and mesoscale weather conditions have a major influence on the intensity of the storms studied cases. In addition to the enhancement of the lightning and precipitation rates, the electric activity within the larger circles can precede the rainfall at central point of the areas.
Acesso aberto (Open Access)
Tempestades severas na Região Metropolitana de Belém: avaliação das condições termodinâmicas e impactos sócio-econômicos
(Universidade Federal do Pará, 2009-04-17) TAVARES, João Paulo Nardin; MOTA, Maria Aurora Santos da; http://lattes.cnpq.br/5817549281617240
The region of Belém, capital of the state of Pará, is a location vulnerable to the impact of storms during the year. The heavy rains bring problems to the population, as the flooding of streets and houses, disruption in the power supply and telecommunications, health problems, transportation, and in some cases, even death. This research sought to answer the following questions: What are the mechanisms that cause extreme events of precipitation in the rainy season and dry season? Are the thermodynamic instability indexes appropriated for predicting storms and heavy rain in the region? Is the effect of "Heat Island" affecting the convection in the city, causing an increase in the number and intensity of storms? What is the behavior of extreme events in years of El Niño and La Niña? What are the main social-economic impacts from the storms? Studying basically a time series of daily rainfall, data from soundings and reports published in local newspapers about the damage caused by storms, is that we tried to answer such questions. The results show that, in general, the Convective Available Potential Energy (CAPE) for extreme events in the dry season is greater than in rainy season, because the precipitation in the dry season is very much dependent on the thermodynamic forcing, then, to occur, there must be forcing of a mesoscale (instability line) and the CAPE and the indexes of instability must be very high. In the rainy season extreme precipitation is caused by the interaction between scales, the forcing dynamics (intertropical convergence zone) and thermodynamic forcing, in some cases into the interaction of the mesoscale forcings. The results are huge losses to the population. The data analysis of soundings shows that the indexes of instability are suitable for the rainy season and should be changed to the dry season, but may provide a subsidy for development of regional models, and when analyzed together with CAPE, satellite images and observations of wind field, makes possible the forecast of severe storms, helping decision-makers bodies.