Navegando por Assunto "Atmosfera"

Agora exibindo 1 - 5 de 5

Acesso aberto (Open Access)
Classificação climatológica da energia potencial disponível para a convecção na cidade de Belém-PA
(Universidade Federal do Pará, 2014-12) SANTOS, Josiane Sarmento dos; MOTA, Maria Aurora Santos da; ROCHA, Edson José Paulino da
The climatological classification of the Convection Available Potential Energy (CAPE) was studied in order to verify both the possibility of convection to start and the organizational type, in Belém (Pará - PA, Brazil), associating it to extreme precipitation events (EEPRP). For the CAPE analysis, DTCEA's radiosonde data and precipitation measurements from the INMET's stations, in the period from 1987 to 2011, we used. It was observed that the local atmosphere presented favorable conditions for the development of deep convection, because the most frequent CAPE values were higher than 1000 J/Kg, representing 61% of all radiosonde measurements. According to some authors, a CAPE value of 1000J/Kg is the deep convection limit. The CAPE 2 and 3 classifications presented significant increasing tendencies along the years, whereas CAPE 1 showed a decrease. This is probably due to the air temperature increased at the city, impacting the CAPE value. A low correlation between CAPE and EEPRP, as well as between CAPE and Pacific Ocean Index and the Atlantic Interhemispheric Gradient. was also shown. Therefore CAPE is not sufficient condition for the formation of clouds and precipitation, since meso and large scale dynamical forcing are relevant contributors to the climate modulation on the city.
Acesso aberto (Open Access)
Elementos traço em material particulado atmosférico de uma região agroindustrial do sudeste do Brasil
(2013) OLIVEIRA, Patrícia Lopes de; FIGUEIREDO, Bernardino Ribeiro; CARDOSO, Arnaldo Alves; ANGÉLICA, Rômulo Simões
Trace element concentrations were measured in atmospheric particulate matter collected in 2009 and 2010, in a Brazilian region influenced by pre-harvest burning of sugar cane crops. For coarse particles, high concentrations of Al, Fe, K and Ca suggested that re-suspended soil dust was the main source of aerosol trace elements, subsequently confirmed by XRD analysis. High levels of K, Zn, As, Cd and Pb were found in fine particles, confirming the contribution of biomass burning and vehicle emissions, whereas Na, Al, K, Fe and Zn were the representative elements in ultrafine particles, influenced by a diversity of sources.
Acesso aberto (Open Access)
Importância das condições termodinâmicas nos eventos extremos de precipitação na cidade de Belém e região metropolitana
(Universidade Federal do Pará, 2014-12) GILLE, Felipe do Souto de Sá; MOTA, Maria Aurora Santos da
The purpose of this research was to verify the importance of thermodynamic factors on the occurrence of extreme precipitation events in the city of Belém (PA) and its metropolitan area, during the period of August 2008 to December 2009. The study of the atmosphere thermodynamics was based on the theories of Convective Available Potential Energy (CAPE) and Convective Inhibition Energy (CINE). To classify the extreme precipitation events the decis method was used in order to associate them to the CAPE and CINE values. It was verified that the studied region has strong convective activity during all the year, and that not always high CAPE and low CINE determine precipitation. Those situations in fact determine profound convection, but to ensure precipitation, dynamic enforcement is required. For the occurrence of extreme precipitation events during the rainy season the ITCZ is the forcing dynamic and during the dry season the squall lines contribute to them. Then when the precipitation process is exclusively CAPE dependent, a high CAPE value is required in order to generate deep convection and, consequently, precipitation. Otherwise, for dynamic contribution precipitating process a significant value of CAPE is not needed.
Acesso aberto (Open Access)
Interações entre nuvens, chuvas e a biosfera na Amazônia
(Instituto Nacional de Pesquisas da Amazônia, 2005-06) DIAS, Maria Assunção Faus da Silva; COHEN, Júlia Clarinda Paiva; GANDU, Adilson Wagner
A review of results obtained within the Physical Climate component of LBA with respect to the interaction between the biosphere and cloud and rain formation in the Amazon Basin, in different seasons and different regions within the Basin is presented. The deforestation effect and the effect of biomass burning are discussed and the physical processes highlighted based on the data collected in several LBA intensive field campaigns. The complex interactions and the progress in the understanding their evolution based on the new datasets is presented.
Acesso aberto (Open Access)
Transpiração em espécie de grande porte na Floresta Nacional de Caxiuanã, Pará
(2007-04) COSTA, Rafael Ferreira da; SILVA, Vicente de Paulo Rodrigues da; RUIVO, Maria de Lourdes Pinheiro; MEIR, Patrick; COSTA, Antonio Carlos Lôla da; MALHI, Yadvinder Singh; BRAGA, Alan Pantoja; GONÇALVES, Paulo Henrique Lopes; SILVA JUNIOR, João de Athaydes
During the “Long-term of impact drought on water and carbon dioxide fluxes in Amazonian Tropical Rainforest Experiment” (ESECAFLOR), this study was carried out, which is a subproject of Large Scale Biosphere Atmosphere Experiment in Amazônia (LBA), located in the Ferreira Penna Scientific Station (FPSS) in the Caxiuanã National Forest (CNF) in Pará State (1o 42’ 30’’ S; 51o 31’45’’ W; 62 m altitude). The region has a well-preserved forest, with canopy of 35 m. The predominate tree species in the landscape are Eschweilera coriacea (White Matá-matá), Voucapoua americana (Acapu) and Protium pallidum (White Pitch). Sap flow measurements were made in the wet season (03-16 December 2000 and 12-25 January 2003), to evidence the effect of long term induced drought, aiming to determinate the transpiration of Eschweilera coriacea. The ESECAFLOR site consists of two different areas with 1 ha each. Plot A (control) and Plot B (rainfall exclusion). The Trunk Heat Balance (THB)method was applied to sap flow measurements, by Sap Flow Meter P4.1 system. Between analysed periods, the mean transpiration of E. Coriacea increased 56% in the tree A237 (control plot) and decreased 68% in B381 (drought plot)