Analysis of errors in solar heating rate calculations with broadband radiation codes in cloud layers
The accuracy of broadband radiation codes for models is less studied for cloudy atmosphere than for cloud- free atmosphere. In this study, various test cases are proposed for atmosphere with clouds. The calculations of the heating rate (HR) profiles were made for 15 cloudy test cases with vertical r...
por Portal Padrão
publicado
26/08/2009
1:20 PM
Filtragem de momentum por escala pelo dossel da floresta amazônica
São utilizados dados de velocidade do vento obtidos por anemômetros dispostos verticalmente em uma torre de 60m na Rebio- Jarú, RO, projeto LBA. O objetivo foi de analisar as características da filtragem de momentum por escala pelo dossel da floresta amazônica. Aplicou-se a ondeleta de Morlet ...
por Portal Padrão
publicado
26/08/2009
1:19 PM
High-speed video observations of positive ground flashes produced by intracloud lightning
High-speed video recordings of two lightning flashes confirm that positive cloud-to-ground (CG) strokes can be produced by extensive horizontal intracloud (IC) discharges within and near the cloud base. These recordings constitute the first observations of CG leaders emanating from IC discharges of ...
por Portal Padrão
publicado
26/08/2009
1:18 PM
Archaeological mounds in Marajó Island in northern Brazil: a geological perspective integrating remote sensing and sedimentology
Earthen mounds with archaeological artifacts have been well known in Marajó Island since the 19th century. Their documented dimensions are impressive, e.g., up to 20 m high, and with areas as large as 90 ha. The mounds, locally known as tesos, impose a significant relief on the very low-lying lands...
por Portal Padrão
publicado
26/08/2009
1:17 PM
Patterns of water and heat flux across a biome gradient from tropical forest to savanna in Brazil
We investigated the seasonal patterns of water vapor and sensible heat flux along a tropical biome gradient from forest to savanna. We analyzed data from a network of flux towers in Brazil that were operated within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA). These tower sites ...
por Portal Padrão
publicado
26/08/2009
1:16 PM
Trends in the sources and sinks of carbon dioxide
Efforts to control climate change require the stabilization of atmospheric CO(2) concentrations. This can only be achieved through a drastic reduction of global CO(2) emissions. Yet fossil fuel emissions increased by 29% between 2000 and 2008, in conjunction with increased contributions from emergin...
por Portal Padrão
publicado
26/08/2009
1:16 PM
Tipping points for the Amazon forest
The stability of the Amazon forestclimate equilibrium is being perturbed by a number of human drivers of change (e.g. deforestation, global warming, forest fires, higher CO2 concentrations, and increased frequency of droughts and floods). Quantitative assessments for the maintenance of the tropical ...
por Portal Padrão
publicado
26/08/2009
1:15 PM
Dynamical coupling of multiscale land change models modelling, Amazonia: deforestation models
No single model or scale can fully capture the causes of land change. For a given region, land changes may have different impacts at different places. Limits and opportunities imposed by biophysical and socio-economic conditions, such as local policies and accessibility, may induce distinct land cha...
por Portal Padrão
publicado
26/08/2009
1:14 PM
Meteorological downscaling methods and artificial neural network models
The mathematical models used to simulate the present climate and project future climate when forced by greenhouse gases and aerosols are generally referred to as General Circulation Models (GCMs). While they have demonstrated significant skill in the continental and hemispherical scales and incorpor...
por Portal Padrão
publicado
26/08/2009
1:13 PM
Future change of temperature and precipitation extremes in South America as derived from the PRECIS regional climate modeling system
Using the PRECIS regional climate modeling system this study analyses the distribution of extremes of temperature and precipitation in South America in the recent past (19611990) and in a future (20712100) climate under the IPCC SRES A2 and B2 emissions scenarios. The results show that for the prese...
por Portal Padrão
publicado
26/08/2009
1:12 PM
Tropical South America east of the Andes
Most of tropical South America east of the Andes and south of 23°S experienced a warm 2008, with annual mean temperatures 2° to 3°C warmer than normal. Likewise, warm conditions (1° to 2°C above normal) were observed in northern Venezuela, interior Brazil between Amazonia and Northeast Brazil, ...
por Portal Padrão
publicado
26/08/2009
1:10 PM
Long-term trends and cycles in the hydrometeorology of the Amazon basin since the late 1920s
Rainfall and river indices for both the northern and southern Amazon were used to identify and explore long-term climate variability on the region. From a statistical analysis of the hydrometeorological series, it is concluded that no systematic unidirectional long-term trends towards drier or wette...
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