Reciclagem de precipitação na Amazônia: clima presente e cenários futuros
The objective of this work is to assess the spatiotemporal distribution of water budget components and precipitation recycling in the Amazon basin for the present climate, through an observational study using the ECMWF (Era-Interim) reanalysis for period 1980-2005, and impacts in future scenarios us...
| Autor principal: | Rocha, Vinícius Machado |
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| Grau: | Tese |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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| Assuntos: | |
| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/12678 http://lattes.cnpq.br/7236768567156050 |
| Resumo: |
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The objective of this work is to assess the spatiotemporal distribution of water budget
components and precipitation recycling in the Amazon basin for the present climate, through
an observational study using the ECMWF (Era-Interim) reanalysis for period 1980-2005, and
impacts in future scenarios using the Eta Regional Climate Model forced by RCP 8.5
emissions scenario from the HadGEM2-ES earth system model. To estimate precipitation
recycling were adopted methods based on the atmosphere moisture balance. In general, the
observational study with the ECMWF reanalysis showed that, the Amazon basin acts as a sink
for atmospheric moisture receiving water vapor transported from the ocean and from
precipitation recycled from evapotranspiration by the forest. At the regional scale, the
Amazon basin is an important source of water vapor, contributing to precipitation in other
remote locations of South America. On average, precipitation recycling in the Amazon basin
is 20%, approximately, varying between 10-15% in the northern portion and 40-50% in the
southern portion. Thus, 20% of the total rainfall in the basin is derived from local
evapotranspiration processes indicating that the local contribution to the total precipitation
represents a significant contribution to the regional water budget and plays an important role
in the Amazon water cycle. In the Amazon basin, on average, advection processes are more
important for precipitation while local evapotranspiration processes play a more important
role in the precipitation regime in the southern portion of the basin. Considering the EtaHadGEM2-ES model simulation for the present climate (without the RCP 8.5 emissions
scenario), on average, precipitation recycling in the Amazon basin is 22%, with spatial and
seasonal variation, and more intense recycling in the southern Amazon (27%). The changes
projected for future climate show that the impacts on the water budget components were more
significant during the rainy season and southern basin sector, especially at the end of the 21 st
century. The positive feedback mechanism is configured during the austral summer and on
average annually, i.e., the reduction of moisture convergence (due to change the
thermodynamic structure of the atmosphere and regional circulation patterns) and surface
evapotranspiration acted in the same way to reduce total precipitation. The negative feedback
mechanism is seen during the austral winter, where the reduction of evapotranspiration is
partially offset by the increase in moisture convergence, however, not sufficient to offset the
reduction in precipitation. The reduction in total precipitation in the Amazon was due to both
the decrease of local and advective precipitation, but the advective had a major role due to
changes in the regional circulation and moisture transport over the basin. In general, the
reduction of precipitation recycling in the Amazon was predicted to be more pronounced in
the dry season, reaching 40% at the end of the 21 st century, and was directly influenced by the
reduction in surface evaporation, but was primarily driven by enhancing the moisture
transport over the basin. However, the change in recycling is higher in the southern Amazon –
a reduction of around 50% in the dry season at the end of the century. The results suggest that
climate change due to increased greenhouse effects can significantly affect the components of
the water budget and precipitation recycling in the Amazon basin, resulting in serious
ecological consequences for the biome, such as affecting ecosystem dynamics, reduction in
the forest's ability to absorb carbon from the atmosphere, causing the occurrence of extreme
events (drought and flooding), increasing the surface temperature, and hence, the frequency
and intensity of fires. |