Estimativa do Footprint de Torres em Área de Platô e baixio na Reserva Cuieiras, Amazônia Central

Estimativa do footprint de torres em área de platô e baixiona Reserva Cuieiras, Amazônia Centra

Reactive and Non-Reactive Trace gas Exchange Within and Above an Amazonian Rainforest

In 2011 the currently highest atmospheric research tower of Amazonia was erected at the ATTO site (02°08’38,8’’S, 58°59’59,5’’W) (whereas ATTO stands for Amazon Tall Tower Observatory), which is monitoring concentration gradients regarding 5 trace gases (H2O, CO2, O3, NO, NO2) from 8 different heights between 0,05 m and 79,3 m, which enables the possibility to get new results regarding transport processes in and above the canopy. Never before there have been made profile measurements up to that height in the Amazonian rainforest.

Direct evidence for phosphorus limitation on Amazon forest productivity

The productivity of rainforests growing on highly weathered tropical soils is expected to be limited by phosphorus availability1. Yet, controlled fertilization experiments have been unable to demonstrate a dominant role for phosphorus in controlling tropical forest net primary productivity. Recent syntheses have demonstrated that responses to nitrogen addition are as large as to phosphorus2, and adaptations to low phosphorus availability appear to enable net primary productivity to be maintained across major soil phosphorus gradients3. Thus, the extent to which phosphorus availability limits tropical forest productivity is highly uncertain. The majority of the Amazonia, however, is characterized by soils that are more depleted in phosphorus than those in which most tropical fertilization experiments have taken place2. Thus, we established a phosphorus, nitrogen and base cation addition experiment in an old growth Amazon rainforest, with a low soil phosphorus content that is representative of approximately 60% of the Amazon basin. Here we show that net primary productivity increased exclusively with phosphorus addition. After 2 years, strong responses were observed in fine root (+29%) and canopy productivity (+19%), but not stem growth. The direct evidence of phosphorus limitation of net primary productivity suggests that phosphorus availability may restrict Amazon forest responses to CO2 fertilization4, with major implications for future carbon sequestration and forest resilience to climate change

A simulation of Amazonian deforestation using a GCM calibrated with ABRACOS and ARME data

As parametrizações dos processos de superfície usadas nos MCGA (Modelos de Circulação Geral da Atmosfera) foram bastante aprimoradas na última década, com a inclusão de uma representação explícita da vegetação e dos processos físicos relacionados a ela. No CNRM (Météo-France) um novo esquema, chamado de esquema ISBA (Interações entre Solo, Biosfera e Atmosfera) desenvolvido por Noilhan e Planton (1989), foi implementado no AGCM Espectral EMERAUDE (Manzi e Planton, 1994). Este acoplamento ISBNAGCM é uma ferramenta poderosa para se investigar mudanças de origem natural e antropogênica nas superfícies continentais, como os processos de desertificação ou desmatamento. Neste artigo são apresentados resultados de uma simulação de desmatamento de 4 anos sobre a Amazônia, onde a floresta tropical chuvosa natural e as savanasde uma extensa área da América do Sul foram substituídas por pastagens degradadas. O esquema ISBA foi testado cuidadosamente usando dados dos experimentos observacionais ARME (Experimento Micrometeorológico da Região Amazônica) e ABRACOS, respectivamente, para floresta e pastagem. A simulação com a Amazônia desmatada mostrou um enfraquecimento do ciclo hidrológico e uma amplificação do ciclo diurno da temperatura de superfície quando comparada com a simulação de controle. Um estudo de sensitividade mostrou a grande importância do albedo de superfície e do comportamento da rugosidade na resposta ao desmatamento.Pages: 505-52

Implementation of the ISBA parametrization sheme for land surface processes in a GCM an annual cycle experiment

A parameterization scheme for the Interactions between Soil Biosphere and Atmo- sphere (ISBA), is implemented in the French Spectral General Circulation Model (GCM) Emeraude. ISBA represents surface physical processes including the variability of soil hydrological properties and the influence of vegetation cover on the exchanges between the soil/ cover system and the atmosphere. This paper describes briefiy the scheme and the chosen method to define the parameters at the GCM grid scale. Two annual cycles carried out with and without ISBA are compared with special emphasis given to the simulation of the Amazon Basin region. It is found that the model response to the new scheme is mainly regional, changes at the global scale being explained for the most part by albedo changes. The results over the Amazon forest with the new scheme are in general agreement both with similar numerical experiments performed with other GCM, and with available data set collected in this region. The impact of the scheme on the simulated surface fields also point out some interaction mechanisms associating surface processes, convection, and radiation through the representation of convective cloudiness. The characteristic times of the soil moisture initialization are also examined according to the variability of soil and vegetation types. It is found that the most rapid adjustment time is mainly textural dependent as the response time related to the water transfer into the soil is mainly dependent on moisture conditions. Vegetation cover also introduces a lag time in the adjustment process due to the interception of precipitation.Pages: 1-3

Implementation of a soil-vegetation transfer scheme in an atmospheric general circulation model

A new land surface parameterization scheme designed for climate and mesoscale models has recently been developed at the CNRM(METEO-FRANCE). This scheme (1) reproduces a dependence of water and heat transfers into the soil upon their water content and texture. The main physical processes linked to vegetation are also reproduced such as interception of precipitation by the canopy or transpiration of plants that is modulated by a surface resistance. This scheme has first been tested in an atmospheric mesoscale model on the HAPEX-MOBILHY experiment data set that took piare in southwestern France in 1986 (2). It Was recently included in the spectral French AGCM EMERAUDE in arder to carry out climatic simulations, particularly impact experiments of deforestation over tropical regions.Pages: 955-95

Climatic impact os tropical deforestation simulations

Two Amazonian deforestation simulation experimenta have been performed with the French spectral GCM EMERAUDE coupled wlth the ISBA land surface parameterisations of Noilhan and Planton (1989). The deep convection scheme ot Bouqeault (1985) was used in the first experiment while the Ruo scheme (1965, 1974), includinq the modifications of Geleyn (1985), was used in the second one. For each experiment the model was inteqrated with the original soil and veqetation types from the classification of Wilson and Henderson-Sellers (1985) in the contraI case (ctrl). In the deforested case (def) a hypothetical qrass land cover replaced the rainforest over a larqe surface over the Amazonian reqion. The main ISBA parameters for forest and qrass land are respectively: albedo 12.5t and 19ti rouqhness lenqth 2 m and 6 cmi active soil column depth 4 m and 2 mi and minimum surface resistance 42 sim and 75 sim. The initial soil water content used are that from Mintz and Seratini (1989) climatoloqy for a mid-Cecember situation. The precipitation pattern obtained with the Kuo scheme seems in better aqreement with the climatoloqy over the South America continent than that obtained with the Bouqeault one. Over the deforested reqion the precipitation decreases, followinq the decreased evapotranspiration, when the Kuo scheme is used while the humidity converqence, of about 50t of precipitation, remains unchanqed. An increase of precipitation resulta from the deforestation when the Bouqeault scheme is used as a consequence of the increased humidity converqence. The impact ot the increased albedo is compensated by a decreased cloudiness in both simulations. The resulted averaqed surface temperatura remains almost unchanqed, althouqh the daily temperature amplitude is larqer in the def experimento This increased daily temperatura amplitude may be explained by the decreased rouqhness lenqth. An increased runoff resulta from the lower soil water capacity.Pages: 37

Performance dos modelos operacinais de previsao numerica de tempo do CPTEC/INPE na previsao da radiacao solar e terrestre em diferentes sitios na regiao Amazonica

O estudo da interação da radiação solar com uma superfície vegetada, ainda é um campo de estudo relativamente novo e complexo o qual exige o entendimento dos fenômenos físicos e fisiológicos que ocorrem em uma área vegetada (Moura, 2000). O desmatamento, que normalmente ocorre via queimadas, põe em questionamento o equilíbrio do sistema natural, sob o aspecto hidrometeorológico, biogeoquimico, etc. Neste trabalho as observações de radiação solar e terrestre em ambiente de floresta e pastagem são utilizados para avaliar o desempenho dos modelos operacionais de previsão numérica de tempo global e de área limitada do Centro de Previsão de Tempo e Estudos Climáticos do Instituto Nacional de Pesquisas Espaciais do Brasil (CPTEC/INPE), com o objetivo de avalíar a conveniência da utilização desses modelos em simulações dos impactos das modificações da cobertura vegetal da Amazônia. Os resultados dos modelos mostraram que ambos os modelos sãO capazes de reproduzir razoavelmente bem a integração da radiação para os horários sinóticos.Pages: 643-64