Estimations of temperature and humidity of the canopy in Amazon Forest using microwave data from SMMR sensor of Nimbus-7 satellite / Estimativas da temperatura e umidade do dossel na Floresta Amazônica, utilizando dados de microondas do sensor SMMR do satélite Nimbus-7

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

The forest canopy humidity and temperature of the region of Manaus (3o S, 60° W) have been estimated for the 1985 wet (April-May) and dry (July-August) seasons at 12:00 and 00:00 local standard time, from spaceborne microwave radiometer, along with microwave emission models. The satellite data consist of SMMR (Scanning Multichannel Microwave Radiometer) Nimbus-7 corrected brightness temperatures for the 6.6, 10.7, 18.0 and 37.0 GHz frequencies. To model the signal emitted by the forest canopy, two different numerical models were used: a discrete model, which calculates the scattering and absorbing coefficients of each bioelement of the canopy (stems, branches and leaves), and a continuous model, which uses a statistical description of the canopy dielectric properties canopy. Micrometeorological data obtained from the GTE/ABLE-2A (GLOBAL Tropospheric Experiment/Amazon Boundary Layer Experiment 2A), and ARME (Anglo-Brazilian Amazon Region Micrometeorological Experiment) at the Duck Reserve (2°,57 S, 59°57 W) have been used. A sensitivity study of the models has also been conducted to evaluate the influence of the moisture, temperature gradient and vegetal biomass on the brightness temperatures simulated by the models. The sensitivity test has indicated that it is necessary to use both the 37.0 GHz and low frequencies to carry out the inversion of the structure parameters, moisture and temperature. The moisture values obtained through the inversion of the continuous model have been consistent with the ones obtained by other authors in field experiements in the Amazon region. A moisture index has been defined (normalized difference of the optimized moisture at 37.0 and 6.6 GHz frequencies), and has shown to be a good index of the vegetation stomatal resistance.

ASSUNTO(S)

atmospheric temperature canopies (vegetation) dossel (vegetação) microondas humidity climatologia temperatura atmosférica nimbus-7 brightness temperature florestas variação anual climatologia satélites nimbus humidade microwaves radiometers vegetacao microwaves emission annual variations floresta amazônia (região)

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