Homepage of Mauro Antonio Homem Antunes

Contents

BIOGRAPHICAL INFORMATION

Professional Experience and Employment Status:

1997. Became a member of the Geoscience and Remote Sensing Society of the Institute of Electrical and Electronics Engineers (IEEE).

1992-93. Worked for eight months as assistant researcher at INPE.

1992. Worked in a project to map and estimate the cultivated Citrus area in Brazil using remote sensing satellite images.

1990. Participated in the 1990 field experiment for the project ESTIMA (acronym for crop yield forecasting; a series of experiments sponsored by the Brazilian Bank Foundation).

1988. Worked as an Agronomic extension agent in a Cooperative of Farmers at Goias State, Brazil.

Right now I am not employed and I welcome any contact from Brazilian University or Research Institute interested on my expertise. My plan is to finish the Ph.D. program by September 1997 and return to Brazil by then. If an open position is not available for the moment, I welcome a temporary position as a postdoc, sponsored either by National agencies (e.g., CNPq, CAPES) or by local funding sources.

Back to Top

CURRENT PROJECTS

1. A Simple Canopy Radiative Transfer Model

Reliable extraction of information from remotely-sensed data regarding vegetative growth and function is dependent on our understanding and numerical simulation of the physical relationships between canopy bidirectional reflectance and canopy attributes. This understanding has been accomplished by complex radiative transfer models, which in turn are difficult to be inverted to estimate canopy variables. This led us to the development of a Simple Invertible Model (SIM), designed for inverting reflectance data for estimating canopy parameters.

The model has the following characteristics:

Bidirectional reflectance (factor) is calculated as the sum of the intensities from single scattering of illuminated and shaded scenes plus the multiple scattering from the turbid medium vegetation, calculated as the complement of gaps in the canopy. The model has been tested for maize bidirectional reflectance factor in the red and near infrared bands. The results were presented on February 6 at the Ninth Conference on Atmospheric Radiation, 77th Annual Meetings of the American Meteorological Society, (Long Beach, CA, 2-7 Feb/1997). It has also been successfully evaluated for alfalfa and soybean canopies using the red and near-infrared bands. The model has recently been tested against the turbid medium model DISORD (Discrete Ordinated Radiative Transfer Model) using alfalfa data. A good agreement was reached between the two models with exceptional performance in the near infrared. In the red region the simple model tends to overestimate a little bit the bidirectional reflectance factor because it allows gaps in the canopy. This simple model however still lacks the hot spot as it is modeled by the DISORD model. A hot spot model can easily be included in the simple model to account for the sharp increase in reflected fluxes when the instrument's viewing direction approaches the sun direction.

One application of the model is the calculation of the fraction of photosynthetically active radiation absorbed by the canopy (fAPAR), which in turn is important for crop growth and yield modeling. A good agreement was found between model simulated fAPAR and field measured fAPAR. Next the model will be implemented to calculate the surface albedo.

2. Inversion of Canopy Radiative Transfer Models

Four approaches are currently in use estimate vegetation canopy attributes from remotely-sensed data to: visual interpretation of images, empirical relationships (curve fitting) of the attributes with remotely-sensed data or its transforms (e.g., vegetation indices), look-up tables and inversion of canopy radiative transfer models.

Inversion of canopy radiative transfer models is the second part of my Ph.D. research project. The inversion of the simple model has been implemented to estimate LAI using the AMOEBA minimization routine. The inversion results for alfalfa, maize and soybean show that the model is invertible for LAI and the estimation of fAPAR using the inverted LAI has been successful. The next step will be the evaluation of inversions of the model to estimate all the other canopy parameters as well.

Back to Top

RESEARCH INTERESTS

My expertise is multi-disciplinary and embraces the fields of remote sensing, agronomy, agricultural meteorology and ecology. My studies during the Ph.D. program are aimed to seek a compromise between an eclectic base knowledge and focused research. I think that both this compromise and training in team work are important aspects of scientist's formation.

Remote sensing of vegetation

My research interest in this area includes modeling canopy reflectance response to canopy parameters, the use of remote sensing for crop monitoring and yield forecasting and environmental monitoring. Remote sensing is a useful tool to estimate the canopy albedo and the fraction of photosynthetically active radiation absorbed by the canopy (fAPAR), and to estimate canopy attributes like leaf area index, leaf angle distribution, biomass and phenology. Another enticing application for remote sensing that I am interested in is the use as a tool for precision farming. I also have some experience with field radiometric measurements and would like to extend this knowledge to measurements from airplane or helicopter platforms.

Modeling the radiation regime in plant communities

Modeling the radiation regime in plant canopies is useful for several reasons. It can be used to understand the relationships between canopy parameters and reflected and absorbed radiation. It can also be used to model canopy state variables (i.e., albedo, fAPAR and photosynthetic capacity) as a function of canopy attributes and responses of the state variables to changes in the light environment.

Micrometeorology of the vegetative environment

Study of the effects of micrometeorological variables on vegetation and plant responses to changes on those variables.

Crop growth and yield modeling and crops responses to environment

In this area my interest is related to modeling crop photosynthesis, water use efficiency, growth, phenology and crop yield. Regarding crop yield I think that the combination of crop models with remote sensing models has a great potential to improve yield forecasts. I'm also interested in the study of crop responses to air pollution, in particular responses to ozone pollution.

Turbulent transfer in the atmospheric surface layer

Estimates of CO2 and water vapor fluxes inside and above vegetation canopies by micrometeorological techniques.

Agricultural climatology

Study of climatic effects on crops and crop responses to climatic changes.

Soil-plant-water relations

Ecology of vegetation and the role played by radiation and micrometeorological variables

Back to Top

TO CONTACT ME

Electronic mail address:
mantunes@unlgrad1.unl.edu

School Address:
Department of Agricultural Meteorology
L. W. Chase Hall
P.O. Box 830728
Lincoln, NE, 68583-0728

Office phone: 402-472-0284 FAX: 402-472-6614

Back to Top

FEEDBACK

Please send me email telling me what you think about this page and how I might improve it.
Back to Top

SOME INTERESTING WEBSITES

Sites at the University of Nebraska-Lincoln:

About Brazil:

Sites About Lincoln:

Sites Related to Atmospheric Sciences and Remote Sensing:

Search Engines:

Back to Top

ABOUT MYSELF

I am originally from southeast Minas Gerais State, Brazil, where I was born and grew up in a farm near Paiva (a too small town to appear on maps). I left the farm when I was 15 years old to attend high school and then to pursue higher education. I enjoy reading History and Philosophy and besides being passionate about science and teaching I enjoy outdoor activities. Mine (and my wife's) preferred outdoor activities are fishing and camping. Yes, I have a motto: "Neither the sky nor the ground is the limit. Time is the limit."
Back to Top
Web page written and maintained by Mauro A. Homem Antunes.
Last revised: July 29, 1997.

(Like in real life, always under construction despite it may not change for quite some time)