Vulnerabilidade do patrimônio ambiental tombado em Campinas-SP e sua relação com índice de vegetação.

Research conducted in forest fragments have contributed to the development of models for recovery of degraded areas, generating decrease deployment costs with increased efficiency, helping in forest management studies, and effectively preserving the remaining vegetation when considering the dynamics of regeneration compared to patterns of space occupation. The survey of the occupation history for the surrounding urban forest fragments located in the city of Campinas, São Paulo, Brazil, structured in a Geographical Information System (GIS), allowed to establish a classification which indicates the degree of vulnerability of these forests remnants based on the degree of deterioration of the landscape caused by the incidence of certain activities. The survey was made using legal decisions, occupation history, fauna and flora surveys, environmental reports, information on plant and animal biodiversity as well as the physical characteristics of the fragment?s area, which exemplified the degree and pattern of human occupation. The extraction of the Normalized Difference Vegetation Index (NDVI) for each area allowed to establish a relation between the occupation pattern for the surrounding and the changes in vegetation cover within these forests fragments, which presented a good match with the degree of vulnerability attributed in previous step

Análise comparativa de três métodos de correção atmosférica de imagens Landsat 5 - TM para obtenção de reflectância de superfície e NDVI.

The present study has compared three methods of atmospheric correction, two dark object subtraction (DOS) methods and one method based on the fourth component of the tasseled cap transformation (TC4), to obtain reflectance and NDVI values of Landsat 5 ? TM satellite images. For each atmospheric correction method, reflectance and NDVI values of five targets (crop/pasture, forest, straw, bare soil and water) were analyzed in three images (Landsat path-row 222-75). The study area is localized in the west of Sao Paulo State, Brazil. The images were acquired on 29/10/2009, 02/02/2010 and 26/06/2010 with solar zenith angles of 28°, 34° and 55°, correspondingly. The TC4 was the only method which eliminated the haze in the image, but it is not recommended if the objective is to obtain reflectance values. The DOS methods did not removed the image haze but performed reasonably to obtain reflectance values. For the visible bands, both DOS methods analyzed performed well. The DOS method which considered the atmospheric transmittance (DOS2), although more indicated to correct the infrared bands, it is dependent of the image solar zenith angle. The image acquired under a zenith angle of 55°, after been corrected using the DOS2 method, presented reflectance values overestimated. Without the atmospheric correction the NDVI of vegetation targets tended to be underestimated

Análise de metodologias para correção atmosférica e estimativa do albedo da superfície usando imagens Landsat 5, TM.

Este trabalho objetivou analisar a aplicação de diferentes metodologias para correção atmosférica e estimativa do albedo da superfície com imagens Landsat 5 ? TM para a região que abrange parte do megaleque aluvial do rio Taquari (Pantanal). Foram avaliados os métodos de correção atmosférica DOS (dark object subtraction), método de correção baseado na componente haze da transformação tasseled cap, o 6S (Second Simulation of the Satellite Signal in the Solar Spectrum) e o método de correção implementado no algoritmo SEBAL (Surface Energy Balance Algorithm for Land). Para o cálculo do albedo, três diferentes fórmulas de estimativas foram utilizadas. Os resultados obtidos apontam a existência de uma forte variação dos valores de albedo encontrados conforme o método de correção dos efeitos atmosféricos e da escolha da fórmula de estimativa do albedo de superfície. Dentre as fórmulas utilizadas para estimativa do albedo, a fórmula de Allen et al. foi a que apresentou menos sensibilidade ao tipo de correção atmosférica adotada

Mudança no uso da terra pela agricultura brasileira de 1990 a 2014.

In this work, we used data on area harvested and quantity produced from the three major Brazilian crops in the area: soybean, sugarcane and corn, provided by the IBGE Municipal Agricultural Research (PAM), for the period between 1990 and 2014, to evaluate the dynamics of agriculture in Brazil. The analysis focused on the increase in time and the change in the space occupied by the production. We used images of the sensors OLI and TM on board the Landsat-8 and Landsat-5 satellites, respectively, to exemplify changes in land use and land cover in selected areas. In 25 years, the combination of increased Brazilian agricultural productivity with the large-scale adoption of the safrinha or second crop season (intensification of agriculture) resulted in a 197% increase in the production of these crops, without expanding the cultivated area in the same proportion of production. There was also a significant change in production sites. We have confirmed that the changes recorded by the official data were in accordance with the ones that are showed by the remote sensing images. Municipalities responding for 25% national production dramatically changed in number and in its spatial distribution in this short period, moving the grain pole from South and Southeastern region to Central-West region of Brazil

Understanding the dynamic of tropical agriculture for remote sensing applications: a case study of Southeastern Brazil.

Abstract: The agricultural activity can greatly benefit from remote sensing technology (RS). Optical passive RS has been vastly explored for agricultural mapping and monitoring, in despite of cloud cover issue. This is observed even in the tropics, where frequency of clouds is very high. However, more studies are needed to better understand the high dynamism of tropical agriculture and its impact on the use of passive RS. In tropical countries, such as in Brazil, the use of current agricultural technologies, associated with favourable climate, allow the planting period to be wide and to have plants of varying phenological cycles. In this context, the main objective of the current study is to better understand the dynamics of a selected area in Southeast of São Paulo state, and its impact on the use of orbital passive RS. For that purpose, data (from field and satellite) from 55 agricultural fields, including annual, semi-perennial and perennial crops and silviculture, were acquired between July 2014 and December 2016. Field campaigns were conducted in a monthly base to gather information about the condition of the crops along their development (data available in a website). Field data corresponding to the 2014-2015 crop year were associated with a time series of Landsat-8/OLI RGB false-colour compositions images and MODIS/Terra NDVI profiles. The type of information that can be extracted (such as specie identification, crop management practices adopted, date of harvest, type o production system used etc) by combining passive remote sensing data with field data is discussed in the paper

Cloud cover assessment for operational crop monitoring systems in tropical areas.

Abstract: The potential of optical remote sensing data to identify, map and monitor croplands is well recognized. However, clouds strongly limit the usefulness of optical imagery for these applications. This paper aims at assessing cloud cover conditions over four states in the tropical and sub-tropical Center-South region of Brazil to guide the development of an appropriate agricultural monitoring system based on Landsat-like imagery. Cloudiness was assessed during overlapping four months periods to match the typical length of crop cycles in the study area. The percentage of clear sky occurrence was computed from the 1 km resolution MODIS Cloud Mask product (MOD35) considering 14 years of data between July 2000 and June 2014. Results showed high seasonality of cloud occurrence within the crop year with strong variations across the study area. The maximum seasonality was observed for the two states in the northern part of the study area (i.e., the ones closer to the Equator line), which also presented the lowest averaged values (15%) of clear sky occurrence during the main (summer) cropping period (November to February). In these locations, optical data faces severe constraints for mapping summer crops. On the other hand, relatively favorable conditions were found in the southern part of the study region. In the South, clear sky values of around 45% were found and no signi?cant clear sky seasonality was observed. Results underpin the challenges to implement an operational crop monitoring system based solely on optical remote sensing imagery in tropical and sub-tropical regions, in particular if short-cycle crops have to be monitored during the cloudy summer months. To cope with cloudiness issues, we recommend the use of new systems with higher repetition rates such as Sentinel-2. For local studies, Unmanned Aircraft Vehicles(UAVs) might be used to augment the observing capability. Multi-sensor approaches combining optical and microwave data can be another option. In cases where wall-to-wall maps are not mandatory, statistical sampling approaches might also be a suitable alternative for obtaining useful crop area information

Análise da cobertura de nuvens no nordeste do Brasil e seus impactos no sensoriamento remoto agrícola operacional.

O presente trabalho tem como objetivo caracterizar a cobertura de nuvens para o Nordeste do Brasil nos doze meses do ano, bem como discutir os impactos para o monitoramento agrícola das principais áreas produtoras da região

Using Landsat 8 image time series for crop mapping in a region of Cerrado, Brazil.

Abstract: The objective of this research is to classify agricultural land use in a region of the Cerrado (Brazilian Savanna) biome using a time series of Enhanced Vegetation Index (EVI) from Landsat 8 OLI. Phenological metrics extracted from EVI time series, a Random Forest algorithm and data mining techniques are used in the process of classification. The area of study is a region in the Cerrado in a region of the municipality of Casa Branca, São Paulo state, Brazil. The results are encouraging and demonstrate the potential of phenological parameters obtained from time series of OLI vegetation indices for agricultural land use classification