J. Vanderlei Martins

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Observations of the aerosol optical thickness (AOT) by the MODIS instruments aboard Terra and Aqua satellites are being used extensively for applications to climate and air quality studies, as indicated from 28 publications in 2004 alone. Data quality is essential for these studies. Here we add to the published MODIS validations by investigating the effects(More)
The effect of anthropogenic aerosols on clouds is one of the most important and least understood aspects of human-induced climate change. Small changes in the amount of cloud coverage can produce a climate forcing equivalent in magnitude and opposite in sign to that caused by anthropogenic greenhouse gases, and changes in cloud height can shift the effect(More)
[1] As a part of the EAST-AIRE study, Nuclepore filters were collected in two size ranges (coarse, 2.5 mm < d < 10 mm, and fine, d < 2.5 mm) from January to May 2005 in Xianghe, about 70 km southeast of Beijing, and analyzed for aerosol mass concentration, spectral absorption efficiency and absorption coefficient. Twelve-hour aerosol mass concentration(More)
[1] Major uncertainties exist for observing and modeling ice content inside deep convective clouds (DCC). One of the difficulties has been the lack of characterization of vertical profiles of cloud hydrometeor phase. Here we propose a technique to estimate the DCC glaciation temperature using passive remote sensing data. It is based on a conceptual model of(More)
1. INTRODUCTION NASA has developed an Earth Observing System (EOS) consisting of a series of satellites designed to study global change from space. The EOS " flagship " is the EOS TERRA satellite, launched in December 1999, equipped with five unique sensors to monitor and study the Earth's heat budget and many of the key controlling variables governing the(More)
Using a simple sampling apparatus, aerosol particles were collected on a polycarbonate substrate in various locations around the world. The focus of this study was Xianghe, China, an industrial town 70 km southeast of Beijing. The Nuclepore filters were collected in two size ranges (coarse, 2.5µm < d < 10µm, and fine, d < 2.5µm) from January-December 2005,(More)
[1] The retrieval of aerosol optical depth (t a) over land by satellite remote sensing is still a challenge when a high spatial resolution is required. This study presents a tool that uses satellite measurements to dynamically identify the aerosol optical model that best represents the optical properties of the aerosol present in the atmosphere. We use(More)
1. Land: New inversion algorithm implemented. 2. Land: Valid range of AOD extended to-0.1 3. Land: Aerosol models now based on Dubovik (2002) and new geographic distribution 4. Land: Surface reflectance relationships a function of vegetation index and scattering angle. 5. Land: Subpixel snow mask implemented 6. Land: Cloud mask adjusted and QA flag set to 0(More)