Search results for "Remote Sensing"

Climatology of the aerosol extinction-to-backscatter ratio from sun-photometric measurements

2010

The elastic lidar equation contains two unknown atmospheric parameters, namely, the particulate optical extinction and backscatter coefficients, which are related through the lidar ratio (i.e., the particulate-extinction-to-backscatter ratio). So far, independent inversion of the lidar signal has been carried out by means of Raman lidars (usually limited to nighttime measurements), high-spectral-resolution lidars, or scanning elastic lidars under the assumption of a homogeneously vertically stratified atmosphere. In this paper, we present a procedure to obtain the lidar ratio at 532 nm by a combined Sunphotometer– aerosol-model inversion, where the viability of the solution is largely reinf…

Aerosol Lidar Intercomparison in the Framework of SPALINET—The Spanish Lidar Network: Methodology and Results

2009

Abstract—A group of eight Spanish lidars was formed in order to extend the European Aerosol Research Lidar Network–Advanced Sustainable Observation System (EARLINET-ASOS)project. This study presents intercomparisons at the hardware and software levels. Results of the system intercomparisons are based on range-square-corrected signals in cases where the lidars viewed the same atmospheres. Comparisons were also made for aeros backscatter coefficients at 1064 nm (2 systems) and 532 nm (all systems), and for extinction coefficients at 532 nm (2 systems). In total, three field campaigns were carried out between 2006 and 2007. Comparisons were limited to the highest layer found before the free tr…

Intercomparison of spanish advanced lidars in the framework of EARLINET

2007

To extend and reinforce the action of the EARLINET- ASOS project, a nucleus of Spanish advanced lidars was created. Four systems were intercompared satisfactorily in terms of backscatter coefficients at two elastic wavelengths. Peer Reviewed

A fuzzy multi-criteria decision-making methodology to optimise olive agro-engineering processes based on geo-spatial technologies

2016

In southern Italy, the olive oil sector is an important part of the primary sector and its development requires support from research to ensure its sustainability. This work proposes the first step for set up a decision support system (DSS) for establishing mechanisation in agricultural operations for different olive groves. To contribute to this goal researches have been carried out to test the ability of remote sensing (RS) and geographic information system (GIS) to map olive groves and their agronomic characteristics. In detail, this study aimed to classify olives grove areas in terms of agronomic suitability and detect horticultural characteristics of olive groves in order to develop a …

How Universal Is the Relationship between Remotely Sensed Vegetation Indices and Crop Leaf Area Index? A Global Assessment

2016

This study aims to assess the relationship between Leaf Area Index (LAI) and remotely sensed Vegetation Indices (VIs) for major crops, based on a globally explicit dataset of in situ LAI measurements over a significant set of locations. We used a total of 1394 LAI measurements from 29 sites spanning 4 continents and covering 15 crop types with corresponding Landsat satellite images. Best-fit functions for the LAI-VI relationships were generated and assessed in terms of crop type, vegetation index, level of radiometric/atmospheric processing, method of LAI measurement, as well as the time difference between LAI measurements and satellite overpass. These global LAI-VI relationships were evalu…

A SIMPLIFIED ALGORITHM FOR THE EVALUATION OF FROST-AFFECTED CITRUS

1990

Current air quality analytics and monitoring: a review.

2014

This review summarizes the different tools and concepts that are commonly applied in air quality monitoring. The monitoring of atmosphere is extremely important as the air quality is an important problem for large communities. Main requirements for analytical devices used for monitoring include a long period of autonomic operation and portability. These instruments, however, are often characterized by poor analytical performance. Monitoring networks are the most common tools used for monitoring, so large-scale monitoring programmes are summarized here. Biomonitoring, as a cheap and convenient alternative to traditional sample collection, is becoming more and more popular, although its main …

Measurement and correction of atmospheric effects in O<inf>2</inf>-B and O<inf>2</inf>-A absorption bands in the context of s…

2014

Under sun-light illumination, the shape of the atmospheric oxygen bands (O 2 -B, 687 nm and O 2 -A, 760 nm) of the vegetation radiance is modified by chlorophyll fluorescence. However for far-range measurements, atmospheric effects also modify this shape. In this study, measurements in O 2 -A and O 2 -B absorption bands have been performed at different altitudes up to 3123 m over bare soil and wheat fields. It is observed that bands depth increase significantly with altitude. In O 2 -B band, the total magnitude of variation is of the same order of magnitude as the change induced by vegetation fluorescence, while it is much greater in O 2 -A band. We used MODTRAN 4 to correct measurements fr…

A method for the surface reflectance retrieval from PROBA/CHRIS data over land: application to ESA SPARC campaigns

2005

The Compact High Resolution Imaging Spectrometer (CHRIS) onboard the Project for On-Board Autonomy (PROBA) platform system provides the first high spatial resolution hyper-spectral/multiangular remote sensing data from a satellite system, what represents a new source of information for Earth Observation purposes. A fully consistent radiative transfer approach is always preferred when dealing with the retrieval of surface reflectance from hyperspectral/multiangular data. However, due to the reported calibration anomalies for CHRIS data, a direct atmospheric correction based on physical radiative transfer modeling is not possible, and the method must somehow compensate for such calibration pr…

Exploring the validity of the long term data record V4 database for land surface monitoring

2015

The last (and final) version of the Long Term Data Record (LTDR) — Version 4 — has been released recently by NASA. This database includes daily information for all AVHRR (Advanced Very High Resolution Radiometer) channels, as well as ancillary data, since July 1981 up to present. This database is the longest available record of remotely sensed data useful for land surface monitoring, since it allows the estimation of vegetation indices at daily resolution, as well as the daily estimation of land surface temperature (LST). Here, we analyze the fitness of this database for land surface monitoring. To that end, we first estimated NDVI (Normalized Difference Vegetation Index), LST, as well as e…