Search results for "Remote Sensing"
showing 10 items of 1262 documents
Developments for vegetation fluorescence retrieval from spaceborne high-resolution spectrometry in the O2-A and O2-B absorption bands
2010
Solar-induced chlorophyll fluorescence is a weak electromagnetic signal emitted in the red and far-red spectral regions by vegetation chlorophyll under excitation by solar radiation. Chlorophyll fluorescence has been demonstrated to be a close proxy to vegetation physiological functioning. The basis for fluorescence retrieval from passive space measurements is the exploitation of the O2-A and O2-B atmospheric absorption features to isolate the fluorescence signal from the solar radiation reflected by the surface and the atmosphere. High spectral resolution measurements and a precise modeling of the atmospheric radiative transfer in the visible and near-infrared regions are mandatory. Recent…
Apparent absorption of solar spectral irradiance in heterogeneous ice clouds
2010
[1] Coordinated flight legs of two aircraft above and below extended ice clouds played an important role in the Tropical Composition, Cloud and Climate Coupling Experiment (Costa Rica, 2007). The Solar Spectral Flux Radiometer measured up- and downward irradiance on the high-altitude (ER-2) and the low-altitude (DC-8) aircraft, which allowed deriving apparent absorption on a point-by-point basis along the flight track. Apparent absorption is the vertical divergence of irradiance, calculated from the difference of net flux at the top and bottom of a cloud. While this is the only practical method of deriving absorption from aircraft radiation measurements, it differs from true absorption when…
MINISAT-01: Hybrid satellite for science and technology
2003
Abstract The MINISAT-01 is a good example of a small hybrid space mission for science and technology. The MINISAT-01 main goal was to prove the Spanish industrial capability to develop a space mission including flight hardware, ground segment support, launch and operations. MINISAT-01 science was addressed to perform astronomical observations and microgravity experiments. The Payload has also a hybrid character. It is a combination of a previously flown experiment on fluid mechanics in microgravity (CPLM), a fully developed astronomical far-ultraviolet spectroscope (EURD) and a demonstrator of technology for a gamma-ray imagers (LEGRI). A small experiment to deploy systems in space was also…
Intercomparison of spectroradiometers for global and direct solar irradiance in the visible range.
2003
This paper presents the results of the analysis of the spectral, global, and direct solar irradiance measurements in the visible range (400–700 nm) that were made in the framework of the first Iberian UV–visible (VIS) instruments intercomparison. The instruments used in this spectral range were four spectroradiometers: three Licor 1800s equipped with different receiver optics and one Optronic 754. For the direct solar irradiance measurements the spectroradiometers were equipped with collimators with different fields of view. Parallel studies have been carried out with the data given by the spectroradiometers with their original calibration file and with the same data that is corrected, foll…
Extreme, wintertime Saharan dust intrusion in the Iberian Peninsula: Lidar monitoring and evaluation of dust forecast models during the February 2017…
2019
The research leading to these results has received funding from the H2020 program from the European Union (grant agreement no. 654109, 778349) and also from the Spanish Ministry of Industry, Economy and Competitiviness (MINECO, ref. CGL2013-45410-R, CGL2016-81092-R, CGL2017-85344-R, TEC2015-63832-P), the Spanish Ministry of Science, Innovation and Universities (ref. CGL2017-90884-REDT); the CommSensLab "Maria de Maeztu" Unity of Excellence (ref. MDM-2016-0600) financed by the Spanish Agencia Estatal de Investigación. Co-funding was also provided by the European Union through the European Regional Development Fund (ref. POCI-01-0145-FEDER-007690, ALT20-03-0145-FEDER-000004, ALT20-03-0145-FED…
Aerosol closure study by lidar, sun photometry, and airborne optical counters during DAMOCLES field campaign at El Arenosillo sounding station, Spain
2011
We present a comparison of aerosol properties derived from in situ and remote sensing instruments during DAMOCLES campaign, aimed at investigating the equivalence between the instrumentation and methodologies employed by several Spanish groups to study atmospheric aerosols at a regional background site. The complete set of instruments available during this closure experiment allowed collecting a valuable high-resolution aerosol measurement data set. The data set was augmented with airborne in situ measurements carried out in order to characterize aerosol particles during the midday of 29 June 2006. This work is focused on aerosol measurements using different techniques of high-quality instr…
Early detection of volcanic hazard by lidar measurement of carbon dioxide
2016
Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidars has been undertaken at ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high spatial and temporal resolution. A differential absorption lid…
Foam effect on the sea surface emissivity in the 8–14μm region
2007
[1] The effect of foam on the sea surface emission has been studied in the microwave region, but its effect on thermal infrared emissivity and temperature has not been sufficiently analyzed in the literature. This paper presents thermal infrared measurements of foam-covered seawaters carried out under controlled conditions using a multichannel radiometer working in the 8–14 μm region. The experimental data show a negligible foam effect at low observation angles but a significant increase of emissivity with foam at angles above 45°. Differences between foam and foam-free emissivities are about +0.04 for observation angles of 65°, depending slightly on the radiometric spectral band. The effec…
Application Of Microholography for Ground-based In Situ Measurements in Stratus Cloud Layers: A Case Study
1993
Abstract A holographic droplet and aerosol recording system (HODAR) has been designed and operated in situ in a low-level stratus cloud layer adopting the Fraunhofer in-line technique to measure sizes and velocity vectors of cloud droplets as well as to determine sizes and shapes of other hydrometeors (e.g., graupel). The particle-size radii covered by this ground-based instrument range from three to several hundred micrometers. A case study conducted on the Kleiner Feldberg Mountain Observatory near Frankfurt, Germany, during November 1990 documents the temporal evolution of the cloud-droplet size distribution over a period of 19 h during which the size distribution changed from monomodal …
Downstream Services for Rice Crop Monitoring in Europe: From Regional to Local Scale
2017
The ERMES agromonitoring system for rice cultivations integrates EO data at different resolutions, crop models, and user-provided in situ data in a unified system, which drives two operational downstream services for rice monitoring. The first is aimed at providing information concerning the behavior of the current season at regional/rice district scale, while the second is dedicated to provide farmers with field-scale data useful to support more efficient and environmentally friendly crop practices. In this contribution, we describe the main characteristics of the system, in terms of overall architecture, technological solutions adopted, characteristics of the developed products, and funct…