Publications (22) View all
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Article: Results of site testing using an aerosol, backscatter lidar at the Roque de los Muchachos Observatory
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ABSTRACT: Because of the high quality of its sky, the Roque de los Muchachos Observatory (ORM), located on the island of La Palma in the Canary Islands, is home to many astronomical facilities. In the context of the Extremely Large Telescope Design Study, two intensive lidar campaigns were performed at the ORM near the Jacobus Kapteyn Telescope between 2007 July 9 and 11 and between 2008 May 26 and June 14. The goal of the campaign was to characterize the atmosphere in terms of the height of the planetary boundary layer (PBL) and the aerosol stratification versus synoptic conditions. Three typical synoptic situations were found, which supported the intrusion of aerosols from marine/oceanic, anthropogenic and Saharan origins, respectively. All measurements revealed a multilayer stratification with a mean PBL height of 546 ± 198 m agl and top layers as high as ∼8400 m asl. As a by-product, an estimate of the aerosol optical thickness was also obtained and compared to the total atmospheric extinction coefficient measured by the Carlsberg Meridian Telescope. Except in the presence of Saharan dust, the aerosol optical thickness is very low; the average values are 0.0405 at 532 nm and 0.0055 at 1064 nm. In the presence of Saharan dust, values of 0.233 and 0.157 were found at 532 and 1064 nm, respectively. The proportion of aerosol optical thickness contained in the layers above the PBL against that contained in the PBL is in all cases greater or equal to 50 per cent. This emphasizes the importance of the upper layers in the scattering and absorption of astronomical signals. Additionally, for the first time, spaceborne lidar measurements were also compared to those of a ground lidar, in order to evaluate the use of a spaceborne active instrument for aerosol content monitoring at an astronomical site.Monthly Notices of the Royal Astronomical Society 06/2010; 405(1):129 - 142. · 4.90 Impact Factor -
Article: Quasi-analytical determination of noise-induced error limits in lidar retrieval of aerosol backscatter coefficient by the elastic, two-component algorithm.
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ABSTRACT: The elastic, two-component algorithm is the most common inversion method for retrieving the aerosol backscatter coefficient from ground- or space-based backscatter lidar systems. A quasi-analytical formulation of the statistical error associated to the aerosol backscatter coefficient caused by the use of real, noise-corrupted lidar signals in the two-component algorithm is presented. The error expression depends on the signal-to-noise ratio along the inversion path and takes into account "instantaneous" effects, the effect of the signal-to-noise ratio at the range where the aerosol backscatter coefficient is being computed, as well as "memory" effects, namely, both the effect of the signal-to-noise ratio in the cell where the inversion is started and the cumulative effect of the noise between that cell and the actual cell where the aerosol backscatter coefficient is evaluated. An example is shown to illustrate how the "instantaneous" effect is reduced when averaging the noise-contaminated signal over a number of cells around the range where the inversion is started.Applied Optics 02/2009; 48(2):176-82. · 1.41 Impact Factor -
Conference Proceeding: Overview of Wind Lidar Techniques and Current Related Developments at the Technical University of Catalonia.
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ABSTRACT: The Lidar group in the Technical University of Catalonia is actively working in wind lidar techniques. An extensive review of such techniques is presented. A special emphasis is made on the direct Doppler technique and the direct motion technique with a lines-of-sight scanning pattern. Current developments are also mentioned.IEEE International Geoscience & Remote Sensing Symposium, IGARSS 2008, July 8-11, 2008, Boston, Massachusetts, USA, Proceedings; 01/2008 -
Conference Proceeding: Planetary Boundary Layer Height and Wind Field Characterization by Means of a Lidar at the Teide Observatory in the Canary Islands.
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ABSTRACT: A lidar field campaign was performed between 30<sup>th</sup> June and 4<sup>th</sup> July 2007 in the Teide Observatory in the Canarian island of Tenerife to characterize the atmosphere of this astrophysical observation site in terms of nocturnal boundary layer height and wind fields. The nocturnal boundary layer height was found lower than 810 m in all cases and the aerosol optical thickness lower than 0.005 and 0.03 at 1064 and 532 nm, respectively. Wind fields could hardly be retrieved because of faint signals and very weak wind velocities observed during the campaign.IEEE International Geoscience & Remote Sensing Symposium, IGARSS 2008, July 8-11, 2008, Boston, Massachusetts, USA, Proceedings; 01/2008 -
Conference Proceeding: Speed measurements with a continuous wave lidar prototype.
IEEE International Geoscience & Remote Sensing Symposium, IGARSS 2007, July 23-28, 2007, Barcelona, Spain, Proceedings; 01/2007
