Detection of Scattering Layers in the Upper Atmosphere (60–140 km) by Optical Radar

Fiocco, G.; Smullin, Louis D.

doi:10.1038/1991275a0

Cited by 203 publications

(63 citation statements)

References 2 publications

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“…Here, we focus our attention on aerosol backscatter coefficients from lidar data. Lidar measurements have been used to detect stratospheric particles since the early 1960s (Junge et al, 1961;Fiocco and Smullins, 1963). They have been used as a proxy for the stratospheric aerosol loading (David et al, 1997;ASAP, 2006).…”

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Statistical estimation of stratospheric particle size distribution by combining optical modelling and lidar scattering measurements

et al. 2008

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Abstract.A method for estimating the stratospheric particle size distribution from multiwavelength lidar measurements is presented. It is based on matching measured and modelsimulated backscatter coefficients. The lidar backscatter coefficients measured at the three commonly used wavelengths 355, 532 and 1064 nm are compared to a precomputed lookup table of model-calculated values. The optical model assumes that particles are spherical and that their size distribution is unimodal. This inverse problem is not trivial because the optical model is highly non-linear with a strong sensitivity to the size distribution parameters in some cases. The errors in the lidar backscatter coefficients are explicitly taken into account in the estimation. The method takes advantage of the statistical properties of the possible solution cluster to identify the most probable size distribution parameters. In order to discard model-simulated outliers resulting from the strong non-linearity of the model, solutions farther than one standard deviation of the median values of the solution cluster are filtered out, because the most probable solution is expected to be in the densest part of the cluster. Within the filtered solution cluster, the estimation algorithm minimizes a cost function of the misfit between measurements and model simulations.Two validation cases are presented on Polar Stratospheric Cloud (PSC) events detected above the ALOMAR observatory (69 • N -Norway). A first validation is performed against optical particle counter measurements carried out in January 1996. In non-depolarizing regions of the cloud (i.e. spherical particles), the parameters of an unimodal size distribution and those of the optically dominant mode of a bimodal size distribution are quite successfully retrieved, especially for the median radius and the geometrical standard deviation. As expected, the algorithm performs poorly when Correspondence to: J. Jumelet (julien.jumelet@aero.jussieu.fr) solid particles drive the backscatter coefficient. A small bias is identified in modelling the refractive index when compared to previous works that inferred PSC type Ib refractive indices. The accuracy of the size distribution retrieval is improved when the refractive index is set to the value inferred in the reference paper.Our results are then compared to values retrieved with another similar method that does not account for the effect of the measurements errors and the non-linearity of the optical model on the likelihood of the solution. The case considered is a liquid PSC observed over northern Scandinavia on January 2005. An excellent agreement is found between the two methods when our algorithm is applied without any statistical filtering of the solution cluster. However, the solution for the geometrical standard deviation appears to be rather unlikely with a value close to unity (σ ≈1.04). When our algorithm is applied with solution filtering, a more realistic value of the standard deviation (σ ≈1.27) is found. This highlights the importance of taking int...

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Statistical estimation of stratospheric particle size distribution by combining optical modelling and lidar scattering measurements

et al. 2008

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“…Lidar has been used in optical remote sensing technique to study atmospheric particulate and gas pollutants over half of the century (Grant, 1987;Killinger and Menyuk, 1987;Killinger and Mooradian, 1983;Measures, 1984). Lidar has the ability to measure remotely atmospheric aerosols (Carswell, 1983;Fiocco and Smullin, 1963). Remote sensing of atmosphere applying Lidar technique depends on backscattering light of particles.…”

Section: Lidarmentioning

confidence: 99%

Two-dimensional Simulation of Aerosol?Cloud Profile

Alias¹,

MatJafri²,

San³

et al. 2009

MAS

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Developments of algorithm and computer graphics simulation are important to distinguish between aerosols and clouds in remote sensing data and images. The distribution of aerosols and clouds are need to be distinguishable in order to study their interactions with one another and identify both affecting factors towards Earth's climate stability. The objective of this paper is to expand the current work done in building new algorithm and simulation method to differentiate aerosols and clouds in spaceborne lidar data and images using image processing and computer graphics software, PCI Geomatica 10.1 and SCION Image. The new algorithm and simulation that has developed showed good results and clarify the vertical distribution of aerosols and clouds in the atmosphere. Plot profiles of clouds on both days showed higher pixel values than aerosols. Aerosols have been found consistently to have higher mean at altitude 0−5 km and 15−20 km on both days.

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“…In the year 2006 the humans living in urban areas have reached 50% of the entire world population and it is estimated that by 2050 more than 75% of humanity will be living in cities [1]. These areas, characterized by an high density of people, are particularly vulnerable to the increasing of pollution.…”

Section: Introductionmentioning

confidence: 99%

Detection of pollutant sources in the atmosphere with Lidar/Dial techniques: Results of an experimental campaign in the south of Italy

Gelfusa

Malizia

Parracino

et al. 2014

2014 Fotonica AEIT Italian Conference on Photonics Technologies

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In the last years, surveying large regions of the atmosphere in an automatic way, for early detection of pollutant sources in urban and industrial areas, has become a strategic objective of various public health organizations. The Lidar/Dial technique has become a well-established laser remote sensing method for atmosphere monitoring. It is often used to probe almost any level of the atmosphere and to acquire information necessary to validate theoretical models about different topics of atmospheric physics. It can also be deployed for environment surveying by monitoring particles, aerosols and molecules. For these reasons, an experimental campaign for evaluating the performances of a Lidar/Dial system in detecting pollutants (particulate and/or chemical compounds) has been carried out in an industrial area in the south of Italy. In this work, a homemade Lidar/Dial system (developed and built by the authors) and the results of the experimental campaign will be presented and discussed.

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Detection of Scattering Layers in the Upper Atmosphere (60–140 km) by Optical Radar

Cited by 203 publications

References 2 publications

Statistical estimation of stratospheric particle size distribution by combining optical modelling and lidar scattering measurements

Statistical estimation of stratospheric particle size distribution by combining optical modelling and lidar scattering measurements

Two-dimensional Simulation of Aerosol?Cloud Profile

Detection of pollutant sources in the atmosphere with Lidar/Dial techniques: Results of an experimental campaign in the south of Italy

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