Novel polarization-sensitive micropulse lidar measurement technique

Flynn, Connor; Mendoza, Albert; Zheng, Yunhui; Mathur, Savyasachee

doi:10.1364/oe.15.002785

Cited by 153 publications

(132 citation statements)

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“…the signal measured in the relative "co-polar" and "cross-polar" channels of the instrument, denoted by P co (z) and P cr (z) signals, respectively; see Sigma Space Corp. Manual, 2012, for more details). By adapting the methodology described in Flynn et al (2007), the parallel and perpendicular P-MPL range-corrected signals (RCS, also called normalized relative backscatter signals, NRB), represented by P || (z) and P ⊥ (z) can be expressed in terms of those P-MPL co-and cross-channel signals, P co (z) and P cr (z), as (hereafter, the dependence with height is omitted for simplicity)…”

Section: Polarized Micro-pulse Lidar (P-mpl) Systemmentioning

confidence: 99%

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Separation of the optical and mass features of particle components in different aerosol mixtures by using POLIPHON retrievals in synergy with continuous polarized Micro-Pulse Lidar (P-MPL) measurements

et al. 2018

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Abstract. The application of the POLIPHON (POlarizationLIdar PHOtometer Networking) method is presented for the first time in synergy with continuous 24/7 polarized MicroPulse Lidar (P-MPL) measurements to derive the vertical separation of two or three particle components in different aerosol mixtures, and the retrieval of their particular optical properties. The procedure of extinction-to-mass conversion, together with an analysis of the mass extinction efficiency (MEE) parameter, is described, and the relative mass contribution of each aerosol component is also derived in a further step. The general POLIPHON algorithm is based on the specific particle linear depolarization ratio given for different types of aerosols and can be run in either 1-step (POL-1) or 2 steps (POL-2) versions with dependence on either the 2-or 3-component separation. In order to illustrate this procedure, aerosol mixing cases observed over Barcelona (NE Spain) are selected: a dust event on 5 July 2016, smoke plumes detected on 23 May 2016 and a pollination episode observed on 23 March 2016. In particular, the 3-component separation is just applied for the dust case: a combined POL-1 with POL-2 procedure (POL-1/2) is used, and additionally the fine-dust contribution to the total fine mode (fine dust plus non-dust aerosols) is estimated. The high dust impact before 12:00 UTC yields a mean mass loading of 0.6 ± 0.1 g m −2 due to the prevalence of Saharan coarse-dust particles. After that time, the mean mass loading is reduced by two-thirds, showing a rather weak dust incidence. In the smoke case, the arrival of fine biomass-burning particles is detected at altitudes as high as 7 km. The smoke particles, probably mixed with less depolarizing non-smoke aerosols, are observed in air masses, having their origin from either North American fires or the Arctic area, as reported by HYSPLIT backtrajectory analysis. The particle linear depolarization ratio for smoke shows values in the 0.10-0.15 range and even higher at given times, and the daily mean smoke mass loading is 0.017 ± 0.008 g m −2 , around 3 % of that found for the dust event. Pollen particles are detected up to 1.5 km in height from 10:00 UTC during an intense pollination event with a particle linear depolarization ratio ranging between 0.10 and 0.15. The maximal mass loading of Platanus pollen particles is 0.011 ± 0.003 g m −2 , representing around 2 % of the dust loading during the higher dust incidence. Regarding the MEE derived for each aerosol component, their values are in agreement with others referenced in the literature for the specific aerosol types examined in this work: 0.5 ± 0.1 and 1.7 ± 0.2 m 2 g −1 are found for coarse and fine dust particles, 4.5 ± 1.4 m 2 g −1 is derived for smoke and 2.4 ± 0.5 m 2 g −1 for non-smoke aerosols with Arctic origin, and a MEE of 2.4 ± 0.8 m 2 g −1 is obtained for pollen particles, though it can reach higher or lower values depending on predomiPublished by Copernicus Publications on behalf of the European Geosciences Union. 4776 C. Córdoba...

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Section: Polarized Micro-pulse Lidar (P-mpl) Systemmentioning

confidence: 99%

“…Then, the linear volume depolarization ratio δ V for a MPL system (Flynn et al, 2007) can be easily expressed as…”

Section: Polarized Micro-pulse Lidar (P-mpl) Systemmentioning

confidence: 99%

Separation of the optical and mass features of particle components in different aerosol mixtures by using POLIPHON retrievals in synergy with continuous polarized Micro-Pulse Lidar (P-MPL) measurements

et al. 2018

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“…There may be more than one population of particles present in any given scattering volume. The calculation to determine the change in polarization requires a ratio of the intensity of light which is returned unpolarized to the total intensity of light which is returned in any and all polarization states (Flynn et al, 2008;Gimmestad, 2008). Expressed in this manner, the quantity of interest is d, the depolarization parameter: the portion of the total light intensity I which has become depolarized through scattering.…”

Section: Depolarization Lidar Theorymentioning

confidence: 99%

Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada

et al. 2017

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Abstract. The Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh-Mie-Raman lidar (CRL) at Eureka, Nunavut, has measured tropospheric clouds, aerosols, and water vapour since 2007. In remote and meteorologically significant locations, such as the Canadian High Arctic, the ability to add new measurement capability to an existing well-tested facility is extremely valuable. In 2010, linear depolarization 532 nm measurement hardware was installed in the lidar's receiver. To minimize disruption in the existing lidar channels and to preserve their existing characterization so far as is possible, the depolarization hardware was placed near the end of the receiver cascade. The upstream optics already in place were not optimized for preserving the polarization of received light. Calibrations and Mueller matrix calculations are used to determine and mitigate the contribution of these upstream optics on the depolarization measurements. The results show that with appropriate calibration, indications of cloud particle phase (ice vs. water) through the use of the depolarization parameter are now possible to a precision of ±0.05 absolute uncertainty (≤ 10 % relative uncertainty) within clouds at time and altitude resolutions of 5 min and 37.5 m respectively, with higher precision and higher resolution possible in select cases. The uncertainty is somewhat larger outside of clouds at the same altitude, typically with absolute uncertainty ≤ 0.1. Monitoring changes in Arctic cloud composition, including particle phase, is essential for an improved understanding of the changing climate locally and globally.

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“…MPL is being widely used to monitor meteorological parameters and atmospheric constituents. [3][4][5] Polarization MPL has been used to study various phenomenon in the atmosphere, such as hydrometeors, 6 clouds, 7 volcanic aerosols, 8 and polar stratospheric clouds. 9,10 The space-based lidars such as CALIPSO include a crosspolarization receiver channel because of the valuable information that it provides.…”

Section: Introductionmentioning

confidence: 99%

Depolarization ratio measurement using single photomultiplier tube in micropulse lidar

Dubey

Jain

Arya

et al. 2009

Review of Scientific Instruments

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The conventional dual polarization micropulse lidar uses two separate photomultiplier tubes ͑PMT͒ to detect both the copolarized and cross-polarized beam. The prominent sources of error in the depolarization ratio measurement are mismatch in PMT, improper selection of discriminator threshold and unequal PMT high voltage. In the present work a technique for the measurement of lidar depolarization ratio using only one PMT sensor has been developed. The same PMT detects both copolarized and cross-polarized lidar backscatter. A stepper motor is used along with the mirrors to bring both the received polarization signals over the PMT window. Application of the same PMT minimizes the error caused in the depolarization ratio measurement due to error in photon counting of an individual channel. The design description of this technique along with the preliminary results depicting its functionality has been mentioned in this article.

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Novel polarization-sensitive micropulse lidar measurement technique

Cited by 153 publications

References 13 publications

Separation of the optical and mass features of particle components in different aerosol mixtures by using POLIPHON retrievals in synergy with continuous polarized Micro-Pulse Lidar (P-MPL) measurements

Separation of the optical and mass features of particle components in different aerosol mixtures by using POLIPHON retrievals in synergy with continuous polarized Micro-Pulse Lidar (P-MPL) measurements

Depolarization calibration and measurements using the CANDAC Rayleigh–Mie–Raman lidar at Eureka, Canada

Depolarization ratio measurement using single photomultiplier tube in micropulse lidar

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