Depolarization ratio of polar stratospheric clouds in coastal Antarctica: comparison analysis between ground-based Micro Pulse Lidar and space-borne CALIOP observations

Abstract. Polar stratospheric clouds (PSCs) play an important role in polar ozone depletion, since they are involved in diverse ozone destruction processes (chlorine activation, denitrification). The degree of that ozone reduction is depending on the type of PSCs, and hence on their occurrence. Therefore PSC characterization, mainly focused on PSC-type discrimination, is widely demanded. The backscattering (R) and volume linear depolarization (δV) ratios are the parameters usually used in lidar measurements for PSC detection and identification. In this work, an improved version of the standard NASA/Micro Pulse Lidar (MPL-4), which includes a built-in depolarization detection module, has been used for PSC observations above the coastal Antarctic Belgrano II station (Argentina, 77.9° S 34.6° W, 256 m a.s.l.) since 2009. Examination of the MPL-4 δV feature as a suitable index for PSC-type discrimination is based on the analysis of the two-channel data, i.e., the parallel (p-) and perpendicular (s-) polarized MPL signals. This study focuses on the comparison of coincident δV-profiles as obtained from ground-based MPL-4 measurements during three Antarctic winters with those reported from the space-borne lidar CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite in the same period (83 simultaneous cases are analysed for 2009–2011 austral winter times). Three different approaches are considered for the comparison analysis between both lidar profile data sets in order to test the degree of agreement: the correlation coefficient (CC), as a measure of the relationship between both PSC vertical structures; the mean differences together with their root mean square (RMS) values found between data sets; and the percentage differences (BIAS), parameter also used in profiling comparisons between CALIOP and other ground-based lidar systems. All of them are examined as a function of the CALIPSO ground-track distance from the Belgrano II station. Results represent a relatively good agreement between both ground-based MPL-4 and space-borne CALIOP profiles of the volume linear depolarization ratio δV for PSC events, once the MPL-4 depolarization calibration parameters are applied. Discrepancies between CALIOP and MPL-4 profiles in vertical layering structure are enhanced from 20 km up, likely due to a decrease of the signal-to-noise ratio (SNR) for both lidar systems at those altitudes. Regarding the results obtained from the mean and the percentage differences found between MPL-4 and CALIOP δV profiles, a predominance of negative values is also observed, indicating a generalized underestimation of the MPL-4 depolarization as compared to that reported by CALIOP. However, absolute differences between those δV-profile data sets are no higher than a 10 ± 11% in average. Moreover, the degree of agreement between both lidar δV data sets is slightly dependent on the CALIPSO ground-track overpass distance from the Belgrano II station. That is, small discrepancies are found when CALIPSO ground-track distance is as close as far from the ground-based station. These results would indicate that MPL-4 depolarization observations would reflect relatively well the PSC field that CALIOP can detect at relatively large distances from the ground-based station. As a consequence, PSC properties can be statistically similar, on average, over large volumes, and hence the present weak disagreement found between both the lidar δV data sets can be likely dominated by small spatial PSC inhomogeneities along the CALIPSO separation from the station. This statement is based on the fact that Belgrano II is a station located well inside the stable Antarctic polar vortex, allowing determined thermodynamic conditions leading to a very low variability in the PSC field, and in their properties.

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Depolarization ratio of Polar Stratospheric Clouds in coastal Antarctica: profiling comparison analysis between a ground-based Micro Pulse Lidar and the space-borne CALIOP

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-5-8051-2012 ◽

2012 ◽

Vol 5 (5) ◽

pp. 8051-8084 ◽

Cited By ~ 1

Author(s):

C. Córdoba-Jabonero ◽

J. L. Guerrero-Rascado ◽

D. Toledo ◽

M. Parrondo ◽

M. Yela ◽

...

Keyword(s):

Spatial Inhomogeneity ◽

Comparison Analysis ◽

Polar Stratospheric Clouds ◽

Ice Clouds ◽

Height Range ◽

Detection And Identification ◽

Percentage Difference ◽

Suitable Index ◽

Micro Pulse Lidar ◽

Stratospheric Clouds

Abstract. Polar Stratospheric Clouds (PSCs) play an important role in polar ozone depletion. In particular ice clouds, type PSC-II, with respect to the type PSC-I (nitric acid clouds) produce the most significant effects. Therefore PSC characterization, mainly focused on PSC-II discrimination is needed. The backscattering (R) and volume linear depolarization (δV) ratios are the parameters usually used in lidar measurements for PSC detection and identification. In this work, an improved version of the standard NASA/Micro Pulse Lidar (MPL-4), which includes a built-in depolarization detection module, has been used for PSC observations above the coastal Antarctic Belgrano II station (Argentina, 77.9° S 34.6° W, 256 m a.s.l.) since 2009. Examination of the MPL-4 δV feature as a suitable index for PSC-type discrimination is based on the analysis of the two-channel data, i.e. the parallel (p-) and perpendicular (s-) polarized MPL signals. This study focuses on the comparison of simultaneous δV-profiles as obtained from ground-based MPL-4 measurements during three Antarctic winters with those reported from the space-borne lidar CALIOP aboard the CALIPSO satellite in the same period (48 simultaneous cases are analysed for 2009–2011 austral winter times). Two different variables are considered for the comparison analysis between both lidar datasets in order to test the degree of agreement: the correlation coefficient (CC) and the percentage difference (BIAS). Results indicate a relatively good correlation between the δV-profiles once MPL-4 depolarization calibration parameters are applied. This correlation is based on the linear fitted height-range of the layered structure, obtaining CC values higher than 0.5 for 54% (26 cases) out of all the analysed cases (48 in total). However, less satisfactory results are found when the BIAS test is used in the comparison procedure to test the degree of agreement between the lidar datasets. A predominance of negative BIAS values are observed showing that the MPL-4 δV values are underestimated with respect to CALIOP data; however, differences between the MPL-4 datasets are no greater than an 11% (absolute value) with respect to CALIOP values. Moreover, the agreement appears to be unexpectedly independent of the CALIPSO ground-track overpass distance from the Belgrano II station. Consequently, differences between the δV datasets are not dominated by spatial inhomogeneity of the PSC field.

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Micro-Pulse Lidar Cruising Measurements in Northern South China Sea

Remote Sensing ◽

10.3390/rs12101695 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1695

Author(s):

Yuan Li ◽

Baomin Wang ◽

Shao-Yi Lee ◽

Zhijie Zhang ◽

Ye Wang ◽

...

Keyword(s):

Boundary Layer ◽

South China Sea ◽

South China ◽

Vertical Profiles ◽

Depolarization Ratio ◽

Layer Height ◽

Boundary Layer Height ◽

The Mean ◽

Micro Pulse Lidar ◽

Atmospheric Boundary Layer Height

A shipborne micro-pulse lidar (Sigma Space Mini-MPL) was used to measure aerosol extinction coefficient over the northern region of the South China Sea from 9 August to 7 September 2016, the first time a mini-MPL was used for aerosol observation over the cruise region. The goal of the experiment was to investigate if the compact and affordable mini-MPL was usable for aerosol observation over this region. The measurements were used to calculate vertical profiles of volume extinction coefficient, depolarization ratio, and atmospheric boundary layer height. Aerosol optical depth (AOD) was lower over the southwest side of the cruise region, compared to the northeast side. Most attenuation occurred below 3.5 km, and maximum extinction values over coastal areas were generally about double of values offshore. The extinction coefficients at 532 nm (aerosol and molecular combined) over coastal and offshore areas were on average 0.04 km−1 and 0.02 km−1, respectively. Maximum values reached 0.2 km−1 and 0.14 km−1, respectively. Vertical profiles and back-trajectory calculations indicated vertical and horizontal layering of aerosols from different terrestrial sources. The mean volume depolarization ratio of the aerosols along the cruise was 0.04. The mean atmospheric boundary layer height along the cruise was 653 m, with a diurnal cycle reaching its mean maximum of 1041 m at 12:00 local time, and its mean minimum of 450 m at 20:00 local time. Unfortunately, only 11% of the measurements were usable. This was due to ship instability in rough cruise conditions, lack of stabilization rig, water condensation attached to the eye lens, and high humidity attenuating the echo signal. We recommend against the use of the mini-MPL in this cruise region unless substantial improvements are made to the default setup, e.g., instrument stabilization, instrument protection cover, and more theoretical work taking into account atmospheric gas scattering or absorption.

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Polar Stratospheric Clouds: Satellite Observations, Processes, and Role in Ozone Depletion

10.5194/egusphere-egu21-6643 ◽

2021 ◽

Author(s):

Ines Tritscher ◽

Michael C. Pitts ◽

Lamont R. Poole ◽

Thomas Peter ◽

Keyword(s):

Ozone Depletion ◽

Stratospheric Ozone ◽

Michelson Interferometer ◽

Orthogonal Polarization ◽

Polar Stratospheric Clouds ◽

Spatial And Temporal Distributions ◽

Stratospheric Clouds ◽

Polar Ozone ◽

Made In

<p>The important role of polar stratospheric clouds (PSCs) in stratospheric ozone depletion during winter and spring at high latitudes has been known since the 1980s. However, contemporary observations by the spaceborne instruments MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), MLS (Microwave Limb Sounder), and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) have brought about a comprehensive and clearer understanding of PSC spatial and temporal distributions, their conditions of existence, and the processes through which they impact polar ozone. Within the SPARC (Stratosphere-troposphere Processes And their Role in Climate) PSC initiative (PSCi), those datasets have been synthesized and discussed in depth with the result of a new vortex-wide climatology of PSC occurrence and composition. We will present our results within this vPICO together with a review of the significant progress that has been made in our understanding of PSC nucleation, related dynamical processes, and heterogeneous chlorine activation. Moreover, we have compiled different techniques for parameterizing PSCs and we will show their effects in global models.</p>

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Quasi-coincident observations of polar stratospheric clouds by ground-based lidar and CALIOP at Concordia (Dome C, Antarctica) from 2014 to 2018

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-2165-2021 ◽

2021 ◽

Vol 21 (3) ◽

pp. 2165-2178

Author(s):

Marcel Snels ◽

Francesco Colao ◽

Francesco Cairo ◽

Ilir Shuli ◽

Andrea Scoccione ◽

...

Keyword(s):

Orthogonal Polarization ◽

Data Sampling ◽

Polar Stratospheric Clouds ◽

Air Masses ◽

Ground Based Lidar ◽

Stratospheric Clouds ◽

Observation Geometry ◽

The Antarctic ◽

Seasonal And Interannual Variations ◽

Good Agreement

Abstract. Polar stratospheric clouds (PSCs) have been observed from 2014 to 2018 from the lidar observatory at the Antarctic Concordia station (Dome C), included as a primary station in the NDACC (Network for Detection of Atmospheric Climate Change). Many of these measurements have been performed in coincidence with overpasses of the satellite-borne CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) lidar, in order to perform a comparison in terms of PSC detection and composition classification. Good agreement has been obtained, despite intrinsic differences in observation geometry and data sampling. This study reports, to our knowledge, the most extensive comparison of PSC observations by ground-based and satellite-borne lidars. The PSCs observed by the ground-based lidar and CALIOP form a complementary and congruent dataset and allow us to study the seasonal and interannual variations in PSC occurrences at Dome C. Moreover, a strong correlation with the formation temperature of NAT (nitric acid trihydrate), TNAT, calculated from local temperature, pressure, and H2O and HNO3 concentrations is shown. PSCs appear at Dome C at the beginning of June up to 26 km and start to disappear in the second half of August, when the local temperatures start to rise above TNAT. Rare PSC observations in September coincide with colder air masses below 18 km.

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Mountain-wave-induced polar stratospheric clouds and their representation in the global chemistry model ICON-ART

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-9515-2021 ◽

2021 ◽

Vol 21 (12) ◽

pp. 9515-9543

Author(s):

Michael Weimer ◽

Jennifer Buchmüller ◽

Lars Hoffmann ◽

Ole Kirner ◽

Beiping Luo ◽

...

Keyword(s):

Antarctic Peninsula ◽

Scale Effects ◽

Hot Spot ◽

Orthogonal Polarization ◽

Polar Stratospheric Clouds ◽

Mountain Wave ◽

Mountain Waves ◽

Stratospheric Clouds ◽

Wave Induced ◽

The Antarctic

Abstract. Polar stratospheric clouds (PSCs) are a driver for ozone depletion in the lower polar stratosphere. They provide surface for heterogeneous reactions activating chlorine and bromine reservoir species during the polar night. The large-scale effects of PSCs are represented by means of parameterisations in current global chemistry–climate models, but one process is still a challenge: the representation of PSCs formed locally in conjunction with unresolved mountain waves. In this study, we investigate direct simulations of PSCs formed by mountain waves with the ICOsahedral Nonhydrostatic modelling framework (ICON) with its extension for Aerosols and Reactive Trace gases (ART) including local grid refinements (nesting) with two-way interaction. Here, the nesting is set up around the Antarctic Peninsula, which is a well-known hot spot for the generation of mountain waves in the Southern Hemisphere. We compare our model results with satellite measurements of PSCs from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and gravity wave observations of the Atmospheric Infrared Sounder (AIRS). For a mountain wave event from 19 to 29 July 2008 we find similar structures of PSCs as well as a fairly realistic development of the mountain wave between the satellite data and the ICON-ART simulations in the Antarctic Peninsula nest. We compare a global simulation without nesting with the nested configuration to show the benefits of adding the nesting. Although the mountain waves cannot be resolved explicitly at the global resolution used (about 160 km), their effect from the nested regions (about 80 and 40 km) on the global domain is represented. Thus, we show in this study that the ICON-ART model has the potential to bridge the gap between directly resolved mountain-wave-induced PSCs and their representation and effect on chemistry at coarse global resolutions.

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Properties of polar stratospheric clouds obtained by combined ACE-FTS and ACE-Imager extinction measurements

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-13271-2007 ◽

2007 ◽

Vol 7 (5) ◽

pp. 13271-13290 ◽

Cited By ~ 6

Author(s):

A. Y. Zasetsky ◽

K. Gilbert ◽

I. Galkina ◽

S. McLeod ◽

J. J. Sloan

Keyword(s):

Atmospheric Chemistry ◽

Aerosol Particles ◽

The Arctic ◽

Polar Stratospheric Clouds ◽

Near Ir ◽

Mean Size ◽

Extensive Information ◽

The Mean ◽

Stratospheric Clouds ◽

Chemistry Experiment

Abstract. We report the compositions and size distributions of aerosol particles in typical polar stratospheric clouds (PSCs) observed between 24 January and 28 February 2005 in the Arctic stratosphere. The results are obtained by combining the extinction measurements made by the Atmospheric Chemistry Experiment (ACE) Fourier-Transform Spectrometer and the visible/near IR imagers on the SCISAT satellite. The extended wavenumber range provided by this combination (750 to 20 000 cm−1) enables the retrieval of aerosol particle sizes between 0.05 and 10 μm as well as providing extensive information about the compositions. Our results indicate that liquid ternary solutions with a high (>30 wt%) content of HNO3 were the most probable component of the clouds at the (60–70° N) latitudes accessible by ACE. The mean size of these ternary aerosol particles is in the range of 0.3 to 0.8 μm. Less abundant, although still frequent, were clouds composed of NAT particles having radii in the range of 1 μm and clouds of ice particles having mean radii in the 4–5 μm range. In some cases, these last two types were found in the same observation.

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Heterogeneous formation of polar stratospheric clouds – Part 1: Nucleation of nitric acid trihydrate (NAT)

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-9577-2013 ◽

2013 ◽

Vol 13 (18) ◽

pp. 9577-9595 ◽

Cited By ~ 53

Author(s):

C. R. Hoyle ◽

I. Engel ◽

B. P. Luo ◽

M. C. Pitts ◽

L. R. Poole ◽

...

Keyword(s):

Nitric Acid ◽

Companion Paper ◽

Solid Particles ◽

The Arctic ◽

Orthogonal Polarization ◽

Polar Stratospheric Clouds ◽

Formation Pathway ◽

Immersion Freezing ◽

Heterogeneous Formation ◽

Stratospheric Clouds

Abstract. Satellite-based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current understanding, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid-December 2009, a heterogeneous nucleation mechanism is required, occurring via immersion freezing on the surface of solid particles, likely of meteoritic origin. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along more than sixty thousand trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) observation points. Comparing the optical properties of the modelled NAT with these observations enabled a thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM). The parameterisation is based on active site theory, is simple to implement in models and provides substantial advantages over previous approaches which involved a constant rate of NAT nucleation in a given volume of air. It is shown that the new method is capable of reproducing observed polar stratospheric clouds (PSCs) very well, despite the varied conditions experienced by air parcels travelling along the different trajectories. In a companion paper, ZOMM is applied to a later period of the winter, when ice PSCs are also present, and it is shown that the observed PSCs are also represented extremely well under these conditions.

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Biomass Burning Measurements in Earlinet

EPJ Web of Conferences ◽

10.1051/epjconf/202023705005 ◽

2020 ◽

Vol 237 ◽

pp. 05005

Author(s):

Mariana Adam ◽

Doina Nicolae ◽

Livio Belegante ◽

Iwona S. Stachlewska ◽

Dominika Szczepanik ◽

...

Keyword(s):

Quality Control ◽

Biomass Burning ◽

Long Range Transport ◽

Data Sets ◽

Depolarization Ratio ◽

Backscatter Coefficient ◽

Backward Trajectory ◽

Range Transport ◽

The Mean ◽

Linear Depolarization Ratio

The biomass burning events are analyzed using the EARLINET-ACTRIS atmospheric profiling of aerosols using lidars. The period of 2008-2017 was chosen to analyze all the events assigned in the EARLINET database under Forest Fire category. A number of fourteen stations were considered. The data provided, ranged from complete data sets (backscatter, extinction and particle linear depolarization ratio) to single profiles (backscatter coefficient). A thorough quality control was performed. Smoke layers geometry was evaluated and the mean properties within each layer were computed. The Hysplit backward-trajectory technique and the FIRMS fire database were used to double check the source of each layer. Discussions were made under the following scenarios: fire events seen by two stations, long range transport from North America, and geographical clusters.

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Detection of polar stratospheric clouds over Antarctica using AVHRR images obtained at Palmer Station during August 1992

Polar Record ◽

10.1017/s0032247400013711 ◽

1995 ◽

Vol 31 (177) ◽

pp. 211-226 ◽

Cited By ~ 5

Author(s):

Oswaldo Garcia ◽

Kathy L. Pagan ◽

Patricia G. Foschi ◽

Steven E. Gaines ◽

R. Stephen Hipskind

Keyword(s):

Satellite Images ◽

Weddell Sea ◽

Joint Analysis ◽

Data Sets ◽

Polar Stratospheric Clouds ◽

Cold Temperatures ◽

Palmer Station ◽

Sea Area ◽

Stratospheric Clouds ◽

The Antarctic

AbstractFour case studies are presented that focus on a joint analysis of AVHRR images with other independently obtained data sets to identify examples of both optically thick and thin polar stratospheric clouds (PSCs) over Antarctica. Optically thick PSCs are shown to be readily identifiable by the temperature signatures in AVHRR channel 5 images over the Antarctic Peninsula–Weddell Sea area. A time series of optically thick PSCs as seen in satellite images obtained at Palmer Station, Antarctica, is produced and discussed. Four events are identified and discussed where the areal coverage by cold temperatures indicative of PSCs expands to cover a significant portion of the area sampled. Plans for further research are outlined.

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Quasi-coincident Observations of Polar Stratospheric Clouds by Ground-based Lidar and CALIOP at Concordia (Dome C, Antarctica) from 2014 to 2018

10.5194/acp-2020-972 ◽

2020 ◽

Author(s):

Marcel Snels ◽

Francesco Colao ◽

Ilir Shuli ◽

Andrea Scoccione ◽

Mauro De Muro ◽

...

Keyword(s):

Orthogonal Polarization ◽

Data Sampling ◽

Polar Stratospheric Clouds ◽

Air Masses ◽

Ground Based Lidar ◽

Stratospheric Clouds ◽

Observation Geometry ◽

The Antarctic ◽

Seasonal And Interannual Variations ◽

Good Agreement

Abstract. Polar stratospheric clouds (PSCs) have been observed from 2014 to 2018 from the lidar observatory at the Antarctic Concordia station (Dome C), included as a primary station in the NDACC (Network for Detection of Atmospheric Climate Change). Many of these measurements have been performed in coincidence with overpasses of the satellite-borne CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) lidar, in order to perform a comparison in terms of PSC detection and 5 composition classification. Good agreement has been obtained, despite of intrinsic differences in observation geometry and data sampling. This study reports, up to our knowledge, the most extensive comparison of PSC observations by ground-based and satellite-borne lidars. The PSCs observed by the ground-based lidar and CALIOP form a complementary and congruent dataset, and allow to study the seasonal and interannual variations of PSC occurrences at Dome C. Moreover a strong correlation with the formation temperature of NAT (Nitricacidtrihydrate), TNAT, calculated from local temperature, pressure and H2O and HNO3 concentrations is shown. PSCs appear at Dome C at the beginning of June up to 26 km, and start to disappear at the second half of August, when the local temperatures start to rise above TNAT. Rare PSC observations in September coincide with colder air masses below 18 km.

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