scholarly journals Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

2011 ◽  
Vol 11 (16) ◽  
pp. 8471-8487 ◽  
Author(s):  
F. Khosrawi ◽  
J. Urban ◽  
M. C. Pitts ◽  
P. Voelger ◽  
P. Achtert ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Box Model ◽  
Cloud Formation ◽  
The Arctic ◽  
Temperature History ◽  
Model Simulations ◽  
Backward Trajectories ◽  
Measuring Period ◽  
Polar Stratospheric Cloud ◽  
Ground Based Lidar

Abstract. The sedimentation of HNO3 containing Polar Stratospheric Cloud (PSC) particles leads to a permanent removal of HNO3 and thus to a denitrification of the stratosphere, an effect which plays an important role in stratospheric ozone depletion. The polar vortex in the Arctic winter 2009/2010 was very cold and stable between end of December and end of January. Strong denitrification between 475 to 525 K was observed in the Arctic in mid of January by the Odin Sub Millimetre Radiometer (Odin/SMR). This was the strongest denitrification that had been observed in the entire Odin/SMR measuring period (2001–2010). Lidar measurements of PSCs were performed in the area of Kiruna, Northern Sweden with the IRF (Institutet för Rymdfysik) lidar and with the Esrange lidar in January 2010. The measurements show that PSCs were present over the area of Kiruna during the entire period of observations. The formation of PSCs during the Arctic winter 2009/2010 is investigated using a microphysical box model. Box model simulations are performed along air parcel trajectories calculated six days backward according to the PSC measurements with the ground-based lidar in the Kiruna area. From the temperature history of the backward trajectories and the box model simulations we find two PSC regions, one over Kiruna according to the measurements made in Kiruna and one north of Scandinavia which is much colder, reaching also temperatures below Tice. Using the box model simulations along backward trajectories together with the observations of Odin/SMR, Aura/MLS (Microwave Limb Sounder), CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) and the ground-based lidar we investigate how and by which type of PSC particles the denitrification that was observed during the Arctic winter 2009/2010 was caused. From our analysis we find that due to an unusually strong synoptic cooling event in mid January, ice particle formation on NAT may be a possible formation mechanism during that particular winter that may have caused the denitrification observed in mid January. In contrast, the denitrification that was observed in the beginning of January could have been caused by the sedimentation of NAT particles that formed on mountain wave ice clouds.

scholarly journals Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

2011 ◽  
Vol 11 (4) ◽  
pp. 11379-11415 ◽  
Author(s):  
F. Khosrawi ◽  
J. Urban ◽  
M. C. Pitts ◽  
P. Voelger ◽  
P. Achtert ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Box Model ◽  
Cloud Formation ◽  
The Arctic ◽  
Temperature History ◽  
Model Simulations ◽  
Measuring Period ◽  
Polar Stratospheric Cloud ◽  
Ground Based Lidar

Abstract. The sedimentation of HNO3 containing Polar Stratospheric Cloud (PSC) particles leads to a permanent removal of HNO3 and thus to a denitrification of the stratosphere, an effect which plays an important role in stratospheric ozone depletion. The polar vortex in the Arctic winter 2009/2010 was very cold and stable between end of December and end of January. Strong denitrification was observed in the Arctic in mid of January by the Odin Sub Millimetre Radiometer (Odin/SMR) which was the strongest denitrification that had been observed in the entire Odin/SMR measuring period (2001–2010). Lidar measurements of PSCs were performed in the area of Kiruna, Northern Sweden with the IRF (Institutet för Rymdfysik) lidar and with the Esrange lidar in January 2010. The measurements show that PSCs were present over the area of Kiruna during the entire period of observations. The formation of PSCs during the Arctic winter 2009/2010 is investigated using a microphysical box model. Box model simulations are performed along air parcel trajectories calculated six days backward according to the PSC measurements with the ground-based lidar in the Kiruna area. From the temperature history of the trajectories and the box model simulations we find two PSC regions, one over Kiruna according to the measurements made in Kiruna and one north of Scandinavia which is much colder, reaching also temperatures below Tice. Using the box model simulations along backward trajectories together with the observations of Odin/SMR, CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) and the ground-based lidar we investigate how and by which type of PSC particles the denitrification that was observed during the Arctic winter 2009/2010 was caused. From our analysis we find that due to an unusually strong synoptic cooling event in mid January, ice particle formation on NAT may be a possible mechanism that caused denitrification during the Arctic winter 2009/2010.

The Influence of Ozone Feedbacks on Surface Climate following Spring Arctic Ozone Depletion

2021 ◽  
Author(s):  
Marina Friedel ◽  
Gabriel Chiodo ◽  
Andrea Stenke ◽  
Daniela Domeisen ◽  
Stefan Muthers ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Arctic Oscillation ◽  
Stratospheric Ozone ◽  
The Arctic ◽  
Model Simulations ◽  
Temperature Anomalies ◽  
Surface Climate ◽  
Anomalous Surface ◽  
Surface Weather ◽  
Surface Patterns

<p>Links between springtime Arctic stratospheric ozone anomalies and anomalous surface weather in the Northern Hemisphere have been found recently. Stratospheric ozone thus provides valuable information which may help to improve seasonal predictability. However, the extent and causality of the ozone-surface climate coupling remain unclear and many state-of-the-art forecast models lack any representation of ozone feedbacks on planetary circulation.</p><p>We investigate the importance of the ozone-surface climate coupling with two Chemistry Climate Models, contrasting simulations with fully interactive ozone against prescribed zonally averaged climatological ozone under fixed present-day boundary conditions. We focus on springtime Arctic ozone minima and compare subsequent surface patterns in runs with and without interactive ozone, thus rendering a detailed and physically-based quantification of the stratospheric ozone impact on surface climate possible.  </p><p>All model simulations show a connection between Arctic ozone minima and a positive phase of the Arctic Oscillation in the month after the depletion in spring. Runs with interactive ozone chemistry show an amplified surface response and a 40% stronger Arctic Oscillation index after ozone depletion. This amplified Arctic Oscillation goes along with enhanced positive surface temperature anomalies over Eurasia. Moreover, composite surface patterns after spring ozone minima in model simulations with interactive ozone show a better agreement with composites in reanalysis data compared to runs with prescribed ozone.</p><p>Mechanisms whereby stratospheric ozone affects both the stratospheric and tropospheric circulation are explored. These include the reduction of short-wave heating over the pole due to ozone loss, thus amplifying stratospheric temperature anomalies and allowing for an intensification of the polar vortex with subsequent impacts on wave propagation and the stratospheric meridional circulation. This suggests that ozone is not only passively responding to stratospheric dynamics, but actively feeds back into the circulation. Following these results, stratospheric ozone anomalies actively contribute to anomalous surface weather in spring, emphasizing the potential importance of interactive ozone chemistry for seasonal predictions.</p>

scholarly journals Model simulations of stratospheric ozone loss caused by enhanced mesospheric NO<sub>x</sub> during Arctic Winter 2003/2004

2008 ◽  
Vol 8 (2) ◽  
pp. 4911-4947
Author(s):  
B. Vogel ◽  
P. Konopka ◽  
J.-U. Grooß ◽  
R. Müller ◽  
B. Funke ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Potential Temperature ◽  
Satellite Observations ◽  
The Arctic ◽  
Local Production ◽  
Model Simulations ◽  
Ozone Loss ◽  
Upper Limit ◽  
Non Local ◽  
The Impact

Abstract. Satellite observations show that the enormous solar proton events (SPEs) in October–November 2003 had significant effects on the composition of the stratosphere and mesosphere in the polar regions. After the October–November 2003 SPEs and in early 2004 significant enhancements of NOx(=NO+NO2) in the upper stratosphere and lower mesosphere in the Northern Hemisphere were observed by several satellite instruments. Here we present global full chemistry calculations performed with the CLaMS model to study the impact of mesospheric NOx intrusions on Arctic polar ozone loss processes in the stratosphere. Several model simulations are preformed with different upper boundary conditions for NOx at 2000 K potential temperature (≈50 km altitude). In our study we focus on the impact of the non-local production of NOx which means the downward transport of enhanced NOx from the mesosphere in the stratosphere. The local production of NOx in the stratosphere is neglected. Our findings show that intrusions of mesospheric air into the stratosphere, transporting high burdens of NOx, affect the composition of the Arctic polar region down to about 400 K (≈17–18 km). We compare our simulated NOx and O3 mixing ratios with satellite observations by ACE-FTS and MIPAS processed at IMK/IAA and derive an upper limit for the ozone loss caused by enhanced mesospheric NOx. Our findings show that in the Arctic polar vortex (Equivalent Lat.>70° N) the accumulated column ozone loss between 350–2000 K potential temperature (≈14–50 km altitude) caused by the SPEs in October–November 2003 in the stratosphere is up to 3.3 DU with an upper limit of 5.5 DU until end of November. Further we found that about 10 DU but lower than 18 DU accumulated ozone loss additionally occurs until end of March 2004 caused by the transport of mesospheric NOx-rich air in early 2004. In the lower stratosphere (350–700 K≈14–27 km altitude) the SPEs of October–November 2003 have negligible small impact on ozone loss processes until end of November and the mesospheric NOx intrusions in early 2004 yield ozone loss about 3.5 DU, but clearly lower than 6.5 DU until end of March. Overall, the non-local production of NOx is an additional variability to the existing variations of the ozone loss observed in the Arctic.

scholarly journals Location controls the findings of ground-based PSC observations

2020 ◽  
Author(s):  
Matthias Tesche ◽  
Peggy Achtert ◽  
Michael C. Pitts
Keyword(s):  
Signal To Noise Ratio ◽  
The Arctic ◽  
Orthogonal Polarization ◽  
Microphysical Properties ◽  
Polar Stratospheric Cloud ◽  
Comprehensive Picture ◽  
Ground Based Lidar ◽  
Stratospheric Clouds ◽  
The Antarctic ◽  
Lidar Observations

Abstract. Spaceborne observations of Polar Stratospheric Clouds (PSCs) with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provide a comprehensive picture of the occurrence of Arctic and Antarctic PSCs as well as their microphysical properties. However, advances in understanding PSC microphysics also require measurements with ground-based instruments, which are often superior to CALIOP in terms of, e.g. time resolution, measured parameters, and signal-to-noise ratio. This advantage is balanced by the location of ground-based PSC observations and their dependence on tropospheric cloudiness. CALIPSO observations during the boreal winters from December 2006 to February 2018 and the austral winters 2012 and 2015 are used to assess the representativeness of ground-based PSC observations with lidar in the Arctic and Antarctic, respectively. Information on tropospheric and stratospheric clouds from the CALIPSO Cloud Profile product (05kmCPro version 4.10) and the Polar Stratospheric Cloud (PSC) mask version 2, respectively, is combined on a profile-by-profile basis to identify conditions under which a ground-based lidar is likely to perform useful measurements for the analysis of PSC occurrence. It is found that the location of a ground-based measurement together with the related tropospheric cloudiness can have a profound impact on the derived PSC statistics and that these findings are rarely in agreement with polar-wide results from CALIOP observations. Considering the current polar research infrastructure, it is concluded that the most suitable sites for the expansion of capabilities for ground-based lidar observations of PSCs are Summit and Villum in the Arctic and Concordia, Troll, and Vostok in the Antarctic.

scholarly journals Comparison of ECHAM5/MESSy Atmospheric Chemistry (EMAC) Simulations of the Arctic winter 2009/2010 and 2010/2011 with Envisat/MIPAS and Aura/MLS Observations

2018 ◽  
Author(s):  
Farahnaz Khosrawi ◽  
Oliver Kirner ◽  
Gabriele Stiller ◽  
Michael Höpfner ◽  
Michelle L. Santee ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Michelson Interferometer ◽  
Volume Density ◽  
Cloud Formation ◽  
The Arctic ◽  
Cold Temperatures ◽  
Vertical Extension ◽  
Polar Stratospheric Cloud ◽  
Realistic Representation

Abstract. We present model simulations with the atmospheric chemistry-climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) nudged toward European Center for Medium-Range Weather Forecasts (ECMWF) reanalyses for the Arctic winter 2009/2010 and 2010/2011. This study is the first to perform an extensive assessment of the performance of the EMAC model for Arctic winters; previous studies have only made limited evaluations of EMAC simulations for the Arctic. We have chosen the two extreme Arctic winters 2009/2010 and 2010/2011 to evaluate the formation of polar stratospheric clouds (PSCs) and the representation of the chemistry and dynamics of the polar winter stratosphere in EMAC. The EMAC simulations are compared to observations by the Michelson Interferometer for Passive Atmospheric Soundings (Envisat/MIPAS) and the observations from the Aura Microwave Limb Sounder (Aura/MLS). The Arctic winter 2010/2011 was one of the coldest winters on record, leading to the strongest depletion of ozone measured in the Arctic. The Arctic winter 2009/2010 was, from the climatological perspective, one of the warmest winters on record. However, it was distinguished by an exceptionally cold stratosphere (colder than the climatological mean). Cold temperatures prevailed from mid December 2009 to mid January 2010, leading to prolonged PSC formation and existence. Significant denitrification, the removal of HNO3 from the stratosphere by sedimentation of HNO3 containing polar stratospheric cloud particles, occurred. In our comparison, we focus on polar stratospheric cloud formation and denitrification. The comparisons between EMAC simulations and satellite observations show that model and measurements compare well for these two Arctic winters (differences for HNO3 generally within ±20 %) and thus that EMAC nudged toward ECMWF reanalyses is capable of giving a realistic representation of the evolution of PSCs and the associated sequestration of gas-phase HNO3 in the polar winter stratosphere. However, simulated PSC volume densities are several orders of magnitude smaller than the ones derived from Envisat/MIPAS observations. Further, PSCs in EMAC are not simulated as high up as they are observed. This underestimation of PSC volume density and vertical extension of the PSCs results in an underestimation of the vertical redistribution of HNO3 due to denitrification/re-nitrification.

scholarly journals Response of the AMOC to reduced solar radiation – the modulating role of atmospheric chemistry

2016 ◽  
Vol 7 (4) ◽  
pp. 877-892 ◽  
Author(s):  
Stefan Muthers ◽  
Christoph C. Raible ◽  
Eugene Rozanov ◽  
Thomas F. Stocker
Keyword(s):  
Solar Radiation ◽  
North Atlantic ◽  
Stratospheric Ozone ◽  
Meridional Overturning Circulation ◽  
The Arctic ◽  
Solar Radiation Management ◽  
Solar Forcing ◽  
Model Simulations ◽  
The North ◽  
The North Atlantic

Abstract. The influence of reduced solar forcing (grand solar minimum or geoengineering scenarios like solar radiation management) on the Atlantic Meridional Overturning Circulation (AMOC) is assessed in an ensemble of atmosphere–ocean–chemistry–climate model simulations. Ensemble sensitivity simulations are performed with and without interactive chemistry. In both experiments the AMOC is intensified in the course of the solar radiation reduction, which is attributed to the thermal effect of the solar forcing: reduced sea surface temperatures and enhanced sea ice formation increase the density of the upper ocean in the North Atlantic and intensify the deepwater formation. Furthermore, a second, dynamical effect on the AMOC is identified driven by the stratospheric cooling in response to the reduced solar forcing. The cooling is strongest in the tropics and leads to a weakening of the northern polar vortex. By stratosphere–troposphere interactions, the stratospheric circulation anomalies induce a negative phase of the Arctic Oscillation in the troposphere which is found to weaken the AMOC through wind stress and heat flux anomalies in the North Atlantic. The dynamic mechanism is present in both ensemble experiments. In the experiment with interactive chemistry, however, it is strongly amplified by stratospheric ozone changes. In the coupled system, both effects counteract and weaken the response of the AMOC to the solar forcing reduction. Neglecting chemistry–climate interactions in model simulations may therefore lead to an overestimation of the AMOC response to solar forcing.

scholarly journals Particle formation in the Arctic free troposphere during the ASTAR 2004 campaign: a case study on the influence of vertical motion on the binary homogeneous nucleation of H<sub>2</sub>SO<sub>4</sub>/H<sub>2</sub>O

2010 ◽  
Vol 10 (3) ◽  
pp. 1105-1120 ◽  
Author(s):  
F. Khosrawi ◽  
J. Ström ◽  
A. Minikin ◽  
R. Krejci
Keyword(s):  
Vertical Motion ◽  
Particle Formation ◽  
The Other ◽  
Box Model ◽  
The Arctic ◽  
Free Troposphere ◽  
Nucleation Event ◽  
Model Simulations ◽  
Nucleation Mode ◽  
New Particles

Abstract. During the ASTAR (Arctic Study of Tropospheric Aerosol and Radiation) campaign nucleation mode particles (4 to 13 nm) were quite frequently observed at altitudes below 4000 m. However, in the upper free troposphere, nucleation mode particles were only observed once, namely during the flight on 24 May 2004 (7000 m). To investigate if vertical motion were the reason for this difference that on one particular day nucleation mode particles were observed but not on the other days we employ a microphysical box model. The box model simulations were performed along air parcel trajectories calculated 6-d backwards based on European Center for Medium-Range Weather Forecasts (ECMWF) meteorological analyses using state parameters such as pressure and temperature in combination with additional parameters such as vertical stability. Box model simulations were performed for the 24 May where nucleation mode particles were observed (nucleation event) as well as for the days with measurements before and after (22 and 26 May) which are representative for no nucleation (non-nucleation event). A nucleation burst was simulated along all trajectories, however, in the majority of the simulations the nucleation rate was either too low or too high so that no nucleation mode particles were left at the time when the measurements were performed. Further, the simulation results could be divided into three cases. Thereby, we found that for case 1 the temperature was the only driving mechanism for the formation of new particles while for case 2 and 3 vertical motion have influenced the formation of new particles. The reason why nucleation mode particles were observed on 24 May, but not on the other days, can be explained by the conditions under which particle formation occurred. On 24 May the particle formation was caused by a slow updraft, while on the other two days the particle formation was caused by a fast updraft.

scholarly journals The potential impact of ClO<sub>x</sub> radical complexes on polar stratospheric ozone loss processes

2006 ◽  
Vol 6 (1) ◽  
pp. 981-1022
Author(s):  
B. Vogel ◽  
W. Feng ◽  
M. Streibel ◽  
R. Müller
Keyword(s):  
Equilibrium Constant ◽  
Stratospheric Ozone ◽  
Potential Temperature ◽  
The Arctic ◽  
Dimer Formation ◽  
Model Simulations ◽  
Ozone Loss ◽  
Radical Complex ◽  
Potential Impact ◽  
Complex Chemistry

Abstract. The importance of radical-molecule complexes for atmospheric chemistry has been discussed in recent years. In particular, the existence of a ClO·O2 and ClOx water radical complexes like ClO·H2O, OClO·H2O, OClO·(H2O)2, and ClOO·H2O could play a role in enhancing the ClO dimer (Cl2O2) formation and therefore may constitute an important intermediate in polar stratospheric ozone loss cycles. Model simulations performed with the Chemical Lagrangian Model of the Stratosphere (CLaMS) will be presented to study the role of radical complexes on polar stratospheric ozone loss processes. The model simulations are performed for the Arctic winter 2002/2003 at a level of 500 K potential temperature and the results are compared to observed ozone loss rates determined by the Match technique. Moreover, recently reported values for the equilibrium constant of the ClO dimer formation are used to restrict the number of possible model results caused by large uncertainties about radical complex chemistry. Our model simulations show that the potential impact of ClO·O2 on polar ozone loss processes is small (dO3/dt≪0.5 ppb/sunlight h) provided that the ClO·O2 complex is only weakly stable. Assuming that the binding energies of the ClOx water complexes are much higher than theoretically predicted an enhancement of the ozone loss rate by up to ≈0.5 ppb/sunlight h is simulated. Because it is unlikely that the ClOx water complexes are much more stable than predicted we conclude that these complexes have no impact on polar stratospheric ozone loss processes. Although large uncertainties about radical complex chemistry exist, our findings show that the potential impact of ClOx radical molecule complexes on polar stratospheric ozone loss processes is very small considering pure gas-phase chemistry. However the existence of ClOx radical-molecule complexes could possibly explain discrepancies for the equilibrium constant of the ClO dimer formation found between recent laboratory and stratospheric measurements.

scholarly journals The potential impact of ClO<sub>x</sub> radical complexes on polar stratospheric ozone loss processes

2006 ◽  
Vol 6 (10) ◽  
pp. 3099-3114 ◽  
Author(s):  
B. Vogel ◽  
W. Feng ◽  
M. Streibel ◽  
R. Müller
Keyword(s):  
Equilibrium Constant ◽  
Stratospheric Ozone ◽  
Potential Temperature ◽  
The Arctic ◽  
Dimer Formation ◽  
Model Simulations ◽  
Ozone Loss ◽  
Radical Complex ◽  
Potential Impact ◽  
Complex Chemistry

Abstract. The importance of radical-molecule complexes for atmospheric chemistry has been discussed in recent years. In particular, the existence of a ClO·O2 and ClOx water radical complexes like ClO·H2O, OClO·H2O, OClO·(H2O)2, and ClOO·H2O could play a role in enhancing the ClO dimer (Cl2O2) formation and therefore may constitute an important intermediate in polar stratospheric ozone loss cycles. Model simulations performed with the Chemical Lagrangian Model of the Stratosphere (CLaMS) will be presented to study the role of radical complexes on polar stratospheric ozone loss processes. The model simulations are performed for the Arctic winter 2002/2003 at a level of 500 K potential temperature and the results are compared to observed ozone loss rates determined by the Match technique. Moreover, recently reported values for the equilibrium constant of the ClO dimer formation are used to restrict the number of possible model results caused by large uncertainties about radical complex chemistry. Our model simulations show that the potential impact of ClO·O2 on polar ozone loss processes is small (dO3/dt≪0.5 ppb/sunlight h) provided that the ClO·O2 complex is only weakly stable. Assuming that the binding energies of the ClOx water complexes are much higher than theoretically predicted an enhancement of the ozone loss rate by up to ≈0.5 ppb/sunlight h is simulated. Because it is unlikely that the ClOx water complexes are much more stable than predicted we conclude that these complexes have no impact on polar stratospheric ozone loss processes. Although large uncertainties about radical complex chemistry exist, our findings show that the potential impact of ClOx radical molecule complexes on polar stratospheric ozone loss processes is very small considering pure gas-phase chemistry. However the existence of ClOx radical-molecule complexes could possibly explain discrepancies for the equilibrium constant of the ClO dimer formation found between recent laboratory and stratospheric measurements.

scholarly journals On the best locations for ground-based polar stratospheric cloud (PSC) observations

2021 ◽  
Vol 21 (1) ◽  
pp. 505-516 ◽  
Author(s):  
Matthias Tesche ◽  
Peggy Achtert ◽  
Michael C. Pitts
Keyword(s):  
Signal To Noise Ratio ◽  
The Arctic ◽  
Orthogonal Polarization ◽  
Microphysical Properties ◽  
Polar Stratospheric Cloud ◽  
Comprehensive Picture ◽  
Ground Based Lidar ◽  
Stratospheric Clouds ◽  
Cloud Mask ◽  
The Antarctic

Abstract. Spaceborne observations of polar stratospheric clouds (PSCs) with the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provide a comprehensive picture of the occurrence of Arctic and Antarctic PSCs as well as their microphysical properties. However, advances in understanding PSC microphysics also require measurements with ground-based instruments, which are often superior to CALIOP in terms of, for example, time resolution, measured parameters, and signal-to-noise ratio. This advantage is balanced by the location of ground-based PSC observations and their dependence on tropospheric cloudiness. CALIPSO observations during the boreal winters from December 2006 to February 2018 and the austral winters 2012 and 2015 are used to assess the effect of tropospheric cloudiness and other measurement-inhibiting factors on the representativeness of ground-based PSC observations with lidar in the Arctic and Antarctic, respectively. Information on tropospheric and stratospheric clouds from the CALIPSO Cloud Profile product (05kmCPro version 4.10) and the CALIPSO polar stratospheric cloud mask version 2, respectively, is combined on a profile-by-profile basis to identify conditions under which a ground-based lidar is likely to perform useful measurements for the analysis of PSC occurrence. It is found that the location of a ground-based measurement together with the related tropospheric cloudiness can have a profound impact on the derived PSC statistics and that these findings are rarely in agreement with polewide results from CALIOP observations. Considering the current polar research infrastructure, it is concluded that the most suitable sites for the expansion of capabilities for ground-based lidar observations of PSCs are Summit and Villum in the Arctic and Mawson, Troll, and Vostok in the Antarctic.

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