Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature

Abstract. More than a decade ago it was suggested that a cooling of stratospheric temperatures by 1 K or an increase of 1 ppmv of stratospheric water vapour could promote denitrification, the permanent removal of nitrogen species from the stratosphere by solid polar stratospheric cloud (PSC) particles. In fact, during the two Arctic winters 2009/10 and 2010/11 the strongest denitrification in the recent decade was observed. Sensitivity studies along air parcel trajectories are performed to test how a future stratospheric water vapour (H2O) increase of 1 ppmv or a temperature decrease of 1 K would affect PSC formation. We perform our study based on measurements made during the Arctic winter 2010/11. Air parcel trajectories were calculated 6 days backward in time based on PSCs detected by CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder satellite observations). The sensitivity study was performed on single trajectories as well as on a trajectory ensemble. The sensitivity study shows a clear prolongation of the potential for PSC formation and PSC existence when the temperature in the stratosphere is decreased by 1 K and water vapour is increased by 1 ppmv. Based on 15 years of satellite measurements (2000–2014) from UARS/HALOE, Envisat/MIPAS, Odin/SMR, Aura/MLS, Envisat/SCIAMACHY and SCISAT/ACE-FTS it is further investigated if there is a decrease in temperature and/or increase of water vapour (H2O) observed in the polar regions similar to that observed at midlatitudes and in the tropics. Performing linear regression analyses we derive from the Envisat/MIPAS (2002–2012) and Aura/MLS (2004–2014) observations predominantly positive changes in the potential temperature range 350 to 1000 K. The linear changes in water vapour derived from Envisat/MIPAS observations are largely insignificant, while those from Aura/MLS are mostly significant. For the temperature neither of the two instruments indicate any significant changes. Given the strong inter-annual variation observed in water vapour and particular temperature the severe denitrification observed in 2010/11 cannot be directly related to any changes in water vapour and temperature since the millennium. However, the observations indicate a clear correlation between cold winters and enhanced water vapour mixing ratios. This indicates a connection between dynamical and radiative processes that govern water vapour and temperature in the Arctic lower stratosphere.

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Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-17743-2015 ◽

2015 ◽

Vol 15 (13) ◽

pp. 17743-17796 ◽

Cited By ~ 2

Author(s):

F. Khosrawi ◽

J. Urban ◽

S. Lossow ◽

G. Stiller ◽

K. Weigel ◽

...

Keyword(s):

Water Vapour ◽

Recent Decade ◽

Sensitivity Study ◽

Cloud Formation ◽

The Arctic ◽

Polar Regions ◽

Mixing Ratios ◽

Polar Stratospheric Cloud ◽

The Tropics ◽

Stratospheric Water Vapour

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Linking the uncertainty in simulated arctic ozone losses to modelling of tropical stratospheric water vapour

10.5194/acp-2018-310 ◽

2018 ◽

Author(s):

Laura Thölix ◽

Alexey Karpechko ◽

Leif Backman ◽

Rigel Kivi

Keyword(s):

Water Vapour ◽

Climate Models ◽

Polar Vortex ◽

The Arctic ◽

Ozone Loss ◽

Tropical Tropopause ◽

Water Vapour Concentration ◽

Vapour Concentration ◽

The Impact ◽

Stratospheric Water Vapour

Abstract. Stratospheric water vapor plays a key role in radiative and chemical processes, it e.g. influences the chemical ozone loss via controlling the polar stratospheric cloud formation in the polar stratosphere. The amount of water entering the stratosphere through the tropical tropopause differs substantially between chemistry-climate models. This is because the present-day models have difficulties in capturing the whole complexity of processes that control the water transport across the tropopause. As a result there are large differences in the stratospheric water vapour between the models. In this study we investigate the sensitivity of simulated Arctic ozone loss to the amount of water, which enters the stratosphere through the tropical tropopause. We used a chemical transport model, FinROSE-CTM, forced by ERA-Interim meteorology. The water vapour concentration in the tropical tropopause was varied between 0.5 and 1.6 times the concentration in ERA-Interim, which is similar to the range seen in chemistry climate models. The water vapour changes in the tropical tropopause led to about 1.5 and 2 ppm more water vapour in the Arctic polar vortex compared to the ERA-Interim, respectively. We found that the impact of water vapour changes on ozone loss in the Arctic polar vortex depend on the meteorological conditions. Polar stratospheric clouds form in the cold conditions within the Arctic vortex, and chlorine activation on their surface lead to ozone loss. If the cold conditions persist long enough (e.g. in 2010/11), the chlorine activation is nearly complete. In this case addition of water vapour to the stratosphere increased the formation of ICE clouds, but did not increase the chlorine activation and ozone destruction significantly. In the warm winter 2012/13 the impact of water vapour concentration on ozone loss was small, because the ozone loss was mainly NOx induced. In intermediately cold conditions, e.g. 2013/14, the effect of added water vapour was more prominent than in the other studied winters. The results show that the simulated water vapour concentration in the tropical tropopause has a significant impact on the Arctic ozone loss and deserves attention in order to improve future projections of ozone layer recovery.

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Trends and variability of midlatitude stratospheric water vapour deduced from the re-evaluated Boulder balloon series and HALOE

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-1391-2008 ◽

2008 ◽

Vol 8 (5) ◽

pp. 1391-1402 ◽

Cited By ~ 83

Author(s):

M. Scherer ◽

H. Vömel ◽

S. Fueglistaler ◽

S. J. Oltmans ◽

J. Staehelin

Keyword(s):

Water Vapour ◽

Linear Trend ◽

Potential Temperature ◽

Data Series ◽

Explanatory Variables ◽

Time Period ◽

Corrected Data ◽

Instrumental Bias ◽

The Tropics ◽

Stratospheric Water Vapour

Abstract. This paper presents an updated trend analysis of water vapour in the lower midlatitude stratosphere from the Boulder balloon-borne NOAA frostpoint hygrometer measurements and from the Halogen Occulation Experiment (HALOE). Two corrections for instrumental bias are applied to homogenise the frostpoint data series, and a quality assessment of all soundings after 1991 is presented. Linear trend estimates based on the corrected data for the period 1980–2000 are up to 40% lower than previously reported. Vertically resolved trends and variability are calculated with a multi regression analysis including the quasi-biennal oscillation and equivalent latitude as explanatory variables. In the range of 380 to 640 K potential temperature (≈14 to 25 km), the frostpoint data from 1981 to 2006 show positive linear trends between 0.3±0.3 and 0.7±0.1%/yr. The same dataset shows trends between −0.2±0.3 and 1.0±0.3%/yr for the period 1992 to 2005. HALOE data over the same time period suggest negative trends ranging from −1.1±0.2 to −0.1±0.1%/yr. In the lower stratosphere, a rapid drop of water vapour is observed in 2000/2001 with little change since. At higher altitudes, the transition is more gradual, with slowly decreasing concentrations between 2001 and 2007. This pattern is consistent with a change induced by a drop of water concentrations at entry into the stratosphere. Previously noted differences in trends and variability between frostpoint and HALOE remain for the homogenised data. Due to uncertainties in reanalysis temperatures and stratospheric transport combined with uncertainties in observations, no quantitative inference about changes of water entering the stratosphere in the tropics could be made with the mid latitude measurements analysed here.

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The water vapour distribution in the Arctic lowermost stratosphere during the LAUTLOS campaign and related transport processes including stratosphere-troposphere exchange

Atmospheric Chemistry and Physics ◽

10.5194/acp-7-107-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 107-119 ◽

Cited By ~ 9

Author(s):

A. Karpechko ◽

A. Lukyanov ◽

E. Kyrö ◽

S. Khaikin ◽

L. Korshunov ◽

...

Keyword(s):

Water Vapour ◽

Potential Temperature ◽

Thick Layer ◽

Transport Processes ◽

The Arctic ◽

Air Masses ◽

Air Turbulence ◽

Cross Correlation Analysis ◽

Northern Atlantic ◽

Strong Winds

Abstract. Balloon-borne water vapour measurements during January and February 2004, which were obtained as part of the LAUTLOS campaign at Sodankylä, Finland, 67° N, were used to analyse the water vapour distribution in the wintertime Arctic lowermost stratosphere. A 2.5 km thick layer (or 30 K in the potential temperature scale) above the tropopause is characterized by a significant water vapour variability on a synoptic timescale with values between stratospheric and tropospheric, which is in good agreement with previously reported measurements. A cross-correlation analysis of ozone and water vapour confirms that this layer contains a mixture of stratospheric and tropospheric air masses. Some of the flights sampled laminae of enhanced water vapour above the tropopause. Meteorological analyses and backward trajectory calculations show that these features were related to filaments that had developed along the flanks of cut-off anticyclones, which had been active at this time over the Northern Atlantic. The role of the filaments was however not to transport water vapour from the troposphere to the stratosphere but rather to transport it within the stratosphere away from regions where intensive two-way stratosphere-troposphere exchange (STE) was identified. Intensive STE occurred around cut-off anticyclones in regions of strong winds, where calculations suggest the presence of clear-air turbulence (CAT). Evidences that CAT contributes to the troposphere-to-stratosphere transport (TST) are presented. However, statistically, relation between TST and CAT during the studied period is weak.

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-8471-2011 ◽

2011 ◽

Vol 11 (16) ◽

pp. 8471-8487 ◽

Cited By ~ 44

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.

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Comparison of the CMAM30 data set with ACE-FTS and OSIRIS: polar regions

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-11179-2015 ◽

2015 ◽

Vol 15 (8) ◽

pp. 11179-11221

Author(s):

D. Pendlebury ◽

D. Plummer ◽

J. Scinocca ◽

P. Sheese ◽

K. Strong ◽

...

Keyword(s):

Water Vapour ◽

Southern Hemisphere ◽

Atmospheric Chemistry ◽

Middle Atmosphere ◽

Imaging System ◽

Polar Vortex ◽

Cloud Formation ◽

Polar Regions ◽

Data Set ◽

Chemical Tracers

Abstract. CMAM30 is a 30 year data set extending from 1979 to 2010 that is generated using a version of the Canadian Middle Atmosphere Model (CMAM) in which the winds and temperatures are relaxed to the Interim Reanalysis product from the European Centre Medium-Range for Weather Forecasts (ERA-Interim). The data set has dynamical fields that are very close to the reanalysis below 1 hPa and chemical tracers that are self-consistent with respect to the model winds and temperature. The chemical tracers are expected to be close to actual observations. The data set is here compared to two satellite records – the Atmospheric Chemistry Experiment Fourier Transform Spectometer and the Odin Optical Spectrograph and InfraRed Imaging System – for the purpose of validating the temperature, ozone, water vapour and methane fields. Data from the Aura Microwave Limb Sounder is also used for validation of the chemical processing in the polar vortex. It is found that the CMAM30 temperature is warm by up to 5 K in the stratosphere, with a low bias in the mesosphere of ~ 5–15 K. Ozone is reasonable (± 15%) except near the tropopause globally, and in the Southern Hemisphere winter polar vortex. Water vapour is consistently low by 10–20%, with corresponding high methane of 10–20%, except in the Southern Hemisphere polar vortex. Discrepancies in this region are shown to stem from the treatment of polar stratospheric cloud formation in the model.

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Stratospheric water vapour as tracer for vortex filamentation in the Arctic winter 2002/2003

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-3-4393-2003 ◽

2003 ◽

Vol 3 (4) ◽

pp. 4393-4410 ◽

Cited By ~ 2

Author(s):

M. Müller ◽

R. Neuber ◽

F. Fierli ◽

A. Hauchecorne ◽

H. Vömel ◽

...

Keyword(s):

Water Vapour ◽

Large Scale ◽

Polar Vortex ◽

The Arctic ◽

Edge Region ◽

Mixing Ratio ◽

Particle Sedimentation ◽

Frost Point ◽

Contour Advection ◽

Stratospheric Water Vapour

Abstract. During winter 2002/2003, three balloon-borne frost point hygrometers measured high-resolution profiles of stratospheric water vapour above Ny-Ålesund, Spitsbergen. All measurements reveal a high H2O mixing ratio of about 7 ppmv above 24 km, thus differing significantly from the 5 ppmv that are commonly assumed for the calculation of polar stratospheric cloud existence temperatures. The profiles obtained on 12 December 2002 and on 17 January 2003 provide an insight into the vertical distribution of water vapour in the core of the polar vortex. Unlike the earlier profiles, the water vapour sounding on 11 February 2003 detected the vortex edge region in the lower part of the stratosphere. Here, a striking diminuition in H2O mixing ratio stands out between 16 and 19 km. The according stratospheric temperatures clarify that this dehydration can not be caused by the presence of polar stratospheric clouds or earlier PSC particle sedimentation. On the same day, ozone observations by lidar indicate a large scale movement of the polar vortex, while an ozone sonde measurement even shows laminae in the same altitude range as in the water vapour profile. Tracer lamination in the vortex edge region is caused by filamentation of the vortex. The link between the observed water vapour diminuition and filaments in the vortex edge region is highlighted by results of the MIMOSA contour advection model. In the altitude of interest, adjoined filaments of polar and mid-latitudinal air can be identified above the Spitsbergen region. A vertical cross-section reveals that the water vapour sonde has flown through polar air in the lowest part of the stratosphere. Where the low water vapour mixing ratio was detected, the balloon passed through air from a mid-latitudinal filament from about 425 to 445 K, before it finally entered the polar vortex above 450 K. The MIMOSA model results elucidate the correlation that on 11 February 2003 the frost point hygrometer measured strongly variable water vapour concentrations as the sonde detected air with different origins, respectively. Instead of being linked to dehydration due to PSC particle sedimentation, the local diminuition in the stratospheric water vapour profile of 11 February 2003 has been found to be caused by dynamical processes in the polar stratosphere.

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Comparison of the CMAM30 data set with ACE-FTS and OSIRIS: polar regions

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-12465-2015 ◽

2015 ◽

Vol 15 (21) ◽

pp. 12465-12485 ◽

Cited By ~ 9

Author(s):

D. Pendlebury ◽

D. Plummer ◽

J. Scinocca ◽

P. Sheese ◽

K. Strong ◽

...

Keyword(s):

Water Vapour ◽

Southern Hemisphere ◽

Atmospheric Chemistry ◽

Middle Atmosphere ◽

Imaging System ◽

Polar Vortex ◽

Cloud Formation ◽

Polar Regions ◽

Data Set ◽

Chemical Tracers

Abstract. CMAM30 is a 30-year data set extending from 1979 to 2010 that is generated using a version of the Canadian Middle Atmosphere Model (CMAM) in which the winds and temperatures are relaxed to the Interim Reanalysis product from the European Centre for Medium-Range Weather Forecasts (ERA-Interim). The data set has dynamical fields that are very close to the reanalysis below 1 hPa and chemical tracers that are self-consistent with respect to the model winds and temperature. The chemical tracers are expected to be close to actual observations. The data set is here compared to two satellite records – the Atmospheric Chemistry Experiment Fourier transform spectrometer and the Odin Optical Spectrograph and Infrared Imaging System – for the purpose of validating the temperature, ozone, water vapour and methane fields. Data from the Aura microwave limb sounder are also used for validation of the chemical processing in the polar vortex. It is found that the CMAM30 temperature is warmer by up to 5 K in the stratosphere, with a low bias in the mesosphere of ~ 5–15 K. Ozone is reasonable (±15 %), except near the tropopause globally and in the Southern Hemisphere winter polar vortex. Water vapour is consistently low by 10–20 %, with corresponding high methane of 10–20 %, except in the Southern Hemisphere polar vortex. Discrepancies in this region are shown to stem from the treatment of polar stratospheric cloud formation in the model.

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Assessing the vertical structure of Arctic aerosols using balloon-borne measurements

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-1737-2021 ◽

2021 ◽

Vol 21 (3) ◽

pp. 1737-1757

Author(s):

Jessie M. Creamean ◽

Gijs de Boer ◽

Hagen Telg ◽

Fan Mei ◽

Darielle Dexheimer ◽

...

Keyword(s):

Vertical Structure ◽

Potential Temperature ◽

Atmospheric Stability ◽

Surface Energy Budget ◽

Radiative Properties ◽

Cloud Formation ◽

The Arctic ◽

Cloud Base ◽

Cloud Environment ◽

Near Surface

Abstract. The rapidly warming Arctic is sensitive to perturbations in the surface energy budget, which can be caused by clouds and aerosols. However, the interactions between clouds and aerosols are poorly quantified in the Arctic, in part due to (1) limited observations of vertical structure of aerosols relative to clouds and (2) ground-based observations often being inadequate for assessing aerosol impacts on cloud formation in the characteristically stratified Arctic atmosphere. Here, we present a novel evaluation of Arctic aerosol vertical distributions using almost 3 years' worth of tethered balloon system (TBS) measurements spanning multiple seasons. The TBS was deployed at the U.S. Department of Energy Atmospheric Radiation Measurement Program's facility at Oliktok Point, Alaska. Aerosols were examined in tandem with atmospheric stability and ground-based remote sensing of cloud macrophysical properties to specifically address the representativeness of near-surface aerosols to those at cloud base. Based on a statistical analysis of the TBS profiles, ground-based aerosol number concentrations were unequal to those at cloud base 86 % of the time. Intermittent aerosol layers were observed 63 % of the time due to poorly mixed below-cloud environments, mostly found in the spring, causing a decoupling of the surface from the cloud layer. A uniform distribution of aerosol below cloud was observed only 14 % of the time due to a well-mixed below-cloud environment, mostly during the fall. The equivalent potential temperature profiles of the below-cloud environment reflected the aerosol profile 89 % of the time, whereby a mixed or stratified below-cloud environment was observed during a uniform or layered aerosol profile, respectively. In general, a combination of aerosol sources, thermodynamic structure, and wet removal processes from clouds and precipitation likely played a key role in establishing observed aerosol vertical structures. Results such as these could be used to improve future parameterizations of aerosols and their impacts on Arctic cloud formation and radiative properties.

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Validation of stratospheric water vapour measurements from the airborne microwave radiometer AMSOS

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-1635-2008 ◽

2008 ◽

Vol 8 (1) ◽

pp. 1635-1671 ◽

Cited By ~ 2

Author(s):

S. C. Müller ◽

N. Kämpfer ◽

D. G. Feist ◽

A. Haefele ◽

M. Milz ◽

...

Keyword(s):

Water Vapour ◽

Microwave Radiometer ◽

Estimation Method ◽

Optimal Estimation ◽

Horizontal Resolution ◽

Polar Regions ◽

Upper Troposphere ◽

Vertical Range ◽

Stratospheric Water Vapour

Abstract. We present the validation of a water vapour dataset obtained by the Airborne Microwave Stratospheric Observing System AMSOS, a passive microwave radiometer operating at 183 GHz. Vertical profiles are retrieved from spectra by an optimal estimation method. The useful vertical range lies in the upper troposphere up to the mesosphere with an altitude resolution of 8 to 16 km and a horizontal resolution of about 57 km. Flight campaigns were performed once a year from 1998 to 2006 measuring the latitudinal distribution of water vapour from the tropics to the polar regions. The obtained profiles show clearly the main features of stratospheric water vapour in all latitudinal regions. Data are validated against a set of instruments comprising satellite, ground-based, airborne remote sensing and in-situ instruments. It appears that AMSOS profiles have a dry bias of 3–20%, when compared to satellite experiments. A good agreement with a difference of 3.3% was found between AMSOS and in-situ hygrosondes FISH and FLASH and an excellent matching of the lidar measurements from the DIAL instrument in the short overlap region in the upper troposphere.

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