Variability of water vapour in the Arctic stratosphere

Abstract. This study evaluates the stratospheric water vapour distribution and variability in the Arctic. A FinROSE chemistry climate model simulation covering years 1990–2013 is compared to observations (satellite and frostpoint hygrometer soundings) and the sources of stratospheric water vapour are studied. According to observations and the simulations the water vapour concentration in the Arctic stratosphere started to increase after year 2006, but around 2011 the concentration started to decrease. Model calculations suggest that the increase in water vapour during 2006–2011 (at 56 hPa) is mostly explained by transport related processes, while the photochemically produced water vapour plays a relatively smaller role. The water vapour trend in the stratosphere may have contributed to increased ICE PSC occurrence. The increase of water vapour in the precense of the low winter temperatures in the Arctic stratosphere led to more frequent occurrence of ICE PSCs in the Arctic vortex. The polar vortex was unusually cold in early 2010 and allowed large scale formation of the polar stratospheric clouds. The cold pool in the stratosphere over the Northern polar latitudes was large and stable and a large scale persistent dehydration was observed. Polar stratospheric ice clouds and dehydration were observed at Sodankylä with accurate water vapour soundings in January and February 2010 during the LAPBIAT atmospheric sounding campaign. The observed changes in water vapour were reproduced by the model. Both the observed and simulated decrease of the water vapour in the dehydration layer was up to 1.5 ppm.

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Variability of water vapour in the Arctic stratosphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-4307-2016 ◽

2016 ◽

Vol 16 (7) ◽

pp. 4307-4321 ◽

Cited By ~ 5

Author(s):

Laura Thölix ◽

Leif Backman ◽

Rigel Kivi ◽

Alexey Yu. Karpechko

Keyword(s):

Water Vapour ◽

Large Scale ◽

Decadal Variability ◽

Transport Model ◽

Model Simulation ◽

The Arctic ◽

Arctic Water ◽

Model Calculations ◽

Water Vapour Concentration ◽

Stratospheric Water Vapour

Abstract. This study evaluates the stratospheric water vapour distribution and variability in the Arctic. A FinROSE chemistry transport model simulation covering the years 1990–2014 is compared to observations (satellite and frost point hygrometer soundings), and the sources of stratospheric water vapour are studied. In the simulations, the Arctic water vapour shows decadal variability with a magnitude of 0.8 ppm. Both observations and the simulations show an increase in the water vapour concentration in the Arctic stratosphere after the year 2006, but around 2012 the concentration started to decrease. Model calculations suggest that this increase in water vapour is mostly explained by transport-related processes, while the photochemically produced water vapour plays a relatively smaller role. The increase in water vapour in the presence of the low winter temperatures in the Arctic stratosphere led to more frequent occurrence of ice polar stratospheric clouds (PSCs) in the Arctic vortex. We perform a case study of ice PSC formation focusing on January 2010 when the polar vortex was unusually cold and allowed large-scale formation of PSCs. At the same time a large-scale persistent dehydration was observed. Ice PSCs and dehydration observed at Sodankylä with accurate water vapour soundings in January and February 2010 during the LAPBIAT (Lapland Atmosphere–Biosphere facility) atmospheric measurement campaign were well reproduced by the model. In particular, both the observed and simulated decrease in water vapour in the dehydration layer was up to 1.5 ppm.

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-3-1991-2003 ◽

2003 ◽

Vol 3 (6) ◽

pp. 1991-1997 ◽

Cited By ~ 7

Author(s):

M. Müller ◽

R. Neuber ◽

F. Fierli ◽

A. Hauchecorne ◽

H. Vömel ◽

...

Keyword(s):

Water Vapour ◽

Large Scale ◽

Polar Vortex ◽

The Arctic ◽

Edge Region ◽

Particle Sedimentation ◽

Frost Point ◽

Lagrangian Advection ◽

Stratospheric Clouds ◽

Stratospheric Water Vapour

Abstract. Balloon-borne frost point hygrometers measured three high-resolution profiles of stratospheric water vapour above Ny-Ålesund, Spitsbergen during winter 2002/2003. 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. The water vapour sounding on 11 February 2003 was obtained within the vortex edge region of the lower stratosphere. Here, a significant reduction of water vapour mixing ratio was observed between 16 and 19 km. The stratospheric temperatures indicate that this dehydration was not caused by the presence of polar stratospheric clouds or earlier PSC particle sedimentation. Ozone observations on this day indicate a large scale movement of the polar vortex and show laminae in the same altitude range as the water vapour profile. The link between the observed water vapour reduction and filaments in the vortex edge region is indicated in the results of the semi-lagrangian advection model MIMOSA, which show that adjacent filaments of polar and mid latitude air can be identified above the Spitsbergen region. A vertical cross-section produced by the MIMOSA model reveals that the water vapour sonde flew through polar air in the lowest part of the stratosphere below 425 K, then passed through filaments of mid latitude air with lower water vapour concentrations, before it finally entered the polar vortex above 450 K. These results indicate that on 11 February 2003 the frost point hygrometer measured different water vapour concentrations as the sonde detected air with different origins. Instead of being linked to dehydration due to PSC particle sedimentation, the local reduction in the stratospheric water vapour profile was in this case caused by dynamical processes in the polar stratosphere.

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Linking uncertainty in simulated Arctic ozone loss to uncertainties in modelled tropical stratospheric water vapour

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-15047-2018 ◽

2018 ◽

Vol 18 (20) ◽

pp. 15047-15067

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 vapour influences the chemical ozone loss in the polar stratosphere via control of the polar stratospheric cloud formation. The amount of water vapour entering the stratosphere through the tropical tropopause differs substantially between simulations from chemistry–climate models (CCMs). This is because the present-day models, e.g. CCMs, 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 simulated amount of water vapour that 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 ppmv less and 2 ppmv more water vapour in the Arctic polar vortex compared to the ERA-Interim, respectively. The change induced in the water vapour concentration in the tropical tropopause region was seen as a nearly one-to-one change in the Arctic polar vortex. We found that the impact of water vapour changes on ozone loss in the Arctic polar vortex depends on the meteorological conditions. The strongest effect was in intermediately cold stratospheric winters, such as the winter of 2013/2014, when added water vapour resulted in 2 %–7 % more ozone loss due to the additional formation of polar stratospheric clouds (PSCs) and associated chlorine activation on their surface, leading to ozone loss. The effect was less pronounced in cold winters such as the 2010/2011 winter because cold conditions persisted long enough for a nearly complete chlorine activation, even in simulations with prescribed stratospheric water vapour amount corresponding to the observed values. In this case addition of water vapour to the stratosphere led to increased areas of ICE PSCs but it did not increase the chlorine activation and ozone destruction significantly. In the warm winter of 2012/2013 the impact of water vapour concentration on ozone loss was small because the ozone loss was mainly NOx-induced. The results show that the simulated water vapour concentration in the tropical tropopause has a significant impact on the Arctic ozone loss and therefore needs to be well simulated in order to improve future projections of the recovery of the ozone layer.

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Middle atmospheric water vapour and dynamics in the vicinity of the polar vortex during the Hygrosonde-2 campaign

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-4407-2009 ◽

2009 ◽

Vol 9 (13) ◽

pp. 4407-4417 ◽

Cited By ~ 9

Author(s):

S. Lossow ◽

M. Khaplanov ◽

J. Gumbel ◽

J. Stegman ◽

G. Witt ◽

...

Keyword(s):

Water Vapour ◽

Middle Atmosphere ◽

Polar Vortex ◽

The Arctic ◽

Small Scale ◽

Air Masses ◽

Mixing Ratios ◽

Water Vapour Concentration ◽

Wind Shears

Abstract. The Hygrosonde-2 campaign took place on 16 December 2001 at Esrange/Sweden (68° N, 21° E) with the aim to investigate the small scale distribution of water vapour in the middle atmosphere in the vicinity of the Arctic polar vortex. In situ balloon and rocket-borne measurements of water vapour were performed by means of OH fluorescence hygrometry. The combined measurements yielded a high resolution water vapour profile up to an altitude of 75 km. Using the characteristic of water vapour being a dynamical tracer it was possible to directly relate the water vapour data to the location of the polar vortex edge, which separates air masses of different character inside and outside the polar vortex. The measurements probed extra-vortex air in the altitude range between 45 km and 60 km and vortex air elsewhere. Transitions between vortex and extra-vortex usually coincided with wind shears caused by gravity waves which advect air masses with different water vapour volume mixing ratios. From the combination of the results from the Hygrosonde-2 campaign and the first flight of the optical hygrometer in 1994 (Hygrosonde-1) a clear picture of the characteristic water vapour distribution inside and outside the polar vortex can be drawn. Systematic differences in the water vapour concentration between the inside and outside of the polar vortex can be observed all the way up into the mesosphere. It is also evident that in situ measurements with high spatial resolution are needed to fully account for the small-scale exchange processes in the polar winter middle atmosphere.

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Middle atmospheric water vapour and dynamics in the vicinity of the polar vortex during the Hygrosonde-2 campaign

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-12227-2008 ◽

2008 ◽

Vol 8 (3) ◽

pp. 12227-12252 ◽

Cited By ~ 1

Author(s):

S. Lossow ◽

M. Khaplanov ◽

J. Gumbel ◽

J. Stegman ◽

G. Witt ◽

...

Keyword(s):

Water Vapour ◽

Middle Atmosphere ◽

Polar Vortex ◽

The Arctic ◽

Small Scale ◽

Water Vapour Concentration ◽

Exchange Processes ◽

Vapour Concentration ◽

Wind Shears

Abstract. The Hygrosonde-2 campaign took place on 16 December 2001 at Esrange/Sweden, with the aim to investigate the small scale distribution of water vapour in the middle atmosphere in the vicinity of the Arctic polar vortex. In-situ balloon and rocket-borne measurements of water vapour were performed by means of OH fluorescence hygrometry. The combined measurements yielded a high resolution water vapour profile up to an altitude of 75 km. Using water vapour as a dynamical tracer it was possible to directly relate the water data to the position of the polar vortex. The measurement probed extra-vortex air below 19 km and in the altitude range between 45 km and 60 km and vortex air elsewhere. Transitions between vortex and extra-vortex usually coincided with wind shears caused by gravity waves which advect air masses with different water vapour characteristics. From the combination of the results from the Hygrosonde-2 campaign and the first flight of the optical hygrometer in 1994 (Hygrosonde-1) a clear picture of the characteristic water vapour distribution inside and outside the polar vortex can be drawn. Systematic differences in the water vapour concentration between the inside and outside of the polar vortex can be observed all the way up into the mesosphere and are consistent with efficient downward transport of air inside the vortex. It is evident that in-situ measurements with high spatial resolution are needed to fully account for the small-scale exchange processes in the polar winter middle atmosphere.

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Stratospheric water vapour in the vicinity of the Arctic polar vortex

Annales Geophysicae ◽

10.5194/angeo-24-1511-2006 ◽

2006 ◽

Vol 24 (6) ◽

pp. 1511-1521 ◽

Cited By ~ 6

Author(s):

M. Maturilli ◽

F. Fierli ◽

V. Yushkov ◽

A. Lukyanov ◽

S. Khaykin ◽

...

Keyword(s):

Water Vapour ◽

Climate Models ◽

Polar Vortex ◽

Relative Difference ◽

Specific Humidity ◽

The Arctic ◽

Lyman Alpha ◽

Lagrangian Advection ◽

Stratospheric Water Vapour ◽

Dry Bias

Abstract. The stratospheric water vapour mixing ratio inside, outside, and at the edge of the polar vortex has been accurately measured by the FLASH-B Lyman-Alpha hygrometer during the LAUTLOS campaign in Sodankylä, Finland, in January and February 2004. The retrieved H2O profiles reveal a detailed view on the Arctic lower stratospheric water vapour distribution, and provide a valuable dataset for the validation of model and satellite data. Analysing the measurements with the semi-lagrangian advection model MIMOSA, water vapour profiles typical for the polar vortex' interior and exterior have been identified, and laminae in the observed profiles have been correlated to filamentary structures in the potential vorticity field. Applying the validated MIMOSA transport scheme to specific humidity fields from operational ECMWF analyses, large discrepancies from the observed profiles arise. Although MIMOSA is able to reproduce weak water vapour filaments and improves the shape of the profiles compared to operational ECMWF analyses, both models reveal a dry bias of about 1 ppmv in the lower stratosphere above 400 K, accounting for a relative difference from the measurements in the order of 20%. The large dry bias in the analysis representation of stratospheric water vapour in the Arctic implies the need for future regular measurements of water vapour in the polar stratosphere to allow the validation and improvement of climate models.

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The Diurnal Variation in Stratospheric Ozone from MACC Reanalysis, ERA-Interim, WACCM, and Earth Observation Data: Characteristics and Intercomparison

Atmosphere ◽

10.3390/atmos12050625 ◽

2021 ◽

Vol 12 (5) ◽

pp. 625

Author(s):

Ansgar Schanz ◽

Klemens Hocke ◽

Niklaus Kämpfer ◽

Simon Chabrillat ◽

Antje Inness ◽

...

Keyword(s):

Diurnal Variation ◽

Climate Model ◽

Stratospheric Ozone ◽

Polar Vortex ◽

Model Systems ◽

Atmospheric Composition ◽

The Arctic ◽

Observation Data ◽

High Latitudes ◽

Free Running

In this study, we compare the diurnal variation in stratospheric ozone of the MACC (Monitoring Atmospheric Composition and Climate) reanalysis, ECMWF Reanalysis Interim (ERA-Interim), and the free-running WACCM (Whole Atmosphere Community Climate Model). The diurnal variation of stratospheric ozone results from photochemical and dynamical processes depending on altitude, latitude, and season. MACC reanalysis and WACCM use similar chemistry modules and calculate a similar diurnal cycle in ozone when it is caused by a photochemical variation. The results of the two model systems are confirmed by observations of the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) experiment and three selected sites of the Network for Detection of Atmospheric Composition Change (NDACC) at Mauna Loa, Hawaii (tropics), Bern, Switzerland (midlatitudes), and Ny-Ålesund, Svalbard (high latitudes). On the other hand, the ozone product of ERA-Interim shows considerably less diurnal variation due to photochemical variations. The global maxima of diurnal variation occur at high latitudes in summer, e.g., near the Arctic NDACC site at Ny-Ålesund, Svalbard. The local OZORAM radiometer observes this effect in good agreement with MACC reanalysis and WACCM. The sensed diurnal variation at Ny-Ålesund is up to 8% (0.4 ppmv) due to photochemical variations in summer and negligible during the dynamically dominated winter. However, when dynamics play a major role for the diurnal ozone variation as in the lower stratosphere (100–20 hPa), the reanalysis models ERA-Interim and MACC which assimilate data from radiosondes and satellites outperform the free-running WACCM. Such a domain is the Antarctic polar winter where a surprising novel feature of diurnal variation is indicated by MACC reanalysis and ERA-Interim at the edge of the polar vortex. This effect accounts for up to 8% (0.4 ppmv) in both model systems. In summary, MACC reanalysis provides a global description of the diurnal variation of stratospheric ozone caused by dynamics and photochemical variations. This is of high interest for ozone trend analysis and other research which is based on merged satellite data or measurements at different local time.

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Simulation of the isotopic composition of stratospheric water vapour – Part 1: Description and evaluation of the EMAC model

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-5537-2015 ◽

2015 ◽

Vol 15 (10) ◽

pp. 5537-5555 ◽

Cited By ~ 8

Author(s):

R. Eichinger ◽

P. Jöckel ◽

S. Brinkop ◽

M. Werner ◽

S. Lossow

Keyword(s):

Isotopic Composition ◽

Water Vapour ◽

General Circulation ◽

Climate Model ◽

Hydrological Cycle ◽

Circulation Model ◽

Isotope Ratios ◽

Physical Fractionation ◽

Water Isotopologues ◽

Stratospheric Water Vapour

Abstract. This modelling study aims at an improved understanding of the processes that determine the water vapour budget in the stratosphere by means of the investigation of water isotope ratios. An additional (and separate from the actual) hydrological cycle has been introduced into the chemistry–climate model EMAC, including the water isotopologues HDO and H218O and their physical fractionation processes. Additionally an explicit computation of the contribution of methane oxidation to H2O and HDO has been incorporated. The model expansions allow detailed analyses of water vapour and its isotope ratio with respect to deuterium throughout the stratosphere and in the transition region to the troposphere. In order to assure the correct representation of the water isotopologues in the model's hydrological cycle, the expanded system has been evaluated in several steps. The physical fractionation effects have been evaluated by comparison of the simulated isotopic composition of precipitation with measurements from a ground-based network (GNIP) and with the results from the isotopologue-enabled general circulation model ECHAM5-wiso. The model's representation of the chemical HDO precursor CH3D in the stratosphere has been confirmed by a comparison with chemical transport models (1-D, CHEM2D) and measurements from radiosonde flights. Finally, the simulated stratospheric HDO and the isotopic composition of water vapour have been evaluated, with respect to retrievals from three different satellite instruments (MIPAS, ACE-FTS, SMR). Discrepancies in stratospheric water vapour isotope ratios between two of the three satellite retrievals can now partly be explained.

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