scholarly journals Observations of meteoritic material and implications for aerosol nucleation in the winter Arctic lower stratosphere derived from in situ particle measurements

2005 ◽  
Vol 5 (4) ◽  
pp. 5039-5080 ◽  
Author(s):  
J. Curtius ◽  
R. Weigel ◽  
H.-J. Vössing ◽  
H. Wernli ◽  
A. Werner ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Particle Density ◽  
Aerosol Particles ◽  
Potential Temperature ◽  
Polar Vortex ◽  
The Arctic ◽  
Particle Nucleation ◽  
Particle Measurements ◽  
Total Particle

Abstract. Number concentrations of total and non-volatile aerosol particles with size diameters >0.01 µm as well as particle size distributions (0.4–23 µm diameter) were measured in situ in the Arctic lower stratosphere (10–20.5 km altitude). The measurements were obtained during the campaigns European Polar Stratospheric Cloud and Lee Wave Experiment (EUPLEX) and Envisat-Arctic-Validation (EAV). The campaigns were based in Kiruna, Sweden, and took place from January to March 2003. Measurements were conducted onboard the Russian high-altitude research aircraft Geophysica using the low-pressure Condensation Nucleus Counter COPAS (COndensation PArticle Counter System) and a modified FSSP 300 (Forward Scattering Spectrometer Probe). Around 18–20 km altitude typical total particle number concentrations nt range at 10–20 cm−3 (ambient conditions). Correlations with the trace gases nitrous oxide (N2O) and trichlorofluoromethane (CFC-11) are discussed. Inside the polar vortex the total number of particles >0.01 µm increases with potential temperature while N2O is decreasing which indicates a source of particles in the above polar stratosphere or mesosphere. A separate channel of the COPAS instrument measures the fraction of aerosol particles non-volatile at 250°C. Inside the polar vortex a much higher fraction of particles contained non-volatile residues than outside the vortex (~24% outside vortex). This is most likely due to a strongly increased fraction of meteoritic material in the particles which is transported downward from the mesosphere inside the polar vortex. The high fraction of non-volatile residual particles gives therefore experimental evidence for downward transport of mesospheric air inside the polar vortex. It is also shown that the fraction of non-volatile residual particles serves directly as a suitable experimental vortex tracer. Nanometer-sized meteoritic smoke particles may also serve as nuclei for the condensation of gaseous sulfuric acid and water in the polar vortex and these additional particles may be responsible for the increase in the observed particle concentration at low N2O. The number concentrations of particles >0.4 µm measured with the FSSP decrease markedly inside the polar vortex with increasing potential temperature, also a consequence of subsidence of air from higher altitudes inside the vortex. Another focus of the analysis was put on the particle measurements in the lowermost stratosphere. For the total particle density relatively high number concentrations of several hundred particles per cm3 at altitudes below ~14 km were observed in several flights. To investigate the origin of these high number concentrations we conducted air mass trajectory calculations and compared the particle measurements with other trace gas observations. The high number concentrations of total particles in the lowermost stratosphere are probably caused by transport of originally tropospheric air from lower latitudes and are potentially influenced by recent particle nucleation.

scholarly journals Observations of meteoric material and implications for aerosol nucleation in the winter Arctic lower stratosphere derived from in situ particle measurements

2005 ◽  
Vol 5 (11) ◽  
pp. 3053-3069 ◽  
Author(s):  
J. Curtius ◽  
R. Weigel ◽  
H.-J. Vössing ◽  
H. Wernli ◽  
A. Werner ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Aerosol Particles ◽  
Potential Temperature ◽  
Polar Vortex ◽  
The Arctic ◽  
Particle Nucleation ◽  
Particle Measurements ◽  
Total Particle ◽  
Meteoric Material

Abstract. Number concentrations of total and non-volatile aerosol particles with size diameters >0.01 μm as well as particle size distributions (0.4–23 μm diameter) were measured in situ in the Arctic lower stratosphere (10–20.5 km altitude). The measurements were obtained during the campaigns European Polar Stratospheric Cloud and Lee Wave Experiment (EUPLEX) and Envisat-Arctic-Validation (EAV). The campaigns were based in Kiruna, Sweden, and took place from January to March 2003. Measurements were conducted onboard the Russian high-altitude research aircraft Geophysica using the low-pressure Condensation Nucleus Counter COPAS (COndensation PArticle Counter System) and a modified FSSP 300 (Forward Scattering Spectrometer Probe). Around 18–20 km altitude typical total particle number concentrations nt range at 10–20 cm−3 (ambient conditions). Correlations with the trace gases nitrous oxide (N2O) and trichlorofluoromethane (CFC-11) are discussed. Inside the polar vortex the total number of particles >0.01 μm increases with potential temperature while N2O is decreasing which indicates a source of particles in the above polar stratosphere or mesosphere. A separate channel of the COPAS instrument measures the fraction of aerosol particles non-volatile at 250°C. Inside the polar vortex a much higher fraction of particles contained non-volatile residues than outside the vortex (~67% inside vortex, ~24% outside vortex). This is most likely due to a strongly increased fraction of meteoric material in the particles which is transported downward from the mesosphere inside the polar vortex. The high fraction of non-volatile residual particles gives therefore experimental evidence for downward transport of mesospheric air inside the polar vortex. It is also shown that the fraction of non-volatile residual particles serves directly as a suitable experimental vortex tracer. Nanometer-sized meteoric smoke particles may also serve as nuclei for the condensation of gaseous sulfuric acid and water in the polar vortex and these additional particles may be responsible for the increase in the observed particle concentration at low N2O. The number concentrations of particles >0.4 μm measured with the FSSP decrease markedly inside the polar vortex with increasing potential temperature, also a consequence of subsidence of air from higher altitudes inside the vortex. Another focus of the analysis was put on the particle measurements in the lowermost stratosphere. For the total particle density relatively high number concentrations of several hundred particles per cm3 at altitudes below ~14 km were observed in several flights. To investigate the origin of these high number concentrations we conducted air mass trajectory calculations and compared the particle measurements with other trace gas observations. The high number concentrations of total particles in the lowermost stratosphere are probably caused by transport of originally tropospheric air from lower latitudes and are potentially influenced by recent particle nucleation.

scholarly journals Aircraft-based observation of meteoric material in lower-stratospheric aerosol particles between 15 and 68° N

2021 ◽  
Vol 21 (2) ◽  
pp. 989-1013
Author(s):  
Johannes Schneider ◽  
Ralf Weigel ◽  
Thomas Klimach ◽  
Antonis Dragoneas ◽  
Oliver Appel ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Lower Stratosphere ◽  
Aerosol Particles ◽  
Potential Temperature ◽  
Polar Vortex ◽  
Stratospheric Aerosol ◽  
Loss Mechanism ◽  
Lower Altitude ◽  
Tropospheric Aerosol ◽  
Meteoric Material

Abstract. We analyse aerosol particle composition measurements from five research missions between 2014 and 2018 to assess the meridional extent of particles containing meteoric material in the upper troposphere and lower stratosphere (UTLS). Measurements from the Jungfraujoch mountaintop site and a low-altitude aircraft mission show that meteoric material is also present within middle- and lower-tropospheric aerosol but within only a very small proportion of particles. For both the UTLS campaigns and the lower- and mid-troposphere observations, the measurements were conducted with single-particle laser ablation mass spectrometers with bipolar-ion detection, which enabled us to measure the chemical composition of particles in a diameter range of approximately 150 nm to 3 µm. The five UTLS aircraft missions cover a latitude range from 15 to 68∘ N, altitudes up to 21 km, and a potential temperature range from 280 to 480 K. In total, 338 363 single particles were analysed, of which 147 338 were measured in the stratosphere. Of these total particles, 50 688 were characterized by high abundances of magnesium and iron, together with sulfuric ions, the vast majority (48 610) in the stratosphere, and are interpreted as meteoric material immersed or dissolved within sulfuric acid. It must be noted that the relative abundance of such meteoric particles may be overestimated by about 10 % to 30 % due to the presence of pure sulfuric acid particles in the stratosphere which are not detected by the instruments used here. Below the tropopause, the observed fraction of the meteoric particle type decreased sharply with 0.2 %–1 % abundance at Jungfraujoch, and smaller abundances (0.025 %–0.05 %) were observed during the lower-altitude Canadian Arctic aircraft measurements. The size distribution of the meteoric sulfuric particles measured in the UTLS campaigns is consistent with earlier aircraft-based mass-spectrometric measurements, with only 5 %–10 % fractions in the smallest particles detected (200–300 nm diameter) but with substantial (> 40 %) abundance fractions for particles from 300–350 up to 900 nm in diameter, suggesting sedimentation is the primary loss mechanism. In the tropical lower stratosphere, only a small fraction (< 10 %) of the analysed particles contained meteoric material. In contrast, in the extratropics the observed fraction of meteoric particles reached 20 %–40 % directly above the tropopause. At potential temperature levels of more than 40 K above the thermal tropopause, particles containing meteoric material were observed in much higher relative abundances than near the tropopause, and, at these altitudes, they occurred at a similar abundance fraction across all latitudes and seasons measured. Above 440 K, the observed fraction of meteoric particles is above 60 % at latitudes between 20 and 42∘ N. Meteoric smoke particles are transported from the mesosphere into the stratosphere within the winter polar vortex and are subsequently distributed towards low latitudes by isentropic mixing, typically below a potential temperature of 440 K. By contrast, the findings from the UTLS measurements show that meteoric material is found in stratospheric aerosol particles at all latitudes and seasons, which suggests that either isentropic mixing is effective also above 440 K or that meteoric fragments may be the source of a substantial proportion of the observed meteoric material.

Modelling the progression in the mix of particles within the Arctic stratospheric aerosol layer, including the seasonal source of meteoric smoke particles from the Arctic winter polar vortex 

2021 ◽  
Author(s):  
Kamalika Sengupta ◽  
Graham Mann ◽  
Ralf Weigel ◽  
James Brooke ◽  
Sandip Dhomse ◽  
...  
Keyword(s):  
Sulphuric Acid ◽  
Particle Concentration ◽  
Aerosol Particles ◽  
Polar Vortex ◽  
Stratospheric Aerosol ◽  
The Arctic ◽  
Smoke Particles ◽  
Meteoric Smoke ◽  
Winter Time

&lt;p&gt;Meteoric smoke particles (MSPs) provide a steady source of condensation nuclei to the Arctic lower stratosphere, with heterogeneous nucleation to sulphuric acid aerosol particles.&amp;#160; Internally mixed meteoric-sulphuric particles likely also play a significant role in the formation of polar stratospheric clouds and thereby influence stratospheric ozone depletion chemistry, particularly in the quiescent stratosphere.&lt;/p&gt;&lt;p&gt;In several Arctic winter field campaigns (EUPLEX&amp;#160;2002/3, RECONCILE 2009/10,&amp;#160;ESSenCe&amp;#160;2010/11),&amp;#160; in-situ&amp;#160;stratospheric aerosol particle concentrations measurements were made from the high-altitude Geophysica aircraft, the COPAS instrument measuring total and refractory (non-volatile) particle concentrations at 20 km altitude (see Curtius et al., 2003; Weigel et al., 2014).&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;These measurements are consistent with there being a substantial seasonal source of meteoric-sulphuric particles to the lower Arctic stratosphere, from each year&amp;#8217;s influx of MSPs&amp;#160; within the winter-time Arctic polar vortex. In this study we investigate the effect of&amp;#160;MSPs&amp;#160;on the quiescent&amp;#160;Junge&amp;#160;layer particle concentration as the polar vortex builds up and after it dissipates.&amp;#160;&lt;/p&gt;&lt;p&gt;We use the nudged configuration of the UM-UKCA&amp;#160;stratosphere-troposphere composition-climate model to reproduce the vertical profile of stratospheric particles measured in-situ&amp;#160;during the COPAS&amp;#160;2003 campaign. Our model simulates two types of stratospheric aerosol particles - pure sulphuric acid particles and sulphuric acid particles with a MSP-core. We show that the model is able to reproduce the vertical profile of aerosol particles observed during the COPAS&amp;#160;measurements in winter 2003.&lt;/p&gt;&lt;p&gt;Our findings illustrate the influx of MSP&amp;#160;and SO2&amp;#160;from higher altitudes through the polar vortex, the winter-time build-up of SO2&amp;#160;triggering homogeneous nucleation of pure sulphuric particles, also with the seasonal source of MSP-core sulphuric particles nucleated heterogeneously. We assess the effects of MSPs&amp;#160;on the quiescent period particle concentration in the Arctic during winter through to spring.&lt;/p&gt;

scholarly journals Aircraft measurements of gravity waves in the upper troposphere and lower stratosphere during the START08 field experiment

2015 ◽  
Vol 15 (13) ◽  
pp. 7667-7684 ◽  
Author(s):  
Fuqing Zhang ◽  
Junhong Wei ◽  
Meng Zhang ◽  
K. P. Bowman ◽  
L. L. Pan ◽  
...  
Keyword(s):  
Power Law ◽  
Gravity Waves ◽  
Lower Stratosphere ◽  
Potential Temperature ◽  
Shear Instability ◽  
Aircraft Measurements ◽  
Upper Troposphere ◽  
Airborne Measurements ◽  
Wide Range

Abstract. This study analyzes in situ airborne measurements from the 2008 Stratosphere–Troposphere Analyses of Regional Transport (START08) experiment to characterize gravity waves in the extratropical upper troposphere and lower stratosphere (ExUTLS). The focus is on the second research flight (RF02), which took place on 21–22 April 2008. This was the first airborne mission dedicated to probing gravity waves associated with strong upper-tropospheric jet–front systems. Based on spectral and wavelet analyses of the in situ observations, along with a diagnosis of the polarization relationships, clear signals of mesoscale variations with wavelengths ~ 50–500 km are found in almost every segment of the 8 h flight, which took place mostly in the lower stratosphere. The aircraft sampled a wide range of background conditions including the region near the jet core, the jet exit and over the Rocky Mountains with clear evidence of vertically propagating gravity waves of along-track wavelength between 100 and 120 km. The power spectra of the horizontal velocity components and potential temperature for the scale approximately between ~ 8 and ~ 256 km display an approximate −5/3 power law in agreement with past studies on aircraft measurements, while the fluctuations roll over to a −3 power law for the scale approximately between ~ 0.5 and ~ 8 km (except when this part of the spectrum is activated, as recorded clearly by one of the flight segments). However, at least part of the high-frequency signals with sampled periods of ~ 20–~ 60 s and wavelengths of ~ 5–~ 15 km might be due to intrinsic observational errors in the aircraft measurements, even though the possibilities that these fluctuations may be due to other physical phenomena (e.g., nonlinear dynamics, shear instability and/or turbulence) cannot be completely ruled out.

scholarly journals Simulation of denitrification and ozone loss for the Arctic winter 2002/2003

2005 ◽  
Vol 5 (6) ◽  
pp. 1437-1448 ◽  
Author(s):  
J.-U. Grooß ◽  
G. Günther ◽  
R. Müller ◽  
P. Konopka ◽  
S. Bausch ◽  
...  
Keyword(s):  
Inorganic Nitrogen ◽  
Potential Temperature ◽  
Three Dimensional ◽  
Lagrangian Model ◽  
The Arctic ◽  
Particle Nucleation ◽  
Ozone Loss ◽  
Dimensional Version ◽  
Total Inorganic Nitrogen ◽  
Catalytic Cycles

Abstract. We present simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) for the Arctic winter 2002/2003. We integrated a Lagrangian denitrification scheme into the three-dimensional version of CLaMS that calculates the growth and sedimentation of nitric acid trihydrate (NAT) particles along individual particle trajectories. From those, we derive the HNO3 downward flux resulting from different particle nucleation assumptions. The simulation results show a clear vertical redistribution of total inorganic nitrogen ( ), with a maximum vortex average permanent removal of over 5ppb in late December between 500 and 550K and a corresponding increase of of over 2ppb below about 450K. The simulated vertical redistribution of is compared with balloon observations by MkIV and in-situ observations from the high altitude aircraft Geophysica. Assuming a globally uniform NAT particle nucleation rate of 7.8x10-6cm-3h-1 in the model, the observed denitrification is well reproduced. In the investigated winter 2002/2003, the denitrification has only moderate impact (≤14%) on the simulated vortex average ozone loss of about 1.1ppm near the 460K level. At higher altitudes, above 600K potential temperature, the simulations show significant ozone depletion through -catalytic cycles due to the unusual early exposure of vortex air to sunlight.

scholarly journals Polar processing in a split vortex: early winter Arctic ozone loss in 2012/13

2015 ◽  
Vol 15 (4) ◽  
pp. 4973-5029 ◽  
Author(s):  
G. L. Manney ◽  
Z. D. Lawrence ◽  
M. L. Santee ◽  
N. J. Livesey ◽  
A. Lambert ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Lower Stratosphere ◽  
Polar Vortex ◽  
The Arctic ◽  
Early Winter ◽  
Sudden Stratospheric Warming ◽  
Ozone Loss ◽  
Chlorine Monoxide ◽  
Polar Stratospheric Cloud ◽  
Vortex Split

Abstract. A sudden stratospheric warming (SSW) in early January 2013 caused the polar vortex to split. After the lower stratospheric vortex split on 8 January, the two offspring vortices – one over Canada and the other over Siberia – remained intact, well-confined, and largely at latitudes that received sunlight until they reunited at the end of January. As the SSW began, temperatures abruptly rose above chlorine activation thresholds throughout the lower stratosphere. The vortex was very disturbed prior to the SSW, and was exposed to much more sunlight than usual in December 2012 and January 2013. Aura Microwave Limb Sounder (MLS) nitric acid (HNO3) data and observations from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) indicate extensive polar stratospheric cloud (PSC) activity, with evidence of PSCs containing solid nitric acid trihydrate particles during much of December 2012. Consistent with the sunlight exposure and PSC activity, MLS observations show that chlorine monoxide (ClO) became enhanced early in December. Despite the cessation of PSC activity with the onset of the SSW, enhanced vortex ClO persisted until mid-February, indicating lingering chlorine activation. The smaller Canadian offspring vortex had lower temperatures, lower HNO3, lower hydrogen chloride (HCl), and higher ClO in late January than the Siberian vortex. Chlorine deactivation began later in the Canadian than in the Siberian vortex. HNO3 remained depressed within the vortices after temperatures rose above the PSC existence threshold, and passive transport calculations indicate vortex-averaged denitrification of about 4 ppbv; the resulting low HNO3 values persisted until the vortex dissipated in mid-February. Consistent with the strong chlorine activation and exposure to sunlight, MLS measurements show rapid ozone loss commencing in mid-December and continuing through January. Lagrangian transport estimates suggest ~ 0.7–0.8 ppmv (parts per million by volume) vortex-averaged chemical ozone loss by late January near 500 K (~ 21 km), with substantial loss occurring from ~ 450 to 550 K. The surface area of PSCs in December 2012 was larger than that in any other December observed by CALIPSO. As a result of denitrification, HNO3 abundances in 2012/13 were among the lowest in the MLS record for the Arctic. ClO enhancement was much greater in December 2012 through mid-January 2013 than that at the corresponding time in any other Arctic winter observed by MLS. Furthermore, reformation of HCl appeared to play a greater role in chlorine deactivation than in more typical Arctic winters. Ozone loss in December 2012 and January 2013 was larger than any previously observed in those months. This pattern of exceptional early winter polar processing and ozone loss resulted from the unique combination of dynamical conditions associated with the early January 2013 SSW, namely unusually low temperatures in December 2012 and offspring vortices that remained well-confined and largely in sunlit regions for about a month after the vortex split.

The prevalence of meteoric-sulphuric particles within the stratospheric aerosol layer

2021 ◽  
Author(s):  
Graham Mann ◽  
James Brooke ◽  
Kamalika Sengupta ◽  
Lauren Marshall ◽  
Sandip Dhomse ◽  
...  
Keyword(s):  
High Latitude ◽  
Climate Model ◽  
Polar Vortex ◽  
Stratospheric Aerosol ◽  
Light Extinction ◽  
The Arctic ◽  
Aerosol Layer ◽  
Aerosol Composition ◽  
Particle Layer

&lt;p&gt;The widespread presence of meteoric smoke particles (MSPs) within a distinct class of stratospheric aerosol particles has become clear from in-situ measurements in the Arctic, Antarctic and at mid-latitudes.&lt;br&gt;&amp;#160;&lt;br&gt;We apply an adapted version of the interactive stratosphere aerosol configuration of the composition-climate model UM-UKCA, to predict the global distribution of meteoric-sulphuric particles nucleated heterogeneously on MSP cores. We compare the UM-UKCA results to new MSP-sulphuric simulations with the European stratosphere-troposphere chemistry-aerosol modelling system IFS-CB05-BASCOE-GLOMAP.&lt;/p&gt;&lt;p&gt;&lt;br&gt;The simulations show a strong seasonal cycle in meteoric-sulphuric particle abundance results from the winter-time source of MSPs transported down into the stratosphere in the polar vortex. Coagulation during downward transport sees high latitude MSP concentrations reduce from ~500 per cm3 at 40km to ~20 per cm3 at 25km, the uppermost extent of the stratospheric aerosol particle layer (the Junge layer).&lt;br&gt;&amp;#160;&lt;br&gt;Once within the Junge layer's supersaturated environment, meteoric-sulphuric particles form readily on the MSP cores, growing to 50-70nm dry-diameter (Dp) at 20-25km. Further inter-particle coagulation between these non-volatile particles reduces their number to 1-5 per cc at 15-20km, particle sizes there larger, at Dp ~100nm.&lt;/p&gt;&lt;p&gt;&lt;br&gt;The model predicts meteoric-sulphurics in high-latitude winter comprise &gt;90% of Dp&gt;10nm particles above 25km, reducing to ~40% at 20km, and ~10% at 15km.&lt;br&gt;&amp;#160;&lt;br&gt;These non-volatile particle fractions are slightly less than measured from high-altitude aircraft in the lowermost Arctic stratosphere (Curtius et al., 2005; Weigel et al., 2014), and consistent with mid-latitude aircraft measurements of lower stratospheric aerosol composition (Murphy et al., 1998), total particle concentrations &amp;#160;also matching in-situ balloon measurements from Wyoming (Campbell and Deshler, 2014).&lt;br&gt;&amp;#160;&lt;br&gt;The MSP-sulphuric interactions also improve agreement with SAGE-II observed stratospheric aerosol extinction in the quiescent 1998-2002 period.&amp;#160;&lt;br&gt;&amp;#160;&lt;br&gt;Simulations with a factor-8-elevated MSP input form more Dp&gt;10nm meteoric-sulphurics, but the increased number sees fewer growing to Dp ~100nm, the increased MSPs reducing the stratospheric aerosol layer&amp;#8217;s light extinction.&lt;/p&gt;

scholarly journals Evidence for long-lived polar vortex air in the mid-latitude summer stratosphere from in situ laser diode CH<sub>4</sub> and H<sub>2</sub>O measurements

2005 ◽  
Vol 5 (6) ◽  
pp. 1467-1472 ◽  
Author(s):  
G. Durry ◽  
A. Hauchecorne
Keyword(s):  
High Resolution ◽  
Laser Diode ◽  
Polar Vortex ◽  
The Arctic ◽  
Concentration Profiles ◽  
Spatial Structures ◽  
Laser Spectrometer ◽  
Southern France ◽  
Diode Laser Spectrometer

Abstract. A balloon borne diode laser spectrometer was launched in southern France in June 2000 to yield in situ stratospheric CH4 and H2O measurements. In the altitude region ranging from 20km to 25km, striking large spatial structures were observed in the vertical concentration profiles of both species. We suggest these patterns are due to the presence of long-lived remnants of the wintertime polar vortex in the mid-latitude summer stratosphere. To support this interpretation, a high resolution advection model for potential vorticity is used to investigate the evolution of the Arctic vortex after its breakdown phase in spring 2000.

scholarly journals Investigation of Arctic middle-atmospheric dynamics using 3 years of H<sub>2</sub>O and O<sub>3</sub> measurements from microwave radiometers at Ny-Ålesund

2019 ◽  
Author(s):  
Franziska Schranz ◽  
Brigitte Tschanz ◽  
Rolf Rüfenacht ◽  
Klemens Hocke ◽  
Mathias Palm ◽  
...  
Keyword(s):  
Water Vapour ◽  
Middle Atmosphere ◽  
Microwave Radiometer ◽  
Polar Vortex ◽  
The Arctic ◽  
High Time Resolution ◽  
Middle Atmospheric Dynamics ◽  
Wind Profiles ◽  
Microwave Radiometers

Abstract. We use 3 years of water vapour and ozone measurements to analyse dynamical events in the polar middle atmosphere such as sudden stratospheric warmings (SSW), polar vortex shifts, water vapour descent rates and periodicities. The measurements were performed with the two ground-based microwave radiometers MIAWARA-C and GROMOS-C which are co-located at the AWIPEV research base at Ny-Ålesund, Svalbard (79° N, 12° E) since September 2015. The almost continuous datasets of water vapour and ozone are characterised by a high time resolution in the order of hours. A thorough intercomparison of these datasets with models and measurements from satellite, ground-based and in-situ instruments was performed. In the upper stratosphere and lower mesosphere the MIAWARA-C profiles agree within 5 % with SD-WACCM simulations and ACE-FTS measurements whereas AuraMLS measurements show an average offset of 10–15 % depending on altitude but constant in time. Stratospheric GROMOS-C profiles are within 5 % of the satellite instruments AuraMLS and ACE-FTS and the ground-based microwave radiometer OZORAM which is also located at Ny-Ålesund. During these first three years of the measurement campaign typical phenomena of the Arctic middle atmosphere took place and we analysed their signatures in the water vapour and ozone datasets. Inside of the polar vortex in autumn we found the descent rate of mesospheric water vapour to be 435 m/day on average. In early 2017 distinct increases in mesospheric water vapour of about 2 ppm were observed when the polar vortex was displaced and midlatitude air was brought to Ny-Ålesund. Two major sudden stratospheric warmings took place in March 2016 and February 2018 where ozone enhancements of up to 4 ppm were observed. The zonal wind reversals accompanying a major SSW were captured in the GROMOS-C wind profiles which are retrieved from the ozone spectra. After the SSW in February 2018 the polar vortex re-established and the water vapour descent rate in the mesosphere was 355 m/day. In the water vapour and ozone time series signatures of atmospheric waves with periods close to 2, 5, 10 and 16 days were found.

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