Nitrification of the lowermost stratosphere during the exceptionally
cold Arctic winter 2015/16

Braun, Marleen; Grooß, Jens‐Uwe; Woiwode, Wolfgang; Johansson, Sören; Höpfner, Michael; Friedl-Vallon, Felix; Oelhaf, H.; Preusse, Peter; Ungermann, Jörn; Sinnhuber, Björn-Martin; Ziereis, H.; Braesicke, Peter

doi:10.5194/acp-2019-108

Cited by 3 publications

(6 citation statements)

References 20 publications

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“…HNO 3 shows agreement between MLS and CLaMS, but in the beginning of the winter lower VMRs are simulated than observed at 380 K. This disagreement is considered to result from an underestimation by CLaMS of renitrification at this level from the sedimentation of HNO 3containing PSC particles from above. It is known that denitrification and re-nitrification are difficult to simulate in the LMS (Braun et al, 2019). Comparisons of CH 3 Cl show agreement between measurement and simulation for the beginning of the winter at 380 K, but starting in January measured CH 3 Cl decreases notably, while the simulated CH 3 Cl remains almost constant.…”

Section: Comparison Of Satellite Measurements To Model Simulationsmentioning

confidence: 61%

“…Vertical resolutions of 400-1000 m are achieved. During parts of some of these PGS flights, the GLORIA measurement mode was changed to a reduced spectral and enhanced spatial resolution (also known as "dynamics mode"; see Ungermann et al, 2015). These measurements are not discussed in this work and may appear as missing data.…”

Section: Pgs Campaign and Gloria Observationsmentioning

confidence: 99%

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Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

Johansson

Santee

Grooß³

et al. 2019

Atmos. Chem. Phys.

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Abstract. The Arctic winter 2015/16 was characterized by cold stratospheric temperatures. Here we present a comprehensive view of the temporal evolution of chlorine in the lowermost stratosphere over the course of the studied winter. We utilize two-dimensional vertical cross sections of ozone (O3) and chlorine nitrate (ClONO2), measured by the airborne limb imager GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) during the POLSTRACC/GW-LCYCLE II/GWEX/SALSA campaigns, to investigate the tropopause region in detail. Observations from three long-distance flights in January, February, and March 2016 are discussed. ClONO2 volume mixing ratios up to 1100 pptv were measured at 380 K potential temperature in mesoscale structures. Similar mesoscale structures are also visible in O3 measurements. Both trace gas measurements are applied to evaluate simulation results from the chemistry transport model CLaMS (Chemical Lagrangian Model of the Stratosphere) and the chemistry–climate model EMAC (ECHAM5/MESSy Atmospheric Chemistry). These comparisons show agreement within the expected performance of these models. Satellite measurements from Aura/MLS (Microwave Limb Sounder) and SCISAT/ACE-FTS (Atmospheric Chemistry Experiment – Fourier Transform Spectrometer) provide an overview over the whole winter and information about the stratospheric situation above the flight altitude. Time series of these satellite measurements reveal unusually low hydrochloric acid (HCl) and ClONO2 at 380 K from the beginning of January to the end of February 2016, while chlorine monoxide (ClO) is strongly enhanced. In March 2016, unusually rapid chlorine deactivation into HCl is observed instead of deactivation into ClONO2, the more typical pathway for deactivation in the Arctic. Chlorine deactivation observed in the satellite time series is well reproduced by CLaMS. Sensitivity simulations with CLaMS demonstrate the influence of low abundances of O3 and reactive nitrogen (NOy) due to ozone depletion and sedimentation of NOy-containing particles, respectively. On the basis of the different altitude and time ranges of these effects, we conclude that the substantial chlorine deactivation into HCl at 380 K arose as a result of very low ozone abundances together with low temperatures. Additionally, CLaMS estimates ozone depletion of at least 0.4 ppmv at 380 K and 1.75 ppmv at 490 K, which is comparable to other extremely cold Arctic winters. We have used CLaMS trajectories to analyze the history of enhanced ClONO2 measured by GLORIA. In February, most of the enhanced ClONO2 is traced back to chlorine deactivation that had occurred within the past few days prior to the GLORIA measurement. In March, after the final warming, air masses in which chlorine has previously been deactivated into ClONO2 have been transported in the remnants of the polar vortex towards the location of measurement for at least 11 d.

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Section: Comparison Of Satellite Measurements To Model Simulationsmentioning

confidence: 61%

Section: Pgs Campaign and Gloria Observationsmentioning

confidence: 99%

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

Johansson

Santee

Grooß³

et al. 2019

Atmos. Chem. Phys.

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“…-R3 starts in October when sunlight returns and the 50 hPa temperatures rise above 195 K. Despite the stratospheric warming with 50 hPa temperatures up to 240 K in summer, the HNO 3 total columns stagnate at the R2 plateau levels (around 1.5× 10 16 molec.cm −2 ). This regime likely reflects the photolysis of NO 3 and HNO 3 itself (Ronsmans et al, 2018) as well as the permanent denitrification of the mid-stratosphere, caused by the PSCs sedimentation, despite the renitrification of the lowermost stratosphere (Braun et al, 2019) where the IASI sensitivity to HNO 3 is lower (Ronsmans et al, 2016). The plateau lasts until approximately February, where HNO 3 total column slowly starts increasing, reaching the April-May maximum in R1.…”

Section: Datamentioning

confidence: 94%

A nitric acid dataset from IASI for polar stratospheric denitrification studies

Ronsmans

Wespes

Clarisse

et al. 2020

Preprint

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Abstract. In this paper, we exploit the first 10-year data-record (2008–2017) of nitric acid (HNO3) total columns measured by the IASI-A/Metop infrared sounder, characterized by an exceptional daily sampling and a good vertical sensitivity in the mid-stratosphere (around 50 hPa), to monitor the causal relationship between the temperature decrease and the observed HNO3 loss that occurs each year in the Antarctic stratosphere during the polar night. Since the HNdepletion results from the formation of polar stratospheric clouds (PSCs) which trigger the development of the ozone (O3) hole, its continuous monitoring is of high importance. We verify here, from the 10-year time evolution of the pair HNO3-temperature (taken from reanalysis at 50 hPa), the recurrence of specific regimes in the cycle of IASI HNO3 and identify, for each year, the day and the 50 hPa-temperature (drop temperature) corresponding to the onset of denitrification in Antarctic winter. Although the measured HNO3 total column does not allow differentiating the uptake of HNO3 by different types of PSC particles along the vertical profile, an average drop temperature of ∼ 191 ± 3 K, consistent with the nitric acid trihydrate (NAT) formation temperature (close to 195 K at 50 hPa), is found. The spatial distribution and inter-annual variability of the drop temperature are briefly investigated and discussed in the context of previous PSCs studies. This paper highlights the capability of the IASI sounder to monitor the long-term evolution of the polar stratospheric composition and processes involved in the depletion of stratospheric O3.

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“…7c), a similar pattern is found as for ozone, but with a higher contrast and more pronounced filaments from 17:00 UTC to ~19:00 UTC. Furthermore, the nitric acid distribution shows a local maximum at and below flight altitude from 14 UTC until the end of the flight, which are a consequence of nitrification of the LMS in the same winter (see Braun et al, 2019).…”

Section: Trace Gas Distributionsmentioning

confidence: 99%

“…From the GLORIA limb-imaging observations, vertical distributions of temperature, trace gases and clouds are derived and allow detailed model comparisons (e.g. Khosrawi et al, 2017;Braun et al, 2019;Johansson et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Challenge of modelling GLORIA observations of UT/LMS trace gas and cloud distributions at high latitudes: a case study with state-of-the-art models

Haenel

Woiwode

Schröter

et al. 2021

Preprint

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Abstract. Water vapour and ozone are important for the thermal and radiative balance of the upper troposphere (UT) and lowermost stratosphere (LMS). Both species are modulated by transport processes. Chemical and microphysical processes affect them differently. Thus, representing the different processes and their interactions is a challenging task for dynamical cores, chemical modules and microphysical parameterisations of state-of-the-art atmospheric model components. To test and improve the models, high resolution measurements of the UT/LMS are required. Here, we use measurements taken in a challenging case study by the GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) instrument on HALO. The German research aircraft HALO (High Altitude and LOng range research aircraft) performed a research flight on 26 February 2016, which covered deeply subsided air masses of the aged 2015/16 Arctic vortex, high-latitude LMS air masses, a highly textured troposphere-to-stratosphere exchange mixing region, and high-altitude cirrus clouds. Therefore, it provides a multifaceted case study for comparing GLORIA observations with state-of-the-art atmospheric model simulations in a complex UT/LMS region at a late stage of the Arctic winter 2015/16. Using GLORIA observations in this manifold scenario, we test the ability of the numerical weather prediction (NWP)-model ICON (ICOsahedral Nonhydrostatic) with the extension ART (Aerosols and Reactive Trace gases) and the chemistry-climate model (CCM) EMAC (ECHAM5/MESSy Atmospheric Chemistry) to model the UT/LMS composition of water vapour (H2O), ozone (O3), nitric acid (HNO3) and clouds. Within the scales resolved by the respective model, we find good overall agreement of both models with GLORIA. The applied high-resolution ICON-ART setup involving a R2B7 nest (local grid refinement with a horizontal resolution of about 20 km), covering the HALO flight region, reproduces mesoscale dynamical structures well. An observed troposphere-to-stratosphere exchange connected to an occluded Icelandic low is clearly reproduced by the model. Given the lower resolution (T106) of the nudged simulation of the EMAC model, we find that this model also reproduces these features well. Overall, trace gas mixing ratios simulated by both models are in a realistic range, and major cloud systems observed by GLORIA are mostly reproduced. However, we find both models to be affected by a well-known systematic moist-bias in the LMS. Further biases are diagnosed in the ICON-ART O3, EMAC H2O and EMAC HNO3 distributions. Finally, we use sensitivity simulations to investigate (i) short-term cirrus cloud impacts on the H2O distribution (ICON-ART), (ii) the overall impact of polar winter chemistry and microphysical processing on O3 and HNO3 (ICON-ART/EMAC), (iii) the impact of the model resolution on simulated parameters (EMAC), and (iv) consequences of scavenging processes by cloud particles (EMAC). We find that changing of the horizontal model resolution results in notable systematic changes for all species in the LMS, while scavenging processes play only a role in case of HNO3. We need to understand the representativeness of our results. However, this is a unique opportunity to characterise model biases that potentially affect forecasts and projection (adversely), and to discover deficits and define paths for further model improvements.

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Nitrification of the lowermost stratosphere during the exceptionally cold Arctic winter 2015/16

Cited by 3 publications

References 20 publications

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

Unusual chlorine partitioning in the 2015/16 Arctic winter lowermost stratosphere: observations and simulations

A nitric acid dataset from IASI for polar stratospheric denitrification studies

Challenge of modelling GLORIA observations of UT/LMS trace gas and cloud distributions at high latitudes: a case study with state-of-the-art models

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