Uncertainties in modeling heterogeneous chemistry  and Arctic ozone depletion in the winter 2009/2010

I. Wohltmann; T. Wegner; R. Müller; R. Lehmann; M. Rex; G. L. Manney; M. L. Santee; P. Bernath; O. Sumińska-Ebersoldt; F. Stroh; M. von Hobe; C. M. Volk; E. Hösen; F. Ravegnani; A. Ulanovsky; V. Yushkov

doi:10.5194/acpd-12-26245-2012

Uncertainties in modelling heterogeneous chemistry and Arctic ozone depletion in the winter 2009/2010

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-3909-2013 ◽

2013 ◽

Vol 13 (8) ◽

pp. 3909-3929 ◽

Cited By ~ 43

Author(s):

I. Wohltmann ◽

T. Wegner ◽

R. Müller ◽

R. Lehmann ◽

M. Rex ◽

...

Keyword(s):

Nitric Acid ◽

Reaction Rate ◽

Transport Model ◽

Particle Number Density ◽

Rate Coefficients ◽

The Arctic ◽

Number Density ◽

Ozone Loss ◽

Mixing Ratios ◽

The Impact

Abstract. Stratospheric chemistry and denitrification are simulated for the Arctic winter 2009/2010 with the Lagrangian Chemistry and Transport Model ATLAS. A number of sensitivity runs is used to explore the impact of uncertainties in chlorine activation and denitrification on the model results. In particular, the efficiency of chlorine activation on different types of liquid aerosol versus activation on nitric acid trihydrate clouds is examined. Additionally, the impact of changes in reaction rate coefficients, in the particle number density of polar stratospheric clouds, in supersaturation, temperature or the extent of denitrification is investigated. Results are compared to satellite measurements of MLS and ACE-FTS and to in-situ measurements onboard the Geophysica aircraft during the RECONCILE measurement campaign. It is shown that even large changes in the underlying assumptions have only a small impact on the modelled ozone loss, even though they can cause considerable differences in chemical evolution of other species and in denitrification. Differences in column ozone between the sensitivity runs stay below 10% at the end of the winter. Chlorine activation on liquid aerosols alone is able to explain the observed magnitude and morphology of the mixing ratios of active chlorine, reservoir gases and ozone. This is even true for binary aerosols (no uptake of HNO3 from the gas-phase allowed in the model). Differences in chlorine activation between sensitivity runs are within 30%. Current estimates of nitric acid trihydrate (NAT) number density and supersaturation imply that, at least for this winter, NAT clouds play a relatively small role compared to liquid clouds in chlorine activation. The change between different reaction rate coefficients for liquid or solid clouds has only a minor impact on ozone loss and chlorine activation in our sensitivity runs.

Assimilation of IASI satellite CO fields into a global chemistry transport model for validation against aircraft measurements

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-4493-2012 ◽

2012 ◽

Vol 12 (10) ◽

pp. 4493-4512 ◽

Cited By ~ 19

Author(s):

A. Klonecki ◽

M. Pommier ◽

C. Clerbaux ◽

G. Ancellet ◽

J.-P. Cammas ◽

...

Keyword(s):

Transport Model ◽

Source Region ◽

Specific Treatment ◽

Arctic Region ◽

The Arctic ◽

Chemistry Transport Model ◽

Mixing Ratios ◽

High Concentrations ◽

The Impact

Abstract. This work evaluates the IASI CO product against independent in-situ aircraft data from the MOZAIC program and the POLARCAT aircraft campaign. The validation is carried out by analysing the impact of assimilation of eight months of IASI CO columns retrieved for the period of May to December 2008 into the global chemistry transport model LMDz-INCA. A modelling system based on a sub-optimal Kalman filter was developed and a specific treatment that takes into account the representativeness of observations at the scale of the model grid is applied to the IASI CO columns and associated errors before their assimilation in the model. Comparisons of the assimilated CO profiles with in situ CO measurements indicate that the assimilation leads to a considerable improvement of the model simulations in the middle troposphere as compared with a control run with no assimilation. Model biases in the simulation of background values are reduced and improvement in the simulation of very high concentrations is observed. The improvement is due to the transport by the model of the information present in the IASI CO retrievals. Our analysis also shows the impact of assimilation of CO on the representation of transport into the Arctic region during the POLARCAT summer campaign. A considerable increase in CO mixing ratios over the Asian source region was observed when assimilation was used leading to much higher values of CO during the cross-pole transport episode. These higher values are in good agreement with data from the POLARCAT flights that sampled this plume.

Denitrification by large NAT particles: the impact of reduced settling velocities and hints on particle characteristics

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-11525-2014 ◽

2014 ◽

Vol 14 (20) ◽

pp. 11525-11544 ◽

Cited By ~ 8

Author(s):

W. Woiwode ◽

J.-U. Grooß ◽

H. Oelhaf ◽

S. Molleker ◽

S. Borrmann ◽

...

Keyword(s):

Stratospheric Ozone ◽

Spherical Particles ◽

Lagrangian Model ◽

The Arctic ◽

Reference Scenario ◽

Climate Interactions ◽

Stratospheric Clouds ◽

The Impact ◽

Good Agreement

Abstract. Vertical redistribution of HNO3 through large HNO3-containing particles associated with polar stratospheric clouds (PSCs) plays an important role in the chemistry of the Arctic winter stratosphere. During the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) campaign, apparently very large NAT (nitric acid trihydrate) particles were observed by the airborne in situ probe FSSP-100 (Molleker et al., 2014). Our analysis shows that the FSSP-100 observations associated with the flight on 25 January 2010 cannot easily be explained assuming compact spherical NAT particles due to much too short growing time at temperatures below the existence temperature of NAT (TNAT). State-of-the-art simulations using CLaMS (Chemical Lagrangian Model of the Stratosphere; Grooß et al., 2014) suggest considerably smaller particles. We consider the hypothesis that the simulation reproduces the NAT particle masses in a realistic way, but that real NAT particles may have larger apparent sizes compared to compact spherical particles, e.g. due to non-compact morphology or aspheric shape. Our study focuses on the consequence that such particles would have reduced settling velocities compared to compact spheres, altering the vertical redistribution of HNO3. Utilising CLaMS simulations, we investigate the impact of reduced settling velocities of NAT particles on vertical HNO3 redistribution and compare the results with observations of gas-phase HNO3 by the airborne Fourier transform spectrometer MIPAS-STR associated with two RECONCILE flights. The MIPAS-STR observations confirm conditions consistent with denitrification by NAT particles for the flight on 25 January 2010 and show good agreement with the simulations within the limitations of the comparison. Best agreement is found if settling velocities between 100 and 50% relative to compact spherical particles are considered (slight preference for the 70% scenario). In contrast, relative settling velocities of 30% result in too weak vertical HNO3 redistribution. Sensitivity simulations considering temperature biases of ±1 K and multiplying the simulated nucleation rates by factors of 0.5 and 2.0 affect the comparisons to a similar extent, but result in no effective improvement compared to the reference scenario. Our results show that an accurate knowledge of the settling velocities of NAT particles is important for quantitative simulations of vertical HNO3 redistribution.

Detection in the summer polar stratosphere of pollution plume from East Asia and North America by balloon-borne in situ CO measurements

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-11889-2012 ◽

2012 ◽

Vol 12 (24) ◽

pp. 11889-11906 ◽

Cited By ~ 2

Author(s):

G. Krysztofiak ◽

R. Thiéblemont ◽

N. Huret ◽

V. Catoire ◽

Y. Té ◽

...

Keyword(s):

North America ◽

East Asia ◽

Transport Model ◽

Urban Pollution ◽

The Arctic ◽

Air Masses ◽

Mixing Ratios ◽

Range Transport ◽

Polar Stratosphere

Abstract. The SPIRALE and SWIR balloon-borne instruments were launched in the Arctic polar region (near Kiruna, Sweden, 67.9° N–21.1° E) during summer on 7 and 24 August 2009 and on 14 August 2009, respectively. The SPIRALE instrument performed in situ measurements of several trace gases including CO and O3 at altitudes between 9 and 34 km, with very high vertical resolution (∼ 5 m). The SWIR-balloon instrument measured total and partial column of several species including CO. The CO stratospheric profile from SPIRALE for 7 August 2009 shows some specific structures with large concentrations in the low levels (potential temperatures between 320 and 380 K, i.e. 10–14 km height). These structures are not present in the CO vertical profile of SPIRALE for 24 August 2009, for which the volume mixing ratios are typical from polar latitudes (∼ 30 ppb). CO total columns retrieved from the IASI-MetOp satellite sounder for the three dates of flights are used to understand this CO variability. SPIRALE and SWIR CO partial columns between 9 and 34 km are compared, allowing us to confirm that the enhancement of CO is localised in the stratosphere. The measurements are also investigated in terms of CO:O3 correlations and using several modelling approaches (trajectory calculations, potential vorticity fields, results of chemistry transport model) in order to characterize the origin of the air masses sampled. The emission sources are qualified in terms of source type (fires, urban pollution) using NH3 and CO measurements from IASI-MetOp and fires detection from MODIS on board the TERRA/AQUA satellite. The results give strong evidence that the unusual abundance of CO on 7 August is due to surface pollution plumes from East Asia and North America transporting to the upper troposphere and then entering the lower stratosphere by isentropic advection. This study strengthens evidence that the composition of low polar stratosphere in summer may be affected by anthropogenic surface emissions through long-range transport.

Detection in the summer polar stratosphere of air plume pollution from East Asia and North America by balloon-borne in situ CO measurements

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-15503-2012 ◽

2012 ◽

Vol 12 (6) ◽

pp. 15503-15540

Author(s):

G. Krysztofiak ◽

R. Thiéblemont ◽

N. Huret ◽

V. Catoire ◽

Y. Té ◽

...

Keyword(s):

North America ◽

East Asia ◽

Transport Model ◽

Urban Pollution ◽

The Arctic ◽

Air Masses ◽

Mixing Ratios ◽

Range Transport ◽

Polar Stratosphere

Abstract. The SPIRALE and SWIR balloon-borne instruments have been launched in the Arctic polar region (near Kiruna, Sweden, 67.9° N, 21.1° E) during summer on 7 and 24 August 2009 and on 14 August 2009, respectively. The SPIRALE instrument performed in situ measurements of several trace gases including CO and O3 between 9 and 34 km height, with very high vertical resolution (~5 m). The SWIR-balloon instrument measured total and partial column of several species including CO. The CO stratospheric profile from SPIRALE on 7 August 2009 shows some specific structures with strong abundance of CO in the low levels (potential temperatures between 320 and 380 K, i.e. 10–14 km height). These structures are not present in the CO vertical profile of SPIRALE on 24 August 2009, for which the volume mixing ratios are typical from polar latitudes (~30 ppb). CO total columns retrieved from the IASI-MetOp satellite sounder for the three dates of flights are used to understand this spatial and temporal CO variability. SPIRALE and SWIR CO partial columns between 9 and 34 km are compared, allowing us to confirm that the enhancement of CO is localised in the stratosphere. The measurements are investigated also in terms of CO:O3 correlations and with the help of several modelling approaches (trajectory calculations, potential vorticity fields, results of chemistry transport model), in order to characterize the origin of the air masses sampled. The emission sources are qualified in terms of source type (fires, urban pollution) using NH3 and CO measurements from IASI-MetOp and MODIS data on board the TERRA/AQUA satellite. The results give strong evidence that the unusual abundance of CO on 7 August is due to surface pollution plumes from East Asia and North America transported to the upper troposphere and then entering the lower stratosphere by isentropic advection. This study highlights that the composition of low polar stratosphere in summer can be affected by anthropogenic surface emissions through long range transport.

Denitrification by large NAT particles: the impact of reduced settling velocities and hints on particle characteristics

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-5893-2014 ◽

2014 ◽

Vol 14 (5) ◽

pp. 5893-5927 ◽

Cited By ~ 4

Author(s):

W. Woiwode ◽

J.-U. Grooß ◽

H. Oelhaf ◽

S. Molleker ◽

S. Borrmann ◽

...

Keyword(s):

Mass Density ◽

Spherical Shape ◽

The Arctic ◽

Infrared Spectrometer ◽

Low Mass ◽

Study Support ◽

In Situ Observations ◽

Stratospheric Clouds ◽

The Impact

Abstract. Vertical redistribution of HNO3 through condensation, sedimentation and evaporation of large HNO3-containing particles inside polar stratospheric clouds (PSCs) plays an important role in the chemistry of the Arctic winter stratosphere. In situ observations by the particle probe FSSP-100 during the RECONCILE campaign indicate unexpected large potential NAT (nitric acid trihydrate) particles inside PSCs. The observations can hardly be explained assuming particles with compact morphology and spherical shape due to limited growing time at temperatures below the existence temperature of NAT (TNAT). Utilizing simulations by the CLaMS and measurements by the airborne Fourier transform infrared spectrometer MIPAS-STR we study the impact of reduced settling velocities of NAT particles on vertical HNO3 redistribution. Reduced settling velocities are expected for spherical NAT particles with low mass density or aspheric NAT particles that might explain the maximum sizes of the particles observed in situ. The results of our study support the hypothesis that denitrification is produced by significantly aspheric (i.e. columnar) compact NAT particles which are characterised by reduced settling velocities.

The measurement of groundwater temperature in shallow piezometers and standpipes

Canadian Geotechnical Journal ◽

10.1139/t05-061 ◽

2005 ◽

Vol 42 (5) ◽

pp. 1377-1390 ◽

Cited By ~ 14

Author(s):

Matthew D Alexander ◽

Kerry TB MacQuarrie

Keyword(s):

Finite Element ◽

Statistical Analysis ◽

Transport Model ◽

Shallow Groundwater ◽

Subsurface Temperature ◽

Groundwater Temperature ◽

Monitoring Well ◽

Laboratory Results ◽

The Impact

Accurate measurements of in situ groundwater temperature are important in many groundwater investigations. Temperature is often measured in the subsurface using an access tube in the form of a piezometer or monitoring well. The impact of standpipe materials on the conduction of heat into the subsurface has not previously been examined. This paper reports on the results of a laboratory experiment and a field experiment designed to determine if different standpipe materials or monitoring instrument configurations preferentially conduct heat into the shallow sub surface. Simulations with a numerical model were also conducted for comparison to the laboratory results. Statistical analysis of the laboratory results demonstrates that common standpipe materials, such as steel and polyvinylchloride (PVC), do not affect temperature in the subsurface. Simulations with a finite element flow and heat transport model also confirm that the presence of access tube materials does not affect shallow groundwater temperature measurements. Field results show that different instrument configurations, such as piezometers and water and air filled and sealed well points, do not affect subsurface temperature measurements.Key words: groundwater temperature, temperature measurement, conduction, piezometers, piezometer standpipes, thermal modelling.

Record springtime stratospheric ozone depletion at 80°N in 2020

10.5194/egusphere-egu21-8892 ◽

2021 ◽

Author(s):

Ramina Alwarda ◽

Kristof Bognar ◽

Kimberly Strong ◽

Martyn Chipperfield ◽

Sandip Dhomse ◽

...

Keyword(s):

Ozone Depletion ◽

Transport Model ◽

Stratospheric Ozone ◽

Polar Vortex ◽

The Arctic ◽

Optical Absorption Spectroscopy ◽

Chemical Transport Model ◽

Polar Stratospheric Clouds ◽

Ozone Loss ◽

Stratospheric Clouds

The Arctic winter of 2019-2020 was characterized by an unusually persistent polar vortex and temperatures in the lower stratosphere that were consistently below the threshold for the formation of polar stratospheric clouds (PSCs). These conditions led to ozone loss that is comparable to the Antarctic ozone hole. Ground-based measurements from a suite of instruments at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Canada (80.05&#176;N, 86.42&#176;W) were used to investigate chemical ozone depletion. The vortex was located above Eureka longer than in any previous year in the 20-year dataset and lidar measurements provided evidence of polar stratospheric clouds (PSCs) above Eureka. Additionally, UV-visible zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements showed record ozone loss in the 20-year dataset, evidence of denitrification along with the slowest increase of NO2 during spring, as well as enhanced reactive halogen species (OClO and BrO). Complementary measurements of HCl and ClONO2 (chlorine reservoir species) from a Fourier transform infrared (FTIR) spectrometer showed unusually low columns that were comparable to 2011, the previous year with significant chemical ozone depletion. Record low values of HNO3 in the FTIR dataset are in accordance with the evidence of PSCs and a denitrified atmosphere. Estimates of chemical ozone loss were derived using passive ozone from the SLIMCAT offline chemical transport model to account for dynamical contributions to the stratospheric ozone budget.

Experimental tests of the impact of selected parameters on the indentation rolling resistances

E3S Web of Conferences ◽

10.1051/e3sconf/20182900002 ◽

2018 ◽

Vol 29 ◽

pp. 00002 ◽

Cited By ~ 1

Author(s):

Dariusz Woźniak ◽

Lech Gładysiewicz ◽

Martyna Konieczna

Keyword(s):

Main Part ◽

Rolling Resistance ◽

Experimental Tests ◽

Conveyor Belt ◽

Significant Component ◽

Different Types ◽

Indentation Rolling Resistance ◽

Belt Conveyors ◽

The Impact

Belt conveyors are main part of transporting systems in mines and in many other branches of industry. During conveyor belt works different types of resistances are generated. Indentation rolling resistance is the most significant component of the resistances from the perspective of energy losses and it cause the biggest costs as well. According to latest state of analyses and measurements it is well known that theoretical rolling resistance were underestimated in comparison with the measured in-situ one. In this paper new method for determination indentation rolling resistance is presented. The authors compared theoretically and experimentally established damping factors. The relation between these two values enabled to obtain more precise equation for damping function. This function is one of the most important component in calculation of the rolling resistance. In new theoretical model value of rolling resistance is nearly twice higher than this used so far.

Nitrification of the lowermost stratosphere during the exceptionally cold Arctic winter 2015–2016

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-13681-2019 ◽

2019 ◽

Vol 19 (21) ◽

pp. 13681-13699 ◽

Cited By ~ 1

Author(s):

Marleen Braun ◽

Jens-Uwe Grooß ◽

Wolfgang Woiwode ◽

Sören Johansson ◽

Michael Höpfner ◽

...

Keyword(s):

Nitric Acid ◽

Cross Sections ◽

Large Scale ◽

Potential Temperature ◽

Lagrangian Model ◽

The Arctic ◽

Small Scale ◽

Mixing Ratios ◽

Fine Structures ◽

The Impact

Abstract. The Arctic winter 2015–2016 was characterized by exceptionally low stratospheric temperatures, favouring the formation of polar stratospheric clouds (PSCs) from mid-December until the end of February down to low stratospheric altitudes. Observations by GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) on HALO (High Altitude and LOng range research aircraft) during the PGS (POLSTRACC–GW-LCYCLE II–SALSA) campaign from December 2015 to March 2016 allow the investigation of the influence of denitrification on the lowermost stratosphere (LMS) with a high spatial resolution. Two-dimensional vertical cross sections of nitric acid (HNO3) along the flight track and tracer–tracer correlations derived from the GLORIA observations document detailed pictures of wide-spread nitrification of the Arctic LMS during the course of an entire winter. GLORIA observations show large-scale structures and local fine structures with enhanced absolute HNO3 volume mixing ratios reaching up to 11 ppbv at altitudes of 13 km in January and nitrified filaments persisting until the middle of March. Narrow coherent structures tilted with altitude of enhanced HNO3, observed in mid-January, are interpreted as regions recently nitrified by sublimating HNO3-containing particles. Overall, extensive nitrification of the LMS between 5.0 and 7.0 ppbv at potential temperature levels between 350 and 380 K is estimated. The GLORIA observations are compared with CLaMS (Chemical Lagrangian Model of the Stratosphere) simulations. The fundamental structures observed by GLORIA are well reproduced, but differences in the fine structures are diagnosed. Further, CLaMS predominantly underestimates the spatial extent of HNO3 maxima derived from the GLORIA observations as well as the overall nitrification of the LMS. Sensitivity simulations with CLaMS including (i) enhanced sedimentation rates in case of ice supersaturation (to resemble ice nucleation on nitric acid trihydrate (NAT)), (ii) a global temperature offset, (iii) modified growth rates (to resemble aspherical particles with larger surfaces) and (iv) temperature fluctuations (to resemble the impact of small-scale mountain waves) slightly improved the agreement with the GLORIA observations of individual flights. However, no parameter could be isolated which resulted in a general improvement for all flights. Still, the sensitivity simulations suggest that details of particle microphysics play a significant role for simulated LMS nitrification in January, while air subsidence, transport and mixing become increasingly important for the simulated HNO3 distributions towards the end of the winter.