scholarly journals Observation of Polar Stratospheric Clouds down to the Mediterranean coast

2007 ◽  
Vol 7 (3) ◽  
pp. 6557-6572
Author(s):  
P. Keckhut ◽  
Ch. David ◽  
M. Marchand ◽  
S. Bekki ◽  
J. Jumelet ◽  
...  
Keyword(s):  
Initial Phase ◽  
Western Europe ◽  
Transport Model ◽  
Polar Vortex ◽  
Mediterranean Coast ◽  
Stratospheric Warming ◽  
Chemical Transport Model ◽  
Ozone Destruction ◽  
Stratospheric Clouds ◽  
Lidar Observations

Abstract. A Polar Stratospheric Cloud (PSC) was detected for the first time in January 2006 over Southern Europe after 25 years of systematic lidar observations. This cloud was observed while the polar vortex was highly distorted during the initial phase of a major stratospheric warming. Very cold stratospheric temperatures (<190 K) centred over the Northern-Western Europe were reported, extending down to the South of France where lidar observations were performed. CTM (Chemical Transport Model) investigations show that this event led to a significant direct ozone destruction (35 ppb/day), within and outside the vortex as chlorine activated air masses were moved to sunlight regions allowing ozone destruction. If such exceptional events of mid-latitudes PSCs were to become frequent in the future, they should not compromise the ozone recovery because their effect appears to be limited temporally and spatially. More importantly, these events might tend to be associated with the initial phase of a stratospheric warming that results into a weakening and warming of the polar vortex and hence into a reduced probability occurrence of PSC temperatures during the rest of the winter.

scholarly journals Observation of Polar Stratospheric Clouds down to the Mediterranean coast

2007 ◽  
Vol 7 (19) ◽  
pp. 5275-5281 ◽  
Author(s):  
P. Keckhut ◽  
Ch. David ◽  
M. Marchand ◽  
S. Bekki ◽  
J. Jumelet ◽  
...  
Keyword(s):  
Initial Phase ◽  
Western Europe ◽  
Transport Model ◽  
Polar Vortex ◽  
Mediterranean Coast ◽  
Stratospheric Warming ◽  
Chemical Transport Model ◽  
Ozone Destruction ◽  
Stratospheric Clouds ◽  
Lidar Observations

Abstract. A Polar Stratospheric Cloud (PSC) was detected for the first time in January 2006 over Southern Europe after 25 years of systematic lidar observations. This cloud was observed while the polar vortex was highly distorted during the initial phase of a major stratospheric warming. Very cold stratospheric temperatures (<190 K) centred over the Northern-Western Europe were reported, extending down to the South of France where lidar observations were performed. CTM (Chemical Transport Model) investigations show that this event led to a significant direct ozone destruction (35 ppb/day), within and outside the vortex as chlorine activated air masses were moved to sunlight regions allowing ozone destruction. If such exceptional events of mid-latitudes PSCs were to become frequent in the future, they should not compromise the ozone recovery because their effect appears to be limited temporally and spatially. More importantly, these events might tend to be associated with the initial phase of a stratospheric warming that results into a weakening and warming of the polar vortex and hence into a reduced probability occurrence of PSC temperatures during the rest of the winter.

Record springtime stratospheric ozone depletion at 80°N in 2020

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

&lt;p&gt;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&amp;#176;N, 86.42&amp;#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 NO&lt;sub&gt;2&lt;/sub&gt; during spring, as well as enhanced reactive halogen species (OClO and BrO). Complementary measurements of HCl and ClONO&lt;sub&gt;2&lt;/sub&gt; (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 HNO&lt;sub&gt;3&lt;/sub&gt; 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.&lt;/p&gt;

scholarly journals Detailed PSC formation in a two-dimensional chemical transport model of the stratosphere

1996 ◽  
Vol 14 (3) ◽  
pp. 315-328 ◽  
Author(s):  
D. Fonteyn ◽  
N. Larsen
Keyword(s):  
Transport Model ◽  
Polar Vortex ◽  
Cloud Formation ◽  
Two Dimensional ◽  
Chemical Transport Model ◽  
Polar Stratospheric Clouds ◽  
Zonal Model ◽  
Heterogeneous Processing ◽  
Stratospheric Clouds ◽  
The Antarctic

Abstract. A new two-dimensional zonal model of the stratosphere, based on a formulation in an isentropic framework, with complete chemistry has been coupled with a high resolution detailed microphysical model for polar stratospheric clouds (PSCs). The 2D model chemistry includes all presently known heterogeneous processes on sulfate aerosols and PSCs. The coupling of these two models, with inherently different time scales, is discussed. It is demonstrated that in order to obtain a realistic interrelationship between NOy and N2O an accurate simulation of the sedimentation by PSC particles is necessary. A good agreement of model PSC presence and observations is found for the Antarctic polar winter without the need to impose additional artificial temperature variations in the model. The calculated occurrence of polar stratospheric clouds and resulting heterogeneous chemistry during the Antarctic winter are discussed. Sensitivity of the polar stratospheric chemical composition and cloud formation for different perturbations is investigated by studying the effects of transport across the polar vortex boundary and heterogeneous processing by an enhanced sulfate aerosol load. The importance of including sedimentation for all cases is also discussed.

Analysis of UARS data in the southern polar vortex in September 1992 using a chemical transport model

1996 ◽  
Vol 101 (D13) ◽  
pp. 18861-18881 ◽  
Author(s):  
M. P. Chipperfield ◽  
M. L. Santee ◽  
L. Froidevaux ◽  
G. L. Manney ◽  
W. G. Read ◽  
...  
Keyword(s):  
Transport Model ◽  
Polar Vortex ◽  
Chemical Transport ◽  
Chemical Transport Model

A three-dimensional model comparison of PSC processing during the Arctic winters of 1991/1992 and 1992/1993

1994 ◽  
Vol 12 (4) ◽  
pp. 342-354 ◽  
Author(s):  
M. P. Chipperfield
Keyword(s):  
Model Comparison ◽  
Transport Model ◽  
Three Dimensional ◽  
Polar Vortex ◽  
The Arctic ◽  
Three Dimensional Model ◽  
Polar Stratospheric Clouds ◽  
Ozone Loss ◽  
Stratospheric Clouds ◽  
Compare And Contrast

Abstract. A three-dimensional transport model has been used to compare and contrast the extent of processing by polar stratospheric clouds during the northern hemisphere winters of 1991/1992 and 1992/1993. The model has also been used to compare the potential for ozone loss between these two winters. The TOMCAT off-line model is forced using meteorological analyses from the ECMWF. During winter 1992/1993 polar stratospheric clouds (PSCs) in the model persisted into late February/early March, which is much later than in 1991/1992. This persistence of PSCs should have resulted in much more ozone loss in the later winter. Interestingly, however, the extent of PSC processing and ozone loss was greater in January 1992 than January 1993. In January 1992 PSCs occurred at the edge of a distorted polar vortex whilst in January 1993 the PSCs were located at the centre of a much more zonally symmetrical vortex. In March 1993, distortions of the vortex led to the tearing off of vortex air and its mixing into midlatitudes.

scholarly journals Model simulations and aircraft measurements of vertical, seasonal and latitudinal O<sub>3</sub> and CO distributions over Europe

2006 ◽  
Vol 6 (2) ◽  
pp. 339-348 ◽  
Author(s):  
H. Fischer ◽  
M. Lawrence ◽  
Ch. Gurk ◽  
P. Hoor ◽  
J. Lelieveld ◽  
...  
Keyword(s):  
Western Europe ◽  
Transport Model ◽  
Trace Gas ◽  
High Latitudes ◽  
Aircraft Measurements ◽  
Chemical Transport Model ◽  
Air Masses ◽  
Model Match ◽  
Range Transport ◽  
Model Predictions

Abstract. During a series of 8 measurement campaigns within the SPURT project (2001-2003), vertical profiles of CO and O3 have been obtained at subtropical, middle and high latitudes over western Europe, covering the troposphere and lowermost stratosphere up to ~14 km altitude during all seasons. The seasonal and latitudinal variation of the measured trace gas profiles are compared to simulations with the chemical transport model MATCH. In the troposphere reasonable agreement between observations and model predictions is achieved for CO and O3, in particular at subtropical and mid-latitudes, while the model overestimates (underestimates) CO (O3 in the lowermost stratosphere particularly at high latitudes, indicating too strong simulated bi-directional exchange across the tropopause. By the use of tagged tracers in the model, long-range transport of Asian air masses is identified as the dominant source of CO pollution over Europe in the free troposphere.

scholarly journals Retrieving the vertical distribution of stratospheric OClO from Odin/OSIRIS limb-scattered sunlight measurements

2005 ◽  
Vol 5 (3) ◽  
pp. 2989-3046 ◽  
Author(s):  
P. Krecl ◽  
C. S. Haley ◽  
J. Stegman ◽  
S. M. Brohede ◽  
G. Berthet
Keyword(s):  
Transport Model ◽  
Polar Vortex ◽  
Optical Absorption Spectroscopy ◽  
Polar Regions ◽  
Atmospheric Conditions ◽  
Chemical Transport Model ◽  
Austral Spring ◽  
Data Set ◽  
Spectral Window ◽  
Window Selection

Abstract. The first vertical profiles of stratospheric OClO retrieved from Odin/OSIRIS limb-scattered sunlight radiances are presented. The retrieval method is based on a two-step approach, using differential optical absorption spectroscopy combined with the maximum a posteriori estimator. The details of the spectral window selection, spectral corrections and inversion technique are discussed. The results show that OClO can be detected inside the South polar vortex region between about 12 and 20 km altitude with a 2–5 km height resolution and an estimated retrieval error better than 60% at the peak. OClO concentrations are consistent with chemical transport model simulations and show the expected relation to the atmospheric conditions in the lower stratosphere in the austral spring 2002. This unique data set of OClO profiles is very promising to study the stratospheric chlorine activation in both polar regions.

scholarly journals Response of fine particulate matter concentrations to changes of emissions and temperature in Europe

2012 ◽  
Vol 12 (4) ◽  
pp. 8771-8822 ◽  
Author(s):  
A. G. Megaritis ◽  
C. Fountoukis ◽  
P. E. Charalampidis ◽  
C. Pilinis ◽  
S. N. Pandis
Keyword(s):  
Control Strategy ◽  
Urban Areas ◽  
Western Europe ◽  
Transport Model ◽  
Fine Particulate Matter ◽  
Substantial Reduction ◽  
Effective Control ◽  
Chemical Transport Model ◽  
So2 Emissions ◽  
The Balkans

Abstract. PMCAMx-2008, a three dimensional chemical transport model (CTM), was applied in Europe to quantify the changes in fine particle (PM2.5) concentration in response to different emission reductions as well as to temperature increase. A summer and a winter simulation period were used, to investigate the seasonal dependence of the PM2.5 response to 50% reductions of SO2, NH3, NOx, anthropogenic VOCs and anthropogenic OA emissions and also to temperature increases of 2.5 and 5 K. Reduction of NH3 emissions seems to be the most effective control strategy for reducing PM2.5, in both periods, resulting in a decrease of PM2.5 up to 5.1 μg m−3 and 1.8 μg m−3 (5.5% and 4% on average) during summer and winter respectively, mainly due to reduction of NH4NO3 (20% on average in both periods). The reduction of SO2 emissions decreases PM2.5 in both periods having a significant effect over the Balkans (up to 1.6 μg m−3) during summer, mainly due to decrease of sulfate (30% on average over the Balkans). The anthropogenic OA control strategy reduces total OA by 15% during winter and 8% in the summer. The reduction of total OA is higher in urban areas close to its emissions sources. A slight decrease of OA (8% in summer and 4% in winter) is also predicted after a 50% reduction of VOCs emissions due to the decrease of anthropogenic SOA. The reduction of NOx emissions reduces PM2.5 (up to 3.4 μg m−3) during the summer, due a decrease of NH4NO3, causing although an increase of ozone concentration in major urban areas and over Western Europe. Additionally, the NOx control strategy actually increases PM2.5 levels during the winter. The increase of temperature results in a decrease of PM2.5 in both periods over Central Europe, mainly due to a decrease of NH4NO3 during summer (18%) and fresh POA during winter (35%). Significant increases of OA are usually predicted during summer due mainly to the increase of biogenic VOC emissions. On the contrary, OA is predicted to decrease in the winter due to the dominance of fresh POA reduction and the small biogenic SOA contribution to OA. The resulting increase of oxidant levels from the temperature rise lead to an increase of sulfate levels in both periods, mainly over North Europe and the Atlantic Ocean. The substantial reduction of PM2.5 components due to emissions reductions of their precursors in conjunction with significant changes of PM after increasing the temperature indicate that both emissions and temperature need to be of significant concern for improving air quality.

scholarly journals Evaluation of potential sources of a priori ozone profiles for TEMPO tropospheric ozone retrievals

2018 ◽  
Vol 11 (6) ◽  
pp. 3457-3477 ◽  
Author(s):  
Matthew S. Johnson ◽  
Xiong Liu ◽  
Peter Zoogman ◽  
John Sullivan ◽  
Michael J. Newchurch ◽  
...  
Keyword(s):  
Air Quality ◽  
Tropospheric Ozone ◽  
Transport Model ◽  
A Priori ◽  
Retrieval Algorithm ◽  
Chemical Transport Model ◽  
Diurnal Variability ◽  
Potential Sources ◽  
Tropospheric O3 ◽  
Lidar Observations

Abstract. Potential sources of a priori ozone (O3) profiles for use in Tropospheric Emissions: Monitoring of Pollution (TEMPO) satellite tropospheric O3 retrievals are evaluated with observations from multiple Tropospheric Ozone Lidar Network (TOLNet) systems in North America. An O3 profile climatology (tropopause-based O3 climatology (TB-Clim), currently proposed for use in the TEMPO O3 retrieval algorithm) derived from ozonesonde observations and O3 profiles from three separate models (operational Goddard Earth Observing System (GEOS-5) Forward Processing (FP) product, reanalysis product from Modern-era Retrospective Analysis for Research and Applications version 2 (MERRA2), and the GEOS-Chem chemical transport model (CTM)) were: (1) evaluated with TOLNet measurements on various temporal scales (seasonally, daily, and hourly) and (2) implemented as a priori information in theoretical TEMPO tropospheric O3 retrievals in order to determine how each a priori impacts the accuracy of retrieved tropospheric (0–10 km) and lowermost tropospheric (LMT, 0–2 km) O3 columns. We found that all sources of a priori O3 profiles evaluated in this study generally reproduced the vertical structure of summer-averaged observations. However, larger differences between the a priori profiles and lidar observations were calculated when evaluating inter-daily and diurnal variability of tropospheric O3. The TB-Clim O3 profile climatology was unable to replicate observed inter-daily and diurnal variability of O3 while model products, in particular GEOS-Chem simulations, displayed more skill in reproducing these features. Due to the ability of models, primarily the CTM used in this study, on average to capture the inter-daily and diurnal variability of tropospheric and LMT O3 columns, using a priori profiles from CTM simulations resulted in TEMPO retrievals with the best statistical comparison with lidar observations. Furthermore, important from an air quality perspective, when high LMT O3 values were observed, using CTM a priori profiles resulted in TEMPO LMT O3 retrievals with the least bias. The application of near-real-time (non-climatological) hourly and daily model predictions as the a priori profile in TEMPO O3 retrievals will be best suited when applying this data to study air quality or event-based processes as the standard retrieval algorithm will still need to use a climatology product. Follow-on studies to this work are currently being conducted to investigate the application of different CTM-predicted O3 climatology products in the standard TEMPO retrieval algorithm. Finally, similar methods to those used in this study can be easily applied by TEMPO data users to recalculate tropospheric O3 profiles provided from the standard retrieval using a different source of a priori.

scholarly journals Atmospheric tracers during the 2003–2004 stratospheric warming event and impact of ozone intrusions in the troposphere

2009 ◽  
Vol 9 (6) ◽  
pp. 2157-2170 ◽  
Author(s):  
Y. Liu ◽  
C. X. Liu ◽  
H. P. Wang ◽  
X. X. Tie ◽  
S. T. Gao ◽  
...  
Keyword(s):  
Polar Region ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Planetary Waves ◽  
Chemical Transport Model ◽  
Ozone Concentrations ◽  
Ozone Flux ◽  
Atmospheric Tracers

Abstract. We use the stratospheric/tropospheric chemical transport model MOZART-3 to study the distribution and transport of stratospheric O3 during the remarkable stratospheric sudden warming event observed in January 2004 in the northern polar region. A comparison between observations by the MIPAS instrument on board the ENVISAT spacecraft and model simulations shows that the evolution of the polar vortex and of planetary waves during the warming event plays an important role in controlling the spatial distribution of stratospheric ozone and the downward ozone flux in the lower stratosphere and upper troposphere (UTLS) region. Compared to the situation during the winter of 2002–2003, lower ozone concentrations were transported from the polar region to mid-latitudes, leading to exceptional large areas of low ozone concentrations outside the polar vortex and "low-ozone pockets" in the middle stratosphere. The unusually long-lasting stratospheric westward winds (easterlies) during the 2003–2004 event greatly restricted the upward propagation of planetary waves, causing the weak transport of ozone-rich air originated from low latitudes to the middle polar stratosphere (30 km). The restricted wave activities led to a reduced extratropical downward ozone flux from the lower stratosphere to the lowermost stratosphere (or from the "overworld" into the "middleworld"), especially over East Asia. Consequently, during wintertime (15 December~15 February), the total downward ozone transport on 100 hPa surface by the descending branches of Brewer-Dobson circulation over this region was about 10% lower during the 2003–2004 event. Meanwhile, the extratropical total cross-tropopause ozone flux (CTOF) was also reduced by ~25%. Compared to the cold 1999–2000 winter, the vertical CTOF in high latitudes (60°~90° N) increased more than 10 times during the two warming winters, while the vertical CTOF in mid-latitudes (30°~60° N) decreased by 20~40%. Moreover, during the two warming winters, the meridional CTOF caused by the isentropic transport associating with the enhanced wave activity also increased and played an important role in the total extratropical CTOF budget.

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