scholarly journals Mesosphere-to-stratosphere descent of odd nitrogen in February–March 2009 after sudden stratospheric warming

2011 ◽  
Vol 11 (10) ◽  
pp. 4645-4655 ◽  
Author(s):  
S.-M. Salmi ◽  
P. T. Verronen ◽  
L. Thölix ◽  
E. Kyrölä ◽  
L. Backman ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Polar Vortex ◽  
Polar Regions ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Good Opportunity ◽  
Catalytic Ozone Destruction ◽  
Odd Nitrogen

Abstract. We use the 3-D FinROSE chemistry transport model (CTM) and Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) observations to study connections between atmospheric dynamics and middle atmospheric NOx (NOx = NO + NO2) distribution. Two cases are considered in the northern polar regions: (1) descent of mesospheric NOx in February–March 2009 after a major sudden stratospheric warming (SSW) and, for comparison, (2) early 2007 when no NOx descent occurred. The model uses the European Centre for Medium-Range Weather Forecasts (ECMWF) operational data for winds and temperature, and we force NOx at the model upper altitude boundary (80 km) with ACE-FTS observations. We then compare the model results with ACE-FTS observations at lower altitudes. For the periods studied, geomagnetic indices are low, which indicates absence of local NOx production by particle precipitation. This gives us a good opportunity to study effects of atmospheric transport on polar NOx. The model results show no NOx descent in 2007, in agreement with ACE-FTS. In contrast, a large amount of NOx descends in February–March 2009 from the upper to lower mesosphere at latitudes larger than 60° N, i.e. inside the polar vortex. Both observations and model results suggest NOx increases of 150–200 ppb (i.e. by factor of 50) at 65 km due to the descent. However, the model underestimates the amount of NOx around 55 km by 40–60 ppb. According to the model results, chemical loss of NOx is insignificant during the descent period, i.e. polar NOx is mainly controlled by dynamics. The descent is terminated and the polar NOx amounts return to pre-descent levels in mid-March, when the polar vortex breaks. The break-up prevents the descending NOx from reaching the upper stratosphere, where it could participate in catalytic ozone destruction. Both ACE-FTS observations and FinROSE show a decrease of ozone of 20–30 % at 30–50 km from mid-February to mid-March. In the model, these ozone changes are not related to the descent but are due to solar activation of halogen and NOx chemistry.

scholarly journals Mesosphere-to-stratosphere descent of odd nitrogen in February–March 2009 after sudden stratospheric warming

2011 ◽  
Vol 11 (1) ◽  
pp. 1429-1455 ◽  
Author(s):  
S.-M. Salmi ◽  
P. T. Verronen ◽  
L. Thölix ◽  
E. Kyrölä ◽  
L. Backman ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Good Opportunity ◽  
Weather Forecasts ◽  
Model Study ◽  
Halogen Chemistry ◽  
Odd Nitrogen ◽  
Chemistry Experiment

Abstract. We use the 3-D FinROSE chemistry transport model (CTM) and ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) observations to study the connection between atmospheric dynamics and NOx descent during early 2009 in the northern polar region. We force the model NOx at 80 km poleward of 60° N with ACE-FTS observations and then compare the model results with observations at lower altitudes. Low geomagnetic indices indicate absence of local NOx production in early 2009, which gives a good opportunity to study the effects of atmospheric transport on polar NOx. No in-situ production of NOx by energetic particle precipitation is therefore included. This is the first model study using ECMWF (The European Centre for Medium-Range Weather Forecasts) data up to 80 km and simulating the exceptional winter of 2009 with one of the strongest major sudden stratospheric warmings (SSW). The model results show a strong NOx descent in February–March 2009 from the upper mesosphere to the stratosphere after the major SSW. Both observations and model results suggest an increase of NOx to 150–200 ppb (i.e. by factor of 50) at 65 km due to the descent following the SSW. The model, however, underestimates the amount of NOx around 55 km by 40–60 ppb. The results also show that the chemical loss of NOx was insignificant i.e. NOx was mainly controlled by the dynamics. Both ACE-FTS observations and FinROSE show a decrease of ozone of 20–30% at 30–50 km after mid-February to mid-March. However, these changes are not related to the NOx descent, but are due to activation of the halogen chemistry.

scholarly journals Detecting changes in Arctic methane emissions: limitations of the inter-polar difference of atmospheric mole fractions

2018 ◽  
Vol 18 (24) ◽  
pp. 17895-17907 ◽  
Author(s):  
Oscar B. Dimdore-Miles ◽  
Paul I. Palmer ◽  
Lori P. Bruhwiler
Keyword(s):  
Mole Fraction ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Random Noise ◽  
The Arctic ◽  
Polar Regions ◽  
Annual Growth Rate ◽  
Continuous Version ◽  
The Antarctic

Abstract. We consider the utility of the annual inter-polar difference (IPD) as a metric for changes in Arctic emissions of methane (CH4). The IPD has been previously defined as the difference between weighted annual means of CH4 mole fraction data collected at stations from the two polar regions (defined as latitudes poleward of 53∘ N and 53∘ S, respectively). This subtraction approach (IPD) implicitly assumes that extra-polar CH4 emissions arrive within the same calendar year at both poles. We show using a continuous version of the IPD that the metric includes not only changes in Arctic emissions but also terms that represent atmospheric transport of air masses from lower latitudes to the polar regions. We show the importance of these atmospheric transport terms in understanding the IPD using idealized numerical experiments with the TM5 global 3-D atmospheric chemistry transport model that is run from 1980 to 2010. A northern mid-latitude pulse in January 1990, which increases prior emission distributions, arrives at the Arctic with a higher mole fraction and ≃12 months earlier than at the Antarctic. The perturbation at the poles subsequently decays with an e-folding lifetime of ≃4 years. A similarly timed pulse emitted from the tropics arrives with a higher value at the Antarctic ≃11 months earlier than at the Arctic. This perturbation decays with an e-folding lifetime of ≃7 years. These simulations demonstrate that the assumption of symmetric transport of extra-polar emissions to the poles is not realistic, resulting in considerable IPD variations due to variations in emissions and atmospheric transport. We assess how well the annual IPD can detect a constant annual growth rate of Arctic emissions for three scenarios, 0.5 %, 1 %, and 2 %, superimposed on signals from lower latitudes, including random noise. We find that it can take up to 16 years to detect the smallest prescribed trend in Arctic emissions at the 95 % confidence level. Scenarios with higher, but likely unrealistic, growth in Arctic emissions are detected in less than a decade. We argue that a more reliable measurement-driven approach would require data collected from all latitudes, emphasizing the importance of maintaining a global monitoring network to observe decadal changes in atmospheric greenhouse gases.

scholarly journals Detecting changes in Arctic methane emissions: limitations of the inter-polar difference of atmospheric mole fractions

2018 ◽  
Author(s):  
Oscar B. Dimdore-Miles ◽  
Paul I. Palmer ◽  
Lori P. Bruhwiler
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Random Noise ◽  
Monitoring Network ◽  
The Arctic ◽  
Polar Regions ◽  
Annual Growth Rate ◽  
The Difference ◽  
The Antarctic

Abstract. We consider the utility of the annual inter-polar difference (IPD) as a metric for changes in Arctic emission of methane (CH4). The IPD has been previously defined as the difference between weighted annual means of CH4 mole fraction data collected at polar stations (−53° > latitude > 53°). This subtraction approach (IPDΔ) implicitly assumes that extra-polar CH4 emissions arrive within the same calendar year at both poles. Using an analytic approach we show that a comprehensive description of the IPD includes terms corresponding to the atmospheric transport of air masses from lower latitudes to the polar regions. We show the importance of these transport flux terms in understanding the IPD using idealized numerical experiments with the TM5 global 3-D atmospheric chemistry transport model run from 1980 to 2010. A northern mid-latitude pulse in January 1990, which increases prior emission distributions, arrives at the Arctic with a higher mixing ratio and ≃ 12 months earlier than at the Antarctic. The perturbation at the poles subsequently decays with an e-folding lifetime of ≃ 4 years. A similarly timed pulse emitted from the tropics arrives with a higher value at the Antarctic ≃ 11 months earlier than at the Arctic. This perturbation decays with an e-folding lifetime of ≃ 7 years. These simulations demonstrate that the assumption of symmetric transport of extra-polar emissions to the poles is not realistic, resulting in considerable IPDΔ variations due to variations in emissions and atmospheric transport. We assess how well the annual IPD can detect a constant annual growth rate of Arctic emissions for three scenarios, 0.5 %, 1 %, and 2 %, superimposed on signals from lower latitudes, including random noise. We find that it can take up to 16 years to detect the smallest prescribed trend in Arctic emissions at the 95 % confidence level. Scenarios with higher, but likely unrealistic, growth in Arctic emissions are detected in less than a decade. We argue that a more reliable measurement-driven IPD metric would include data collected from all latitudes, emphasizing the importance of maintaining a global monitoring network to observe decadal changes in atmospheric greenhouse gases.

scholarly journals Analyzing ozone variations and uncertainties at high latitudes during Sudden Stratospheric Warming events using MERRA-2

2021 ◽  
Author(s):  
Shima Bahramvash Shams ◽  
Von P. Walden ◽  
James W. Hannigan ◽  
William J. Randel ◽  
Irina V. Petropavlovskikh ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Polar Vortex ◽  
The Arctic ◽  
High Latitudes ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Total Column Ozone ◽  
Northern Latitudes ◽  
Stratospheric Dynamics ◽  
Zonal Average

Abstract. Stratospheric circulation is a critical part of the Arctic ozone cycle. Sudden stratospheric warming events (SSWs) manifest the strongest alteration of stratospheric dynamics. Changes in planetary wave propagation vigorously influence zonal mean zonal wind, temperature, and tracer concentrations in the stratosphere over the high latitudes. In this study, we examine six major SSWs from 2004 to 2020 using the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2). Using the unique density of observations around the Greenland sector at high latitudes, we perform comprehensive comparisons of high latitude observations with the MERRA-2 ozone dataset during the six major SSWs. Our results show that MERRA-2 captures the high variability of mid stratospheric ozone fluctuations during SSWs over high latitudes. However, larger uncertainties are observed in the lower stratosphere and troposphere. The zonally averaged stratospheric ozone shows a dramatic increase of 9–29 % in total column ozone (TCO) near the time of each SSW, which lasts up to two months. The SSWs exhibit a more significant impact on ozone over high northern latitudes when the polar vortex is mostly elongated as seen in 2009 and 2018 compared to the events in which the polar vortex is displaced towards Europe. The regional impact of SSWs over Greenland has a similar structure as the zonal average, however, exhibits more intense ozone anomalies which is reflected by 15–37 % increase in TCO. The influence of SSW on mid stratospheric ozone levels persists longer than their impact on temperature. This paper is focused on the increased (suppressed) wave activity before (after) the SSWs and their impact on ozone variability at high latitudes. This includes an investigation of the different terms of tracer continuity using MERRA-2 parameters, which emphasizes the key role of vertical advection on mid-stratospheric ozone during the SSWs.

scholarly journals Parallel Comparison of Major Sudden Stratospheric Warming Events in CESM1-WACCM and CESM2-WACCM

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 679 ◽  
Author(s):  
Si-Ming Liu ◽  
Yuan-Hao Chen ◽  
Jian Rao ◽  
Can Cao ◽  
Si-Yu Li ◽  
...  
Keyword(s):  
North America ◽  
Climate Model ◽  
Polar Vortex ◽  
Statistical Characteristics ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Near Surface ◽  
Eddy Heat Flux ◽  
General Statistical ◽  
Vortex Split

After the recent release of the historical runs by community Earth system model version 2–the whole atmosphere community climate model (CESM2-WACCM), the major sudden stratospheric warming (SSW) events in this model and in its previous version (CESM1-WACCM) are compared based on a modern reanalysis (JRA55). Using the World Meteorological Organization (WMO) definition of SSWs and a threshold-based classification method that can describe the polar vortex morphology, SSWs in models and the reanalysis are further classified into two types, vortex displacement SSWs and vortex split SSWs. The general statistical characteristics of the two types of SSW events in the two model versions are evaluated. Both CESM1-WACCM and CESM2-WACCM models are shown to reproduce the SSW frequency successfully, although the circulations differences between vortex displacement SSWs and vortex split SSWs in CESM2-WACCM are smaller than in CESM1-WACCM. Composite polar temperature, geopotential height, wind, and eddy heat flux anomalies in both the two models and the reanalysis show similar evolutions. In addition, positive Pacific–North America and negative Western Pacific patterns in the troposphere preceding vortex displacement and split SSWs are observed in both observations and the models. The strong negative North Atlantic oscillation-like pattern, especially after vortex split SSW onset, is also identified in models. The near-surface cold Eurasia–warm North America pattern before both types of SSW onset, the warm Eurasia–cold North America pattern after displacement SSW onset, and the cold Eurasia–cold North America pattern after split SSW onset are consistently identified in JRA55, CESM1-WACCM, and CESM2-WACCM, although the temperature anomalies after the split SSW onset in CESM2-WACCM are somewhat underestimated.

scholarly journals Winter 2018 major sudden stratospheric warming impact on midlatitude mesosphere from microwave radiometer measurements

2019 ◽  
Vol 19 (15) ◽  
pp. 10303-10317 ◽  
Author(s):  
Yuke Wang ◽  
Valerii Shulga ◽  
Gennadi Milinevsky ◽  
Aleksey Patoka ◽  
Oleksandr Evtushevsky ◽  
...  
Keyword(s):  
Zonal Wind ◽  
Microwave Radiometer ◽  
Polar Vortex ◽  
The Arctic ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Time Data ◽  
Easterly Wind ◽  
The Impact ◽  
Midlatitude Mesosphere

Abstract. The impact of a major sudden stratospheric warming (SSW) in the Arctic in February 2018 on the midlatitude mesosphere is investigated by performing the microwave radiometer measurements of carbon monoxide (CO) and zonal wind above Kharkiv, Ukraine (50.0∘ N, 36.3∘ E). The mesospheric peculiarities of this SSW event were observed using a recently designed and installed microwave radiometer in eastern Europe for the first time. Data from the ERA-Interim and MERRA-2 reanalyses, as well as the Aura microwave limb sounder measurements, are also used. Microwave observations of the daily CO profiles in January–March 2018 allowed for the retrieval of mesospheric zonal wind at 70–85 km (below the winter mesopause) over the Kharkiv site. Reversal of the mesospheric westerly from about 10 m s−1 to an easterly wind of about −10 m s−1 around 10 February was observed. The local microwave observations at our Northern Hemisphere (NH) midlatitude site combined with reanalysis data show wide-ranging daily variability in CO, zonal wind, and temperature in the mesosphere and stratosphere during the SSW of 2018. The observed local CO variability can be explained mainly by horizontal air mass redistribution due to planetary wave activity. Replacement of the CO-rich polar vortex air by CO-poor air of the surrounding area led to a significant mesospheric CO decrease over the station during the SSW and fragmentation of the vortex over the station at the SSW start caused enhanced stratospheric CO at about 30 km. The results of microwave measurements of CO and zonal wind in the midlatitude mesosphere at 70–85 km altitudes, which still are not adequately covered by ground-based observations, are useful for improving our understanding of the SSW impacts in this region.

scholarly journals Ice nucleation by fungal spores from the classes <i>Agaricomycetes</i>, <i>Ustilaginomycetes</i>, and <i>Eurotiomycetes</i>, and the effect on the atmospheric transport of these spores

2014 ◽  
Vol 14 (16) ◽  
pp. 8611-8630 ◽  
Author(s):  
D. I. Haga ◽  
S. M. Burrows ◽  
R. Iannone ◽  
M. J. Wheeler ◽  
R. H. Mason ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Fungal Spores ◽  
Ice Nucleation ◽  
Polar Regions ◽  
Cumulative Number ◽  
Mushroom Species ◽  
Near Surface ◽  
Ice Nuclei ◽  
Wide Range

Abstract. We studied the ice nucleation properties of 12 different species of fungal spores chosen from three classes: Agaricomycetes, Ustilaginomycetes, and Eurotiomycetes. Agaricomycetes include many types of mushroom species and are widely distributed over the globe. Ustilaginomycetes are agricultural pathogens and have caused widespread damage to crops. Eurotiomycetes are found on all types of decaying material and include important human allergens. We focused on these classes because they are thought to be abundant in the atmosphere and because there is very little information on the ice nucleation ability of these classes of spores in the literature. All of the fungal spores investigated contained some fraction of spores that serve as ice nuclei at temperatures warmer than homogeneous freezing. The cumulative number of ice nuclei per spore was 0.001 at temperatures between −19 °C and −29 °C, 0.01 between −25.5 °C and −31 °C, and 0.1 between −26 °C and −31.5 °C. On average, the order of ice nucleating ability for these spores is Ustilaginomycetes > Agaricomycetes ≃ Eurotiomycetes. The freezing data also suggests that, at temperatures ranging from −20 °C to −25 °C, all of the fungal spores studied here are less efficient ice nuclei compared to Asian mineral dust on a per surface area basis. We used our new freezing results together with data in the literature to compare the freezing temperatures of spores from the phyla Basidiomycota and Ascomycota, which together make up 98% of known fungal species found on Earth. The data show that within both phyla (Ascomycota and Basidiomycota), there is a wide range of freezing properties, and also that the variation within a phylum is greater than the variation between the average freezing properties of the phyla. Using a global chemistry–climate transport model, we investigated whether ice nucleation on the studied spores, followed by precipitation, can influence the transport and global distributions of these spores in the atmosphere. Simulations suggest that inclusion of ice nucleation scavenging of these fungal spores in mixed-phase clouds can decrease the annual mean concentrations of fungal spores in near-surface air over the oceans and polar regions, and decrease annual mean concentrations in the upper troposphere.

scholarly journals Gravity Waves excited during a Minor Sudden Stratospheric Warming

2018 ◽  
Author(s):  
Andreas Dörnbrack ◽  
Sonja Gisinger ◽  
Natalie Kaifler ◽  
Tanja Portele ◽  
Martina Bramberger ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Polar Vortex ◽  
Internal Gravity Waves ◽  
The Arctic ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Coherent Wave ◽  
Propagating Waves ◽  
A Minor ◽  
Inertia Gravity Waves

Abstract. An exceptionally deep upper-air sounding launched from Kiruna airport (67.82° N, 20.337° E) on 30 January 2016 stimulated the current investigation of internal gravity waves excited during a minor sudden stratospheric warming (SSW) in the Arctic winter 2015/16. The analysis of the radiosonde profile revealed large kinetic and potential energies in the upper stratosphere without any simultaneous enhancement of upper tropospheric and lower stratospheric values. Upward propagating inertia-gravity waves in the upper stratosphere and downward propagating modes in the lower stratosphere indicated a region of gravity wave generation in the stratosphere. Two-dimensional wavelet analysis was applied to vertical time series of temperature fluctuations in order to determine the vertical propagation direction of the stratospheric gravity waves in one-hourly high-resolution meteorological analyses and short-term forecasts. The separation of up- and downward propagating waves provided further evidence for a stratospheric source of gravity waves. The scale-dependent decomposition of the flow into a balanced component and inertia-gravity waves showed that coherent wave packets preferentially occurred at the inner edge of the Arctic polar vortex where a sub-vortex formed during the minor SSW.

scholarly journals Dynamical evolution of a minor sudden stratospheric warming in the Southern Hemisphere in 2019

2021 ◽  
Author(s):  
Guangyu Liu ◽  
Toshihiko Hirooka ◽  
Nawo Eguchi ◽  
Kirstin Krüger
Keyword(s):  
Southern Hemisphere ◽  
Vertical Component ◽  
Polar Vortex ◽  
Planetary Waves ◽  
High Latitudes ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Zonal Wavenumber ◽  
Westerly Winds ◽  
A Minor

Abstract. This study analyzes the Japanese 55-year Reanalysis (JRA-55) dataset from 2002 to 2019 to examine the sudden stratospheric warming event that occurred in the Southern Hemisphere (SH) in 2019 (hereafter referred to as SSW2019). Strong warming at the polar cap and decelerated westerly winds were observed, but since there was no reversal of westerly winds to easterly winds at 60° S in the middle to lower stratosphere, the SSW2019 is classified as a minor warming event. The results show that quasi-stationary planetary waves of zonal wavenumber 1 developed during the SSW2019. The strong vertical component of the Eliassen–Palm flux with zonal wavenumber 1 is indicative of pronounced propagation of planetary waves to the stratosphere. The wave driving in September 2019 shows that the values are larger than those of the major SSW event in 2002 (hereafter referred to as SSW2002). Since there was no pronounced preconditioning (as in SSW2002) and the polar vortex was already strong before the SSW2019 occurred, a major disturbance of the polar vortex was unlikely to have taken place. The strong wave driving in SSW2019 occurred in high latitudes. Waveguides (i.e., positive values of the refractive index) are found at high latitudes in the upper stratosphere during the warming period, which provided favorable conditions for quasi-stationary planetary waves to propagate upward and poleward.

scholarly journals Comparison of the CMAM30 data set with ACE-FTS and OSIRIS: polar regions

2015 ◽  
Vol 15 (8) ◽  
pp. 11179-11221
Author(s):  
D. Pendlebury ◽  
D. Plummer ◽  
J. Scinocca ◽  
P. Sheese ◽  
K. Strong ◽  
...  
Keyword(s):  
Water Vapour ◽  
Southern Hemisphere ◽  
Atmospheric Chemistry ◽  
Middle Atmosphere ◽  
Imaging System ◽  
Polar Vortex ◽  
Cloud Formation ◽  
Polar Regions ◽  
Data Set ◽  
Chemical Tracers

Abstract. CMAM30 is a 30 year data set extending from 1979 to 2010 that is generated using a version of the Canadian Middle Atmosphere Model (CMAM) in which the winds and temperatures are relaxed to the Interim Reanalysis product from the European Centre Medium-Range for Weather Forecasts (ERA-Interim). The data set has dynamical fields that are very close to the reanalysis below 1 hPa and chemical tracers that are self-consistent with respect to the model winds and temperature. The chemical tracers are expected to be close to actual observations. The data set is here compared to two satellite records – the Atmospheric Chemistry Experiment Fourier Transform Spectometer and the Odin Optical Spectrograph and InfraRed Imaging System – for the purpose of validating the temperature, ozone, water vapour and methane fields. Data from the Aura Microwave Limb Sounder is also used for validation of the chemical processing in the polar vortex. It is found that the CMAM30 temperature is warm by up to 5 K in the stratosphere, with a low bias in the mesosphere of ~ 5–15 K. Ozone is reasonable (± 15%) except near the tropopause globally, and in the Southern Hemisphere winter polar vortex. Water vapour is consistently low by 10–20%, with corresponding high methane of 10–20%, except in the Southern Hemisphere polar vortex. Discrepancies in this region are shown to stem from the treatment of polar stratospheric cloud formation in the model.

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