ISSN 1028334X, Doklady Earth Sciences, 2016, Vol. 468, Part 2, pp. 602–606. © Pleiades Publishing, Ltd., 2016. Original Russian Text © A.N. Gruzdev, E.P. Kropotkina, S.V. Solomonov, A.S. Elokhov, 2016, published in Doklady Akademii Nauk, 2016, Vol. 468, No. 4, pp. 451–455.
GEOPHYSICS
Anomalies of the Ozone and Nitrogen Dioxide Contents in the Stratosphere over Moscow Region as a Manifestation of the Dynamics of the Stratospheric Polar Vortex A. N. Gruzdeva, E. P. Kropotkinab, S. V. Solomonovb, and A. S. Elokhova Presented by Academician G.S. Golitsyn April 9, 2015 Received April 23, 2015
Abstract—Measurements of the stratospheric contents of O3 and NO2 in the Moscow region were used to analyze the anomalies of these species related to the sudden stratospheric warming in the winter and the fol lowing deformation of the stratospheric circumpolar vortex in early February 2010 and the latitudinal dis placement of the vortex towards the European sector in late March 2011 before the final warming in the spring. In the first case, an increase in the O3 and NO2 contents up to 85% and by two times, respectively, was recorded. In the second case, the O3 content decreased by onefourth and the NO2 content dropped by two times as compared to the average values for the periods that preceded the beginning of the anomalies. DOI: 10.1134/S1028334X16060088
1. The dynamic and chemical processes in the extratropical stratosphere in the winter–spring period are related to the spatial–time evolution of the strato spheric circumpolar vortex to a considerable degree [1, 2]. A strong steady vortex causes dynamic isolation of the Arctic stratosphere, leads to increased cooling of the stratosphere, and restrains the accumulation of ozone in the internal area of the vortex. If the cooling of the stratosphere is rather strong and is followed by the formation of polar stratospheric clouds and strato spheric denitrification as happened in 2011, there can be additional destruction of stratospheric ozone [3]. During the winter, a largescale disturbance, a so called sudden stratospheric warming (SSW), can develop in the Arctic stratosphere, which affects the thermal regime, the structure and the circulation of the middle atmosphere [4, 5]. When the warming is strong (major), the zonal wind changes its direction, and the circumpolar vortex degrades and is strongly displaced from the pole. Such warming events lead to considerable redistributions of the atmospheric ozone field. This work presents new experimental results of studying the influence of the SSW on the stratospheric content of NO2. 2. This work demonstrates the results of simulta neous observations of vertical distributions of O3 and a Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, Moscow, Russia email:
[email protected] b Lebedev Institute of Physics, Russian Academy of Sciences, Moscow, Russia
NO2 over the Moscow region during the SSW in 2010 and the Arctic ozone “hole” in 2011. Denitrification of the Arctic stratosphere at the end of the winter of 2011 and, as a result, a decrease in the stratospheric content of NO2 were established in [3, 6, 7]. The total content and the vertical distribution of NO2 were measured in the visible region by zenith scattered solar radiation at the Zvenigorod Scientific Station of the Obukhov Institute of Atmospheric Physics located 50 km west to Moscow [8]. The verti cal distribution of O3 in the stratosphere was deter mined by groundbased measurements of thermal emission of O3 at the wavelength of 2.1 mm at the Leb edev Physical Institute by using an original highsen sitive spectrometer [9]. The total error of the O3 profile retrieval at the heights of 20–50 km usually does not exceed 5–7% and increases gradually in the higher and lower layers. The field of view of the spectrometer is oriented approximately to the region of the strato sphere above the Zvenigorod station. In this work we also used data on the temperature, the wind velocity, and the potential vorticity that were obtained at the British Atmospheric Data Center (BADC, http://badc.nerc.ac.uk/home/index.html), the data of global ERAInterim reanalysis from the European Center for MediumRange Weather Fore casts (http://apps.ecmwf.int/datasets/), and the results of measuring the total ozone content (TOC) by the OMI instrument on board the EOSAura satellite that were obtained from the Giovanni online data sys tem, developed and maintained by the NASA GES DISC (http://disc.sci.gsfc.nasa.gov/giovanni).
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Fig. 1. O3 mixing ratio on the isobaric surface of 10 hPa (1) and 20 hPa (2), and the deviation of the NO2 stratospheric content from its annual course (3) in (a) January–April 2010 and (b) March–April 2011; (c) the zonal mean velocity of the zonal wind u on the 10 hPa isobaric surface and the latitude 60° N (1), and the difference between the zonal mean temperature values, ΔT, at 60° and 85°N and on the 10 hPa isobaric surface (2) from October 2009 until May 2010. The vertical dashed straight lines in Figs. 1a–1b correspond to the dates of the O3 and NO2 anomalies, and in Fig. 1c, they correspond to the date of the O3 and NO2 positive anomaly and the date of the maximum phase of the stratospheric warming.
3. Figures 1a and 1b illustrate the O3 mixing ratios on the isobaric surfaces of 10 and 20 hPa and the devi ation of the stratospheric column NO2 content from the NO2 annual cycle in the periods of 2010 and 2011 under analysis. The annual cycle of NO2 is removed due to its high amplitude to visualize the anomalies [6, 8]. During a considerable part of January 2010, the stratosphere above the Moscow region was under the influence of the stratospheric polar vortex and was characterized by relatively small variations in the O3 and NO2 contents (Fig. 1a). At the end of January and the beginning of February 2010, the O3 and NO2 con tents sharply increased; the concentration maxima were reached on February 3–5 (Figs. 1a, 2a, 2b). The rise in the concentrations was recorded in the entire stratospheric layer, but it was not equal at different heights (Fig. 2d). According to the ERAInterim data, the temperature in the 15–30 km stratospheric DOKLADY EARTH SCIENCES
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layer over Moscow increased and the increase near the 25kmheight amounted to approximately 40°C for eight days. It is in a neighbourhood of this altitude there was the largest increase by 85% in the O3 con centration, while the NO2 concentration grew by three times (Fig. 2c). The increase in the O3 concentration at the heights of 25–35 km (20–5 hPa) relative to the values averaged for the preceding days of January ranged from 30 to 85% with an increasing amplitude of the anomaly from top to bottom. The TOC increased by onefourth, and the NO2 content in the strato spheric column doubled. The February anomaly was preceded by the dis placement of the stratospheric vortex from the high latitudes towards Eurasia from January 20th until the end of January, when there was polar vortex air in the stratosphere over Moscow. As a result of the subse quent deformation, the vortex split into two parts, and
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Fig. 2. Vertical profiles of (a) O3 and (b) NO2 on January 27 (1) and February 4 (2), 2010; (c) the ratio of the O3 (1) and NO2 (2) concentrations on February 4 to the concentrations on January 27, 2010; vertical profiles of (d) O3 and (e) NO2 on March 25 (1) and March 29 (2), 2011; (f) the ratio of the O3 (1) and NO2 (2) concentrations on March 29 to the concentrations on March 25, 2011. Hor izontal segments in Figs. 2b and 2e are random errors of the NO2 profile retrieval.
the stratosphere over Moscow was outside the vortex. Such evolution of the vortex is typical of the SSW epi sodes. Figure 1c shows that from mid November 2009 until the first ten days of January 2010 the velocity of the zonal wind increased due to the establishment of the winter type of stratospheric circulation, which was discontinued in late January–early February by the stratospheric warming that led to a sharp drop in the zonal mean velocity of the wind and the smoothing of the zonal mean meridional temperature gradient. In accordance with the WMO criteria, February 9th cor responds to the date of the SSW, i.e. the moment when the sign in the wind velocity changed [5, Fig. 1c]. After the warming, the wind velocity and the temperature meridional gradient remained weak. The positive anomalies of the O3 and NO2 contents over Moscow at the beginning of February are the result of the SSW development accompanied by the meridional advection of the stratospheric air with enhanced ozone content and, with respect to the meridional NO2 gradient [10], by the high NO2 con
tent in the stratosphere. We note that changes in the ozone content caused by stratospheric warmings were also observed in other regions [11, 12]. 4. We proceed to the effect that in certain sense is opposite to that described above. In February–March 2011, there was record high stratospheric ozone deple tion. Its amplitude was comparable to a decrease in ozone over Antarctica during the period of the ozone “hole” [3]. Low activity of planetary waves with a strong stratospheric polar vortex facilitated this [13]. The record negative anomalies of the NO2 strato spheric content, the ozone vertical distribution, and TOC related to the Arctic ozone “hole” were detected in March–April 2011 in the middle latitudes [6, 7, 14]. These anomalies of O3 and NO2 at the end of March 2011 are shown in Fig. 1b. The O3 concentra tion in the 20–5 hPa layer decreased by onefourth at the anomaly peak, and the NO2 content in the strato spheric column decreased by two times. The O3 and NO2 concentrations decreased mostly in the strato sphere below 40 km; the relative decrease in the lower DOKLADY EARTH SCIENCES
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layers was greater than in the upper ones (Figs. 2d–2f). The strongest decrease in the NO2 concentration, more than to a half value, exceeded the double value occurred in the vicinity of the 20kmheight, where a maximum increase in the temperature was also observed. The center of the stratospheric polar vortex retained its position in the vicinity of the pole, and the stratospheric contents of O3 and NO2 over the Mos cow region were relatively stable until March 20 (Fig. 1b). At the end of March, the vortex center sharply moved towards the European sector, and the boundary of the vortex was displaced southward of Moscow. The contents of O3 and NO2 over the Moscow region dropped as a result of the inflow of the stratospheric air with a deficit of O3 and NO2 that appeared in the area of the Arctic ozone “hole.” In the following days up to the beginning of weak ening and decaying of the polar vortex on April 11–20, the vortex was shifted towards Siberia, which caused negative anomalies in O3 and NO2 in this region [7]. The consequences of the ozone and nitrogen dioxide deficit in the internal segment of the vortex in the spring of 2011 were also manifested as episodes of a decrease in the content of these gases over the Moscow region in April (Fig. 1b). 5. A considerable decrease in the O3 and NO2 con tent over Moscow by ~20% was also observed at the end of March 2010 despite the previous SSW (Fig. 1a). After the stratospheric warming, the polar vortex did not disappear; both of its segments were displaced rel ative to the northern pole. One of the vortex fragments decayed at the end of February, but it covered Moscow on February 11–20. Despite this fact, in general, the NO2 content did not strongly deviate from the normal value after the warming until the middle of March. The second fragment drifted from the Canadian sector of the Arctic to the European part of the Rus sian Arctic through the middle of March. The negative anomalies of the O3 and NO2 contents on March 24– 25, 2010, were caused by the subsequent southward displacement of its southern periphery. We emphasize that the anomalies were caused by the fragment that was located mostly in the polar latitudes during the winter. The negative March anomalies of ozone in 2010 and 2011 do not differ much in amplitude. The some what greater amplitude of the anomaly in 2011 is apparently a result of the additional ozone depletion during the winter of 2011 that was favorable for the implementation of the photochemical mechanism of the ozone “hole.” However, the probability and effi ciency of this mechanism during the winter of 2010 should be considered to be significantly less. We may conclude that the key role in the decrease in the ozone content is played by dynamic isolation of the internal region of the stratospheric polar vortex, when ozone is destroyed in a chemical way. At a smaller speed, the DOKLADY EARTH SCIENCES
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chemical destruction also occurs under conditions unfavorable for the mechanism of the ozone “hole.” 6. The cases considered point to the fact that the significant negative anomalies of the O3 and NO2 con tents observed in March are caused by episodes of dis placement of the polar vortex boundary southward of the midlatitude observation station, if in the winter period the polar vortex was mainly located in the polar latitudes. Circulation processes caused by SSWs can lead to considerable positive anomalies of the O3 and NO2 stratospheric contents above the midlatitude observation station located at that time in the zone of the stratospheric southwestern flow from the external southeastern periphery of the polar vortex. Analysis of correlations of the O3 and NO2 strato spheric contents with the potential vorticity on the isentropic surface with 850 K potential temperature (~10 gPa) in the winter and spring seasons of 2010 and 2011 showed that the ozone content at the considered levels of 5, 10, and 20 gPa and the NO2 content in the stratospheric column can be better indicators of the processes associated with the evolution of the strato spheric polar vortex than the total ozone content. ACKNOWLEDGMENTS The authors are grateful to S.B. Rozanov, A.N. Lukin, A.N. Ignat’ev, and M.A. Kolesnikova for their assistance. In this work we used the data obtained from the British Atmospheric Data Center (BADC), the European Center for MediumRange Weather Forecasts (ECMWF), and the Goddard Earth Sci ences Data and Information Services Center (GES DISC). This work was supported by the Programs of the Presidium of the Russian Academy of Sciences “Nat ural Catastrophes and Adaptation Processes under Conditions of Changing Climate and Development of the Nuclear Power Industry,” the Division of the Earth Sciences of the Russian Academy of Sciences “Pro cesses in the Atmosphere and Cryosphere as a Factor of Changes in the Natural Environment,” the Divi sion of Physical Sciences of the Russian Academy of Sciences “Modern Problems of Radiophysics,” and “Radioelectronic Methods in Studying the Natural Environment and Humans,” and a grant of the Edu cational and Scientific Complex of the Lebedev Phys ical Institute. REFERENCES 1. M. R. Schoeberl, L. R. Lait, P. A. Newman, and J. E. Rosenfield, J. Geophys. Res. 97 (D8), 7859–7882 (1992). 2. V. I. Bekoryukov, I. V. Bugaeva, V. N. Glazkov, E. A. Zhadin, B. M. Kiryushov, D. A. Tarasenko, and V. V. Fedorov, Izv. Atmos. Ocean. Phys. 37 (6), 757– 763 (2001).
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Translated by L. Mukhortova
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