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ISSN 1028-334X, Doklady Earth Sciences, 2006, Vol. 408, No. 4, pp. 595–598. © Pleiades Publishing, Inc., 2006.Original Russian Text © V.A. Zubov, E.V. Rozanov, A.V. Shirochkov, L.N. Makarova, T.A. Egorova, A.A. Kiselev, Yu.E. Ozolin, I.L. Karol, W.K. Schmutz, 2006, published inDoklady Akademii Nauk, 2006, Vol. 408, No. 2, pp. 243–246.

At present, chemical climate models (CCM) arewidely used to estimate the contribution of atmosphericphotochemistry to the formation of the modern climateand future evolution of the climate system under differ-ent scenarios of emission of greenhouse and ozone-destroying gases [1]. As a rule, the CCMs represent aconsistent complex of 3D global (general atmosphericcirculation and transport photochemical) models. Sucha combination makes possible a detailed global-scaledescription of the main interacting processes of atmo-spheric physics, photochemistry, and atmospherictransport. However, modern CCM results differ signif-icantly from observation data. For example, the major-ity of CCMs underestimate the air temperature in thelower stratosphere by 10–15 K [1, 2].

One of the ways to correct these discrepancies is toapply parameterization and include new mechanisms ofadditional heating of the lower stratosphere in theCCM. This work presents a possible realization of suchan approach.

The rate of additional heating of the lower strato-sphere arising from electric currents in the stratosphere(Joule heating) was calculated on the basis of parame-terization suggested in [3, 4] and included in the CCM.Parametric relations couple the characteristics of thesolar wind and vertical components of the interplane-tary magnetic field at the level of the earth’s magneto-pause to the intensity of electric currents in the lowerstratosphere. The thermal effect of the currents pro-vides additional Joule heating (AJH) of the atmo-

spheric air. Monthly mean (for January), zonal averagevalues of AJH during a minimum of the 11-yr solarcycle (11-yr SC) are shown in Fig. 1 in [3]. During thelow level of solar activity, the AJH values reach a max-imum in the middle atmosphere in polar regions (~0.15K/day). At the peak of the 11-yr SC, the AJH maximaare also located in the middle polar stratosphere.However, their values are smaller than the AJH valuesduring the 11-yr SC minimum (~0.10 K/day). Thisdifference in the AJH rates during the 11-yr SC maxi-mum and minimum can be explained by the knownnegative influence of the solar wind on the fluxes ofgalactic cosmic rays, which are the main source of ion-ization in the lower stratosphere [5, Chapter 6].

The SOCOL model developed in cooperation byspecialists from the Swiss Technological Institute (Zur-ich), Physical Meteorological Observatory (Davos),and Voeikov Main Geophysical Observatory (St.Petersburg) [6] was used as a CCM. The SOCOL CCMis a combination of the well-known model of generalatmospheric circulation MA-ECHAM4 (the version forinvestigating the middle atmosphere) [7] and a modi-fied version of the transport photochemical model ofthe University of Illinois (Urbana-Champaign, UnitedStates) [8]. Using the SOCOL CCM coupled with theAJH parameterization, we carried out four numericalexperiments with the prescribed boundary conditions,which are typical of the 1990s: (1) 20-yr-long experi-ment without accounting for additional heating (controlexperiment 1, C1) at solar (visible and ultraviolet) radi-ation fluxes corresponding to the 11-yr SC minimum;(2) control experiment 2 (C2) similar to the first oneexcept for the radiation fluxes, which in this case corre-spond to the 11-yr SC maximum; (3) 15-yr modelexperiment (perturbed experiment 1, P1) performedaccounting for the AJH and radiation fluxes character-istic of the 11-yr SC minimum period; (4) perturbedexperiment 2 (P2) similar to the third experiment butunder conditions of the 11-yr SC maximum.

Influence of Solar Wind on Ozone and Circulationin the Middle Atmosphere: A Model Study

V. A. Zubov

a

, E. V. Rozanov

b, c

, A. V. Shirochkov

d

, L. N. Makarova

d

, T. A. Egorova

b

, A. A. Kiselev

a

, Yu. E. Ozolin

a

, I. L. Karol

a

, W. K. Schmutz

b

Presented by Academician G. S. Golitsyn September 16, 2005

Received September 16, 2005

DOI:

10.1134/S1028334X06040192

a

Voeikov Main Geophysical Observatory, ul. Karbysheva 7, St. Petersburg, 194018 Russia

b

Physical Meteorological Observatory, World Radiation Center, Dorfstrasse 33, Davos, CH-7260 Switzerland

c

Swiss Federal Institute of Technology, Zurich, Switzerland

d

Arctic and Antarctic Research Institute, ul. Beringa 38, St. Petersburg, 199397 Russia

GEOPHYSICS

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In order to take into account the influence of inter-annual variability of model calculations on the resultsof comparison of numerical experiments (P1–C1 andP2–C2), we estimated the statistical significance of thedifference between simulated fields (Student’s

t

-test [9]).The analysis of these differences makes it possible to dis-tinguish three main forms of response of the modelstratosphere to the AJH caused by the transformation ofthe solar wind energy and interplanetary magnetic field.

(1) During the warm half of the year (from May toSeptember), the model temperature in the NorthernHemisphere increases by 2–4 K in the lower and middlepolar stratosphere and decreases by 1–2 K in the upperstratosphere. These variations are clearly seen in Fig. 1a,which shows the annual mean values of the atmo-

spheric variables during the 11-yr SC minimum period.The analysis of annual mean values, which conserveinformation about the main variations during the entireyear, makes it possible to distinguish the strongestand/or most prolonged response of the model to theAJH. Figure 1b demonstrates the corresponding varia-tions in the ozone concentration, which decreases by 2–5% during the warm half of the year in the middlestratosphere of the Northern Hemisphere and increasesat northern latitudes of the upper stratosphere. Signifi-cant negative correlation between the variations in theO

3

concentration and temperature are worth noting.Such correlation between ozone and temperature iswell known in the theory of gas phase photochemicalprocesses [5, Chapter 7]. In this case, the statistical sig-

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Fig. 1.

Annual mean and zonal average changes of (a) temperature (K) and (b) ozone concentrations (%) due to AJH during the11-yr SC minimum (light shading denotes significance level of 80% or more; dark shading, 95% or more).

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nificance of the response of the stratosphere to the AJHis sufficiently high (95% or more).

(2) Another typical peculiarity of the response ofsimulated stratosphere to the AJH was found in thepolar stratosphere of the Southern Hemisphere duringthe autumn to summer period. From September toDecember, the polar ozone concentrations in the 100–10 hPa range increase statistically significantly by 10–15%. The influence of this increase is seen in annualmean latitudinal altitude distributions of variations inozone concentrations caused by the inclusion of AJH inthe model calculations (Fig. 1b). The variation in the O

3

concentration can be explained by a significantdecrease in the polar stratospheric clouds of the secondtype during this period owing to the AJH warming in

the polar stratosphere of the Southern Hemisphere dur-ing the polar night (May–September) (see, for example,[10, Chapter 4]).

(3) During the cold period, significant variations inthe stratospheric circulation are possible in both hemi-spheres owing to the inclusion of AJH in the model. Inthis case, the analysis of annual mean values appearsinefficient. Therefore, monthly mean values are consid-ered here. Figure 2 presents the variations in themonthly mean, zonal average values of the westernwind (Fig. 2a) and ozone concentrations (Fig. 2b) inDecember as functions of the AJH during the 11-yr SCminimum period. One can see that the velocity of thewestern stratospheric transport decreases by 8–10 m/sat midlatitudes of the Northern Hemisphere. This is

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(b)

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10

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Fig. 2.

Monthly mean and zonal average changes of (a) zonal wind velocity (m/s) and (b) ozone concentrations (%) due to AJHduring the 11-yr SC minimum in December (light shading denotes significance level of 80% or more; dark shading, 95% or more).

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accompanied by intensification of the activity of planetarywaves and meridional circulation [5, Chapter 3]. In turn,the aforementioned process provides a significantincrease in the model concentration of ozone in polarregions of the Northern Hemisphere (5–7%) accordingto the Brewer–Dobson mechanism. One can also see anincrease in the ozone concentration in the lower strato-sphere over Antarctica by 7–10% as a result of themechanism described in item (2).

Annual mean temperature variations caused by tak-ing AJH into account are more clearly seen during the11-yr SC minimum (Fig. 1a) than similar variationsduring the 11-yr SC maximum.

In order to check the importance of the suggestedparameterization of AJH using the SOCOL CCM formodeling the present climate and its possible changesin future, the fields of annual mean and zonal averagetemperature calculated in numerical experiments C1,C2, P1, and P2 were compared to the correspondingfields from the NCEP/NCAR reanalysis data for 1958–1998 [11]. The results of comparison show that theSOCOL CCM, like the majority of chemical climatemodels, significantly underestimates the temperature inthe lower stratosphere, especially in the polar regions(~9 K). However, inclusion of AJH in the model calcu-lations according to the suggested parameterizationmakes it possible to correct the aforementioned devia-tion substantially. In the Northern Hemisphere, themodel error decreases by 2 K in the lower polar strato-sphere. In the Southern Hemisphere, the influence ofAJH on the model distribution of annual mean temper-ature is small.

ACKNOWLEDGMENTSThis work was supported by INTAS (grant INTAS-

01-0432); the Russian Foundation for Basic Research(project no. 05-05-64496) (I.K., A.K., Yu.O., and V.Z.);the Swiss Federal Institute of Technology, Zurich; andthe Physical Meteorological Observatory, Davos (E.R.and T.E.).

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