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The influence of magnetospheric electric fields on the distribution of oxygen in the mesosphere and lower thermosphere
JamalcfAaMIphericd Tm Physics.V&.41,pp.447-451 @ptrermonReaUd.1979.RintedinNortbmIrehd
0021-9169/79/[email protected]/0
The intluence of magnetospheric electric fields on the distmiintfon of oxygen in the mesosphere and lower thermosphere* N. N. KLIMOV and N. A. SUTYRIN Siberian Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Academy of Sciences of the U.S.S.R., Siberian Department, Irkutsk, U.S.S.R.
(Receioed
3 Nooember 1977; in revisedform 27 July 1978)
IM’RODUCDON
redistribution of density in the upper atmosphere due to transport has been discussed by (JOHNSON, 1973; MAYR and VOLLAND, 1972; KLIMov and Su-rvnr~, 1974a, b). These papers included the large scale motions of the atmosphere induced by the thermal and gravitational tides coupled with the effects of the Earth’s rotation and electrodynamic friction. The magnetospheric convection electric field induces ionospheric plasma motions which change the planetary motion of the neutral components due to collisions. Neutral wind observations made by Buns (1971) at high latitudes indicated that the direction and the velocity of the wind depend strongly on the level of magnetic activity. Theoretical papers by VOLLAND and MAYR (1973), BLUM and HARRIS (1975), DICKINSONet al. (1975), and CREEKMOREet al. (1975) on the effects of ion drag did not consider the influence of magnetospheric electric fields but the action of these fields was taken into account by STRAUS et al. (1976) who demonstrated that the effect on the density and temperature was significant. Density and temperature changes affect the dissociation and recombination of oxygen molecules and atoms as well as atmospheric diffusion and hence the magnetospheric convection electric field will change the atmosphere composition. Measurements on OGO-6 and ESRO-4 satellites have shown that in summer the oxygen density is less than in winter. In this connection it would be interesting to determine how the atomic oxygen content changes when the atmospheric composition is simulated with account of meridional transport affected by ions which participate in convection motion.
The
In the present paper by means of a computer model of the system of equations describing the main processes that determine the behavior of the atmosphere in the altitude range 60-160 km an attempt will be made to show that external electric fields influence the distribution of the oxygen density in the mesosphere and lower thermosphere. Thus quiet and moderately disturbed geomagnetic conditions for which at high latitudes the value of electric field does not exceed 20-30 mV/m will be considered. THEF0RMuL4
The distribution of the density variations in space and time may be obtained from the continuity and momentum equations. These were formulated (including the chemical reactions of dissociation, recombination and ozone photolysis) for a rotating spherical coordinate system (r, A, cp) (radial distance, longitude, latitude). We use the continuity equation for the ith sort of particles (the index i refers to 0 or 02):
an, ,=qi-I+(r%) ----&+oscp)
2
(1)
where n, is the density of the ith component, qi and 4 are production and loss velocities, 4 is the vertical flow due to molecular difhrsion and turbulent transport, IJ is the meridional component of wind velocity. A detailed description of these equations has been @en by KLIMov and Su-rvm~ (1974a, b). Horizontal molecular and eddy diffusion have not been included in the divergence term of the continuity equations which include only vertical molecular and eddy difIusion and meridional transport. The influence of vertical macroscopic movement on the atmospheric composition has been studied by KOSHELEV (1976). The transport velocity u of the atmosphere was obtained from the momentum and conductivity
* Presented at the 1977 IAGA/IAMAP General Scientitic Assembly session JS-U-‘Recent Advances in Neutral and Ionospheric
TION OF TED3 PROBLEM
Models in the Thermosphere’.
447
448
N. N. KLIMOV
and N. A. SUTYRIN
equations
f3V
;JxB,+V
-g+2wxv=g+
(k7’&)
(2)
(3) where w is the angular rate of the Earth rotation, p is the density, g is the gravity acceleration, B, is the geomagnetic field, n, is the density of ith component, ii is the plasma conductivity tensor, T is the temperature, E is the magnetospheric convection electric field which is taken for this model from the paper of V~LLAND (1975).
when the velocity of the vertical motion of the atmosphere changes. Experimental data on atmospheric temperature are fairly well reffected in the JACCHIA (1971) model. Here we will not consider the equation of heat balance but we shall use the temperature from the JACCHIA model. For the quiet and moderately disturbed geomagnetic conditions in question the above effects of the temperature change have apparently rather thorou~y been taken into account in the empirical model.
where
Thus the problem reduced to the solution for four equations: two continuity equations of the form (1) for 0 and O2 and two equations which are projections of vector equation (2) onto directions A and cp with account of (3) and (4). The Nz density was obtained as functions of time, aititude and latitude from the atmospheric models of GROVES (1970) and JACCHIA (1971). The eiec-
L = rl(a cos’tp); Lo = 8.547 (for cp at the iatitude 70” on the Earth’s surface; a is the E%uth’s radius). In equation (2) the non-linear term and viscosity terms were neglected. When the atmosphere participates in additional convection motion, the value of Joule heating must cha&ge. In addition, the temperature of the atmosphere changes due to the adiabatic process
coefficient was assumed equal to 10’ cm* se-’ and calcuiations were made for three values of the electric field El = 0.5 mV/m, I mV/m and 0. The system of equations was solved numerically by the finite difference method for the latitude interval 80”S-80”N with Aq = 5”, Ar = 5 km, and AA = 15”. The approximations and the method of solution have been described by SUTYRIN (1973). The boundary condition at the 60 km level for the 0 concentration was zero, and the value for the 02
E=-9@,=
-$_--
1
aQt -- CY#
rcosqaah’
rarp
(4)
tron density was taken from the paper of DVINSKIKH and IVANOV (1971). The eddy diffusion
I
106
‘3O”N
40’
0”
-_._.L__“. 4OQ
i.-
.-j
EW’3
Fig. 1. Latitude variations of oxygen concentration at 95 km and 120 km. The curves with the circles are for solstice conditions and the ones without the circles are fbr equinox. Ihe broken curves are with the external electric field and the solid curves&or zero electric field.
449
The influence of magnetospheric electric fields on the distribution of oxygen density was taken from GROVES (1970). boundary condition used at the 160 km level the condition that the vertical flux is equal to in the infinity in the same manner as STROBEL MCELROY (1970 and SHMAZAKI (1972):
The was zero and
loo t qId
70-s 120 km \\
50-
E
@,(Z=m)=O where the integral is taken from the upper boundary, Zm.
0
4
I 8
I 12
I 16
I 20
24
LST
REsIJLTY5ANDDiscusIoN The change of the wind magnitude and direction caused by insertion into (3) of an external electric field, redistributes atmospheric constituent densities for which continuity equations are solved. The external electric field also changes the kinetic energy of horizontal motion of the atmosphere. As shown by estimations made in this paper, the energy of the summer hemisphere changes approximately for 24 h by 3-1022erg. In the formulation of the problem stated above the effect of meridional transport only has been singled out, although other components of the neutral wind (the zonal and the vertical ones) can influence the change of atmospheric composition.
104
106
Fig. 2. The daily variations of the meridional component of the wind at 120 km altitude and 70”s latitude. The types of curve are as described for Fig. 1. The latitude distributions of atomic oxygen density at two altitudes (95 and 120 km) are presented in Fig. 1. The case when the electric field is zero, is shown by solid lines, and broken lines are used when the electric field is not zero. Both curves with the circles are computed for the December solstice conditions and the ones without the circles are for the equinox. For the equinox case the curves are symmetrical about the equator and are thus only shown for northern latitudes. It is seen that the electric field has most influence on the
II 0
IO.8 LQ ni,
II 2
cm-3
Fig. 3. The altitude profiles of [0] and [OJ at 70% for 1200 WI. The types of curve are as described for Fig. 1.
450
N. N. KLMOVand N. A. SLWRIN
Fig. 4. The altitude profiles at 6CE3 for the three times. “Be broken curves are with the external ekc&ictWdandthesoiiicurvesforzeroeiectric6eld.-and-for4h,--0-and-0-for l2h,-O---andandffor20h.
atomic oxygen density at high latitudes in the summer hemisphere. For 120 km altitude and 70”s latitude the density decreases by a factor of 1.5 and for the equinox case it is 1.2 times less. This may be explained by the fact that the largest changes in the horizontal velocity occur at high latitudes in the summer hemisphere under the influence of the electric field (Fig. 2). The external field influence in the winter hemisphere might be larger if a more exact ionospheric model than that given in the paper of DVINSKIKHand IVANOV (1971) had been used for the determinative of the ~ndu~ti~ty. The altitude profiles of the atomic oxygen density for 12 h LT and 70% are presented in Fig. 3. It is seen that the density decreases for all altitudes under the action of the external electric field. The atomic oxygen density progles for 4, 12 and 20 h LT at 60% latitude for the solstice condition are presented in Fig. 4. It will be seen that daily variations appear at altitudes higher than 100 km. At 120-130 km altitude the atomic oxygen density changes during the day by approximately a factor of 2. For solstice conditions at 50-70” latitudes the decrease is largest during the day and morning and decreases at night as shown in Fig. 5. This explains the experimental data which shows changes in composition observed in the daytime hours mentioned by RISHBETH (1968).
We conclude that the external magnetospheric convection electric field leads to considerable variations in the neutral component concentrations in the upper atmosphere-the diurnal variations increase and the altitude and latitude distributions change, especially at high latitudes.
iST
Fig. 5. Tbe daily variations of the oxygen con~n~atio~s at 14Okm for di&ent latitude8 for soWiCe. The broken curve are with the e&em& ebMxic fieid avhe solid curves for zero &ctrk field. - and -@-- for 503, -0-and --CL- for 60’S, --- and - for 70%
The influenceof magnetosphericelectric fields on tbe distributionof oxygen
BLUM P. W. and HARRIS I. CREEXMORES. P., Smus J. M., HARRIS P. M., CHmo B. K. and CHIUY. T. DICXINSONR. E., RIDLEY E. C. and ROBLER. G. DVINSKIKHR. H. and IVANOVK. G. JOHNSON F. S. KLIMOVN. N. and SUWRINN. A. KUMOVN. N. and SUTYRIN N. A. KOSHELEV V. V. MAYR H. G. and Vow H. Raes D. RIWBEIWH. SHIMAUKIT. Snuus J. M., CIWEKMORE S. P., HARFUS R. M., CfilNGB. k. and CHIUY. T. STROBELD. F. and MCELROY M. B. SUTYRIN N. A. VOLL.AND H. VOLLANDH. and MAYR H. G.
1975 1975
J. afmos. Phys. 37, 193. .l. atmos. ten. Phys. 37, 491.
1975 1971 1973 1974a 1974b 1976 1972 1971 1968 1972 1975
J. atmos. terr.Phys. 37, 1737. Z&d. Gemnagn. Acmnom. Fiz. Solntsa 19, 112. Pkznet. space sci. 2% 1001. J. atmos. ten. Phys. 36, 1863. Z&d. Geomagn. Aerrmom. Fiz. Solntsa 32, 14 J. atmos. #en. Phys. 38, 991. Planet. Space Sci. 20, 379. J. Br. interplanct.Sot. 24,223. Rev. Geophys. 6, 33-71. Radio Sci. 7,695. J. atmos. urr. Phys. 37, 1245.
1970 1973 1975 1973
Plane?. Space Sci. 18, 1181. Z&d. Geomagn. Acnnwm. Fiz. Sofntsa. 28, 56. Annls Geophys. 31, 154. Annls Gtophys. 29,61.
1970 1971 1976
AE.RL.-70-0261 No. 218. SAO Spec. Rep. No. 332. Aerospace Rep. No. ATR-76(8203)-4.
Refermcc is also made to following unpublished material: GROVESG. V. JAM L. G. STRAUS J. M. and !5cxw~m
451
0021-9169/79/[email protected]/0
The intluence of magnetospheric electric fields on the distmiintfon of oxygen in the mesosphere and lower thermosphere* N. N. KLIMOV and N. A. SUTYRIN Siberian Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Academy of Sciences of the U.S.S.R., Siberian Department, Irkutsk, U.S.S.R.
(Receioed
3 Nooember 1977; in revisedform 27 July 1978)
IM’RODUCDON
redistribution of density in the upper atmosphere due to transport has been discussed by (JOHNSON, 1973; MAYR and VOLLAND, 1972; KLIMov and Su-rvnr~, 1974a, b). These papers included the large scale motions of the atmosphere induced by the thermal and gravitational tides coupled with the effects of the Earth’s rotation and electrodynamic friction. The magnetospheric convection electric field induces ionospheric plasma motions which change the planetary motion of the neutral components due to collisions. Neutral wind observations made by Buns (1971) at high latitudes indicated that the direction and the velocity of the wind depend strongly on the level of magnetic activity. Theoretical papers by VOLLAND and MAYR (1973), BLUM and HARRIS (1975), DICKINSONet al. (1975), and CREEKMOREet al. (1975) on the effects of ion drag did not consider the influence of magnetospheric electric fields but the action of these fields was taken into account by STRAUS et al. (1976) who demonstrated that the effect on the density and temperature was significant. Density and temperature changes affect the dissociation and recombination of oxygen molecules and atoms as well as atmospheric diffusion and hence the magnetospheric convection electric field will change the atmosphere composition. Measurements on OGO-6 and ESRO-4 satellites have shown that in summer the oxygen density is less than in winter. In this connection it would be interesting to determine how the atomic oxygen content changes when the atmospheric composition is simulated with account of meridional transport affected by ions which participate in convection motion.
The
In the present paper by means of a computer model of the system of equations describing the main processes that determine the behavior of the atmosphere in the altitude range 60-160 km an attempt will be made to show that external electric fields influence the distribution of the oxygen density in the mesosphere and lower thermosphere. Thus quiet and moderately disturbed geomagnetic conditions for which at high latitudes the value of electric field does not exceed 20-30 mV/m will be considered. THEF0RMuL4
The distribution of the density variations in space and time may be obtained from the continuity and momentum equations. These were formulated (including the chemical reactions of dissociation, recombination and ozone photolysis) for a rotating spherical coordinate system (r, A, cp) (radial distance, longitude, latitude). We use the continuity equation for the ith sort of particles (the index i refers to 0 or 02):
an, ,=qi-I+(r%) ----&+oscp)
2
(1)
where n, is the density of the ith component, qi and 4 are production and loss velocities, 4 is the vertical flow due to molecular difhrsion and turbulent transport, IJ is the meridional component of wind velocity. A detailed description of these equations has been @en by KLIMov and Su-rvm~ (1974a, b). Horizontal molecular and eddy diffusion have not been included in the divergence term of the continuity equations which include only vertical molecular and eddy difIusion and meridional transport. The influence of vertical macroscopic movement on the atmospheric composition has been studied by KOSHELEV (1976). The transport velocity u of the atmosphere was obtained from the momentum and conductivity
* Presented at the 1977 IAGA/IAMAP General Scientitic Assembly session JS-U-‘Recent Advances in Neutral and Ionospheric
TION OF TED3 PROBLEM
Models in the Thermosphere’.
447
448
N. N. KLIMOV
and N. A. SUTYRIN
equations
f3V
;JxB,+V
-g+2wxv=g+
(k7’&)
(2)
(3) where w is the angular rate of the Earth rotation, p is the density, g is the gravity acceleration, B, is the geomagnetic field, n, is the density of ith component, ii is the plasma conductivity tensor, T is the temperature, E is the magnetospheric convection electric field which is taken for this model from the paper of V~LLAND (1975).
when the velocity of the vertical motion of the atmosphere changes. Experimental data on atmospheric temperature are fairly well reffected in the JACCHIA (1971) model. Here we will not consider the equation of heat balance but we shall use the temperature from the JACCHIA model. For the quiet and moderately disturbed geomagnetic conditions in question the above effects of the temperature change have apparently rather thorou~y been taken into account in the empirical model.
where
Thus the problem reduced to the solution for four equations: two continuity equations of the form (1) for 0 and O2 and two equations which are projections of vector equation (2) onto directions A and cp with account of (3) and (4). The Nz density was obtained as functions of time, aititude and latitude from the atmospheric models of GROVES (1970) and JACCHIA (1971). The eiec-
L = rl(a cos’tp); Lo = 8.547 (for cp at the iatitude 70” on the Earth’s surface; a is the E%uth’s radius). In equation (2) the non-linear term and viscosity terms were neglected. When the atmosphere participates in additional convection motion, the value of Joule heating must cha&ge. In addition, the temperature of the atmosphere changes due to the adiabatic process
coefficient was assumed equal to 10’ cm* se-’ and calcuiations were made for three values of the electric field El = 0.5 mV/m, I mV/m and 0. The system of equations was solved numerically by the finite difference method for the latitude interval 80”S-80”N with Aq = 5”, Ar = 5 km, and AA = 15”. The approximations and the method of solution have been described by SUTYRIN (1973). The boundary condition at the 60 km level for the 0 concentration was zero, and the value for the 02
E=-9@,=
-$_--
1
aQt -- CY#
rcosqaah’
rarp
(4)
tron density was taken from the paper of DVINSKIKH and IVANOV (1971). The eddy diffusion
I
106
‘3O”N
40’
0”
-_._.L__“. 4OQ
i.-
.-j
EW’3
Fig. 1. Latitude variations of oxygen concentration at 95 km and 120 km. The curves with the circles are for solstice conditions and the ones without the circles are fbr equinox. Ihe broken curves are with the external electric field and the solid curves&or zero electric field.
449
The influence of magnetospheric electric fields on the distribution of oxygen density was taken from GROVES (1970). boundary condition used at the 160 km level the condition that the vertical flux is equal to in the infinity in the same manner as STROBEL MCELROY (1970 and SHMAZAKI (1972):
The was zero and
loo t qId
70-s 120 km \\
50-
E
@,(Z=m)=O where the integral is taken from the upper boundary, Zm.
0
4
I 8
I 12
I 16
I 20
24
LST
REsIJLTY5ANDDiscusIoN The change of the wind magnitude and direction caused by insertion into (3) of an external electric field, redistributes atmospheric constituent densities for which continuity equations are solved. The external electric field also changes the kinetic energy of horizontal motion of the atmosphere. As shown by estimations made in this paper, the energy of the summer hemisphere changes approximately for 24 h by 3-1022erg. In the formulation of the problem stated above the effect of meridional transport only has been singled out, although other components of the neutral wind (the zonal and the vertical ones) can influence the change of atmospheric composition.
104
106
Fig. 2. The daily variations of the meridional component of the wind at 120 km altitude and 70”s latitude. The types of curve are as described for Fig. 1. The latitude distributions of atomic oxygen density at two altitudes (95 and 120 km) are presented in Fig. 1. The case when the electric field is zero, is shown by solid lines, and broken lines are used when the electric field is not zero. Both curves with the circles are computed for the December solstice conditions and the ones without the circles are for the equinox. For the equinox case the curves are symmetrical about the equator and are thus only shown for northern latitudes. It is seen that the electric field has most influence on the
II 0
IO.8 LQ ni,
II 2
cm-3
Fig. 3. The altitude profiles of [0] and [OJ at 70% for 1200 WI. The types of curve are as described for Fig. 1.
450
N. N. KLMOVand N. A. SLWRIN
Fig. 4. The altitude profiles at 6CE3 for the three times. “Be broken curves are with the external ekc&ictWdandthesoiiicurvesforzeroeiectric6eld.-and-for4h,--0-and-0-for l2h,-O---andandffor20h.
atomic oxygen density at high latitudes in the summer hemisphere. For 120 km altitude and 70”s latitude the density decreases by a factor of 1.5 and for the equinox case it is 1.2 times less. This may be explained by the fact that the largest changes in the horizontal velocity occur at high latitudes in the summer hemisphere under the influence of the electric field (Fig. 2). The external field influence in the winter hemisphere might be larger if a more exact ionospheric model than that given in the paper of DVINSKIKHand IVANOV (1971) had been used for the determinative of the ~ndu~ti~ty. The altitude profiles of the atomic oxygen density for 12 h LT and 70% are presented in Fig. 3. It is seen that the density decreases for all altitudes under the action of the external electric field. The atomic oxygen density progles for 4, 12 and 20 h LT at 60% latitude for the solstice condition are presented in Fig. 4. It will be seen that daily variations appear at altitudes higher than 100 km. At 120-130 km altitude the atomic oxygen density changes during the day by approximately a factor of 2. For solstice conditions at 50-70” latitudes the decrease is largest during the day and morning and decreases at night as shown in Fig. 5. This explains the experimental data which shows changes in composition observed in the daytime hours mentioned by RISHBETH (1968).
We conclude that the external magnetospheric convection electric field leads to considerable variations in the neutral component concentrations in the upper atmosphere-the diurnal variations increase and the altitude and latitude distributions change, especially at high latitudes.
iST
Fig. 5. Tbe daily variations of the oxygen con~n~atio~s at 14Okm for di&ent latitude8 for soWiCe. The broken curve are with the e&em& ebMxic fieid avhe solid curves for zero &ctrk field. - and -@-- for 503, -0-and --CL- for 60’S, --- and - for 70%
The influenceof magnetosphericelectric fields on tbe distributionof oxygen
BLUM P. W. and HARRIS I. CREEXMORES. P., Smus J. M., HARRIS P. M., CHmo B. K. and CHIUY. T. DICXINSONR. E., RIDLEY E. C. and ROBLER. G. DVINSKIKHR. H. and IVANOVK. G. JOHNSON F. S. KLIMOVN. N. and SUWRINN. A. KUMOVN. N. and SUTYRIN N. A. KOSHELEV V. V. MAYR H. G. and Vow H. Raes D. RIWBEIWH. SHIMAUKIT. Snuus J. M., CIWEKMORE S. P., HARFUS R. M., CfilNGB. k. and CHIUY. T. STROBELD. F. and MCELROY M. B. SUTYRIN N. A. VOLL.AND H. VOLLANDH. and MAYR H. G.
1975 1975
J. afmos. Phys. 37, 193. .l. atmos. ten. Phys. 37, 491.
1975 1971 1973 1974a 1974b 1976 1972 1971 1968 1972 1975
J. atmos. terr.Phys. 37, 1737. Z&d. Gemnagn. Acmnom. Fiz. Solntsa 19, 112. Pkznet. space sci. 2% 1001. J. atmos. ten. Phys. 36, 1863. Z&d. Geomagn. Aerrmom. Fiz. Solntsa 32, 14 J. atmos. #en. Phys. 38, 991. Planet. Space Sci. 20, 379. J. Br. interplanct.Sot. 24,223. Rev. Geophys. 6, 33-71. Radio Sci. 7,695. J. atmos. urr. Phys. 37, 1245.
1970 1973 1975 1973
Plane?. Space Sci. 18, 1181. Z&d. Geomagn. Acnnwm. Fiz. Sofntsa. 28, 56. Annls Geophys. 31, 154. Annls Gtophys. 29,61.
1970 1971 1976
AE.RL.-70-0261 No. 218. SAO Spec. Rep. No. 332. Aerospace Rep. No. ATR-76(8203)-4.
Refermcc is also made to following unpublished material: GROVESG. V. JAM L. G. STRAUS J. M. and !5cxw~m
451