Oct 20, 1994 - atmosphere during the extremely strong solar proton events (SPE) of October 1989 ... electric field strength of 12 V/m was detected in the lower ...
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 99, NO. D10, PAGES 21,059-21,069, OCTOBER 20, 1994
Middle atmosphereresponseto the solar proton eventsof October 1989 using the results of rocket measurements A.M. Zadorozlmy,V. N. Kikhtenko,G. A. Kokin,2G. A. Tuchkov, A. A. Tyutin, A. F. Chizhov,2and O. V. Shtirkov2 Abstract. The resultsof rocket measurementsof ozoneand nitric oxide concentrations,vertical
componentof the electricfield strength,positiveion density,and temperatureof the middle atmosphere duringthe extremelystrongsolarprotonevents(SPE) of October1989 are presented. The measurements weretakenin the southernhemispherein the Indian Ocean(40ø60øSand45ø-75øE)on boardthe researchvesselAkadernikShirshov.A greatincreasein ion densitiesabove-30 km and nitric oxideconcentrations above-40 km with maximum [NO]
-2x109 cm'3 at•45-to55-km heights were observed during theSPE. A decrease inozone concentrations above-3 5 km with the maximumdecreaseof about20-25% at-50-kin height andcoolingof the atmosphere at -40- to 60-km heightswith the maximumtemperaturedecrease of about14øKnear 50 km werealsoobserved. An unexpectedly largevalueof the vertical electricfield strengthof 12 V/m wasdetectedin the lowermesosphere at about58 km at 58ø30'S duringthe SPE. The obtainedresultson ozone,nitric oxide,ion concentration, and temperature qualitativelyagreewith the existingphotochemical concepts on the impactof solarprotonevents
on the middleatmosphere, whilethe measured coolingof the stratopause is greaterthanthat predictedby theoreticalmodels.The increaseof the verticalelectricfield strengthobserved duringthe SPEpointsouta veryhigh electricalactivityof the mesosphere andunknown generationmechanisms of electricalphenomena in the middleatmosphere. Introduction
The theoreticalmodelsalsopredicta temperature decrease in
the stratopause regionduringSPEthrougha decrease in [03]
An ozone decrease in the upper stratosphereand the [e.g., Reaganet al., 1981; Dyominovet al., 1989; Reid and mesosphere duringsolarprotonevents(SPEs) was observedby Solomon, 1991]. Unfortunately, there were not enough Weekset al. [1972], in a singlerocketexperimenton November experimental datato commenton this decrease duringeventhe 1969. Similar results were obtained from satellite measurements strongestSPE of August1972. on Januaryand September1971, August 1972, Juneand August The first in situ measurementsof solar proton event 1979,October1981, andJulyandDecember1982 [Heathet al., modificationof the middle atmosphericelectric fields were 1977;Reaganet al., 1981;McPeters et al., 1981; Thomaset al., madein the stratosphere at high latitudesduringthe SPE of 1983; Maeda et al., 1984; McPeters and Jackman, 1985]. August1972by Ho!zworthandMozer [1979].The 1 orderof Accordingto modemphotochemical modelsa decreasein ozone magnitude decrease of the verticalcomponent of the electric duringSPEsresultsfrom an increasein nitrogenand hydrogen fieldstrength at 30-kmheightwasobserved simultaneously with constituents formed by particlesbombardingthe atmosphere boththe increaseof a solarprotonflux measured by Explorer41 [e.g., Crutzenet al., 1975; Dyominovand Zadorozhny,1980; and the radiation intensitymeasuredby balloon-borneX ray Jackmanet al., 1980, 1989; Ruschet al., 1981; Solomonet al., detectors, i.e., simultaneously with the increasein stratospheric 1981; Dyominovet al., 1989; Zadorozhnyet al., 1989a;Reid
conductivity. Anotherobservation of how solarprotonevents and Solomon,1991]. The nitric oxide increasebringsabout affect the electricalstructureof the stratosphereshowedan long-termchangesin ozoneconcentration, while the increaseof increasein both conductivityand the vertical electric field the hydrogenconstituentsresults in only short-term(about strength at-26kmwithinthepolarcapregionduringtheSPEof several hours)variations of [03] in themesosphere. Theonly February1984[Holzworth et al., 1987].Theelectricfieldsin the direct experimentalevidenceof the nitric oxide increasein the mesosphere duringthe solarprotoneventshavestill not been middle atmosphereduring SPE remains in the increaseof measured. backscattered sunlightin ¾bandsof NO, that was observedby In this paper, the results are given of the first in situ Nimbus7 afteran SPEof July 13, 1982 [McPeters,1986].This simultaneous rocket measurements of ozone and nitric oxide observation enabled an increase in the total column of nitric
oxideabove-50 km in the southern(winter)hemisphere to be deœmed.
concentrations, temperature,ion density, and the vertical componentof the electric field strengthin the middle atmosphereduring the strong SPE of October 1989. The measurements werecarriedoutduringthe 46th expeditionof the
•Novosibirsk StateUniversity, Novosibirsk, Russia. former Soviet scientific research vessel Akademik Shirshov at 2Central Aerological Observatory, Dolgoprudny, MoscowOblast, southernlatitudesof the Indian Ocean.Somepreliminaryresults Russia. Copyright1994 by the AmericanGeophysical Union. Papernumber93JD03194. 0148-0227/94/93
JD-03194505.00
of thesemeasurements are givenby Zadorozhnyet al. [1992a]. The lower ionosphere'saspects of nitric oxide variations observed duringthisexpeditionaswell as couplingof measured electricalparameters of the middleatmosphere and aerosolsare discussed in otherpapers[Zadorozhnyet al., 1992b,c, 1994].
21,059
21,060
ZADOROZHNY
ET AL.: SOLAR PROTONS
AND THE MIDDLE
ATMOSPHERE
October 19, at about 1300 UT [National Oceanic and Atmospheric Administration/National Geophysical Data Center The measurementsof ozone and nitric oxide concentrations, (NOAA/NGDC), 1989]. Other strongflares were registeredon temperature,ion density, and the vertical componentof the October22 and 24, 1989. In accordancewith GOES 7 satellite electricfield strengthwere carriedout by meansof instruments measurementsthe flares were accompaniedby a very strong installedin the toppart of the meteorological rocketM-100B. increasein fluxes of high-energyprotons(E = 4.2-850 MeV) Instruments
Vertical
and Methods
distribution
of
of Measurements
ozone
was
obtained
from
measurements of absorptionof solarultravioletradiationin the Hartley band [Bresginet al., 1980]. In the experiment,a twochannel ozonometerwas used with maximum sensibilityin spectralrangesof 260 and 300 nm. The bandof sensitivityfor each channelwas formedby meansof interferencefilters, an optical color glass,and vacuumphotocells.The accuracyof ozonemeasurementwith the given ozonometeris within 5-10% at altitudes of 30-50 km.
andelectrons (E > 2 MeV) whichwere observed until the endof October[NOAA/NGDC, 1989]. Figure 1 showsthe data from one of sevenGOES 7 protonflux channelswith energiesfrom 4.2 MeV to 8.7 MeV. The time dependencefor particleswith higherenergiesis similar to this one. On October20, 1989, the protonflux with maximummeasuredenergiesof 640-850 MeV
(andhence penetrated most deeply intotheatmos•phere) reached 2 s-1 ster-lMeV a peakvalue of5x10-3 particles cm-1. This
valueexceedsappreciablythe flux of analogous particlesduring Nitric oxide was measuredby meansof a photoionization the well-knownSPE of August 1972 [Reaganet al., 1981], the methodproposedby Pontanoand Hale [1970] and basedon strongest in the previoustwentiethandtwentyfirst solarcycles. selectiveionizationof NO moleculesby ultravioletradiation Geomagneticactivity was close to its typical long-term with the registration of ionsso created.In our sensor[Tuchkov average value(Kp near2) for thewholefirstpartof October and Zadorozhny,1988; Zadorozhnyand Tuchkov,1988], a 1989.Extremelystrongsolarflaresin the secondpart of October krypton resonantgas-filled lamp is used as a source of induceda very stronggeomagneticstormwith the SSC (sudden ultraviolet radiation, and a Gerdien condenseris used as a
storm commencement)on October 20, 1989, at 0917 UT,
collector ofNO+ ionsproduced. Theaccuracy of nitricoxide peakingwith Kp = 8+ on October20 near1800UT andon
measurement is about85% at heightsof 30-90 km. October21 near 1000 UT. Geomagneticactivity remainedto Temperature data were obtained with a resistance wire some extent disturbed until the second half of November thermometer usedas a standardmeasurement deviceby the net [NOAA/NGDC,1989]. of theRussianstationsfor theupperatmosphere rocketsounding Figure2 showsa heightprofileof the ion pair production rate [Kokinet al., 1969].More detaileddescriptions of the resistance P,.by protonsfor the maximumof protonflux at 1600 UT on thermometer, measurement technique,and the intercomparisonOctober20, 1989 [Zadorozhnyet al., 1992b], calculatedfrom with
other methods of rocket measurements of the middle
GOES 7 databy meansof the methoddescribedby Jackmanet atmosphere temperaturecan be foundin the works of Schmidlin al. [1980].The heightprofilesof the ion pair production rate by et al. [1980] andSchmidlin[1986]. galacticcosmicray at a latitudeof 70ø [Nicolet,1975] are also A sphericalgrid condenserwas usedto measurepositiveion shownin Figure 2 for the maximum and minimum of solar densityni [Kikhtenko,1978].The outergrid of the condenser is activity. Dashed curves in Figure 2 denote the ion pair held at rocketpotential,whereasa fixed negativevoltagebiases production ratesduringthe maximumsof protonfluxesof the the innergrid.This resultsin separationof positiveandnegative solarprotoneventsof August4, 1972, at 1508UT and2208 UT ionspenetratinginto the condenserwith an incomingflux of air. [Reaganet al., 1981]. One can see that in general,SPEs of The value of ni is calculatedfrom the positiveion current August 1972 and October1989 are comparablewith regardto collectedon the inner grid. The potentialdifferencebetweenthe their impact on the middle atmosphere.During these SPEs, grids ensures registration of the ions with mobilities similar valuesof P,. -(2-4) x104 cm-3 s-1 were observedat corresponding to massesup to aboutfew thousands of amu. The altitudesof-45-55 km, where in accordancewith calculations accuracyof the ion density measurements dependson the by Dyominovet al. [1989], the maximum changesin ozone conditions of the measurements and is about 30-50%.
10 • The vertical componentof the electric field strengthwas T,n• 0 T T,ni,E NOT T,n• measuredby means of an electric field mill probe [Tyutin, ß 1976].The electricfield mill operationis basedon principleof a • 10• rotationalcapacitor.Externalelectricfields inducethe chargeon m 10 • platesof the rotationalcapacitor.If the capacitoris loadedby a resistor,an alternatingcurrentis producedin a circuitwith the m 10 t frequencyof rotationof the capacitor.A currentamplitudeis proportionalto the componentof the external electric field, • lo which is perpendicularto the axis of rotationof the capacitor. Placementof the sensorin the payloadwas adjustedfor the -• 1 purposeof measuringa verticalcomponent of the electricfield p 4.2-8.7 MeV nø 10-• strength.The accuracyof the electricfield measurements in the nighttimedoesnot exceed-50%. A moredetaileddescription of I I I I I I I I I I I I I I I I 10 -2 the sphericalion trap and the electricfield mill with a special 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 50 ,31 emphasison a reality of rocketmeasurement of the atmospheric October 1989 electricfields can be foundin the paperof Zadorozhnyet al. Figure 1. Solarprotonflux (E = 4.2-8.7 MeV) for the second [19941. half of October 1989 accordingto GOES 7 satellite data Experiment Conditions [NOAA/NGDC, 1989]. Arrows indicate the time of rocket of ozone(O), nitric oxide (NO), temperature(T), In the secondhalf of October 1989 a seriesof strongsolar measurements flareswas observed,the strongestone (of 4B class)occurredon iondensity (ni),andvertical electric fields(E).
1I I I I I I I I I I I I I I I
_
ZADOROZHNY
ET AL.' SOLAR PROTONS AND •
isshown inFigure 3. Thisis-•(0.2-1)x105 cm -3 atheights of
9o
40-80 80
t-
Solarproton events:
'",,
I- 1. October20, 1989, 16:00UT
\
,,,. v
3. August 4, 1972,22:08UT galactic cosmicrays:
2"., - ",.• /
- 4. 70ø, maximum of solar activity
•./
- 5.70 ø,minimum ofsolar activity
3O 20
10
iIIiJ
i
10
•J •J i iiiiJ
i
i
10 •
i i illlJ
I
I
10 •
I i iiill
i
i
10 •
km.
The height profiles of ion densitymeasuredat middle latitudesof nearly40øS are shownin Figure 4. One can see a muchweakerbut still significantincreasein ion densityduring
,,'•
"'-.3./
L 2. August 4, 1972, 15:08 UT
•< 4o
21,061
limit of the rangeof ion densityvaluesmeasured by our ion trap
lOO
70
MIDDLE ATMOSPHE•
i I
10
Ion pair productionrate, cm-3s -•
SPE (launchon October26 (flight 19)) at heightsof about30-75 km. A much weaker enhancementof ion density observedat lower latitudes may have been due to the fact that the measurement on October26 (flight 19) was made at a latitude below the proton cutoff. Ground-basedmeasurementsof the radio wave absorptionin the lower ionospherecarried out in Central Europe at L shells close to those of the rocket measurementssuggestthat the ion density enhancementon October26 was causedby the SPE [Zadorozhnyet al., 1992b]. The ion densityis connectedwith the ion pair productionrate by the expression
Figure 2. The ion pair productionrates by protonsin the P,= assn, middleatmosphere for maximumsof solarprotonevents(SPEs) of October1989(solidcurve)andAugust1972 (dashedcurves). wherea,ff isaneffective recombination coefficient forpositive The galacticcosmicray productionratesare alsoshown. ions. In the stratosphereand the lower mesasphereat night,
therearenofreeelectrons anda,ff is aneffective coefficient of contentand temperatureare expected.Note that the ion pair productionrate by galacticcosmicrays(the main sourceof ions in the middleatmosphere below-•65 km underquiet conditions) is much lessat all heights.At an altitude of about 50 km the differenceis about5 ordersof the magnitude. During the expedition in the Indian Ocean, rocket measurements were carried out from August 26 until October 26, 1989, between 40øS and 60øS, 45øE and 73øE. The measurements
of ozone and nitric
oxide
concentrations
were
carriedout in the daytime,whereastemperature,ion density,and verticalelectricfield were measuredin the nighttime.The rocket launches carded out in October are listed in Table 1. The arrows
ion-ion recombination.
This coefficient can be determined either
by simultaneous P,. and ni measurements in the atmosphere [Braginet al., 1973; Goldberg, 1989; Zadorozhnyet al., 1993] or by ion-ion recombination kinetics measurementsin the laboratory[Smith and Adams, 1982]. In accordance with GOES 7 data during the launch on October21 (flight 15), the ion pair productionrate by solarprotonsat the heightof 50 km
was-•2.7x102 cm-3 s-1, whichis -•1.35x103 timesmorethan
0.2cm -3 s-1.Thelatter value isanionpairproduction ratefor undisturbedconditionsat 50o-60ø geomagnetic latitude under the high solaractivitycausedby galacticcosmicrays [Nicolet, 1975].It followsfrom (1) that
in Figure 1 indicate the rocket launcheswith payloadsfor measurements of ozone(O), nitric oxides(N), temperature(T),
(2)
positive iondensity (ni),andvertical electric field(E) duringthe SPE.
Measurement
Results and Discussion
During October 1989, six height profiles of ozone concentration, three profiles of nitric oxide concentration,nine profilesof temperature, five profilesof positiveion density,and three profiles of the vertical componentof the electric field strengthwere obtained (see Table 1). Some of these were
measured at middlelatitudes(40ø-46øS)and the othersat high middle latitudes from about 52øS to 59øS.
Ion Density
Figure3 showsthe heightprofilesof ion densitymeasuredat high middle latitudes (52ø-57øS) under quiet conditions (launcheson October12 (flight 9) and October18 (flight 12) (Table 1)) andduringSPE(launchon October21 (flight 15)). Althoughthe last measurements were carriedout after the main
maximumof protonflux hadoccurred (seeFigure1), an increase in ni by morethan 1 orderof magnitudewasdetectedabove-40 km onthe October21 flight.At 50-kmheightduringthe launch on October21 (flight 15), the ion densitywasapproximately 35 timesmorethanan undisturbed valueof ni . Note that the ion densityaboveabout 52 km during the flight on October21 (flight 15) was sogreatthat the ion trapwent off scale,and thus thereare no otherdata availablefor theseheights.The upper
Table 1. List of Rocket
Launches
Date, 1989
Time, UT
1 2 3
September11 October5 October5
2015 0420 1802
52o24' 43o25' 42o57'
4
October 9
1814
44o25 '
45o58 '
T
5 6 7 8 9 10
October11 October11 October12 October12 October12 October15
0430 0701 1405 1530 1830 1130
52o05' 52ø41' 57o08' 57o08' 57o09' 46o12'
44o58' 44o56' 45o03' 45o03' 45ø11' 44o53'
[03] [NO] [NO] [03] T, ni, Ez [03]
11
October 15
1836
46o09 '
45o05 '
T
12 13
October18 October20
1730 0430
52o35' 57o56'
45o53' 48o57'
T, ni [03]
14
October 20
2056
58o33 '
49o30 '
T
15 16
October21 October23
1931 0500
58o30' 55o37'
51ø11' 59ø11'
T, ni, Ez [NO]
17
October23
1240
54o54'
60o20'
[03]
18
October 23
1652
54o48 '
60o30 '
T
19
October26
1931
40o43'
73o10'
T, ni
Flight
Latitude, Longitude, Measured S E parameters
46o07' 48o25' 52o00'
T, E z [03] T, ni, Ez
21,062
ZADOROZHNY
ET AL.' SOLAR PROTONS AND THE MIDDLE
ATMOSPHERE
are shownin Figure 5, togetherwith nitric oxide concentrations observedon board Spacelab1 [Girard et al., 1988]. Rocket 52os_59øS Ocfober •2,
8g
---
Ocfober
8g
-
,........
October 21
89
_
Instrun:entai
limit
•8
!
.
on November 28 to December 8, 1983, at 60øS. Our NO
,,
50
-
40_
30_
I
20
10 •
I
I I IIIII
I
10 3
I
I I IIIIJ
I
10 4
Ion density, cm
launches on October11 (flight 6) andOctober12 (flight7) were performedat latitudesof 52øS and 57øS under almostquiet conditionsand the launch on October 23 (flight 16) was performed at 55.5øSduringthe SPE2.5 daysafterthemaximum of the solarprotonflux duringa secondary peak of the proton flux (Figure1). The Spacelab1 measurements were carriedout
I
I
I
IIII
10 •
-3
Figure 3. The positiveion densityprofilesmeasuredat higher middlelatitudesof 52.5ø-58.5øS [Zadorozhny et al., 1992b].The upperout-of-range limit of ion densityvaluesmeasuredby our ion trap is alsoshown.The ion trap was off scaleaboveabout52 km duringthe SPE flight on October21, 1989.
concentrations, exceptfor the flight duringthe SPE, agreefairly well with the Spacelab 1 measurementsand with rocket midlatitudinal[Barth, 1966; Tisone,1973] and high-latitudinal [Wittet al., 1976;Iwagamiand Ogawa, 1980] dataobtainedby measuringresonantlyscatteredsolarradiationin the • band of NO. However, they are considerablylarger than the NO concentrationsobtained in other similar experiments in moderatelatitudesat 75-90 km [e.g.,Meira, 1971;Baker et al., 1977; Iwagami and Ogawa, 1980]. The nitric oxide concentrations near the mesopausededucedfrom radio wave absorptionmeasurements [Lastovicka,1982] also agree fairly well with the presentdataobtainedunderquietconditions. The differencebetweenthe quiet [NO] profiles,measuredon October11 (flight 6) andOctober12 (flight 7) (seeFigure5), is
at leastpartlyan effectof the latitudinal.dependence of nitric oxideconcentration intensifiedby the large groundlevel solar particle event of September 29, 1989. Nitric oxide measurementscarried out in August to September 1989 at latitudesof about45ø-52øSfit approximately into the rangeof NO concentrations givenby the profilesobtainedon October11 and 12.
The height profile of the nitric oxide concentrationobtained on October23, 1989 (flight 16) duringthe SPE has a definite maximumat heightsof •45-55 km. The maximumconcentration
where the asteriskindicatesdisturbedparameters.Assuming
of NO is -•2x109cm-3, i.e., about50 timesmorethanthe
aef f to be constant duringthe disturbances produced by
concentration underquietconditions (Figure5). At theseheights
additionalionizationof the atmosphere, we obtainfrom (2) and GOES 7 solarprotondata that the ion densityincreaseduring the launchon October21(right 15) at 50 km was-37, whichis in goodagreementwith the measuredvalue. Let us estimate,startingfrom (1), the value of the effective
90
[
] ] ] i ill I
,
[ -]--f-.-ri,,
,
] [
recombination coefficient. Using a value of r/im3x104 cm -3 obtainedduringthe launchon October21 (flight 15) at 50 km
anda value of-2.7x102 cm -3 s-1 forP•.atthesame moment,
weobtain aef f • 3x10 -7cm 3 s-1.Theobtained value agrees well with otherestimations of aef f basedon atmospheric measurementsunder both quiet and disturbed conditions [Goldberg,1989], but it is approximately5 timesmorethanthe simplebinaryion-ionrecombinationcoefficientmeasuredin the laboratoryby Smith and Adams [1982]. This contradiction betweenatmospheric and laboratoryestimationsof the effective ion-ionrecombination coefficientin the upperstratosphere and the mesosphere appearsto be causedby heterogeneous lossof light ions on aerosolparticles [Chesworthand Hale, 1974; Mitchell, 1985;Goldberg,1989;Zadorozhnyet al., 1994]. Thus rather good correspondence of observedion density variationswith variationsof energeticprotonfluxesfrom GOES 7 satellitedata allows us to use calculatedion pair production rates(Figure2) to interpretotherexperimentalresults,suchas, first of all, nitric oxide data. Nitric
Oxide
40ø$-43øE October October
OS, 89 26, 89
-
4O _
_
i
20
10 2
i
i
i iiiii
i
10 3
i
i
i iiiii
i
lO 4
Ion density, cm
i
i
i i iii
lO s
-3
The resultsof our [NO] measurements carriedouton October Figure 4. Thepositiveiondensityprofilesmeasured at middle 11 (flight 6), October12 (flight 7), and October23 (flight 16) latitudesof 40ø-43øS[Zadorozhnyet al., 1992b].
ZADOROZHNY
lOO
i
90
!
i
i
i-•
I
!
;''• ,'
,'
, 70
./
J
i
i
i
i
I
i i I
i
i
i
,
i
/2•.....,.
".,
An increase of the total nitric oxide content above 50 km after
[ /
/
/
'•
f/' [NO]
the SPE of July 13, 1982 observedby McPeters [1986]_only in
thewinter hemisphere attained a value ofabout 1.3x1015cm-2
...... October11, 1989
at 55øS and is half the value obtained in our measurement.
........ October 12, 1989
/
f
21,063
sunlightconditionsin the upper mesaspherefrom the generally acceptedvalueof 1.2-1.6.
i
--
,',:"
