Pe gamon
Ad . Space Res. Vol. 21, No. 6, pp. 831-834, 1998
01998 COSPAR. Published by Else ie Science L d. All igh s ese ed
P in ed in G ea B i ain
0273-I 177198 $19.00+ 0.00
PII: SO273-1177(97)00683-2
A SEARCH FOR EVIDENCE OF TIDAL ACTIVITY IN
OH(3,l) AIRGLOW OMISSIONS RECORDED AT
MAYNOOTH (53.23” N, 6.35” W>
F. J. Mulligan and J. J. Nallen
Depa men o Expe imen al Physics, S . Pa ick’s College, Maynoo h, Co. Kilda e,
I eland
ABSTRACT
S
a.
a o he Meinel hyd oxyl emissions in he wa elen~~ ange LO-l.6 pm, which o gy a
i des close o he mesopause, ha e been ob ained, using a Fou ie ans o m spec ome e a
Maynoo h (53.23°N, 6.35*W), I eland, on all sui able nigh s du ing he pe iod Decembe 1992 o July
1995. Ro a ional empe a u es and in eg a ed band in ensi ies ha e been calcula ed om he spec a o
he OH (3, 1) ib a ional band. These da a ha e been analysed o e idence o idal ac i i y. Ou
esul s show a pos sunse inc ease in he emission b igh ness h oughou he yea ; o e 70% o he
ime his is &owed by a decline o a midnigh ~~, a e which he emission a e eco e s o a
seconda y maximum in he ea ly mo ning. The mon hs o Sep embe and Oc obe show a co n le ely
di e en pa e n wi h he in ensi y and empe a u e da a showing a p~mid~gh maximum o E
owed
by a s eady decline un il dawn. A c oss-co ela ion o he in ensi y and empe a u e da a e eals a
pe iodic a ia ion wi h a pe iod in he ange 8-12 hou s o all mon hs.
INTRODUCTION 01998 COSPAR. Published by Else ie Science L d.
I is now well known ha a mos
he abso p ion o sola ul a io b
he& ides a e he esul o he mal o cing, due in la ge measu e o
adia ion by wa e apou in he oposphe e and abso p ion o
ex eme ul a iole by ozone nea he s a opause and lowe mesosphe e, in con as o ocean ides
which a e he esul o g a i a ional o cing (Lindzen, 1990). These ides a e esponsible o
anspo ing ene gy upwa ds o he uppe mesosphe e and he mosphe e whe e he wa es b eak and
dissipa e hei ene gy. bond-be obse a ions o ai glow emissions ha e long been used o s udy
empe a u e and densi y a ia ions p oduced by a mosphe ic ides (e.g., Pe i didie and Tei elbaum
1977; Takahashi e aL, 1984; My a& and Ha ang, 1988 and e e ences he ein), e en hough hese
measu emen s can be ad e sely a ec ed by he p esence o hin clouds (Lowe and Tu nbull, 1995).
The emissions o a omic and molecula oxygen (557.7 mu, and He&e g bands), sodium and hyd oxyl
(Meinel bands) am among he mos equen ly used o his pu pose. Ai glow luc ua ions a e due
mainly o ~~~a io~ in he numbe densi ies o he species ha eac o p oduce exci ed s a es.
Tempe ahue luc ua ions a e also impo an in pa because he eac ion a es depend on empe a u e.
In h s s udy we use a ia ions in ai glow b igh ness eco ded in I eland in he pe iod om Decembe
1992 un il July 1995 o examine he in luence o a mosphe ic ides on he concen a ion o
achy exci ed OH species.
OBSERVATIONS
Good quali y in a ed spec a in he ange 1.0 -1.6 pm we e acqui ed wi h a Bomem FTIR in a ed
spec ome e on 370 nigh s in he pe iod Decembe 1992 o July 1995 a Maynoo h (53_23*N,
6.35*W), I eland. Sample spec a o he OH(3,l) and OH(4,2) bands eco ded by he speo ome e
a e shown by Mulligan e d. (1995). In his s udy, he PI(~), PI(~) and P (4) lines o he OH{3, 1)
band we e used o de e mine a o a ional empe a u e and he in eg a ed b igh ness o he en i e band
831
832 F. .I. Mulligan and J. J. Nallen
ollowing he me hod ou lined by Si jee and Hamwey (1987). Each in eg a ion pe iod was o 5
minu es du a ion. The mean alue o empe a u e and in ensi y we e de e mined o each nigh , aking
in o accoun he unce ain y on each indi idual measu emen . All o he measu emen s o a pa icula
nigh we e hen no mal&d o he mean o ha nigh and we e binned in o hal -hou ly in e als
a e aged o e an en i e mon h in an e o o educe he e ec o luc ua ions caused by g a i y-wa e
and o he plane a y scale dis u bances. Figu e la shows he mon hly a e aged noc u nal a ia ion in
b igh ness o he 0H(3, 1) band a hal -hou ly in e als o Decembe 1992. Suppo ing e idence is
a ailable in he o m o he co esponding a ia ion in he o a ional empe a u e de i ed om his
band. A subs an ial inc ease in in ensi y occu s sho ly a e sunse and is ollowed by a s eady
dec ease o a minimum nea midnigh . The b igh ness o he band hen eco e s o i s mean alue
o e he nex ou hou s, a e which i begins o decay again be o e sun ise. Da a o all mon hs show
an inc ease in he in ensi y o he band immedia ely a e sunse and is hough o be due mainly o
inc easing concen a ions o ozone in he absence o pho olysis. A nigh , in he absence o pho olysis
o Oz and HzO, odd oxygen and odd hyd ogen mus dec ease, gi ing ise o a s eady dec ease o OH
emission du ing he nigh as equen ly obse ed (Ba ane and Mpez-Mo eno, 1979).
1.8 1.08
1.6 1.06
1.4 1.04
1.2 1.02
1.0 1.00
0.8 0.98
0.6 0.96
#~l,#,l~## III
20 24 28
Uni e sal Time (hou s)
Fig. la. Noc u nal in ensi y and empe a u e
a ia ions nonnalised o mean alue o
Decembe 1992. Sunse occu s sho ly
a e 16 UT o e he en i e mon h.
1.8 ’ ’ ’ ’ ’ ’ ’ ’ ’ 1 1 ’ ’ 1 ’ 1.08
1.6 0 In ensi y
1.4 Oo l Tempe a u e l-O6
1.04
1.2 l-02
1.0 p “,p~cb”o, 1 . .
0.8 W
0.6 El 11 111 I I I I1 I I I cj
20 24 28
Uni e sal Time (hou s)
Fig. lb. Noc u naJ in ensi y and empe a u e
a ia ions no malised o mean alue o
Oc obe 1993. Sunse imes: 18.8 UT a he
beginning o he mon h; 17 UT a he end.
The e is a ai ly ob ious sinusoid p esen in he empe a u e da a, wi h a minimum a ound 2130 UT
and a maximum nea 0200 UT. This a ia ion wi h local ime has been epo ed by se e al obse e s
in he pas , e.g., Pe i didie and Tei elbaum (1977) and Lowe (1995). The in ensi y da a shows a
simila sinusoid wi h a phase lag o abou 2 hou s, bu i appea s o be supe imposed on a decline.
This is simila o he diu nal a ia ion epo ed by Takahashi e al. (1977) in 0H(8, 3) emissions
eco ded a 23OS, in which he mos equen ly obse ed in ensi y a ia ion was a midnigh minimum.
The ampli ude o ou OH in ensi y a ia ions is much g ea e (a ac o o be ween 6 and 8 being
ypical) han he empe a u e changes in ou da a.
This gene al pa e n o a midnigh minimum ollowed by an inc ease in he pos -midnigh pe iod in
bo h in ensi y and empe a u e da a is main ained du ing he mon hs Janua y o May. The sho leng h
o he da a eco d o June and July make i di icul o disce n any pa icula pa e n, bu he da a end
o show an inc ease in in ensi y ollowing midnigh . Densi y and empe a u e pe u ba ions
(Talcahashi e al., 1977) and a ia ions in eddy di usion (Mo eels e al., 1977), esul ing om odal
wa e ene gy inpu , ha e been ad anced as possible explana ions o he inc ease in OH b igh ness
ollowing midnigh . F om Augus onwa ds a new pa e n eme ges which has i s maximum
de elopmen in Oc obe . Figu e lb shows he co esponding in ensi y and empe a u e a ia ions o
Oc obe 1993: he phase o he sinusoid-like in ensi y a ia ion has changed om i s Decembe alue
so ha he maximum now occu s nea 2300 wi h he minimum appea ing a e 0400 UT. The
empe a u e a ia ion has also unde gone a phase shi and is now app oxima ely in-phase wi h he
in ensi y a ia ion. Da a o No embe shows a eco e y owa ds he pa e n shown in Figu e la and
A Sea ch o Tidal Ac i i y in OH(3, I) Ai glow Emissions 833
by Decembe he pa e n has e-es ablished i sel comple ely. This gene al end in he annual
beha iou o he diu nal a ia ion is main ained h oughou he pe iod unde s udy he e.
ANALYSLS AND DLSCUSSION
LoWe (1995) compa ed mon hly a e aged o a ional empe a u es de i ed om OH emissions, simila
o hose n ed in his pape , wi h he al i ude o peak emission o he OH laye ob ained om da a
mco ded by he WINDII ins umen onboa d he UARS sa elli e. His esul s consis en ly showed ha
a dec ease in empe a u e coincided wi h an inc ease in he heigh o he peak o he OH laye ; a lkm
change in he peak heigh co~~nd~ app o~a~ly o a ~ n~m ~ change o 9K. Lowe
in e p e ed hese esul s as being sugges i e o a aising and lowe ing o he heigh o he OH laye in
esponse o idal o cing. Lowe e al. (1995) ha e shown ha he decay o he hyd oxyl a e sunse
occu s as a he bo om side o he a omic oxygen p o ile, and p og esses upwa d in al i ude. This
esul s in an inc ease in he mean emission al i ude o he OH, and a co esponding change in he
empe a u e de i ed om he OH acco ding o he shape o he empe a u e p o ile. One migh
he e o e expec adiance changes associa ed wi h he ~s - augh decay o OH o co ela e wi h
empe a u e changes acco ding o he empe a u e g adien in he icini y o he mesopause. The
Oc obe da a p esen ed in Figu e lb shows a apid ise in empe a u e a he end o he nigh ha is
no accompanied by any inc ease in adiance, despi e he ac ha he adiance and empe a u e
luc ua ions a e in phase nea mid-nigh . This empe a u e ise may be he esul o he mean OH
emission heigh mo ing h ough a minimum ha is loca ed a a lowe al i ude in Oc obe han in
Decembe . Shephe d e al. (1995) ound a simila co espondence be ween he O(Q) 557.7 nm
ai glow emission a e and he mean heigh o he emission laye a he geog aphic equa o om
WINDII da a. The s ong dependence on local ime led Shephe d e al. (1995) o conclude ha he
e ec is idally d i en.
We ha e employed he c oss-co ela ion echnique desc ibed by Si jee e al. (1987) in an e o o
iden i y pe iodic a ia ions ha am p esen in bo h he in ensi y and empe a u e da a o each mon h.
Figu es 2a is a plo o he squa e o he ampli ude o he c oss-spec al densi y as a unc ion o
equency o Decembe 1992. A la ge peak is p esen a a equency o 0.1 pe hou co esponding o
a lo-hou pe iod. The co esponding plo o Oc obe 1993 shown in Figu e 2b also shows a
do n~~ peak a a pe iod comme~a~ wi h a semidiumal ide, bu he limi ed leng h o he da ase
p ecludes he iden i ica ion o he ac ual pe iod. These plo s a e ypical o he esul s o he c oss-
co ela ion analysis o all mon hs.
I1 I , I I I,
QlOL’ “““E”“:
Decembe 1992-
$
Oc obe 1993 -
0.0 0.5 1.0
F equency (l/H .)
Fig. 2a. ‘Ihe squa e o he ampli ude o he
c oss-spec al densi y e sus equency o
Decembe 1992.
40-, , , , , ,,,I-
0.0 0.5 1.0
F equency (l/H .)
Fig. 2b. The squa e o he ampli ude o he
c oss-spec al densi y e sus equency o
Oc obe 1993.
K asso sky’s a io, TQ, de ined as, (~/~)/(AT ~), whe e i and y ep esen he mean alue o
in ensi y and empe a une espec i ely and N and AZ’ ep esen de ia ions om he mean, p o ides a
quan i a i e measu e o he e ec o ides and g a i y wa es on OH nigh glow. We ha e calcula ed
834 F. I. Mulligan and J. J. Nallen
alues o lie o ou mon hs cen ed on he win e sols ice, and in ail cases alues a e in he ange 6-
10, while he phase angle showed no appa en end. These esul s a e in easonable ag eemen wi h
alues epo ed by Vie eck and Deeh (1989) o g a i y wa es wi h pe iods o he o & o 12 houm.
Wal e scheid and Schube (1995) ha e de e mined alues o ?jE o a sui e o idal modes and o
a elling plane a y wa es by applying he heo y o idally d i en luc ua ions in he OH ai glow,
gene al&d o accoun o emission om an ex ended laye , o ai glow luc ua ions due o bo h
mig a ing and zonaliy symme ic ides and ee a elling plane a y (Rossby) wa es. Thei
calcula ions sugges ha he a ia ions obse ed a Maynoo h a e he esul o zonally symme ic ides
wi h pe iods o 12 hou s o less.
In conclusion, ou s udy o he OH(3, 1) da a has shown ha (1) mon hly a e aged alues o he
in eg a ed band b igh ness a hal -hou ly in e als show pe iodic a ia ions wi h pe iods in he ange
8-12 hou s which sugges ha he sou ce o hese a ia ions may be idal in o igin; (2) he
p edominan pa e n is a pos -sunse inc ease in in ensi y ollowed by a dec ease o a midnigh
minimum, a e which a eco e y o a seconda y maximum occu s in he ea ly mo ning; (3) o a ional
empe a u es calcula ed om his band show simila a ia ions wi h a phase lead o 1-2 hou s o e
in ensi y a ia ions du ing mos mon hs; (4) he pa e n o Sep embe and Oc obe shows a p e-
b igh m~um in in ensi y ollowed by a s eady decline ollowing midnigh : ~ n~ a~~ and
in ensi y a ia ions appea o be m-phase du ing hese mon hs, (5) he pa e n is epea ed on an annual
cycle basis o e he pe iod o his s udy; (6) he ampli ude o he in ensi y a ia ions is consis en ly 6-
8 imes la ge han he empe a u e a ia ions.
ACKNO-EMENTS
This eseamb was suppo ed by Fo bai , he I ish Science and Technology agency unde g an s SCkW141 and X/94/231.
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