June 1989

T. Yasunari

NOTES
A Possible
Troposphere

Link

AND

483

CORRESPONDENCE

of the QBOs

and Sea Surface

Betweenthe Stratosphere,

Temperaturein the Tropics

By Tetsuzo Yasunari

Institute of Geoscience,Universityof Tsukuba,Ibaraki305, Japan(Mauscriptreceived15 November1988,in revisedform 14 April 1989)
Abstract
Some evidence is presented on the interaction of the QBOs between the stratospheric and thetropospheric zonal wind in the tropics. Zonal winds over some stations (Singapore, Koror, Ponape)in the equatorial Pacific clearly show the coherent vertical phase structure between the downward
propagation of zonal wind anomalies in the stratosphere and the zonal wind anomalies in the lower
and the upper troposphere. The QBOs in the tropospheric zonal wind are also proved to be coupledwith that in the SST anomalies in the equatorial Pacific.
These results suggest a possible dynamical link of the QBO in the large-scale coupled atmosphere/ocean system over the Asian monsoon region through the equatorial Pacific with that in theequatorial stratosphere.

1. Introduction
The quasi-biennial oscillation (QBO) in the tonal
wind is a predominant phenomenon in the tropical stratosphere. Lindzen and Holton (1968) andHolton and Lindzen (1972) presented a confirmative
theory of this oscillation.
On the other hand, many observations have suggested similar QBO-like oscillations in the troposphere (Trenberth, 1975;1980; Ebdon, 1975; Angell
and Korshover,1974; 1975;Gordon and Wells, 1975;
Yasunari, 1981 etc.). Some studies also focused on
the problem of the inter-relation of QBOs between
the troposphere in the mid latitudes and the stratosphere in the tropics (Trenberth, 1980;Gray, 1984).
However,there has been so far no certain evidenceof
coupling of the QBOs between the troposphere andstratosphere. Some theoretical studies presented asomewhat different mechanism of the tropospheric
QBO (Brier, 1978; Nicholls, 1978).
The previous studies on the coupling of the QBOs
have dealt with the correlation of some specific parameters in the higher-latitude troposphere and the
QBO in the tropical stratosphere. The present
study, however, will present some evidence of thein situ association of the QBOs between the strato©1989, MeteorologicalSociety of Japan

sphere and the troposphere in the tropics. This approach may be important, since the stratospheric
QBO is based on forcing in the tropical troposphere(Holton, 1972).
2. DataMonthly mean zonal winds at 850mb through
30mb over Singapore, Koror, Truk and Ponapefor 18 years (1964-1981) are adopted. Additionally, monthly mean zonal winds at 200mb and700mb (10*10*) from NMC operational windfield analysis for 18 years (1968-1985) were utilized.
Monthly mean sea surface temperatures (SST) for
173 months (Jan. 1964 to May 1978) were also
adopted, which were originally compiled by NOAA
(Reynolds, 1983).
3. Stratosphere-troposphere
coupling of
QBOs in the zonal winda. QBOs in the equatorial Pacific
Holton and Lindzen's theory on the QBO in thestratospheric zonal wind in the tropics assumes arandom forcing by wave energy of the eastwardmoving Kelvin waves and the westward-moving
Rossby-gravitywaves from the lower boundary (i.e.,from the troposphere), which interact with the zonal
mean flow in the stratosphere. However, the ac-

484

Journalof the MeteorologicalFig. 1. Frequency distribution of tonal wind
acceleration at 50mb over Singapore
which exceeds +5ms-1 month for eachmonth of year. Period for the statistics
23 years (1961-1983).

tual forcing by the wavesfor the stratospheric QBO
seems to have a strong seasonality. Fig. 1, for example, shows the frequency of westerly (easterly)
acceleration of the zonal wind at 50mb over Singapore that exceeds +5ms-1 month. The timings
of maximum westerly (or easterly) acceleration appear mostly during March through July. That is,
the upward wave-energypropagation from the lower
stratosphere through the upper troposphere apparently shows seasonal phase-locking, which suggests
the influence of the seasonal change of the wave energy activity in the troposphere on the stratospheric
QBO.
The dominant periodicities of zonal wind at eachlevel are examined from the stratosphere down to
the lower troposphere. Fig. 2 shows the results of
MEM (Maximum Entropy Method) power spectra
for 9 levels from 30mb through 850mb. At 30mb
and 50mb the QBO is shown as a single dominantpeak, while at the tropopause level (100mb) boththe QBO and the annual cycle (12-month period),show maximum power. In contrast, in the upper troposphere (150mb, 200mb and 300mb) the peaks
associated with the annual cycle (12-month and 6month period) predominantly appear. The peakwith a period range from 35 to 55 months also exists
as a dominant interannual mode, which is associatedwith the El Nino/Southern Oscillation (ENSO) cycle (Yasunari, 1987). It is interesting to note thatin the lower troposphere (700mb and 850mb) excepting the annual cycle the period with QBO timescale again appear as a dominant interannual mode.
Cross-spectral analysis was then applied to thezonal wind at 50mb and 700mb, to examine thecoherence of two QBOs in the stratosphere and in
the lower troposphere. Fig. 3 shows the coherence
spectra between the 50mb and 700mb zonal windSocietyof JapanVol. 67, No. 3

by using FFT cross-spectral analysis for the periodof 173 months (Jan. 1964-May 1978). High coherence values of more than 0.9 are noted in the QBO
period range. To see the phase relationships among
each level for the QBO mode, the time-height section of the filtered tonal wind anomalies is composed as shown in Fig. 4. The Butterworth recursive filter (M. Murakami, 1981) with the maximum
response of 22 to 32 months centered at 27 months
is adopted for the filtered series. This figure surprisingly shows a possibility of coupling of the QBO in
the stratospheric zonal wind with that in the troposphere. The downwardpropagation of the anomalies
in the stratosphere are well synchronized with the
upward propagation of anomalies at the tropopause
through the upper troposphere. In the troposphere,
the phase of anomalies show an upward propagationfrom the surface level to the upper troposphere, andthe easterly (westerly) anomalies in the upper levelare simultaneously coupled with the westerly (easterly) anomalies in the lower troposphere, which suggests the existence of the QBO mode in the largescale convective activity.
The non-existence of the QBO signal in the upper troposphere at Singapore may be, at least
partly, related to its location in the tonal structure of the tropospheric QBO. As shownin Yasunari(1985), the tropospheric QBO in the zonal wind
has a zonally-standing component with some quasistanding nodes, though it totally shows an eastward
propagation with a structure of zonal wavenumber
one and/or two. For example, Fig. 5 shows thelongitude-time section of the QBO mode in the tonal
wind at 200mb with easterly and westerly maxima at 700mb. This diagram shows that the timemean amplitude of this mode differs considerablyfrom place to place along the longitudes. Singapore
seems to be located near a node of this mode, orin the area of smaller amplitudes. In fact, the result of the MEM spectral analysis of zonal winds atthree stations (Koror; Truk; Ponape) in the equatorial western and central Pacific (Fig. 6) shows a verylarge power in the QBO mode (20-30 months) in theupper and the lower troposphere ,even compared to
the ENSO mode (40-60 months).
b. Phase structures in vertical-zonalplane
The QBO in the stratosphere has no zonal structure (i.e., the dominanceof wavenumberzero) whilethat in the troposphere has a tonal structure ofwavenumber one and/or two with the eastward
phase propagation as shown in Fig. 5. The featureof vertical coupling between these two QBOs should,
therefore, be different from place to place along theequatorial longitudes.
To examine the vertical phase structure of these
QBO modes along the equatorial Pacific, thevertical-timelag section of the correlations (from

June

1989

T. Yasunari

485

Fig. 2. MEM Power spectra of monthly mean zonal wind at each level (30mb through 850mb) over
Singapore for the period of 18 years (1963-1981). Units are ms-1 month. Maximum lag number of 40
is adopted.

lag=-13to+13 months) between the 700mb zonal
wind and that of each height level are composed forSingapore, Koror and Ponape, as shown in Fig. 7.
Although the band-pass filtered data were adopted
for this computation to see more clearly the phaserelation of the QBOs, the results from the low-passfiltered data containing the components of broader
frequency band show fundamentally the same correlation structures.
The vertical structure of Singapore in this diagram has confirmed the anomaly structure in Fig.
4. That is, the downward propagation of positive(negative) correlations are combined together withthe positive (negative) correlations in the upper troposphere. In the extreme phases, the zonal wind

anomalies in the lower troposphere are negatively
correlated with those in the upper troposphere, andpositively correlated with those at 50mb.
At Koror and Ponape, although the phase structures in the troposphere are nearly the same as thatat Singapore, the phase relations of the upper (orlower) troposphere to the stratosphere show the systematic time lags from the west (Singapore) to theeast (Ponape). This implies the systematic eastward
propagation of tropospheric QBO anomalies relative
to the stratospheric QBO, since the anomalies in thestratosphere change nearly simultaneously along thewhole equatorial belt.
If we take the phase of maximum correlation of,say, 30mb as a reference of simultaneity, the cor-

486

Journalof the Meteorologicalrelation patterns in the upper (and the lower) troposphere show a systematic phase change between
the maritime continent (Singapore) and the central/western Pacific (Koror and Ponape). Theyshow nearly the opposite signs to each other, whichindicates the Walker-type cell structure in the tonal
wind along the equatorial central/western Pacific.
These features in the tropospheric QBO are consistent with the results by Yasunari (1985, 1989), andGutzler and Harrison (1987). For example, when
the zonal wind at 50mb is changing from the east
to the west, that in the upper (lower) troposphere
over Singapore is nearly the maximum in the easterly (westerly), while that in the upper (lower) troposphere over Koror or Ponape is near the end of
the westerly (easterly) phase.
C. Phase lock to the annual cycle
As mentioned earlier (Fig. 1), the stratospheric
QBO shows a strong phase lock to the annual cycle.
The phase structure of the QBO in the stratospherethrough the troposphere may, if so, be more distinctly exhibited in the composites stratified for the
typical phase of the QBO cycle in the stratosphere.
Fig. 8, for example, shows the composite structure of the tonal wind anomalies for the 7 years(1966, 1969, 1971, 1973, 1975, 1978, 1980) overPonape when the QBO at 50mb changes from theeast to the west (Year-1) and the next years (Year2). The diagram of stratospheric zonal wind in
Maruyama (1988) is adopted for selection of theyears. This diagram clearly shows that the westerly
maximum in the stratosphere is phase-lockedto thewinter season, while the westerly (easterly) maxima
both in the upper and the lower troposphere arephase-locked to the summer through autumn season. Here, we should bear in mind that the seasonal
convectioncenter is located over South Asia throughSocietyof JapanVol. 67 , No. 3

the western Pacific in these seasons, and the westerly (easterly) maximum in the upper (lower) troposphere over this region is associated with the strong
convection over the convection center to the west.
Over Singapore, in contrast, the westerly (easterly)
maximum in the lower (upper) troposphere also appears in the winter season in phase with the westerly maximum in the stratosphere, as is easily deduced from Fig. 7. In other words, a strong winter monsoon over this region is in phase with thewesterly maximum in the lowerstratosphere. In thesummer of Year-2, in contrast, weak convection over
the Asian monsoon region is suggested by the tonal
wind anomalies in the troposphere. At this phaseFig. 3. Coherence
spectra of monthly mean
zonal wind between 50mb and 700mb over
Singapore.
Period of QBO time scale areshaded.

Fig. 4. Height-time section of filtered zonal wind (QBO mode) over Singapore. Units are 3ms-1 andnegative (easterly) anomalies are shaded.

June 1989

T. Yasunari487

Fig. 5. Longitude-time section of filtered tonal wind (QBO mode) at 200mb along the equatorial belt
(10*N-10*S). Units are 0.6 ms-1 and negative (easterly) anomalies are shaded. Phases of westerly(easterly) maxima of filtered zonal wind (QBO mode) at 700mb are also indicated with thick solid(dashed) lines.

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Journalof the MeteorologicalSocietyof JapanVol. 67, No. 2

Fig. 6. MEM power spectra of zonal wind at 700mb and 200mb over Koror (7.3*N, 134.5*E),Truk (7.5*N,
151.9*E) and Ponape (7.0*N, 158.2*E)for 18 years (1964-1981). The power of annual cycle and period
band with less than 6 months are filtered out of time series. Maximum lag number of 40 is adopted.
QBO time scale (20-30 month period) is shown in each diagram.

June 1989

T. Yasunari489

Fig. 7. Vertical-timelag section of correlation between zonal wind at 700mb and that of each level (850mb to 30mb) for Singapore, Koror and Ponape. The contour interval is 0.2 with positive contours
solid (negative contours dashed). Values above 0.6 (below -0.6) are hatched (dotted). The thin solidline at 100mb shows the approximate tropopause level.

the tonal wind in the lower stratosphere appears to
be a strong easterly, which was consistent with theformer finding by Mukherjee et al. (1985). These
results suggest some plausible role of seasonal con-vective activity from summer through winter over
the Asian monsoon region through the western Pacific on the QBO in the stratosphere. This aspect
will be discussed further later.

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Vol. 67, No. 3

Fig. 8. Vertical-time section of tonal wind anomalies over Ponape composited for 7 years when easterly
changes to westerly at 50mb (Year-1) and for the next years (Year-2). Contour interval is 5.0 ms-1 at
30mb and 50mb and 0.5 ms-1 below 100mb levels.

4. QBOs in the tropical troposphereand SST

The results deduced for the troposphere in theprevious section have proved to be part of the tropospheric QBO along the equatorial belt detectedby Yasunari (1985), Gutzler and Harrison (1987)
and Kawamura (1988). That is, in addition to the
ENSO mode (40-60 month period), the zonal windin the tropical troposphere has a component of transient east-west circulation with the QBO time-scale,
whichshows a totally eastward propagation (Fig. 5).
The eastward propagation seems to be partly due tothe seasonal migration of an anomalous wind in thewestern through the eastern Pacific (Meehi, 1987),
as has also been suggested here (Fig. 7 and Fig. 8).
This anomalous east-west circulation should be
associated with the anomalous convection, whichmay, in turn, be connected with the sea-surface temperature (SST) anomalies of the same time scalealong the equatorial Pacific. In fact, it was notedthat the SST anomalies along the equatorial Pacific have the QBO mode as well as the ENSO
mode (Rasmusson and Carpenter, 1982; Yoshino
and Kawamura, 1987). Fig. 9 shows the timelongitude section of the QBO mode in the SST along
the equatorial belt. In this diagram the phases ofwesterly and easterly maximum of the QBO in thezonal wind at 850mb and 50mb over Singapore arealso shown, to see whether both QBOs in the tropical atmosphere and that in the SST coherently fluctuate or not. The westerly (easterly) maxima at 700
mb for the period from 1968 to 1978 (Fig. 5) overthe eastern Pacific (180*-90*W) correspond well to
the SST maxima (minima) over there. Fundamentally the same feature has been noted by Kawamura(1988). Although the SST anomalies in the western

Pacific (100*-150*E)are small compared to the eastern Pacific, these are highly coherent with the zonal
wind anomalies at 850mb over Singapore. That is,
the maximum (minimum) SST appear just in theintermediate stage from the easterly (westerly) to
the westerly (easterly) maximum at 850mb. It isalso interesting to note that the westerly (easterly)
maxima at 50mb, for example, are nearly in phasewith the minimum (maximum) SST anomalies overthe central through the eastern Pacific through thewhole analysis period (1964-78), which is expectedfrom the vertical coupling of tonal winds as shownin Fig. 4.
These coherent phase relations between the SST
and the lower tropospheric zonal wind suggest that
the ENSO-likeatmosphere ocean coupling via convection do exist for the QBO mode over the equatorial Pacific. Very recently, the dynamical coupling of
the tropical east-west circulation and the SST with

the QBOtime 1/N
scalealongthe equatorialbelt has
beencomprehensively
discussed
byYasunari(1989).
5. Summary and discussion
Someevidencehas been presentedfor the couplingof the QBOin the stratosphericzonalwind
withthat in thetroposphericzonalwindin thetropics. In addition,this QBOin the tropospherehas
provedto be coupledwiththat ofthe SSTanomalies
in the equatorialPacific.The QBOsin the troposphericzonalwindandin theSSTsuggestan ENSOlikelarge-scaleatmosphere-ocean
couplingoverthe
equatorialPacific.The signalsof the QBOin zonal
windare predominantly
strong,evencomparedto
the ENSOsignals,over the Indonesianmaritime
continentthroughthe westernPacific.Other surfaceelementsoverthis region,suchas surfacewind

June 1989

T. Yasunari491

Fig. 9. Longitude-time section of filtered SST anomalies (QBO mode) along the equatorial belt (7 .5*N7.5*S). Units are 0.1* and negative anomalies are shaded. Phases of westerly (easterly) maxima offiltered of zonal wind (QBO mode) at 850mb over Singapore are shown with solid (dashed) lines.
Phases of westerly (easterly) maxima of zonal wind at 50mb are also plotted at the right-hand side ofthe diagram with capital letters of W (E).

stress (Kutsuwada, 1987) and rainfall (Yasunari,
1981: Yasunariand Suppiah, 1988)also show significantQBO in the interannualvariation.In otherwords,the coupleatmosphere/oceansystem in thetropicalPacificwith the QBOtime 1/N
scalecenteredin the western Pacific is suggested to be linked with
the QBO in the stratosphere.

As earlier mentioned, these QBOs are strongly
phase-locked to the seasonal cycle. As shown in
Meehl (1987) and Yasunari (1989), the internannual
anomalies in convection (rainfall) over Asian monsoon region through the tropical Pacific is strongly
phase-locked to the northern summer through thenorthern winter season, associated with the sea-

492

Journalof the Meteorologicalsonal migration of the convection center. It may be
postulated, therefore, that the stronger than normal convection over this region from the northernsummer to the winter season is closely related tothe downward phase shift of westerlies in the lower
stratosphere in the same seasons (Fig. 7) possibly
via the stronger than normal Kelvin wave energy.
Very recently, by using a simple one-dimensionalmodel, Tanaka and Yoshizawa (personal communication) has shown that the periodicity of the stratospheric QBO is well synchronized with that of thetropospheric forcing of zonal mean flow. Their results suggest that although the stratospheric QBO
may be undoubtedly interpreted as a typical wavemean flow interaction (Holton and Lindzen, 1972:
Lindzen, 1987), the tropospheric QBO may act asa pacemaker or frequency-modulator of the stratospheric QBO.
Another possibility may be that the QBO in thestratosphere modulates convective activity in the
troposphere via some unknown mechanism. It isinteresting to note in Fig. 8 that the troposphericzonal wind anomalies (associated with the convection anomalies over the maritime continent) seems
to change their signs when the westerlies in thestratosphere reach the tropopause level. In all
events, the strong seasonal phase-lock of both thezonal wind acceleration in the stratosphere and theconvection anomaly, particularly over the maritime
continent, may provide some clue to the solution ofthese problems. Further observational and theoretical studies are apparently needed.
Acknowledgements
I would like to express hearty thanks to Prof. T.N.
Krishnamurti of Florida State University for providing me most of the data for the present study.
Thanks are due to Dr. T.Y. Maruyama, Meteorological Research Institute, for providing me with someaerological data on the stratosphere. This work waspartly sponsored by the Grant-in-Aid for Scientific
Research, the Ministry of Education, Science andCulture 59540236and 62540298.
References
Angell, J.K. and J. Korshover,1974: Quasi-biennial
and long-termfluctuationsin the centersof action.
Mon. Wea. Rev., 96, 778-784.
Angell,J.K. and J. Korshover,1975: Evidencesfor aquasi-biennialvariationin eccentricityof the northpolar vortex. J. Atrnos.Sc., 32, 634-635.
Brier, G.W., 1978: The quasi-biennialoscillationand
feedbackprocessesin the atmospheric-ocean-earthsystem. Mon. Wea. Rev.,106, 938-946.
Ebdon, R.A., 1975:The quasi-biennialoscillationand
its associationwith troposphericcirculation pat-

Society of Japan

tern.

Meteor.

Vol. 67, No. 3

Mag.,

104,

282-297.

Gordon,A.H. and N.C. Wells,
1975:
numberedyear summer
temperature
tral

England.

Gutzler,andNature,296-297.

D.S. and D.E. Harrison,
1987: Theevolutionof seasonal
wind anomalies

near-equatorial

eastern

Oceans.

Wea.

Gray,

256,

Odd and evenpulse in cen-

Mon.

W.M.,

quency.
oscillation

1984:

Indian
Rev.,

and

115,

Atlantic

structureover thewestern

Pacific

169-192.

seasonal

hurricane

fre-Part I: El Nino and 30mb
quasi-biennial
influences.
Mon.
Wea. Rev., 112,1649-

1669.
Holton,sphere

JR.,

1972:

generated

Waves

in

the

by troposphericAtrnos.
Sci., 29, 368-375.
Holton,JR. and R.S. Lindzen,

1972:

equatorial
heat

strato-sources.

An updated

J.
the-

ory for quasi 1/Nbiennialoscillationof the tropicalstratosphere. J. Atrnos. Sci., 29, 1076-1080.
Kawamura, R., 1988: Quasi-biennial oscillation modes
appearing in the tropical sea water temperature and
700mb zonal wind. J. Met. Soc. Japan, 66, 955965.
Kutsuwada, K., 1988: Spatial characteristics of interannual variability in wind stress over the Western
North Pacific. J. of Climate, 1, 333-347.
Lindzen, R.S. and J.R. Holton, 1968: A theory ofthe quasi-biennial oscillation. J. Atmos. Sci., 25,1095-1107.
Lindzen, R.S., 1987: On the development of the theoryof the QBO. Bull. Amer. Meteor. Soc., 68, 329337.
Maruyama, T., 1988: Anomalously short duration of
the easterly wind phase of the QBO at 50 hpa in
1987 and its relationship to an E1 Nino event. J.
Met. Soc. Japan, 66, 629-633.
Meehl, GA., 1987: The annual cycle and interannual
variability in the tropical Pacific and Indian Ocean
regions. Mon. Wea. Rev., 115, 17-50.
Mukherjee,
B.K., K. Indera,
R.S. Reddy and
Bh.V. Ramana Murty, 1985: Quasi-biennial oscillation in stratospheric zonal wind and Indian summer monsoon. Mon. Wea. Rev., 113, 1421-1424.
Murakami, M., 1981: Large-scale aspects of deep convective activity over the Gate area. Mon. Wea.
Rev., 107, 994-1013.
Nicholls, N., 1978: Air-sea interaction and the quasibiennial oscillation. Mon. Wea. Rev., 106, 15051508.
Reynolds, R.W., 1983: A comparison of sea surface
temperature climatologies. J. Climat. App. Met.,22, 447-459.
Trenberth, K.E., 1975: A quasi-biennial standing wave
in the Southern Hemisphere and interrelations withsea surface temperature. Quart. J. Roy. Met. Soc.,
101, 55-74.
Trenberth, K.E., 1980: Atmospheric quasi-biennial oscillation. Mon. Wea. Rev., 108, 1370-1377.
Yasunari, T., 1981: Temporal and spatial variationsof monthly rainfall in Java, Indonesia. Southeast
Asian Studies, 19, 170-186.
Yasunari, T., 1985: Zonally propagating modes of
the global east-west circulation associated with theSouthern Oscillation. J. Met. Soc. Japan, 63,

June

1989

T. Yasunari1013-1029.
Yasunari, T., 1987: Global structure of the El
Nino/Southern Oscillation. Part II. Time Evolution. J. Met. Soc. Japan, 65, 81-102.
Yasunari, T. and R. Suppiah, 1988: Some problems on
the interannual variability of Indonesian monsoon
rainfall. In TropicalRainfall Measurements, Theon,
J.S. and N. Fugono (edi.), A. Deepak Publishing,
Hampton, pp527.

493

Yasunari, T., 1989: Impact of Indian monsoon on the
coupled atmosphere/ocean system in the tropical
Pacific. (submitted to J. Dyn. Met. & Atmos.
Phy.)
Yoshino, M. and R. Kawamura, 1987: Periodicity andpropagation of sea surface temperature fluctuationsin the equatorial Pacific. Beit. Physik. Atmos., 60,
283-293.

熱 帯 の成 層 圏 、対流 圏 お よび海 面 水温 の
準 二 年振 動(QBO)のあ い だの リンクの可能 性 につ いて
安成 哲 三(筑波大学 ・地球科学系)

熱 帯 の成 層 圏 お よ び 対 流 圏 の 東 西 風 に 見 られ るQBOが平 洋 上 の い くつ か の 地 点 に お け る成 層 圏QBOの
レ ン トな 位 相 構 造 が 見 られ る。 対 流 圏QBOは、 相 互 作 用 を し て い る証 拠 を提 示 す る。 赤 道太

下 方 伝 播 と、 対 流 圏QBOの問 には 、鉛 直方 向 に コ ヒー

ま た 、 赤 道 太 平 洋 上 の 海 面 水 温 のQBOと、 対 流 活 動 を通じて 結 合 して い る こ と も示 され た 。
これ らの 結 果 は、 ア ジ ア モ ン ス ー ン 地 域 か ら赤 道 太 平 洋 に か け て の 大 気 ・海 洋 結 合 系 に 見 られ るQBO
が 、 熱 帯 成 層 圏 のQBOと力 学 的 に リ ン ク して い る 可 能 性 を 示 唆 させ る 。