The heat and momentum flux due to standing planetary waves in the stratosphere were calculated on the basis of satellite data. The convergence of these fluxes was investigated and shows an apparent heating and acceleration of the mean zonal state. The Eliassen-Palm flux divergence calculation shows that the mean zonal state is effectively decelerated. Furthermore, the interaction between ultra long waves and k = 4 - 15 in the troposphere was investigated for a winter period and is discussed in connection with the geopotential wave one amplitude, which increases before a stratospheric warming event occurs

Schmitz, G.

English

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ASPECTS OF PLANETARYWAVEYP_NSPORTS IN _llE MIDDLE ATMOSPHERE
G. Schmitz
, Academy of Sciences of the GDR
, Central Institute of Solar-Terrestrial Physics
Observatory of Ionosphere Research
_ DDR-2565_ Kuhlungaborn, GDR
_.. ABSZ_ACr
The heat and momentum flux due to standing planetary waves in the strato-
sphere has been calculated on the basis of satellite data. The convergence of
these fluxes has been investigated and show an apparent heating and acceleration
of the mean zonal state. The Eliassen-Palm flux divergence calculation shows
that the mean zonal state is effectively decelerated. Furthermore the inter-
action between ultra-loog waves and waves k = 4 - 15 in the troposphere has been
investigated for a winter period and has been discussed in connection with the
geopotential wave one amplitude, which increases before _ stratospheric warming
i!:- " event occurs.
_, The inve_.igation of processes which determine the deviation of the zonally
_ averaged temperature and wind _[ieldfrom radiation equilibri_n is a central
question in stratospheric dynamics. LEOVY (1964), ll0LTON and NEIIRBEIN (1980) in
_ their model calculations take into consideration a linear drag that produces a
i.: deceleration proportional to the mean zonal wind, while SC210EBEPJ_and STROBEL
(1978), DETHLOFF and SO[HITZ (1982) additionally consider the mc_nentum transport
_ by planetary waves. On the basis of a stationary model. Dethloff and ScbmiZz
.J _ showed that the planetary wave influences on the mean state are am,all above the
stratopause. In the following at first the standing momentum and heat flux a_d
t',e divergence of the Eliassen-Palm flux is investigated, Furthermore the wave
k - 4 - 15 projection on the ultra-long waves in the troposphere preceding the
occurrence of a stratospheric warming has b_en calculated.
The data basis is the monthly mean standard 500, 200 mb topographies of the
i European l_eteorological Bulletin, the 100, 50, 30, I0 mb topographies from" Obninsk, the synoptical bulletin and the 5, 2, 0.4 mb data source are the NOAA
NHC maps fo_ the winter 1974175 where meteorological rocketsonde and _:tellite
- radiance data are used for .analyses. The high topographies are given once a
• • " • wedk'only. The mo_nentumand heat fluxes are calculated from the planetary wave
• i _mplitudes and phases. In the following the mean December values for the two
years will be discussed. In Figure I the _nplitude of pla:etary wave one is
shown. The maximum of wave one appears at 70°N at a height of about 35 km with
800 gpm. Figure 2 shows the meridional standing momentum transport due to the
sum of waves k - I - 3. The momentum transport has high values in the jet
region of the upper troposphere and at a height of 50 km in middle latitudes.
The meridional heat transport of the waves k = I - 3, given in Figure 3. also
haslargestvaluesin thestratosphere,thetwofluxesbeingessentiallydeter-
mined by the wave one contribution.
These shortly discussed fluxes are the basis for a determination of the
interaction between ultra-long waves and mean zonal circulation, according to
the Euleri.n zonally-averaged momentt_ and thermodynamic equation. The inter-
. action of the zonally averaged state with the planetary waves is explained
through the convergence of momentum and heat fluxes. The effective acceleration
and heating rates, resulting from these terms, have been calculated for the
monthly mean December of the years 1974_ 19_5. The largest acceleration appear_
in high latitudes at 35 Lm with about 12 ms- /day. The convergence of the
meridional heat flux se_s to give strong heating rates of about 4_K/day at high
latitudes and at a height of 40 tan,but cooling in middle latitudes. These
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Figure 1.
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Figure 2.
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Figure 3..
. values are lover than those given by GELLER(1982). because here ve discuss the
I standing part of fluxes onlyo The calculateO ells'clive dynamical _atiu_ tales
l in the stratosphere are approxil_tely equal to the dish•tic heating _ate, Frota
the non•cooler•lion theor_ of O!J_,_;E¥and DF.J_ZI_(1961) and A}_DR_S and
if-. HCIN_YR,E (1976) is knovn that one obtains _isXeading physical information rhea
discussing the iefluences of the planetary rave _ooentu_ or heat fluxes alone,
becau_ steady planetary raves _ithout dissipation or internal forcing do not
force the zonal _ean state, E_ON _t al, (19_0) propose the u6e o£ residual
eean equations for a discussion of the net _ffect of planetary waves fluxes on
the =eaa flay, _he _avea are intzoduced into this _yst_ only through the
divergence of tho _liassen-Pal_ flux in the residual zonal _o_entu_ equation,
Figure 6 shays the £tiasseu-Pal_ flux divergence lor the standing _ves as a
mean value of Decc_.ber 1974119_5, The EPg divergence has negative values at •
latitude of _0"-60"N of the stratosphere, vhereas the divergence ter¢_ of the
_ulerian tonal :o_ent_-_ equation is positive so that the uean zonal state is
.... • • effectively decelerated, in contrast to an acceleration in the Eulerian picture,
GELLEg(1982) discussed this relation /or the data of January 1979 _hete he
found • zo_al _ean state acceleration vhich is reduced by a factor _ _heu cal-
culated fro= the EPF divergence, If _e discuss the December t_ean cot, visting of
only 8 veekly values at 5, 2, 0.6 mb as a stationary solution, then the residual
_etidional flay is induced to bal'..nce the £PF diveegence,
Furthe_ore ve have investigated the connection betveen standing an_
transient fluxes and their spectral characteristics on the data basis of the
vaster period 1970/71, The results suggest a relation between the _onal r_e_n
ultra-long k - 1 - 3 and th_ k - _ - IS _a_e transport, One I_s_ibility for
such a relation is that this process is conducted via the =eaa zo_l state, the
other ia the nonlinear interaction between ultra-long raves and naves k - _ - 15.
We shortly discu,s the latter conception farther, because i_ see_s that the ti_e
variability of ultra-long _aves in the stratosphere is also couueeted vith this
process, Further_.cre the question arises _hether the high increase o1 the
mplitudes of geopotential _ave one or t_o in the troposphere before a strato-
spheric _anaing is related to the interaction betvern ultra-long and _;ves k =
- 15, This question has been investigated by c_lculatin_ the ;.rojecticn of
ll_
_onlir.ear interaction of barocliuic waves with waven,_bera 4 - 15 on the ultra-
lon_ waves at. 200 _b.
/-_ The wave transport ter1_a "_v "i, V-*:v'_, u*-u_ have been investigated, These
transports a[.pear in the _o_cnt_ equations and excite or dzsaipate ultra-long
waves, The aye.be! ( .... ) steads for the waves 1, 2, 3 and ( )* for the bare-
clinic wave k " 4 - l_ contributions, _o we discuss ior r_aple ('v';v-*) I asthe interactioa between the waves k " 15 and the wave k " I. Figuze _ gives
the standing plus tr_n._ie.,t wave k - :, - I_ projection on z_e wsVenu=bera k - I,
2 for the trar. sport v'v*. The interactin_ _ith wave I appears Ducit stronger _.
than that for wave k = 2. It will be _nteresti_._ to deter_ine the i_portance o_
this source for an interpretation of standing ultra-long wa_es in _odels,
Figure 6 shows the _eopotrntlal wave one e---plitude in the period _ron
Dece_brr 1970 to January 1971 at 200 _b, Around 5-Sth December at 55"_, 201h _.
Dec_ber a_ 50"-70,'[_, and abou_ ISth J_nuary at ?5"t; we observed an acceleration
of wave-one _plitude, For the winter 1970171 the war_ing was observed aroucd
lO_h January and it _e(_a that this warning was sti_ulated by the ,_plitude
acceleration a_ about 25th December, This acceleration is _ necessary
prerequisite for the develop=ent of a stratospheric watering, Figure 7 shows the
baroclinic wave Frojection (v*v*_) on the waver.u=ber k - I at 200 mb, The
thickened isoli=ea for the wave projectio, ter_s are larger than the =onthly
nean total value by a factor of two. Comparison of the curves thowu that in
==iddle or high latitudes perieda of atro.g baroclinic wave i_teractieus with
wave I correspond with periods of large wave _plitude accelera_'_ons. Further-
more the _et acceleration of geopote_tial v.ave --_pl.itud_ea wam esti=ated on the
• basis of the divergence of the transports u'v* and v'v* in the eeridion41
_o_entt_ equation, For the _entiont-d ti_e l-eriods one ohtains at _O'B an
acceleration o( about 50-100 t._=p/day which is a reasor_ble value _n _echanist_¢
,_odels to describe a stratospheric war_ing,
In s_rizing, it see'_s that the ti_e variabLlity of ultra-lou_ _aves in
the stratosphere is also determined by Lnteractioa with baroclioic waves in the
upper troposphere,
II_
Figure 6.
If •
/
4
115
!II'" 50- 1
L
Figure 7.
ACK_01,%EDGEH_'f
I th_k Dr. _. Grieger and I.'. Kruger for their efforts in the preparation "
? of the observatioa_l results.
REFERf_C_S
Andrewm, D. G. and H. E. Hclntyre (1976), J. Athos. Sci.+ 333, 2031.
¢harney, J. G. and P. G. Drazin (1961), J. Geophy_. Ees., 6b, 83.
: Dethloff, K. and G. Sct_itz (1982), Phys. Sotaricerr., Potsd_._, 18, 91.
[_'_on, H. J., B. J. Eoskins and H. E. Hclntyre (1980). J. A_os. Sci., 3.._7,
2000.
Celler, H. A. (1982), L_!na_ics of the _iddle at=osphere, Tutorial lecture
delivered nt the Fifth Intcrnatioual Sy=posiu_ on Solar Terrestrial Physics
in Ottawa, Canada. "-"
.... Schoeberl, 8. R. a_d V. F. SCrobel (1978), J. A_os. Sci., 3_.5., 577.
f ............ . __.


Aspects of Planetary Wave Transports in the Middle Atmosphere

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