Mar 5, 1985 - Dewan (1979) proposed a hy- pothesis of co-existence of gravity waves and turbulence. Gage. (1979) compared the spectra with a -5/3 power ...
WRI MAP Research Note-6
WRI MAP Research Note-6
The Power Spectrum of Internal Gravity Waves : Stratospheric Balloon Observations
MARG
and Interpretations Manabu D. YAMANAKA
MIDDLE ATMOSPHERE RESEARCH GROUP WATER RESEARCH INSTITUTE
March, 1985
NAGOYA UNIVERSITY Furo-cho, Chikusa-ku Nagoya 464 JAPAN
MIDDLE ATMOSPHERE
RESEARCH
GROUP WATER RESEARCH INSTITUTE NAGOYA UNIVERSITY
WRI MAP Research Note:
The Power Spectrum of Internal Gravity Waves: Stratospheric Balloon Observations and Interpretations
By
Manabu D. Yamanaka
Water Research Institute, Nagoya University Chikusa- ku, Nagoya 464, Japan
5 March 1985
INTRODUCTION To quantitize the gravity-wave momentum budget is one of the most important targets of MAP, of
mainly because theoretical models
weak zonal wind around the mesopause request momentum
ferred 1981;
from the troposphere by internal gravity waves Matsuno, 1982).
trans-
(Lindzen,
The gravity-wave momentum must contribute
also to maintenance of weak zonal wind in the middle stratosphere (Tanaka and Yamanaka, 1985). the
mean
flows,
Such gravity waves interacting with
either by Lindzen's wavebreaking
process or by Matsuno's dissipation mechanism,
(saturation)
must have a spec-
trum of small intrinsic frequency predominance (see Yamanaka
and
Tanaka, 1984a). However,
the
spectrum of middle-atmospheric gravity waves,
which is necessary to quantitize the momentum flux, clarified airplanes, review). horizontal any is
although not a few studies were done rockets
has not been
using
and radars (see Fritts et al.,
For example,
Matsuno (1982) assumed a
balloons,
1984,
for a
Gaussian-shape
phase velocity spectrum at the -bottom (20 km) without
observational facts. essential
Such zero phase velocity predominance
to act on the general circulation
as
a
Rayleigh
friction (Dunkerton, 1982). There frequencies
have (or
been often observed nearly -5/3 power
horizontal wavenumbers) in the mesoscale
zontal wind power spectra (Mantis, al.,
1982;
Balsley and Carter,
Nastrom and Gage,
laws
1983).
1963;
of
hori-
Dewan, 1979; Larsen et
1982; Lilly and Petersen, 1983;
Identification of them ·with the
-5/3
power law of wavenumber in 3D isotropic turbulence theory may not be
reasonable,
because
the
observed spatial scales
l
are
much
greater
than
the JD-turbulence inertial
subrange.
r---------~----"""16
Bretherton
\
(1969) considered this due to the mesoscale topography which is a possible
origin of gravity waves.
Dewan (1979) proposed a
pothesis of co-existence of gravity waves and (1979)
turbulence.
compared the spectra with a -5/3 power law of
wavenumber
\
hy-
>Eulerian, 65°N, B&C'82 \ . \ 8km,Jun.-Aug. \ \ \ \ \
\
Gage
horizontal
in the reverse-cascading energy inertial range of the
2D turbulence theory.
However,
\
complete to explain why such a power low is realized so commonly.
out
stratosphere and Tanaka,
1984a, c; Yamanaka et al., 1985c).
type (0.005 m/s),
(1985a,
middle
We developed and
b).
al.
Four zero-pressure balloons loading these anemome-
ters were launched during 1982-84 at Sanriku (39°N, 142°E). these observations
( .) ...__... ..--..
4
0)
~
\
J ...__... ....._.
\
\
Lagrangian Mantis '63 rv 40-45°N 24-30km Jul.-Sep.
0.9 m/s) and of
which are described in Yamanaka et
\
I
by balloons and balloon-borne anemometer~ (Yamanaka
used anemometers of propeller type (sensitivity: ionic
\
Y & T'84 25km,Sep.
----CJ)
Lagrangian, 39°N
we have carried
a series of high resolution wind observations in the
...-.. ..--..
\
these approaches do not seem
As an activity of the Japanese MAP project,
5
..--.. 3 ...__...
V
::,
3
u..
0)
0
From
u
we can obtain information on the gravity-wave
2
spectrum, which is the context of this brief note.
• i-----..,__----------1 -5 -4 -3 -2
OBSERVED POWER SPECTRA As shown in Yamanaka and Tanaka (1984c) and Yamanaka et
al.
(1985c), we can obtain two kinds of wind data by balloon tracking
log w(c/s)
and balloon-borne anemometers. On one hand, ridional altitude; data
Lagrangian power spectra of the zonal and
winds obtained by level-flight balloon tracking (25 20-21 September 1982) are shown in Fig.
analyzed
1.
here and the observation circumstance
published in Yamanaka and Tanaka (1984c).
mekm
The wind have
been
Higher frequency por-
Fig. 1
Lagrangian
power
meridional
(v)
t ra eking.
Spectra
1963;
spectrum ("Y & T")
component winds obtained from a obtained by other
authors
( u)
and
balloon (Mantis,
Balsley and Carter, 1982) and the ideal power laws
are also indicated.
Modified from VanZandt
vate communication).
3 2
for zonal
(1984;
pr1-
tions
of
the spectra may not be reliable because of
errors of the tracking antenna (in particular,
mechanical
meridional one is r-i
worse since the balloon moved almost eastward). The Vaisala-Brunt frequency
and
the Coriolis factor are 3xlo-;
and
2x10-s
C
c/s,
Therefore, the spectra correspond nearly to those
respectively.
I s::::
of the internal gravity waves. The
(1)
u
(Mantis,
1963;
noted
that
It should be
our and Mantis' spectra are based on Lagrangian
ob-
in
the middle stratosphere
using
balloons
whereas
observations
is
a Eulerian spectrum obtained from IS
in the upper troposphere.
Also note that
radar Mantis'
Balsley-Carter's are in summer (the mean winds are
and westerly,
easterly
respectively) and ours are in autumn (weak wester-
It is very interesting that all the spectra are similar not
only in respect of form but also in point of magnitude. the balloon-borne anemometer data showed
a "hierarchical structure" in the stratospheric turbulence (Table 1).
The
fluctuations
listed in the class (i) may be
also by rawinsondes or radars (e.g.,
detected
Cadet and Teitelbaum, 1979;
and Woodman,
1982),
whereas (iv) and (v) can be
detected
only
by the ionic anemometers (Barat,
1985a).
We
scanned
Yamanaka et
such microstructures vertically
by
al., using
balloon-borne winches (Matsuzaka et al., 1984, 1985).
propellor
anemometer (Yamanaka et al.,
1985b) leads to a
power
spectrum in terms of the vertical wavenumber as shown in Fig. It
is a problem to determine whether those classes are of
4
2.
waves
b.O
(1) .::
.:: Q.)
b.O
Q.)
> (1) (1) ~::::: I'...
.::
H
>,
"tl
(/)
.... Cl)
Cl)
-I->
-I->
Cl)
u
E: 0 E:
-I->
Cl)
Cl)
"tl :::
s::::
Cl)
Cl)
::s
4-l 0
Q.) .,I,) Q.)
Q.) (.)
Q.) (.)
C
C C
s 0 s Q.) .::
"d I'... 0
(.) Q.)
b.O C C 0 0
r-i ;:i
.,I,) (/J
4-l ;:i Q.)
..Q
....... 0
Cl)
. .....
s::::
Q.) .,I,)
Q.)
(.)
0.. r-i 0 0..
r-i . ..,
Q.) .,I,) Q.)
Q.) .,I,)
"d
.:: ;:i
C ;:i
> r-i
b{) s::::
. .....
"d
00
""'~ "d Q.) Q.)
Q.)
"d
(/)
;:i
..,I,)..,
"d
r-i
.C..,
s0..
:::::
-,
'"'--1
