In 1968 the Soviet equatorial meteor expedition measured, at an altitude of 80 to 105 km, wind velocity disturbances in the equatorial atmosphere with a quasi-two day period. An example of such disturbances is provided which shows time series of wind velocity in the meridional and zonal directions. The results of the time series analysis are discussed

Kalchenko, B. V.

English

NASA Technical Reports Server

112 
CHARACTERISTICS OF ATMOSPHERIC DISTURBANCES WITH 
A QUASI-TWO DAY PERIOD 
B. V. Kalchenko 
Institute of Radioelectronics 
Kharkov, USSR 
In 1968 the Soviet equatorial meteor expedition to Mogadishu (2"N, 45" 
E, July, 1968-July, 1970) measured for the first time at an altitude of 
80-105 km wind velocity disturbances in the equatorial atmosphere with a 
quasi-two day period (KASHCHEYEV et al., 1971; KALCHENKO, BULGAKOV, 1973). 
An example of such disturbances is provided in Fig. 1, which shows time 
series of wind velocity in the meriodional V (t) and zonal VE(t) 
directions. I4 
On September 10-17, 1968, the predominant meriodional northward wind 
velocity was 9.1 mps and that of the predominant zonal westward wind - 38.3 
mps. While the time series themselves show convincingly enough the 
presence of a quasi-two day period in the velocity variations, the results 
of an harmonic analysis of the time series are given below. This table 
shows that a significant anisotropy exists in the wind velocity 
disturbance, with a pronounced mer-iodional maximum. During the period in 
question, VN48 = 64.6 mps and VE48 = 19.3 mps. The mean values of 
different harmonic components are compared in Table 1. 
Table 1. 
Average Values of the Velocity Harmonic Components During the Period 
From September 10 Through 17, 1968 
vO '.t8 '24 3 2  '8 $48 $24 $12 $8 
h h h h -1 -1 -1 -1 -1 m-s m-s m.s mas m*s 
Meriodional 
Direction 9,l 64,6 16,6 9,O 13.9 30,O 16,4 11,9 4,6 
Zonal 
Direction -38,3 19,3 14,9 15,O 7,4 31,O 16,4 7,7 4.6 
The table shows that in the meriodional direction the amplitude of the 
two-day variations exceeds that of the diurnal component almost by a factor 
of four. In the zonal direction harmonics are commensurable but the 
two-day component exceeds the diurnal and semi-dirunal components by a 
factor of 1.3. These results convincingly show that one should take into 
account the velocity component with a quasi-two-day period when analyzing 
t.he wind at mesopause altitudes. The amplitude of the semi-diurnal 
component in the zonal direction is nearly double that in the meridional 
direction. The phase of these components is such that the velocity vector 
of the semi-diurnal tide rotates counter-clockwise. ($N12 - OE12 = 3.2 h). 
https://ntrs.nasa.gov/search.jsp?R=19880005133 2020-03-20T08:57:35+00:00Z
113 
l-5 
h 
I '  
I I 
1(1---- -~ - - 
- d  z - a  
> a 3  0 
\ D r l  - m  $4 
44 aJ a a  c -  o b s .  
4 - 4  u rn 
' c t l  m a  
. r ( - l a J  F 
$ 4 4  $4 
aJw 
aJP m 
u a J a u  
u r n  
c a a  c 
.rl aJc 0 
m a  
rn $4 
a a a  m 
. r ( o c a J  
u d a  a 
.r( $4 a u a m m  
0 aaJ 
4 Q 4  m w 7 m  
a do) c $4 a u  
+ O E C  
zzw add 
m E u o u  u 7
c e r n s  
'5: 2 
The mean values of the diurnal component phase were the same for both 
the zonal and the meridional components. 
Comparison of results obtained in the equatorial zone with those 
obtained in Kharkov and Dushanbe showed the global nature of the quasi-two 
day disturbances, with an amplitude maximum over the equator. The period 
of the discovered variations may be other than 48 hours. For example in 
July-August, 1981, Tx = 4 4 ,  5 hrs., while in July, 1971, Tx = 52, 5 hrs. 
The experiments carried out in the equatorial zone using velocity 
measuring equipment revealed that the two-day disturbance amplitude is 
bigger in the upper layers of the meteor zone and the phase either 
decreases in the upper layers or remains unchanged. Fig. 2 shows the 
results of observations carried out in February-March, 1970. Three 
independent height ranges are presented, with average altitudes of 84.3 km, 
92.7 km, and 100.8 km, with a distinct two-day wave dominating the highest 
altitude. 
It was noticed that the appearance of quasi-two-day variations is 
close in time to the change of polarity of the interplanetary magnetic 
field (IMF). Moreover, the phase of the fluctuations depends on the sign 
change from "+" to "-" or vice versa. 
Experimental data obtained in 1970-1976 (50"N), in 1968-1970 (2"N) and 
in 1972-1974 (67"s) were used in an analysis of the two-day variations at 
different latitudes and in different seasons of the year (Obninsk, 1976, 
iss. 7, 9, 10, 11). For each month the maximum amplitude of the two-day 
wave was chosen for both the meridional and zonal directions. The velocity 
values were averaged for each month using available data and the results 
obtained referred to the middle of each month. Thus, monthly mean values 
were obtained for an average year. A 10-year analysis carried out for 50"N 
for all the measured two-day disturbances yielded about the same results. 
The velocity values V48 are denoted by dots for the meridional direction 
and by circles for the zonal in Fig. 3. One can note that meridional and 
zonal components have nearly the same amplitudes (50"N and 67"s) and 
similar transformation laws. In the equatorial zone the meridional 
component is predominant and its annual variation differs slightly from 
that of the higher latitudes. The zonal component has the same half-year 
period just as at 50"N and 67"s. The maximum amplitude of the two-day 
disturbances is observed in July and January. The results also showed that 
two-day variations with a definite original phase and large amplitude occur 
with a sign change of the IMF provided that the polarity remains relatively 
constant for some days thereafter. 
Simultaneous occurrence of quasi-two-day variations was observed more 
often in geographical points located on the same meridian; for points 
located at other longitudes such variations occur earlier in the east, 
i.e., the appearance of the wave moves from the east to the west. 
According to experimental data the wave number can have values from 3 to 5 .  
Fig. 4 shows a case of quasi-two-day variations observed over Kharkov and 
Kharbarovsk, the longitude separation between these two points being 
!38.34". It is obvious from Fig. 4 that the wind variations of August 17-21 
over Khabarovsk or the same as those of August 19-23 over Kharkov. In this 
case processes observed over Kharkov repeated themselves over Khabarovsk 
115 
28 
Fig. 2 The wind field at three heights for February 28 to March 4 ,  
with two day wave superimposed. Note the rapid increase in 
day wave amplitude with height. 
1970, 
two 
116 
N 
2s t 0 0 
250 L 
rnunth.9 
Fig. 3 Average maximum monthly amplitude of the two day wave from 
data measured at 95 km from Obninsk (50%. 1970-761, 
Mogadishu (2%, 1968-70) and Molodezhnaya (67OS, 1972-741, 
.meridional e, zonal 0 ;  note the obvious correlation with Kc. 
117 
Fig. 4 Quasi two day variations observed simultaneously over Kharkov 
and Kharbarovsk, separated by 9 8 O  in longitude. 
lag of 62-65 hours corresponds to a zonal wave number of 5. 
The phase 
118 
62-65 hours later which corresponds to a wave number K-5.  Similar results 
were obtained when comparing the measurements from two stations with AQ = 
12" (Kharkov, Kazan) obtained from July 30 to August 9, 1978. From data 
obtained during January 15-27, 1978 over Obninsk and Kuhlungsborn (AQ = 
24.5") K = 4.7. 
The obtained results show that quasi-two diurnal variations are due to 
solar activity. 
1. 
2. 
3 .  
4. 
5. 
6.  
References 
Kashchev B.L., B. V. Kalchenko, V. V. Lisogub, et al., 1971, In: 13th 
Plenary Session of the Committee on Comets and Meteors of November 
1-15, 1971, Theses of the reports, Moscow, pp. 29-30. 
Kalchenko B.V., S.B. Bulgakov, 1973, Geomagnetizm i aeronomiya, col. 
13, NO. 6 ,  pp. 1125-1126. 
Wilcos J . M . ,  1975, Solar Activity and the Weather, J. Atm. Terrest. 
Phys., Vol. 37, pp. 237-256. 
Mardia K., 1978, The Statistical Analysis of Angle Observations, 
Science Publishers, Moscow, p. 239. 
The Wind at the Altitude Range of 80-100 km, 1976, Obninsk, Iss. 7, 9. 
Ibid., Iss. 10, 11. 
t 


Characteristics of atmospheric disturbances with a quasi-two day period

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server