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Middle and Upper Atmosphere
Research at LIM
Middle Atmosphere
The middle atmosphere includes the atmospheric region above the
tropopause up to the lower thermosphere (10-100 km). The middle
atmosphere, mainly through wave coupling, acts as a sensor of
lower atmosphere variability. Research at Leipzig mainly aims into
two directions:
VHF radar wind and temperature measurements at 80-100 km
Numerical modeling of the middle and upper atmosphere and its
variability due to natural and anthropogenic forcing
printed at Rechenzentrum Leipzig poster available on http://www.uni-leipzig.de/~jacobi/docs/WG.pdf
Thermosphere/Ionosphere
The thermosphere / ionosphere region is mainly forced by solar
variability, but also reacts on the variability of lower regions.
Research focuses on solar variability, and long-term changes of the
thermosphere and ionosphere system.
EUV measurements on board ISS, and ionization from measured
EUV spectra
Planetary waves in ionospheric electron density
Lower E-region variability
Collm Observatory
At Collm, since the 1950 remote sensing instruments are operated
especially for the investigation of the upper and middle atmosphere,
which form the basis for the middle and upper atmosphere
research:
- VHF meteor radar
- LF receiver
- GPS receiver
At Collm, also seismic measurements are run by the Institute of
Geophysics and Geology of the University of Leipzig.
Information and contact: http://www.uni-leipzig.de/~jacobi/collm
Vertical Coupling
Middle and upper atmosphere dynamics is, besides solar forcing,
also determined by forcing from below. We look for forcing
mechanisms that couple the lower and the upper atmosphere, as
well as the neutral and ionized part.
Fakultät für Physik und Geowissenschaften
Figures show transmitting antenna
(right), and transmitter and receiver
units (above) of the meteor radar.
Left: EUV-TEC index, defined as normalized
primary ionization calculated from TIMED
SEE solar EUV spectra. Also shown is global
total electron content (TEC) and F10.7 solar
proxy. The figure below shows energy
absorbed by different species.
1985 1990 1995 2000 200585
86
87
88
89
90
91
92
93
94
95
96
Year
Collm 21-1 UT mean
LF
nig
httim
e r
efle
ctio
n h
eig
ht (k
m)
Right: The equatorial lower ionosphere shows
a wave 4 signature (colors), owing to neutral
atmosphere dynamcis (contours). The figure
shows GPS sporadic E occurrence rates
together with satellite temperature anomalies.
Figures on the left show zonal (upper panel)
and meridional (lower panel) prevailing winds
at midlatitudes according to measurements.
The zonal mean flow is characterized by
mesospheric westerlies in winter and
easterlies in summer, and a wind reversal in
the lower thermosphere.
This reversal is forced by breaking gravity
waves that also lead to an equatorward
meridional circulation in summer.
Figures on the right show mean temperatures
and zonal winds according to numerical model
results.
In the lower panels differences between solar
maximum and minimum conditions are shown.
Results refer to Northern Hemisphere winter
conditions.
Left: The figure shows solar EUV fluxes as
measured with the SolACES spectrometer
on board ISS (see figures below).
Left: Long-term measurements of LF reflection heights
in the lower ionosphere. The time series show a
decadal change due to the 11-year solar cycle.
-2 -1 0 1 20
3
6
9
12
15
Zo
na
l w
ind
at 9
0 k
m (
m/s
)
NAO index
r = 0.52
Left: The figure shows mesopause region zonal
winds vs. NAO indices. The correlation shows
that there is a coupling throughout the winter
atmosphere via the strength of the polar vortex.
Right: Modulation of gravity waves by
planetary wave (yellow lines) shows the same
seasonal cycle as planetary wave-type os-
cillations (upper line) in the ionosphere do.
This shows that the signature of planetary
waves in the ionosphere is probably due to
modulation of gravity waves.
Left: Sporadic E layers in the lower ionosphere
(colors) show a semidiurnal signature, which is
owing to wind shear variability (contours) in the
neutral atmosphere. The figure shows GPS
measurements together with Collm radar wind
data. The symbols denote the phases of the
semidiurnal signature.
-180° -150° -120° -90° -60° -30° 0° 30° 60° 90° 120° 150° 180°
Longitude
85
90
95
100
105
110
115
120
He
igh
t (k
m)
4/1000
8/1000
12/1000
16/1000
20/1000
Collm Observatory, about 50 km east of
Leipzig, was founded in 1932 by Ludwig
Weickmann, the former Director of the
Geophysical Institute.
SolACES
30 60 90 120 150 180 210 240 270 300 330 360
doy
82
84
86
88
90
92
94
96
heig
ht (k
m)
-35 m/s
-25 m/s
-15 m/s
-5 m/s
5 m/s
15 m/s
25 m/s
35 m/s
30 60 90 120 150 180 210 240 270 300 330 360
doy
82
84
86
88
90
92
94
96
heig
ht (k
m)
-15 m/s
-10 m/s
-5 m/s
0 m/s
5 m/s
10 m/s
0 3 6 9 12 15 18 21 24
Time (LT)
85
90
95
100
105
110
115
120
Heig
ht (k
m)
10
20
30
40
50
1/1000
2008 2009 2010 2011 2012
1.5x10-3
2.0x10-3
2.5x10-3
3.0x10-3
16
-58
nm
flu
x (
Wm
-2)
Year
60
70
80
90
100
110
120
130
140
150
160
170
F1
0.7
(sfu
)