1. IGARSS
Vancouver, Canada July 24 -29,
2011
Advances in Science and Techniques for
Ground-Based Radar Remote-Sensing of the
Earth’s Atmosphere
Shoichiro Fukao
Fukui University of Technology, Fukui
Research Institute for Sustainable Humanosphere, Kyoto University, Kyoto
2. Structure of the Earth’s Atmosphere
Thermosphere/
Ionosphere
Mesosphere and
Stratosphere
Troposphere
3. The Principle of radar techniques
Pulse
Frequency
Antenna
Transmitter
Target
Receiver Echo
Doppler shift
Frequency
4. The latest radar techniques have continuously
been applied to the Earth’s atmosphere
Upper Atmosphere
Middle Atmosphere
First,
meteorologists
Lower Atmosphere
utilized radars for
precipitation
measurement.
5. The latest radar techniques have continuously
been applied to the Earth’s atmosphere
Next,
Upper Atmosphere
radar techniques were
utilized by upper
atmosphere
physicists．
Middle Atmosphere
Lower Atmosphere
6. Scatterer in the ionosphere: Free Electrons
Total cross section is comparable to that of a sphere of 1 cmφ.
Ｉｎｃｏｈｅｒｅｎｔ ｓｃａｔｔｅｒｉｎｇ ｏｒ ＩＳ
7. The latest radar techniques have continuously
been applied to the Earth’s atmosphere.
Upper Atmosphere
Finally,
radar techniques were
Middle Atmosphere
applied to the middle
atmosphere.
Lower Atmosphere
8. Scatterer in the Middle Atmosphere: Turbulence
Bragg scattering
Eddy size responsible for the scattering = One half the radar wavelength
9. Scales of eddies of (Inertial subrange) turbulence
Ionosphere/
Thermosphere
Mesosphere
Stratosphere
Troposphere
Restricting the radar wavelength for middle atmospheric observations to
VHF and UHF.
10. Rapid beam scanning required for
accurate measurement of wind velocity
Wind vector measurement：
Wind velocity assumed to be uniform within
the region where / the duration while
the beam is steered.
Radar antenna
11. The Middle and Upper Atmosphere radar :
The MU radar
Two essential capabilities:
- Beam steering on a pulse-to-
pulse basis, and
- Multiple beam forming
● Several hundred modules of
transmitters/ receivers.
● Computer control of the whole
system
ACTIVE PHASED ARRAY RADAR
12. The MU radar, Shigaraki, Japan
MU
46.5 MHz, 103mφ Yagi array, 1 MW
Research Institute for Sustainable Humanosphere, Kyoto University
14. Atmospheric radars provide continuous wind data with
high time and altitude resolutions that have ever been realized.
Meteorological balloon observation
6 hrs interval
15. Atmospheric radars provide continuous wind data with
high time and altitude resolutions that have ever been realized.
Meteorological balloon observation
Atmospheric radar observation
MUレーダー観測
Passage of a typhoon
16. Atmospheric waves modulate
tropo/stratospheric wind profiles.
Mean wind (20 oblique) Fluctuations from the mean wind
°
Zonal
Meridional
Ur
(Zonal)
Vr
(Meridional)
Daily mean (a) eastward (solid) and northward (dashed) radial velocity profiles and hourly mean
radial velocity fluctuations in the (b) east and (c) north directions for 17/18 October (after Fritts et al., 1988).
18. Analogy to ocean surface waves:
Their growth and breaking
北斎
Woodcut print painted by Hokusai Katsushika (19th century)
19. Atmospheric gravity waves:
Propagation and saturation
Saturation
Deceleration
of mean flow
Wave breaking
Momentum flux
Turbulence
Atmospheric
gravity waves
20. Latitudinal distribution of
zonal wind velocity in the mesosphere
Theoretically, a strong
geostrophic wind exists
above the mesosphere.
Weak wind
Observationally, the wind is
weak irrespective of season
and latitude.
E: Easterly or westward wind
W: Westerly or eastward wind
21. Momentum flux measured with the MU radar
Deceleration of
Mean flow
Deceleration of westward wind
westward eastward wind
Eastward flux
Westward flux
Mean flow
eastward
23. Gravity waves found to be ubiquitous in the ionosphere
and thermosphere
“Gravity waves” continuously
modulate the structure and
dynamics of this region.
25. Hemispheric conjugacy of nighttime MSTIDs
Sata Darwin 630-nm airglow imagers
simultaneously taken at
Sata
conjugate points.
Projected along
geomagnetic
field line
ＥＡＲ
Darwin Darwin
Otsuka et al., 2004
26. The principle of range imaging
Y(t) = [Y1 (t) Y2 (t) L YN−1 (t) YN (t)]T , Yk (t) ：周波数 k の複素受信信号列
適用する空間フィルター： h(z) = [h1 (z) h 2 (z) L h N−1(z) h N (z)]T
−Δr / 2 < z < Δr / 2 Δr = 150m
YF (t) = h† (z)Y(t)
z 2
PF (z) = E{ YF (t) } = h*Rh (輝度分布~強度に比例)
時系列 (I&Q)
Y1 (t ) R = Y (t )Y * (t ) ：(N×N)エルミート行列
h1(z)
Y1(t) X
Reconstructed
Y2 (t ) h2(z) time series at ｚ
Y2(t) X within range volume
Y3 (t ) h3(z)
Y3(t) X Σ YFz (t) =
h4(z)
Y4 (t )
Doppler spectrum
Y4(t) X
h5(z)
Y5 (t )
X レンジ内の任意高度
Y5(t)
z における
-noise,
-power,
-SNR,
-Doppler velocity,
-spectral width
27. MUR in range imaging mode
(Range imaging mode)
⇒ Detailed observation of turbulence and stable layers at a
time and range resolution comparable to standard weather radars.
28. Simultaneous measurements with
cloud radars
Ka-band (35 GHZ) and W-band (95 GHz) Doppler radars
For profiling cloud structures and processes as well as motions
from Doppler shift.
94.79GHz FMCW Falcon radar
Ref: hLp://katla.nd.chiba-‐‑u.jp/intro/fmcw.html
Cirrus detected with a
Ka-‐‑band radar at shigaraki
MUR reflectivity
MUR vertical air velocity
29. Turbulence in clouds
3. A better knowledge of turbulence in clouds and
at cloud edges (mechanisms, occurrence, intensity)
and mainly cirrus
Tools: lidar, weather radars, MU radar, IWP, balloon
KH instability inside cloud observed from lidar
Convective instability at a cloud base (solid line)
observed by MUR
KH Instability at a cirrus cloud base observed by MUR
30. WINDAS : Wind profiler network and data acquisition system
- Japan Meteorological Agency (JMA) 2001 -
WIND PROFILER SITES
CONTROL CENTER (JMA HQ）
RADIOSONDE STATIONS
・Consists of thirty-one
1.3GHz profilers (LTR)
and control center, and
・Provides the NWPs with
initial values of wind field.
0 500km
LTR, RISH Kyoto Univ.
31. Impact of profiler data to MSM for severe rainfall
(a) 3hr forecast of MSM (b) 3hr forecast of MSM (c) Composite of radars
without profiler data including profiler data and rain gauges
Rawinsonde
200km
Profiler
Total Rain Amount for 3hr (mm)
32. Operational Wind Profiler Networks
WINPROF
(CWINDE)
Japan Met
Agency
NOAA
Profiler Network
from www.ecmwf.int
37. Equatorial Atmosphere Radar: EAR
Antenna array (110 m in diameter)
Bukittinggi, West Sumatra,
Indonesia
(0.20 °
100.32 °
S, E,
865 m above sea level)
47MHz, 560 Yagi antennas, 100kW
38. The Equatorial Atmosphere Observatory (EAO)
Kototabang, Indonesia
FMCW radar
VHF radar
EAR receiver
Meteor radar
X-band met radar
RASS sounder
EAR
µ-rain radar
Optical rain gauge
All sky imager
Ceilometer
Lidar
Radiometer
Disdrometer
GPS receiver
39. EAR: Breaking of Kelvin wave at the tropopause
Zonal wind
wave
Breaking Kelvin wave wave
excitation
成層圏と対流圏の
大気の交換
Turbulence
Large-scale convective system of ISV
Increase of turbulence ×：cold-point tropopause
Fujiwara et al., 2003
40. Where will the “gene” of active-phased array radars go?
MAARSY, Andoya
MU radar
An MUR-type radar
being build at
Syowa base in the Antarctic
Equatorial Atmosphere Radar
PANSY radar
41. Concluding Remarks
- In the last forty years, atmospheric radars have
been proving themselves a most powerful tool for
revealing the basic processes of the Earth’s
atmosphere.
- Currently, various new sophisticated techniques are
being developed with atmospheric radars, and
their commercial models are successfully
implemented to operational weather forecast.
- In the future, they will make most important
contributions to studies of the atmospheric sciences,
e.g., the climate change.
