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Improvements in the Upper-Air
Observation Systems in Japan
M. Ishihara, M. Chiba, Y. Izumikawa, N. Kinoshita, and
N. Tsukamoto
Japan Meteorological Agency
WMO Technical Conference on Meteorology and
Environmental Instruments and Methods of Observation
TECO-2006
Geneva
December 3-5, 2006
TECO-2006 Geneva, Dec. 3-5, 2006
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Outline
 Background
 Operations of wind profilers and Doppler radars
 Automatic upper-air observation systems
 Experiment on ground-based microwave
radiometers for operational use
 Operation of GPS-derived IWV Measurement
TECO-2006 Geneva, Dec. 3-5, 2006
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Strategy of JMA for Severe Weather Events
 Improvement of observations and monitoring
Modernization of upper-air observation
systems
 Improvement of forecasting
Non-hydrostatic mesoscale model with
4D-VAR data assimilation
 Enhancement of warning issue
Decreasing size of warning areas and
extension of warning lead-time
TECO-2006 Geneva, Dec. 3-5, 2006
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1. Mesoscale Wind Profiler Network
31 wind profilers are being
operated at 1357MHz-band, and
provide winds aloft from near
the surface to about 5 km in
height every 10 minutes.
Wind Profiler Network and Data
Acquisition System
(WINDAS)
TECO-2006 Geneva, Dec. 3-5, 2006
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2. Replacement of conventional radars
with Doppler radars
 A replacement project from conventional radars to
Doppler radars is started in the radar network.
 The main purpose of introducing Doppler radars is
the assimilation of Doppler velocity data to the
numerical weather prediction model, for increasing
the accuracy of prediction for mesoscale severe
weathers.
TECO-2006 Geneva, Dec. 3-5, 2006
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Replacement Plan of Weather Radars in JMA
• Existing conventional radars
• Doppler radars being installed in 2006-2007 , and 2008
• Doppler weather radars being operated for aviation weathers
120°
140°
40°
40°
30°
30°
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140°
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Impact of Doppler Velocity Data to
Numerical Weather Forecast
 Assimilation of Doppler velocity data to the mesoscale
numerical model using the 4D-VAR was started in 2004.
Tokyo
Verification of 3-hour accumulated rainfall forecasts starting from 1800 UTC on 1 Feb 2004. (a) 12-15 hour
forecast without the assimilation of Doppler velocity data, (b) observation, and (c) forecast with the assimilation
(Ishikawa and Koizumi, 2006). Circles indicate heavy rainfall areas.
TECO-2006 Geneva, Dec. 3-5, 2006
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3. Introduction of Automatic Upper-air
Observation Systems
• Manned stations
• Automatic radiosonde observation systems
being started in 2003-2006 , and 2007
120°
140°
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30°
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120°
140°
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Automatic Upper-air Observation Systems
Station (year of installation)
Manufacturer
Type
Radiosonde
Ground
System
47678
HACHIJOJIMA (2003)
VAISALA
AUTOSONDE
RS92-AGP
DigiCORA III
47945
MINAMIDAITOJIMA
(2005)
VAISALA
AUTOSONDE
RS92-AGP
DigiCORA III
47918
ISHIGAKIJIMA (2006)
MEISEI
ARS
RS-01GM
RD-01G
47909
NAZE (2007)
MEISEI
ARS
RS-01GM
RD-01G
HACHIJOJIMA
(2003)
MINAMIDAITOJIMA
(2005)
TECO-2006 Geneva, Dec. 3-5, 2006
ISHIGAKIJIMA
(2006)
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Automatic Radiosonde Observation Systems
Being Suitable for Our Operation
 The ballon-launching gear of the system was
improved after the installation to endure to strong
wind and high humidity at 47678.
 600g balloons with internal parachutes are used at
47918.
 Some balloons had been tore in the storage room of
the system due to surface ozone at 47918. An airfilter was installed stop the inflow of ozone from the
outside, and then the problem was resolved.
 An unmanned hydrogen generator will be used at
47909 from 2007.
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4. Experiments of Ground-based Microwave
Radiometers for Operational Use
• JMA starts a project for operational use of
ground-based microwave radiometers.
• Field experiments are being made in some
different climate conditions of Japan; in subtropics, in summer and winter at the mid-latitudes.
• Two methods; the built-in algorisms and the 1DVAR with the mesoscale model, are being tested
to retrieve temperature and humidity profiles.
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Field Experiments of ground-based
Microwave Radiometers in 2006-2007
August to Dec.,
RDX WVP-3000
June to July, RDX WVP-3000
July to Sep., RPG HATPRO
Oct. to Dec.,
RPG HATPRO
Morioka
Niigata
July to Dec.,
RDX WVP-3000
Sendai
Tsukuba
Naha
Radiometer Physics GmbH
HATPRO
April to May and Jan. 2007,
RDX WVP-3000
Jan. 2007., RPG HATPRO
TECO-2006 Geneva, Dec. 3-5, 2006
Radiometric
TP/WVP-3000
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• A topic in the field experiment; the radiometer measurements with
the rainfall mitigation system, and in this case, temperature and
water vapor profiles was obtained in good accuracy even in strong
rain as well as in light rain.
strong rain
light rain
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5. Operational Measurement of GPS-derived
Integrated Water Vapor (IWV)
• The operational
measurement of integrated
water vapor (IWV)
measurement using the GPS
receiver network (GEONET)
of the Geophysical Survey
Institute (GSI) has been
planned.
• However, the information on
the orbits and the clocks of
the GPS satellites, which are
needed to calculate IWV, are
not available in real-time.
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Near-real Time Processing of IWV
• The meteorological Institute of JMA (MRI) has
developed a near-real time processing scheme.
Using the ultra-rapid information and the GPS clocks
corrected by the accurate clock of an International
Global Navigation Satellite System Service (IGS)
station.
• The scheme provides enough accuracy of integrated
water vapour (IWV) for assimilation to NWP.
• JMA is going to make a contract with the Geophysical
Survey Institute (GSI) to obtain the GPS network data
in real-time probably in 2007.
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Near-real Time Processing of IWV
Accuracy
Final Orbit
after 2 weeks
Rapid Orbit
after 12 - 36 hours
Ultra-Rapid Orbit
(observed half)
after 2 - 8 hours
Ultra-Rapid Orbit
(Predicted half)
before 24 hours
Rapidity
1) Using the rapid orbit, the error on
the most accurate clock in a GPS
station of Japan (Usuda) is
estimated. The error is
extrapolated in the next 24 hours.
2) Using the corrected time of
Usuda, errors on the clocks of
the GPS satellites are corrected.
3) Using the corrected GPS satellite
clocks and the ultra-rapid orbit,
IWV is estimated at the each GPS
stations.
(Shoji and Kunii, 2006)
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• Convection nowcasting using horizontal water vapor flux convergence
using GPS integrated water vapour (IWV) and surfade winds from the
AWS network (AMeDAS).
Radar Echo
IWV Flux Convergence
05UTC
05UTC
06UTC
06UTC
FLUX CONV (kg m-2s-1)
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Issues and Future Plans
• Re-construction of radiosonde observation
network using automatic systems including
positive and negative targeting,
• Vertical profiling of water vapor from microwave
radiometers, GPS occultation method, wind
profilers,
• Upper-air observations over the ocean.
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