Evaluation for China L band
radiosonde
Dr. LI Wei
CMA Meteorological Observation Centre
Distribution on Sites
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Type
GTS1
GTS1-2
GTS1-2
advanced version
Temperature
Rod thermistor
diameter 1 mm
Rod thermistor
Diameter 1.2 mm
Bead thermistor
diameter 0.5 mm
Pressure
Silicon
piezoresistance
Aneroid capsule
capacitor
Aneroid capsule
capacitor
Humidity
Carbon hygristor
Thin-film
capacitor
Thin-film
capacitor
Sensors
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GTS1
GTS1-2 & GTS1-2 advanced version
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• RS92 as reference radiosonde.
• Multiple radiosondes attached on one balloon.
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• Error separating method
Principle:
(1) If there are enough sample data, the data distribution will
be normalization.
(2) Two radiosondes with the same sensors between which
the statistical systematic errors (SE) should be near zero.
And the STD of each them should be approximately equal.
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Analytical Methods of Dynamic
Measurement Error
1)Taking RS92 as a standard and GTS1, GTS1-2 as tests, the STD of the
tests is given by formula (1):
(1)
2) As the principle, the separated STD of RS92 is given by formula (2):
sRS 92 
ssynthesis ( RS 92)
(2)
2
So the individual STD of RS92, GTS1 and GTS1-2 can be achieved.
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Comparative Trial
• Data description
Comparative trials sites : Yangjiang, Xinlinhaote
and Nanjing upper-air stations
The number of releasing sounding balloons: 65
Available data sets: 59
Nanjing
Yangjiang
Methods of trails:
GTS1-2
RS92
RS92
GTS1
GTS1-2
RS92
Yangjiang, Xinlinhaote
GTS1
RS92
GTS1-2
advanced
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• Results of comparative Trial
P (hPa)
comparative
results
(RS92 is
standard)
GTS1
GTS1-2
≥500hPa
SE
STD
SE
STD
SE
0.76
-1.22
0.23
0.12
5.53
-7.78
0.59
-0.28
0.13
-0.12
GTS1
0.65
-0.98
0.48
-0.45
GTS1-2
advanced
< 500hPa
U (%RH)
STD
GTS1-2
advanced
GTS1-2
T (℃)
≥100hPa
≥-25℃
0.32
0.05
5.97
2.22
0.67
0.14
8.47
2.78
<100hPa
<-25℃
0.40
0.31
0.09
10.53 -4.55
-0.31
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Pressure
GTS1-2-RS92
hPa
GTS1-RS92
0
GTS1-2
GTS1
100
GTS1-2-P
200
RS92-P
PRS92
300
GTS1-P
400
500
600
700
800
900
1000
-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0
Difference between tests and RS92
1100 0
hPa
200
400
600
800
1000
P
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Pressure
hPa
hPa
0
0
100
100
200
200
300
300
400
400
PRS92
PRS92
GTS1-2 advanced version
GTS1-2
500
600
500
600
700
700
800
800
900
900
1000
-1.00
0.00
1.00
2.00
3.00
Difference between PGTS1-2 and PRS92(℃)
℃
1000
-1.50
-1.00
-0.50
0.00
0.50
1.00
hPa
Difference between PGTS1-2 advanced and PRS92
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Temperature
0
100
200
PRS92（hPa）
300
400
GTS1-2-RS92
500
GTS1-2
GTS1-RS92
GTS1
600
GTS1-2-T
700
RS92-T
800
GTS1-T
900
1000
-2.0
-2.0
-1.1
-0.3
0.6
1.5
2.4
Difference T（℃）
-70
-60
-50
-40
-30
-20
1100
-10
0
10
20
T（℃）
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Temperature
GTS1-2 advanced version
hPa
0
100
200
PRS92
300
400
500
600
700
800
900
1000
-1.50
-1.00
-0.50
0.00
0.50
℃
Difference between TGTS1-2 advanced and TRS92
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Humidity
GTS1-2-RS92
GTS1-RS92
GTS1-2-U
RS92-U
GTS1-U
0
100
P R S 92（ hP a ）
200
300
GTS1-2
400
500
600
GTS1
700
800
900
1000
1100
0
Defference U（%RH）
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
U（%RH）
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Wind Direction
Wind Speed
GTS1 & GTS1-2 (using the same type of L-band radar)
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Wind Direction
RS92
GTS1-2 advanced
1000
900
900
800
800
700
700
600
500
400
500
400
300
200
200
100
100
0
0
100
200
Wind direc tion (°)
300
400
GTS1-2 advanced
600
300
0
RS92
1000
P R S 92 (hP a)
P R S 92 (hP a)
Wind Speed
0
5
10
15
20
25
30
Wind s peed (m/s )
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5. Conclusion
• The temperature sensor of radiosonde used
in China has been changed from the rodshaped thermistor to bead thermistor
gradually, the measurement accuracy has
been improved significantly, and the
radiation error has also been effectively
corrected.
• At present, the GTS1-2 radiosonde has
better performance than GTS1, but the
humidity measurement still exist a certain
gap compared with RS92.
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• Through software algorithm, bias for
pressure measurement can be corrected
largely.
• Current operational wind calculation method
has relative large wind pulse affection, and
some real results reflecting the wind speed
and direction have also been smoothed. The
moving average vector method can better
eliminate the pulsation effect. If using the 1
minute moving average window to calculate
the upper-air wind per second, it can be
consistent with GPS wind measurement.
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