The Auxiliary Remote Sensing Observation Data Analysis of
8th Yangjiang International Radiosonde Intercomparison
Li Bai
Beijing，100081,libai@cma.gov.cn
2012/10/16
Main Content
 The Experiment Design and Brief Introduction
 Brief Description of the test results
 Atmospheric Structure and Process Observation
in South China Sea Areas
 Summary
The Major Objective of the Experiment
GPS/Met
X Band Doppler Radar
Micro Pulse Lidar
In order to improve the scientific value of this test, Meteorological Observation
Center of China Meteorological Administration (CMA) co-held a remote-sensing
observation experiment in Yangjiang during the corresponding period together
with more than 10 meteorological observation technology research institutes and
equipment manufacturers.
3 Km Wind Profiler
The Major Objective of the Experiment
By comparing the observation data from radiosondes and various remote
equipment,
 To analysis and verification is to be done to finish the error analysis and
performance evaluation of some China-made remote instruments , such
as X-band dual polarization radars, wind profiler radars, cloud radar, MPL
and cloud automatic observation equipment and etc. ;
 To conduct an integrated observation experiment with the instruments
including radiosondes and various remote equipment in the same region,
 To do the research on the integrated observation methods of multiple
observation instruments;
 To research on the evolution characteristics of typical tropical weather
systems by using high quality radiosondes and remote instruments.
All of Participating Auxiliary Remote Sensor
Equipments
微波辐
Microwave
radiometer
射计
风廓线
Wind
Profiler
雷达
毫米波
Ka
band
Could
云雷达
Radar
地基红外
测云仪
X波段双
X-band
dual
polarization
Doppler
偏振雷达
radars

激光测
Lidar
Ceilometer
云仪
激光测
Laser
风雷达
Doppler
无线电
经纬仪
微脉冲激光雷
Micro Pulse
Lidar
达（2部）
激光测
云仪
扫描式红外
天空成像仪
Radar
GPS-MET
全天空成
像仪
地基全天空
云观测仪
X波段双
X-band
dual
polarization
Doppler
偏振雷达
radars
全天空成
像仪
S-band
S波段
Doppler
雷达
radars
1 profiler radar, 2 MPLs and 1 microwave radiometer at the sounding release point, 2 Ka-band cloud radar and 2 Xband dual polarization Doppler weather radars at different locations about 3km away from the observing station.
Participating Instruments and Data Acquisition
During Total 72 balloons:
 24 hours continuously observation for laser ceilometer,
MPL laser radar, GPS/MET, wind profiler , microwave
radiometer and other fixed remote equipment.
 Total about 60 times for cloud radar and X-band radar
followed the globe, observing with RHI model.
 Observations for typical convective clouds using cloud
radar and X-band radar.
 Observations of No. 2 and No. 3 typhoons in 2010.
The Experiment Design of the Auxiliary Remote Sensor
Observation
The site of X band Doppler radar
and Cloud radar
The site of X band Doppler radar
and Ka band cloud radar
The site of Sounding and S band
Doppler radar
The schematic diagram of
synchronism of the observed space
The layout of X band Doppler radar and
Cloud Radar during the Intercomparision in
Yangjiang
The bird eye view of Yangjiang site
For the goal of comparison among sounding observations and different remote equipments, it is necessary to
realize the synchronism of the observed space, so in order to realize the continuous observation in the same
atmospheric column for the same target and continuously obtain the vertical profiles and detailed cloud
structure of atmospheric elements (temperature, humidity, pressure and wind),
The Airspace and Prevail Wind on Yangjiang Site
The shelter
picture from
eight directions
The photo from
eight directions
Wind Direction Frequency Picture
Design of layout location on Wind Profiler
气球
气球
气球漂移轨迹
气球漂移轨迹
3km
地平面
1.3km
风廓线雷达
气球
气球漂移轨迹
3km
1.3km
地平面
风廓线雷达
风廓线雷达
2km
0.89km
0.89km
2km
2km
0.89km
1km
0.44km
1km
0.44km
3km
1.3km
地平面
1km
0.44km
1.3km
1km
2km
3km
3km
1km
4.5km
2km
4km
3km
4.5km
1km
2km
4km
3km
4.5km
3km
1.3km
2km
0.89km
气球
气球漂移轨迹
0.44km
1km
地平面
Get observation data as
much as possible in same
space during the sounding
风廓线雷达
1km
2km
4km
3km
4.5km
气球
3km
1.3km
气球
气球漂移轨迹
3km
1.3km
地平面
3km
气球漂移轨迹
1.3km
地平面
风廓线雷达
风廓线雷达
0.89km
2km
2km
2km
0.89km
0.89km
气球
气球漂移轨迹
0.44km
1km
地平面
1km
1km
0.44km
0.44km
风廓线雷达
1km
2km
3km
4km
4.5km
1km
2km
3km
4km
4.5km
1km
2km
3km
4km
4.5km
Integrated layout of The remote sensor Equipments
According to the investigation results , we make two layout scheme as follows:
The first scheme is that all of the auxiliary remoter sensor equipments are located
in east side, i.e. in downstream of prevailing wind in Yangjiang;
The second scheme is that all of the auxiliary remoter sensor equipments are
located around the sounding site
X波段天气雷达
X波段天气雷达
云雷达
云雷达
风廓线雷达
风廓线雷达
放球点
放球点
Scheme I
Scheme II
Brief Description of the Test Results
3.1 Verification of the detection performance of radiosondes
This remote-sensing experiment offered very good assistant
observation data for global radiosonde intercomparison, playing a
significant role for WMO to evaluate the detection performance abilities of
the temperature and humidity sensors of various radiosondes.
 Assessment on the influence of upper-air infrared radiation
 Humidity identification and detection of cloud radar and ceilometer
 Vapour measurement comparison between China-made GPS/Met
and radiaosondes
 Intercomparison of wind-measuring capabilities of wind profiler and
radiosondes
Brief Description of the Test Results
(1) Assessment on the influence of upper-air infrared radiation from clouds
Thick High
Cloud
No
Cloud
Weak stratiform
Cloud
The picture is the temperature errors (Black and aluminium coating)
Analysis of night temperature errors from LMS multi-black sensor radiosondes.
During the experiment ,the cloud can be detected by Ka band cloud radar , it can supply whether the clouds exist . When there are clouds in
the stratosphere, typical heat exchange effect of infrared radiation can be produced. Whether it is daytime or nighttime, this effect can cause
the temperature of sensors to drop 0.2K and the cooling effect appears even stronger near the tropopause (Shown as Fig. 2).. Auxiliary remote
sensor observation supply the valuable data whether cloud exist These results have been adopted by WMO Assessment Report
Brief Description of the Test Results
(2) Humidity observation and identification by using the cloud radar and ceilometer
Fig 3 show that the results of the humidity observation in range of the threshold under the clouds
existing ,by using the information obtained by the auxiliary remote equipments,
the cloud observations of cloud radar and ceilometer can also be helpful
 to analyze the intracloud hydrometeor particles phase;
 to judge whether the radiosondes get frozen so that the observation data is missed.
The valuable results also be adopted by WMO Assessment Report
Brief Description of the Test Results
(3) Vapour measurement comparison between China-made GPS/Met and
radiaosondes
The results show that the system error values of the radiosondes in daytime and
nighttime were obtained, which proves again that in the past international
intercomparisons of the radiosondes which detected smaller difference of vapour values
between day and night in the lower troposphere show smaller gap between the day and
night values when compared with GPS.
The Fig show that System deviations of humidity data detected by all types of radiosondes compared to the GPS/Met
vapour amount in Yangjiang, Enping and Yangchun stations.
Brief Description of the Test Results
(4) Intercomparison of wind-measuring capabilities Between wind
profiler and radiosondes

During the Yangjiang EXPERIMENT , wind profiler data, during
launching of 62 balloons is used to compare to the wind
measurement data between the radiosondes and wind profiler.

In addition to evaluating the difference of wind-measuring capabilities
of radiosondes and to analyzing the performance and capability of
wind measurement of wind profilers by taking the sounding data for
reference.
The usable results similarly were adopted by WMO Assessment
Report
3.2 Evaluation on the performance of China-made remote instruments
(1)
Evaluation on Ka-band cloud radar and X-band dual polarization
radar
(2)
Evaluation on Wind Profiler
(3)
Evaluation on Micro Pulse Lidar
(4)
Evaluation on Microwave radiometer
(5)
Evaluation on Doppler wind-lidar
The intercomparsion between the Ka band cloud radar and
X band dual polarization for the same target
Fig show that reflectivity Ka cloud radar and X band
radar
Fig show that doppler velocity between Ka cloud radar
and X band radar
Fig show that spectrum width width between Ka cloud
radar and X band radar
Fig show that LDR between Ka cloud radar and X band
radar
3.2 Evaluation on the performance of China-made
remote instruments
Evaluation on the performance of other remote sensor instruments
 Wind Profiler :
In this test, various radiosondes were compared to the wind profiler. In general, under
the 3000-m height, the mean difference and standard deviation of wind measurement of
the wind profiler and L-band radar are 1.3m/s and 2.0 m/s respectively while those for
wind profiler and GPS are 1.4m/s and 1.9 m/s respectively.
 Microwave radiometer
The Yangjiang experiment provided quite a good test platform for testing the
adaptability of microwave radiometer to local observations and improving the algorithm.
On the basis of utilizing the intercomparison of detected bright temperature and
simulated bright temperature, we used the detected values and the corresponding
sounding samples to adjust the BP neural networks. And finally, the correlation
coefficients of temperature and vapour density could respectively reach 0.98579 and
0.92438.
 Doppler Wind-Lidar
The result shows that the existing laser wind radar can detect not only atmospheric
wind fields, but also clouds and extinction coefficient. Relative to MPL, the mobile
Doppler lidar has much higher power, being able to detect more details of clouds and
multi-layer clouds.
3.2 Evaluation on the performance of China-made
remote instruments
Evaluation on the performance of Micro Pulse Lidar
Return signals of atmosphere particles and depolarization ratio detected by MPL at 23:00 July 20, 2010 in Yangjiang.
By analyzing the depolarization ratio characteristics, the result show that although there are more clouds in
Yangjiang region, the pure ice crystal clouds are not common, and, even in the mixed clouds with ice
crystals, the amount of ice crystal is not too many. The depolarization ratio value does not exceed 0.3
essentially. The mixed clouds mainly appear in the upper atmosphere higher than 9 km. The clouds with the
cloud base height being 3-9km are mostly pure liquid clouds whose depolarization ratio is very small, almost
the same as the depolarization ratio of aerosols at the same height.
3.3 Research on remote sensing observation algorithm
Improvement
The Yangjiang experiment offered a platform to inspect and improve product
algorithm for China-made remote sensing instruments. By the intercomparison of
the various remote sensing data, some differences among the instruments were
discovered and their application capabilities got improved correspondingly.
(1)
Improvement of cloud estimating algorithm for radiosondes
(2) Characteristics of cloud particles and verification on water content
algorithm
(3) Improvement of quality-control algorithm of X-band polarization
radar data
(4) Echo recognition algorithm of X-band polarization radar
3.3 Research on remote sensing observation
algorithm improvement
(1) Improvement of cloud estimating algorithm for radiosondes
The information from the remote sensor observation is helpful to improve the estimating algorithm of
cloud by using sounding data
Comparsion of observation results between the radiosonde
and Ka band cloud radar
2010-07-17 14:51
20
ML-water
ML-ice
Daqiao-water
Midldle-RH
Min-RH
Max-RH
Height (km)
15
第5层
第4层
10
第3层
5
第2层
第1层
0
20
40
60
80
100
Relative humidity (%)
The multi-layer structure of cloud could be detected by cloud radar and
the result can be used to test the radiosonde.
120
3.3 Research on remote sensing observation
algorithm improvement
(2) Echo recognition algorithm of X-band polarization radar
Classification of precipitation particles in stratus clouds on July 22, 2010.
By using X dual polarization doppler radar, we can make the classification of
precipitation particle in stratus including ice crystal ,dry snow , wet snow, drizzle etc.
3.4 Atmospheric structure and process observation in
South China Sea areas
Reflectivity
Linear depolarization ratio
Different Reflectivity
Relative Coefficient
. The 0℃ layer bright band in No. 3 typhoon cloud that X-band radar observed in 2010.
Yangjiang adjoins the South China Sea, having typical atmospheric system structure features. By means of the Yangjiang experiment,
all kinds of advanced remote instruments were used to do scientific observations on the typical and characteristic cloud structures and
weather systems in this region.
By the analysis on the echo reflectivity and linear depolarization ratio (LDR) of cloud radar, it was found that in different heights the
liquid particles are in different sizes and there are up-and-down turbulence motions and obvious fragmentation and evaporation
phenomenon inside the clouds. The previous conventional observations could not reveal these findings.
The feature of the boundary structure and land and sea
breeze in south sea of China
By using Ka band cloud radar and wind profiler , we cloud obtain the land and sea breeze structure in
south sea of china . In daytime , low level blows south wind and high level blows north wind and in
night time, it is opposite . This is helpful to verification of the radiosonde observation
Nighttime
Daytime
2010年07月12日06时44分
2010年07月12日12时59分
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2010年07月20日14时59分
2010年07月20日21时14分
The equipments of cloud automatic observation on surface supply to the
value information for radiosonde
 The value information includes amount
of cloud and hight of cloud base and etc.
 It is helpful to conduct intercomparsion
of radiosondes and improve better the
equipment of cloud observation .
中云
低云
The
ratio of the upper ,middle and low cloud
7月12—20日阳江高中低云比例
高云
中云
低云
7月12日-7月20日阳江云高时间序列图
12000
10000
8000
6000
4000
2000
0
高云
高云平均值
中云平均值
低云平均值
Convective Cloud development detected by Ka
Band Cloud radar
By using Ka band cloud observation , we can find many
detail structure inside of the cloud , such as :
 upper wind shear
 slant updraft
 the drag downdraft
 the involving from middle level
高层切变
倾
斜
上
升
气
流
下
曳
气
流
中层卷入
The analysis of convective precipitation during
Yangjiang Experiment
During Yangjiang Experiment , the convective cloud evolution was observed by
cloud radar and it help to research the weather system
Divergence at
high level
The stage of occurrence and development
Attenuation in
back of the
cloud
Development in
front of the
cloud
The stage of occurrence and development
Divergence at
low level
Convergence
at low level
Existing shear
in middle level
Summary
 The Yangjiang experiment adopted the Integrated observation model, having
done careful observations on the atmospheric structure, cloud classification
and convective weather systems in Yangjiang tropical region. The highprecision and successional observation data afford detailed information for the
research on the basic characteristics and regular patterns of the atmosphere in
this region. Up to now, scientists at home and abroad have utilized these data
and conducted various analyses and studies, obtaining abundant achievements
in the stage
 The Yangjiang experiment was an integrated test in real sense. The test results
show that reasonable observation layouts and the scientific united observation
model that the experiment adopted will directly influence the analysis and
assessment results of the comparison between the remote experiment and
radiosondes as well as the intercomparison of remote sensing instruments
themselves. We have tried to distribute the instruments for this integrated test
reasonably, but there are still many aspects deserving to summarize and study.
 In a word, the 8th WMO Intercomparison of Radiosondes and Integrated
Remote Instruments Experiment have afforded a new means and try for the
remote sensing observation and prepared rich experiences for the future WMO
global radiosonde intercomparison and integrated tests.
Any comments or
questions will be
welcome!
The Action of the Auxiliary Remote Sensor
Observation
Based on the statistics of the WMO Assessment Report, the action as
follow :

among the 72 launched balloons, the cloud radar images from 54
balloons can be used. They are used to estimate the probability of
radiosondes to go through clouds, helping identify the infrared radiation
cooling that the white-painted sensors and black-white sensors have
experienced, judging when the radiosondes gets through the cloud top
near the tropopause in the process of launching balloons at night and,
then, analyzing the variation features of the sensors.