Li Bai Beijing 100081,[email protected]@cma.gov.cn
2012/10/16 The Auxiliary Remote Sensing Observation Data Analysis
of 8th Yangjiang International Radiosonde Intercomparison
Slide 2
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
Slide 3
The Major Objective of the Experiment Cloud Radar Micro Pulse
Lidar GPS/Met 3 Km Wind Profiler X Band Doppler Radar S band
Doppler Radar 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.
Slide 4
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.
Slide 5
All of Participating Auxiliary Remote Sensor Equipments
Microwave radiometer Lidar Ceilometer Wind Profiler X-band dual
polarization Doppler radars Laser Doppler Radar Ka band Could Radar
Micro Pulse Lidar X-band dual polarization Doppler radars S-band
Doppler radars 1 profiler radar, 2 MPLs and 1 microwave radiometer
at the sounding release point, 2 Ka-band cloud radar and 2 X- band
dual polarization Doppler weather radars at different locations
about 3km away from the observing station.
Slide 6
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. Participating Instruments and Data
Acquisition
Slide 7
The Experiment Design of the Auxiliary Remote Sensor
Observation 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 layout of X band Doppler radar and Cloud
Radar during the Intercomparision in Yangjiang The site of Sounding
and S band Doppler radar The site of X band Doppler radar and Ka
band cloud radar The site of X band Doppler radar and Cloud radar
The schematic diagram of synchronism of the observed space The bird
eye view of Yangjiang site
Slide 8
The Airspace and Prevail Wind on Yangjiang Site Wind Direction
Frequency Picture The shelter picture from eight directions The
photo from eight directions
Slide 9
Design of layout location on Wind Profiler Get observation data
as much as possible in same space during the sounding
Slide 10
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 Scheme I Scheme II
Slide 11
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
Slide 12
Brief Description of the Test Results Analysis of night
temperature errors from LMS multi-black sensor radiosondes. (1)
Assessment on the influence of upper-air infrared radiation from
clouds The picture is the temperature errors (Black and aluminium
coating) No Cloud Weak stratiform Cloud Thick High Cloud 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
Slide 13
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
Slide 14
(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. Brief
Description of the Test Results 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.
Slide 15
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
Slide 16
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
Slide 17
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
Slide 18
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 other remote sensor
instruments
Slide 19
3.2 Evaluation on the performance of China-made remote
instruments Evaluation on the performance of Micro Pulse Lidar 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. Return signals of atmosphere particles and depolarization
ratio detected by MPL at 23:00 July 20, 2010 in Yangjiang.
Slide 20
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
Slide 21
(1) Improvement of cloud estimating algorithm for radiosondes
3.3 Research on remote sensing observation algorithm improvement
The information from the remote sensor observation is helpful to
improve the estimating algorithm of cloud by using sounding
data
Slide 22
The multi-layer structure of cloud could be detected by cloud
radar and the result can be used to test the radiosonde. 55 44 33
22 11 Comparsion of observation results between the radiosonde and
Ka band cloud radar
Slide 23
(2) Echo recognition algorithm of X-band polarization radar 3.3
Research on remote sensing observation algorithm improvement
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.
Slide 24
3.4 Atmospheric structure and process observation in South
China Sea areas. The 0 layer bright band in No. 3 typhoon cloud
that X-band radar observed in 2010. ReflectivityDifferent
Reflectivity Linear depolarization ratioRelative Coefficient
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.
Slide 25
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
Slide 26
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. The ratio of the
upper,middle and low cloud
Slide 27
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
Slide 28
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 Convergence at low level Divergence at high level
Existing shear in middle level Divergence at low level Development
in front of the cloud Attenuation in back of the cloud The stage of
occurrence and development
Slide 29
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 high- precision 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.
Slide 30
Any comments or questions will be welcome!
Slide 31
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.