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Li Bai Beijing 100081,libai@cma.gov.cnlibai@cma.gov.cn 2012/10/16 The Auxiliary Remote Sensing Observation Data Analysis of 8th Yangjiang International Radiosonde Intercomparison

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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

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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.

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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.

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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.

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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

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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

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The Airspace and Prevail Wind on Yangjiang Site Wind Direction Frequency Picture The shelter picture from eight directions The photo from eight directions

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Design of layout location on Wind Profiler Get observation data as much as possible in same space during the sounding

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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

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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

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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

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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

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(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.

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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

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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

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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

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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

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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.

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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

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(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

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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

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(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.

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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.

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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

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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

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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

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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

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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.

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Any comments or questions will be welcome!

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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.