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Observations of Cloud Condensation Nuclei in North China

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Acta meteorologica Sinica 2008年第1期22卷 97-106页

作者：石立新段英 weather modification office of Hebei Province

Using a DMT （Droplet Measurement Technologies） continuous flow streamwise thermal gradient cloud condensation nuclei （CCN） counter mounted on a Cheyenne IIIA aircraft, about 20 flights for aircraft mea- surements of CCN over North China were conducted in the autumn of 2005 and spring of 2006. According to the design for aircraft observation, the method of spiral ascent or descent in the troposphere was used for the vertical measurement of CCN, and some certain levels were chosen for horizontal measurement. The vertical distributions of CCN concentrations show that most CCN particles are concentrated in the low level of troposphere and CCN concentration decreased with height increasing. It suggests that the main source of CCN is from the surface. This result is consistent with former studies during 1983-1985 in China with a static thermal gradient CCN counter. The comparison of vertical observations between polluted rural area near Shijiazhuang and non-polluted rural area near Zhangjiakou shows that there is about five times difference in CCN concentration. But over two polluted cities, Shijiazhuang and Handan, there is no notable difference in CCN concentration. The horizontal flight measurements for penetrating the cumulus clouds experiment show the apparent decrease of CCN in clouds. It confirms that cloud has a definite consumptive effect on CCN particles because some CCN particles can form cloud droplets. The surface measurements of CCN in Shijiazhuang City were made during June-August 2005. The statistical CCN data show the great difference in concentration at the same supersaturation （S） in Shijiazhuang summertime. The minimum CCN concentrations were 584, 808, and 2431 cm-3, and the maximum concentrations were 9495, 16332, and 21812 cm-3 at S=0.1%, 0.3%, and 0.5%, respectively. CCN has a diurnal variation cycle. From 0600 BT, the concentration began to increase and reached the maximum at about noon. Then it generally decreased throughout the afternoon. The re

关键词： North China cloud condensation nuclei (CCN) observation

Characteristics of Cloud Water Resource and Precipitation Efficiency of Hydrometeors over Northwest China

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Journal of Meteorological Research 2023年第3期37卷 353-369页

作者： Zhanyu YAO Lin AN Pei ZHANG Liangshu GAO Shuo JIA Weijian WANG Wenhui ZHAO China Meteorological Administration Cloud–Precipitation Physics and weather modification Key Laboratory Weather Modification CentreChina Meteorological AdministrationBeijing 100081

Understanding the characteristics of cloud water resource(CWR)and precipitation efficiency of hydrometeors(PEh)is imperative for the application of CWR in Northwest *** atmospheric precipitable water(PW)in all four seasons and clouds and PEh in summer were studied with ERA-5 and CloudSat data in this *** results show that topography,especially in the Tibetan Plateau,exerts significant impacts on the precipitation and PW in summer,since large amounts of clouds are distributed along the mountain *** study region is divided into four typical areas:the monsoon area in eastern Northwest China(NWE),the Qilian Mountains area(QM),the Tianshan Mountains area(TM),and the Source of Three Rivers area(STR).Over the four areas,cloud top height(6.3 km)and cloud base height(3.3 km)over NWE are higher,and precipitating clouds are thicker(7 km)in the single-layer *** water content decreases with increasing altitude,while the ice water content first increases and then *** water path is higher over NWE(0.11 kg m^(−2))than over TM and STR(0.05 kg m^(−2)),and the ice water path is mainly concentrated within the range of 0.025–0.055 kg m^(−2).The PEh values are distributed unevenly and affected evidently by the *** the PEh values in the four typical areas(0.3–0.6)are higher than those in other regions,the CWR is relatively abundant and has a higher exploitation ***,it is well-founded to exploit CWR for alleviating water shortages in these areas of Northwest China in summer.

关键词： cloud water resource(CWR) precipitation efficiency of hydrometeors(PEh) precipitable water(PW) cloud Northwest China

Shape Classification of Cloud Particles Recorded by the 2D-S Imaging Probe Using a Convolutional Neural Network

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Journal of Meteorological Research 2023年第4期37卷 521-535页

作者： Rong ZHANG Haixia XIAO Yang GAO Haizhou SU Dongnan LI Lei WEI Junxia LI Hongyu LI Cloud–Precipitation Physics and weather modification Key Laboratory(CPML) China Meteorological AdministrationBeijing 100081 CMA weather modification Centre China Meteorological Administration(CMA)Beijing 100081 Key Laboratory of Transportation Meteorology of China Meteorological Administration Nanjing Joint Institute for Atmospheric SciencesNanjing 210041 Heilongjiang weather modification office Harbin 150030

The airborne two-dimensional stereo(2D-S) optical array probe has been operating for more than 10 yr, accumulating a large amount of cloud particle image data. However, due to the lack of reliable and unbiased classification tools,our ability to extract meaningful morphological information related to cloud microphysical processes is limited. To solve this issue, we propose a novel classification algorithm for 2D-S cloud particle images based on a convolutional neural network(CNN), named CNN-2DS. A 2D-S cloud particle shape dataset was established by using the 2D-S cloud particle images observed from 13 aircraft detection flights in 6 regions of China(Northeast, Northwest, North,East, Central, and South China). This dataset contains 33,300 cloud particle images with 8 types of cloud particle shape(linear, sphere, dendrite, aggregate, graupel, plate, donut, and irregular). The CNN-2DS model was trained and tested based on the established 2D-S dataset. Experimental results show that the CNN-2DS model can accurately identify cloud particles with an average classification accuracy of 97%. Compared with other common classification models [e.g., Vision Transformer(ViT) and Residual Neural Network(ResNet)], the CNN-2DS model is lightweight(few parameters) and fast in calculations, and has the highest classification accuracy. In a word, the proposed CNN-2DS model is effective and reliable for the classification of cloud particles detected by the 2D-S probe.

关键词： cloud particles particle shape 2D-S probe shape classification convolutional neural network

Mesoscale Numerical Simulation Study of Warm Fog Dissipation by Salt Particles Seeding

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Advances in Atmospheric Sciences 2016年第5期33卷 579-592页

作者： Hui HE Xueliang GUO Xiang'e LIU Qian GAO Xingcan JIA beijing weather modification office Beijing 100089 Key Laboratory of beijing for Cloud Precipitationand Atmospheric Water ResoumesBeijing 100089 Chinese Academy of Meteorological Sciences Beijing 100081

Based on the dynamic framework of WRF and Morrison 2-moment explicit cloud scheme, a salt-seeding scheme was developed and used to simulate the dissipation of a warm fog event during 6–7 November 2009 in the beijing and Tianjin area. The seeding effect and its physical mechanism were studied. The results indicate that when seeding fog with salt particles sized 80 μm and at a quantity of 6 gm^（-2） at the fog top, the seeding effect near the ground surface layer is negative in the beginning period, and then a positive seeding effect begins to appear at 18 min, with the best effect appearing at 21 min after seeding operation. The positive effect can last about 35 min. The microphysical mechanism of the warm fog dissipation is because of the evaporation due to the water vapor condensation on the salt particles and coalescence with salt *** process of fog water coalescence with salt particles contributed mostly to this warm fog dissipation. Furthermore, two series of sensitivity experiments were performed to study the seeding effect under different seeding amounts and salt particles sizes. The results show that seeding fog with salt particles sized of 80 μm can have the best seeding effect, and the seeding effect is negative when the salt particle size is less than 10 μm. For salt particles sized 80 μm, the best seeding effect, with corresponding visibility of 380 m, can be achieved when the seeding amount is 30 g m^（-2）.

关键词： warm fog fog dissipation salt-seeding scheme physical mechanism seeding effect

Ground-high altitude joint detection of ozone and nitrogen oxides in urban areas of beijing

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Journal of Environmental Sciences 2013年第4期25卷 758-769页

作者： Pengfei Chen Qiang Zhang Jiannong Quan Yang Gao Delong Zhao Junwang Meng beijing weather modification office Institute of Urban Meteorology China Meteorological AdministrationPost-Doctoral Scientific Research Workstation of Urban Meteorology and Urban Disasters

Based on observational data of ozone （O3） and nitrogen oxide （NOx） mixing ratios on the ground and at high altitude in urban areas of beijing during a period of six days in November 2011, the temporal and spatial characteristics of mixing ratios were analyzed. The major findings include： urban O3 mixing ratios are low and NOx mixing ratios are always high near the road in November. Vertical variations of the gases are significantly different in and above the planetary boundary layer. The mixing ratio of O3 is negatively correlated with that of NOx and they are positively correlated with air temperature, which is the main factor directly causing vertical variation of O3 and NOx mixing ratios at 600-2100 m altitude. The NOx mixing ratios elevated during the heating period, while the O3 mixing ratios decreased： these phenomena are more significant at high altitudes compared to lower altitudes. During November, air masses in the urban areas of beijing are brought by northwesterly winds, which transport O3 and NOx at low mixing ratios. Due to beijing＇s natural geographical location, northwest air currents arc beneficial to the dilution and dispersion of pollutants, which can result in lower O3 and NOx background values in the beijing urban area.

关键词： atmospheric pollution ozone nitrogen oxides spatial distribution aircraft sound

Atypical Occlusion Process Caused by the Merger of a Sea-breeze Front and Gust Front

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Advances in Atmospheric Sciences 2015年第10期32卷 1431-1443页

作者： Abuduwaili ABULIKEMU XU Xin WANG Yuan DING Jinfeng WANG Yan Key Laboratory of Mesoscale Severe weather(Ministry of Education) School of Atmospheric SciencesNanjing University Tianjin weather modification office

An atypical occlusion process that occurred in North China on 14 July 2011 is studied based on both observations and a real-data weather Research and Forecasting （WRF） model simulation. The results show that this atypical occlusion process was significantly different from the traditional, synoptic-scale occlusion process that occurs within extratropical cyclones. It was caused by the merger of two cold-type mesoscale fronts. One of the fronts developed from the gust front of convective storms, while the other was a sea-breeze front. As the two fronts moved towards each other, the warm air between them was squeezed and separated from the surface. An atypical occluded front was formed when the two fronts merged, with the warm air forced aloft. This kind of occlusion is termed a ＂merger＂ process, different from the well-known ＂catch-up＂ and ＂wrap-up＂ processes. Moreover, local convection was found to be enhanced during the merger process, with severe convective weather produced in the merger area.

关键词： occlusion process sea-breeze front gust front merger

Analysis of the causes of heavy aerosol pollution in beijing,China:A case study with the WRF-Chem model

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Particuology 2015年第3期13卷 32-40页

作者： Hui He Xuexi Tie Qiang Zhang Xiange Liu Qian Gao Xia Li Yang Gao beijing weather modification office Key Laboratory of Aerosol Science and Technology SKLLQGInstitute of Earth EnvironmentChinese Academy of Sciences National Center for Atmospheric Research

The causes and variability of a heavy haze episode in the beijing region was analyzed. During the episode, the PM2.5 concentration reached a peak value of 450 μg/kg on January 18, 2013 and rapidly decreased to 100μg/kg on January 19, 2013, characterizing a large variability in a very short period. This strong vari- ability provides a good opportunity to study the causes of the haze formation. The in situ measurements （including surface meteorological data and vertical structures of the winds, temperature, humidity, and planetary boundary layer （PBL）） together with a chemical/dynamical regional model （WRF-Chem） were used for the analysis. In order to understand the rapid variability of the PM2.5 concentration in the episode, the correlation between the measured meteorological data （including wind speed, PBL height, relative humidity, etc.） and the measured particle concentration （PM2.5 concentration） was studied. In addition, two sensitive model experiments were performed to study the effect of individual contribution from local emissions and regional surrounding emissions to the heavy haze formation. The results suggest that there were two major meteorological factors in controlling the variability of the PM2.5 concentration, namely, surface wind speed and PBL height. During high wind periods, the horizontal transport of aerosol particles played an important role, and the heavy haze was formed when the wind speeds were very weak （less than 1 m/s）. Under weak wind conditions, the horizontal transport of aerosol particles was also weak, and the vertical mixing of aerosol particles played an important role. As a result, the PBL height was a major factor in controlling the variability of the PM2.5 concentration. Under the shallow PBL height, aerosol particles were strongly confined near the surface, producing a high surface PM2.5 concentration. The sensitivity model study suggests that the local emissions （emissions from the beijing region only） were the major cause for

关键词： PM2.5 in beijingCauses of heavy hazePlanetary boundary layer (PBL)WRF-Chem model

Observation of black carbon aerosol in beijing, 2003

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Frontiers of Environmental Science & Engineering 2007年第3期1卷 345-349页

作者： LOU Shujuan MAO Jietai WANG Meihua beijing weather modification office Beijing 100089China Department of Atmospheric Sciences Peking UniversityBeijing 100871China

The objective of this study was to determine the black carbon concentration in beijing in *** aerosol properties were measured using an Aethalometer and a tapered element oscillating microbalance(TEOM)on the roof of the Physics Building of Peking University(39.99°N,116.31°E)from July to August 2003 and from November 2003 to January *** average black carbon(BC)concentrations in the summer and winter were 8.80 and 11.4μg/m3,*** winter,two different cyclone cut offs were installed at the inlet of an *** BC mass concentration in TSP,PM_(10),and PM_(2.5)were *** results indicated that in winter aerosol,90%of BC exited in PM_(10)and 82.6%of BC exited in PM_(2.5).The BC in PM_(10)accounted for 5.11%of the PM_(10)mass.

关键词： black carbon aerosol PM_(10) Aethalometer

Microphysical Properties of Convective Clouds in Summer over the Tibetan Plateau from SNPP/VIIRS Satellite Data

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Journal of Meteorological Research 2019年第3期33卷 433-445页

作者： Zhiguo YUE Xing YU Guihua LIU Jin DAI Yannian ZHU Xiaohong XU Ying HUI Chuang CHEN Meteorological Institute of Shaanxi Province Xi'an 710014 office of weather modification of Shaanxi Province Xi'an 710014

The Tibetan Plateau (TP) plays an important role in formation and development of the East Asian atmospheric circulation, climate variability, and disastrous weathers in China. Among the many topics on TP meteorology, it is critical to understand the microphysical characteristics of clouds over the TP;however, observations of the cloud microphysics in this area are insufficient mainly due to sparse stations and limited cloud physical data. The Visible Infrared Imaging Radiometer Suite (VⅡRS), onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite, has an improved imaging spectroradiometer with 17 channels of 750-m moderate resolution and 5 channels of 375-m image resolution. The high-resolution instrument has an advantage for observing the small or initial convective clouds. Based on the methodologies that we proposed before for retrieving cloud microphysical properties from SNPP, an automated mapping software package named Automatic Mapping of Convective Clouds (AMCC) has been developed at the scale of satellite swath. The properties of convective clouds are retrieved by AMCC and their values are averaged over 0.33°×0.33° grids based on the SNPP/VⅡRS satellite data over the TP during the summers of 2013-17. The results show that:(1) the temperature of lifting condensation level (TLCL) at Naqu meteorological station and the cloud base temperature (Tb) retrieved from VⅡRS are linearly correlated, with a correlation coefficient of 0.87 and standard deviation (STD) of 3.0℃;(2) convective clouds over the TP have the following macro-and microphysical properties. First, the cloud base temperature (Tb) is about -5℃, the cloud base height above the ground (Hb) ranges between 1800 and 2200 m, and the cloud water content is low. Second, the cloud condensation nuclei concentration (NCCN) is between 200 and 400 mg-1 with 0.7% in maximum supersaturation (Smax);consequently, the condensation growth of water cloud droplet with less NCCN and higher Smax is fast. Thir

关键词： Tibetan Plateau Visible Infrared Imaging Radiometer Suite (VⅡRS) retrieval of cloud microphysical properties convective cloud cloud base temperature cloud condensation nuclei