Microphysical Characteristics of Rainfall Based on Long-Term Observations with a 2DVD in Yangbajain,Tibet

Raindrop size distribution(DSD)plays a crucial role in enhancing the accuracy of radar quantitative precipitation estimates in the Tibetan Plateau(TP).However,there is a notable scarcity of long-term,high-resolution observations in this region.To address this issue,long-term observations from a two-dimensional video disdrometer(2DVD)were leveraged to refine the radar and satellite-based algorithms for quantifying precipitation in the hinterland of the TP.It was observed that weak precipitation(R<1,mm h-1)accounts for 86%of the total precipitation time,while small raindrops(D<2 mm)comprise 99%of the total raindrop count.Furthermore,the average spectral width of the DSD increases with increasing rain rate.The DSD characteristics of convective and stratiform precipitation were discussed across five different rain rates,revealing that convective precipitation in Yangbajain(YBJ)exhibits characteristics similar to maritime-like precipitation.The constrained relationships between the slopeΛand shapeμ,D_(m)and N_(w)of gamma DSDs were derived.Additionally,we established a correlation between the equivalent diameter and drop axis ratio and found that raindrops on the TP attain a nearly spherical shape.Consequently,the application of the rainfall retrieval algorithms of the dual-frequency precipitation radar in the TP is improved based on the statistical results of the DSD.

Erratum to:Deriving Temporal and Vertical Distributions of Methane in Xianghe Using Ground-based Fourier Transform Infrared and Gas-analyzer

“Diurnal variation of CH4 at the surface from spring to winter.The time units are in local time(+8 h UTC).The error bar is 1σfor all the observed hourly mean data within that season at that local time.”in the caption of Fig.8 on Page 604 should be“Diurnal variation of CH4 at the surface from spring to winter.The time units are in UTC.The error bar is 1σfor all the observed hourly mean data within that season at that local time.”

Advances in the Researches of the Middle and Upper Atmosphere in China in 2012–2014

In this report we summarize the research results by Chinese scientists in 2012–2014. The focuses are placed on the researches of the middle and upper atmosphere, specifically the researches related to ground-based observation capability development, dynamical processes, the property of circulation and chemistry-climate coupling of the middle atmospheric layers.

Advances in the Researches of the Middle and Upper Atmosphere in China in 2014-2016

In this report the research results by Chinese scientists in 2014—2016 are summarized.The focuses are placed on the researches of the middle and upper atmosphere,specifically the researches associated with ground-based observation capabihty development,dynamical processes,and properties of circulation and chemistry-climate coupling of the middle atmospheric layers.

Advances in the Researches of the Middle and Upper Atmosphere in China

In this paper we summarize the research results by Chinese scientists in 2016–2018. The focuses are placed on the researches of the middle and upper atmosphere, specifically the researches associated with groundbased observation capability development, dynamical processes, and properties of circulation and chemistryclimate coupling of the middle atmospheric layers.

Distribution of lightning spatial modes and climatic causes in China

本文利用中国气象局国家雷电监测网(CNLDN)的地闪观测数据集,分析了2010-2020年中国陆地区域地闪空间模态分布特征及其可能的气候成因.研究发现,夏季地闪第一模态的方差贡献率为32.86%,其分布从北到南呈现出“-+-”的经向跷跷板模式,当东太平洋和印度洋的海温异常增暖,西北太平洋的海温异常变冷时,在中国黄海,东海及热带西太平洋地区激发出气旋性环流,随着水汽南下至华南地区,与来自孟加拉湾的水汽汇合,上升运动在此加强,从而使得该地区的雷电活动增强.表明厄尔尼诺-南方涛动(ENSO)现象,是发生在中国陆地区域的地闪活动的气候驱动因子。

Comparison between ozonesonde measurements and satellite retrievals over Beijing,China

从2013年开始,作者团队使用自主研发电化学原理臭氧探空仪在华北平原北京地区进行每周一次观测.本研究首次使用2013-2019年期间北京地区臭氧探空数据评估Aqua卫星搭载大气红外探测仪(AIRS)和Aura卫星搭载微波临边探测器(MLS)反演垂直臭氧廓线,并对比臭氧探空,AIRS和Aura卫星搭载臭氧监测仪(OMI)臭氧柱总量结果.尽管臭氧探空与卫星反演垂直臭氧廓线在局部高度处差异较大,但整体来说两者较为接近(相对偏差大多<10%).臭氧探空,AIRS和OMI三种仪器测量臭氧柱总量的年变化特征较为一致,其年均臭氧柱总量分别为351.8±18.4 DU,348.8±19.5 DU和336.9±14.2 DU.后续对国内多站点观测数据分析将有助于进一步理解臭氧探空与卫星反演臭氧资料在不同区域的一致性.

Initial Results of Lidar Measured Middle Atmosphere Temperatures over Tibetan Plateau

During August 2013,a mobile Rayleigh lidar was deployed in Lhasa,Tibet(29.6°N,91.0°E) for making measurements of middle atmosphere densities and temperatures from 30 to 90 km.In this paper,the authors present the initial results from this scientific campaign,Middle Atmosphere Remote Mobile Observatory in Tibet(MARMOT),and compared the results to the MSIS-00(Mass Spectrometer and Incoherent Scatter) model.This work will advance our understanding of middle atmosphere dynamic processes,especially over the Tibetan Plateau area.

Observation of a Summer Tropopause Fold by Ozonesonde at Changchun,China:Comparison with Reanalysis and Model Simulation

Tropopause folds are one of the key mechanisms of stratosphere-troposphere exchange （STE） in extratropical regions, transporting ozone-rich stratospheric air into the middle and lower troposphere. Although there have been many studies of tropopause folds that have occurred over Europe and North America, a very limited amount of work has been carried out over northeastern Asia. Ozonesondes produced by the Institute of Atmospheric Physics were launched in Changchun （43.9°N, 125.2° E）, Northeast China, in June 2013, and observed an ozone-enriched layer with thickness of 3 km and an ozone peak of 180 ppbv at 6 km in the troposphere. The circulation field from the European Centre for Medium-Range Weather Forecasts Interim Reanalysis （ERA-Interim） dataset shows that this ozone peak was caused by a tropopause fold associated with a jet stream at the eastern flank of the East Asian trough. By analyzing the ozone data from the ozone monitoring instrument and Weather Research and Forecasting model with Chemistry （WRF-Chem） simulations, it was found that a high ozone concentration tongue originating from the lower stratosphere at high latitude （near central Siberia） intruded into the middle troposphere over Changchun between 5 and 8 km on 12 June 2013. The high-resolution WRF-Chem simulation was capable of describing events such as the tropopause fold that occurred on the cyclonic shear side of the jet stream. In addition, the TRAJ3D trajectory model was used to trace the origin of measured secondary ozone peaks in the middle troposphere back, for example, to stratospheric intrusion through the tropopause fold.

Dynamic and Thermodynamic Features of Low and Middle Clouds Derived from Atmospheric Radiation Measurement Program Mobile Facility Radiosonde Data at Shouxian, China

By using the radiosonde measurements collected at Shouxian,China,we examined the dynamics and thermodynamics of single- and two-layer clouds formed at low and middle levels.The analyses indicated that the horizontal wind speed above the cloud layers was higher than those within and below cloud layers.The maximum balloon ascent speed（5.3 m s^-1） was located in the vicinity of the layer with the maximum cloud occurrence frequency（24.4%）,indicating an upward motion（0.1-0.16 ms^-1）.The average thickness,magnitude and gradient of the temperature inversion layer above single-layer clouds were117±94 m,1.3±1.3℃ and 1.4±1.5℃（100 m）^-1,respectively.The average temperature inversion magnitude was the same（1.3℃） for single-low and single-middle clouds;however,a larger gradient[1.7±1.8℃（100 m）^-1]and smaller thickness（94±67 m） were detected above single-low clouds relative to those above single-middle clouds[0.9±0.7℃（100 m）^-1 and157±120 m].For the two-layer cloud,the temperature inversion parameters were 106±59 m,1.0±0.9℃ and 1.0±1.0℃（100 m）^-1 above the upper-layer cloud and 82 ± 60 m,0.6±0.9℃ and 0.7±0.6℃（100 m）^-1 above the low-layer cloud.Absolute differences between the cloud-base height（cloud-top height） and the lifting condensation level（equilibrium level）were less than 0.5 km for 66.4%（36.8%） of the cases analyzed in summer.

The Impact of Cut-off Lows on Ozone in the Upper Troposphere and Lower Stratosphere over Changchun from Ozonesonde Observations

In situ measurements of the vertical structure of ozone were made in Changchun （43.53°N, 125.13°E）, China, by the Institute of Atmosphere Physics, in the summers of 2010-13. Analysis of the 89 validated ozone profiles shows the vari- ation of ozone concentration in the upper troposphere and lower stratosphere （UTLS） caused by cut-off lows （COLs） over Changchun. During the COL events, an increase of the ozone concentration and a lower height of the tropopause are observed. Backward simulations with a trajectory model show that the ozone-rich airmass brought by the COL is from Siberia. A case study proves that stratosphere-troposphere exchange （STE） occurs in the COL. The ozone-rich air mass transported from the stratosphere to the troposphere first becomes unstable, then loses its high ozone concentration. This process usually happens during the decay stage of COLs. In order to understand the influence of COLs on the ozone in the UTLS, statistical analysis of the ozone profiles within COLs, and other profiles, are employed. The results indicate that the ozone concentrations of the in-COL profiles are significantly higher than those of the other profiles between ±4 km around the tropopause. The COLs induce an increase in UTLS column ozone by 32% on average. Meanwhile, the COLs depress the lapse-rate tropopause （LRT）/dynamical tropopause height by 1.4/1.7 km and cause the atmosphere above the tropopause to be less stable. The influence of COLs is durable because the increased ozone concentration lasts at least one day after the COL has passed over Changchun. Furthermore, the relative coefficient between LRT height and lower stratosphere （LS） column ozone is -0.62, which implies a positive correlation between COL strength and LS ozone concentration.

Analysis of Low-level Temperature Inversions and Their Effects on Aerosols in the Lower Atmosphere

High-quality and continuous radiosonde, aerosol and surface meteorology datasets are used to investigate the statistical characteristics of meteorological parameters and their effects on aerosols. The data were collected at the Atmospheric Radiation Measurement Southern Great Plains climate research facility during 2000–15. The parameters and vertical distribution of temperature inversion layers were found to have strong diurnal and seasonal changes. For surface-based temperature inversion (SBI), the mean frequency and depth of temperature inversion layers were 39.4% and 198 m, respectively. The temperature difference between the top and bottom of SBI was 4.8℃, and so the temperature gradient was 2.4℃(100 m)^-1. The detailed vertical distributions of temperature inversion had been determined, and only the temperature inversion layers below 1000 m showed diurnal and seasonal variations. Mean surface aerosol number concentrations increased by 43.0%, 21.9% and 49.2% when SBIs were present at 0530, 1730 and 2330 LST, respectively. The effect of SBI on surface aerosol concentration was weakest in summer (18.1%) and strongest in winter (58.4%). During elevated temperature inversion events, there was no noticeable difference in surface aerosol number concentrations. Temperature differences and temperature gradients across SBIs correlated fairly well with aerosol number concentrations, especially for temperature gradients. The vertical distribution of aerosol optical properties with and without temperature inversions was different. Surface aerosol measurements were representative of the air within (below), but not above, SBIs and EIs. These results provide a basis for developing a boundary layer aerosol accumulation model and for improving radiative transfer models in the lower atmosphere.

Simulation of the Madden-Julian Oscillation in Wintertime Stratospheric Ozone over the Tibetan Plateau and East Asia: Results from the Specified Dynamics Version of the Whole Atmosphere Community Climate Model

The authors examined the Madden-Julian Oscillation(MJO) in stratospheric ozone during boreal winter using a simulation from the Specified Dynamics version of the Whole Atmosphere Community Climate Model(SD-WACCM) in 2004 and 2010. Comparison with European Centre for Medium-Range Weather Forecasts Interim Reanalysis(ERA-Interim) data suggested that the model simulation represented well the three-dimensional structure of the MJO-related ozone anomalies in the upper troposphere and stratosphere(i.e., between 200 and 20 h Pa). The negative ozone anomalies were over the Tibetan Plateau and East Asia in MJO phases 3–7, when the MJO convective anomalies travelled from the equatorial Indian Ocean towards the equatorial western Pacific Ocean. Due to the different vertical structures of the MJO-related circulation anomalies, the MJO-related stratospheric ozone anomalies showed different vertical structure over the Tibetan Plateau(25–40°N, 75–105°E) and East Asia(25–40°N, 105–135°E). As a result of the positive bias in the model-calculated ozone in the upper troposphere and lower stratosphere, the amplitude of MJO-related stratospheric ozone column anomalies(10–16 Dobson Units(DU)) in the SD-WACCM simulation was slightly larger than that(8–14 DU) in the ERA-Interim reanalysis.

A multi-location joint field observation of the stratosphere and troposphere over the Tibetan Plateau

The unique geographical location and high altitude of the Tibetan Plateau can greatly influence regional weather and climate.In particular, the Asian summer monsoon(ASM) anticyclone circulation system over the Tibetan Plateau is recognized to be a significant transport pathway for water vapor and pollutants to enter the stratosphere. To improve understanding of these physical processes, a multi-location joint atmospheric experiment was performed over the Tibetan Plateau from late July to August in 2018, funded by the fiveyear(2018–2022) STEAM(stratosphere and troposphere exchange experiment during ASM) project, during which multiple platforms/instruments—including long-duration stratospheric balloons, dropsondes, unmanned aerial vehicles, special sounding systems, and ground-based and satellite-borne instruments—will be deployed. These complementary methods of data acquisition are expected to provide comprehensive atmospheric parameters(aerosol, ozone, water vapor, CO_2, CH_4, CO, temperature, pressure,turbulence, radiation, lightning and wind); the richness of this approach is expected to advance our comprehension of key mechanisms associated with thermal, dynamical, radiative, and chemical transports over the Tibetan Plateau during ASM activity.

Earth Summit Mission 2022:Scientific Expedition and Research on Mt.Qomolangma Helps Reveal the Synergy between Westerly Winds and Monsoon and the Resulting Climatic and Environmental Effects

“Earth summit mission 2022”is one of the landmark scientific research activities of the Second Tibetan Plateau Scientific Expedition and Research(STEP).This scientific expedition firstly used advanced technology and methods to detect vertical meteorological elements and produce forecasts for mountain climbing.The“Earth summit mission 2022”Qomolangma scientific expedition exceeded an altitude of over 8000 meters for the first time and carried out a comprehensive scientific investigation mission on the summit of Mt.Qomolangma.Among the participants,the westerly–monsoon synergy and influence team stationed in the Mt.Qomolangma region had two tasks:1)detecting the vertical structure of the atmosphere for parameters such as wind,temperature,humidity,and pressure with advanced instruments for high-altitude detection at the Mt.Qomolangma base camp;and 2)observing extreme weather processes to ensure that members of the mountaineering team could successfully reach the top.Through this scientific expedition,a better understanding of the vertical structure and weather characteristics of the complex area of Mt.Qomolangma is gained.

Performance Evaluation of a Self-Developed Ozonesonde and Its Application in an Intensive Observational Campaign

To make a detailed test on the reliability and detection performance of the electrochemical concentra- tion cell （ECC） type ozonesonde which had been devel- oped and preliminarily evaluated by the authors, an inten- sive ozonesonde release experiment was held at two sites in Beijing and Changchun in June 2013. The results showed that the mean background current and its standard deviation were 0.03 （0.04） pA and 0.02 （0.03） pA in Bei- jing （Changchun）. The average response time and its standard deviation were 27.8 s （30.4 s） and 4.0 s （3.7 s） in Beijing （Changchun）. The ozone partial pressure profiles at both sites showed a central peak in the stratosphere and a side peak in the boundary layer. Large variation in ozone partial pressure was observed at the middle levels of the atmosphere （10-17 kin）. A more marked gradient of ozone change was observed in Beijing （3.4 mPa km-1） at the lower atmosphere level, as compared to that in Changchun （0.4 mPa km-l）. The results presented in this paper indicate that this self-developed ozonesonde shows a high level of reliability and good performance. The ozonsonde is expected to play an important role in opera- tional observations of ozone profiles.

LLSDA: Design and Implementation of Lightning Location Data Analysis and Visualization

Visualizing lightning location data is necessary in analyzing and researching lightning activity patterns.This article uses C#and the cross-platform.NET framework to develop a lightning location data analysis class library and the data-driven client to help lightning researchers improve work efficiency by avoiding repeated wheel invention.Lightning Location System Data Analyzer(LLSDA)is a suite of software tools that includes a.NET class library for software developers and a desktop application for end users.It supports a wide range of lightning location data formats,such as the University of Washington Global Lightning Location System(WWLLN)and Beijing Huayun Dongfang ADTD Lightning Location System data format,and maintains scalability.The class library can easily read,parse,and analyze lightning location data,and combined with third-party frameworks can realize grid analysis.The desktop application can be combined with MeteoInfo(a GIS open-source project)for secondary development.

Observation and Simulation of Abnormal Transmittance over Yangbajing,Tibet

Defining abnormal transmittance as the case where the magnitude of the shortwave flux transmittance is greater than 1.0,the authors used surface solar irradiance and all-sky images obtained at the Yangbajing site in Tibet to analyze the reasons for the occurrence of abnormal shortwave flux transmittance.Based on the International Intercomparision of Three-Dimensional Radiation Code(I3RC) Monte Carlo community model of three-dimensional radiative transfer,the authors also performed simulations at a nonabsorbing wavelength and an absorbing wavelength through a stratocumulus and a cumulus field.The results showed the detection of abnormal transmittance on more than half the days,and the maximum transmittance was 1.34.The probability of the occurrence of abnormal transmittance appeared to be largest in summer,and on a daily basis was mainly at about noon local time.Abnormal transmittance mainly appeared when clear sky and clouds co-existed,especially at the edges of broken clouds and nearby regions with clear-sky conditions.The flux transmittance decreased as the solar zenith angle increased.

A Deep-Learning and Transfer-Learning Hybrid Aerosol Retrieval Algorithm for FY4-AGRI:Development and Verification over Asia

The Advanced Geosynchronous Radiation Imager(AGRI)is a mission-critical instrument for the Fengyun series of satellites.AGRI acquires full-disk images every 15 min and views East Asia every 5 min through 14 spectral bands,enabling the detection of highly variable aerosol optical depth(AOD).Quantitative retrieval of AOD has hitherto been challenging,especially over land.In this study,an AOD retrieval algorithm is proposed that combines deep learning and transfer learning.The algorithm uses core concepts from both the Dark Target(DT)and Deep Blue(DB)algorithms to select features for the machinelearning(ML)algorithm,allowing for AOD retrieval at 550 nm over both dark and bright surfaces.The algorithm consists of two steps:①A baseline deep neural network(DNN)with skip connections is developed using 10 min Advanced Himawari Imager(AHI)AODs as the target variable,and②sunphotometer AODs from 89 ground-based stations are used to fine-tune the DNN parameters.Out-of-station validation shows that the retrieved AOD attains high accuracy,characterized by a coefficient of determination(R2)of 0.70,a mean bias error(MBE)of 0.03,and a percentage of data within the expected error(EE)of 70.7%.A sensitivity study reveals that the top-of-atmosphere reflectance at 650 and 470 nm,as well as the surface reflectance at 650 nm,are the two largest sources of uncertainty impacting the retrieval.In a case study of monitoring an extreme aerosol event,the AGRI AOD is found to be able to capture the detailed temporal evolution of the event.This work demonstrates the superiority of the transfer-learning technique in satellite AOD retrievals and the applicability of the retrieved AGRI AOD in monitoring extreme pollution events.

Toward Establishing a Low-cost UAV Coordinated Carbon Observation Network(LUCCN):First Integrated Campaign in China

In this study,we introduce our newly developed measurement-fed-perception self-adaption Low-cost UAV Coordinated Carbon Observation Network(LUCCN)prototype.The LUCCN primarily consists of two categories of instruments,including ground-based and UAV-based in-situ measurement.We use the GMP343,a low-cost non-dispersive infrared sensor,in both ground-based and UAV-based instruments.The first integrated measurement campaign took place in Shenzhen,China,4 May 2023.During the campaign,we found that LUCCN’s UAV component presented significant data-collecting advantages over its ground-based counterpart owing to the relatively high altitudes of the point emission sources,which was especially obvious at a gas power plant in Shenzhen.The emission flux was calculated by a crosssectional flux(CSF)method,the results of which differed from the Open-Data Inventory for Anthropogenic Carbon dioxide(ODIAC).The CSF result was slightly larger than others because of the low sampling rate of the whole emission cross section.The LUCCN system will be applied in future carbon monitoring campaigns to increase the spatiotemporal coverage of carbon emission information,especially in scenarios involving the detection of smaller-scale,rapidly varying sources and sinks.