EVOLUTION OF LIQUID WATER CONTENT IN A SEA FOG CONTROLLED BY A HIGH-PRESSURE PATTERN

On March 16–17, 2008, a sea fog occurred in Dianbai in the west of Guangdong Province and was accompanied by a high-pressure synoptic system. Using comprehensive observation datasets, this study analyzes the evolution of liquid water content during this sea fog and investigates the relationships between liquid water content and the average diameters and count densities of fog droplets, air temperature, wind speed and turbulence exchanges. The main results are presented as follows. (1) The sea fog showed a quasi-periodic oscillation characteristic, i.e., it developed, disappeared and then developed again. (2) During the sea fog, the number of fog droplets changed significantly while the changes in average diameter of the fog droplets were relatively small. The development and disappearance of the sea fog correlated significantly with the fog droplet numbers. (3) The air-cooling mechanism played a significant role in sea fog formation and development. However, the influences of this mechanism were not evident during fog persistence. (4) During sea fog formation, weak turbulence exchanges were helpful for fog formation. During sea fog development and persistence, liquid water content increased when turbulence exchanges weakened, and vice versa. The changes in turbulence exchanges were closely related to the quasi-periodic oscillations observed in sea fog presence.

Influence of liquid water content on wind turbine blade icing by numerical simulation

In order to research the influence of liquid water content ( LWC ) on blade icing of wind turbine, a numerical simulation method for blade icing was established. The numerical simulation was based on low speed viscous N-S equation. The trajectory equation of water droplets was established by Lagrangian method. The mass and energy conservation equations of the water droplets impacting on the surface of the blade were solved based on control body theory. Three sections along blade span wise of a 1.5 MW wind turbine were decided to simulate icing. Five kinds of LWC were selected for simulation including 0.2,0.4,0.6,0.8 and 1.0 g/m^3 under two ambient temperatures of -10 ℃ and -20 ℃. The medium volume droplet diameter ( MVD ) was 30μm. The simulations included icing shape on blade surface, dimensionless icing area and dimensionless maximum stagnation thickness. Furthermore, the flow fields around both the iced blade airfoil and the original one were simulated and analyzed. Accor-ding to the results, the typical icing characteristics of icing shape, icing area and thickness were greatly affected by the difference of LWCs. This study can provide theoretical reference for the research on antiicing and deicing of wind turbine blade.

A Comparative Study of Cloud Liquid Water Content from Radiosonde Data at a Tropical Location

In this paper, some features of cloud liquid water content with respect to rain and water vapor are presented. Cloud liquid water density profile is obtained from radiosonde observation with Salonen's model and Karsten's model at Kolkata, a tropical location in the Indian region. Cloud liquid water contents (LWC) are obtained from these profiles which show a prominent seasonal variation. The monsoon months exhibit much higher values of LWC than in other months. However Salonen's model yields higher LWC values than that obtained with Karsten's model. The variation of daily total rainfall with LWC shows a positive relationship indicating the role of LWC in controlling the rainfall. Also the variation pattern of LWC with integrated water vapor (IWV) content of the atmosphere indicates that a threshold value of water vapor is required for cloud to form and once cloud is formed LWC increases with IWV.

Comparison of Liquid Water Content Retrievals for Airborne Millimeter-Wave Radar with Different Particle Parameter Schemes

In the application of the physical iterative method to retrieve millimeter-wave radar liquid water content(LWC)and liquid water path(LWP),particle parameter scheme is the main factor affecting retrieval performance.In this paper,synchronous measurements of an airborne millimeter-wave radar and a hot-wire probe in stratus cloud are used to compare the LWC retrievals of the oceanic and continental particle parameter scheme with diameter less than 50μm and the particle parameter scheme with diameter less than 500μm and 1500μm(scheme 1,scheme 2,scheme 3,and scheme4,respectively).The results show that the particle parameter scheme needs to be selected according to the reflectivity factor when using the physical iterative method to retrieve the LWC and LWP.When the reflectivity factor is less than-30 d BZ,the retrieval error of scheme 1 is the minimum.When the reflectivity factor is greater than-30 d BZ,the retrieval error of scheme 4 is the minimum.Based on the reflectance factor value,the LWP retrievals of scheme 4 are closer to the measurements,the average relative bias is 5.2%,and the minimum relative bias is 4.4%.Compared with other schemes,scheme 4 seems to be more useful for the LWC and LWP retrieval of stratus cloud in China.

Analysis of Vertical Profiles of Precipitable Liquid Water Content in a Tropical Climate Using Micro Rain Radar

In this paper, some distinctive features of the vertical profile of precipitable liquid water content (LWC) with considerable respect to rain rates (R) and radar reflectivity (Z) obtained in a tropical location are presented. Assessment of LWC allows applications in the specific area of flight icing severity, aviation safety as well as signals traversing through the atmosphere. The parameters were typically measured using vertically-pointing Micro Rain Radar (MRR) over a period of 2 years (2011-2012) at Akure, a tropical location of Nigeria. The radar scanned at every 10 seconds and integrated over one minute samples to reduce event logging error associated with the instrument. The vertical profile of the LWC typically reveals a prominent seasonal variation. However, majority of the LWC profiles has low LWC, less than 0.1 gm?3 while the maximum observed LWC is about 3.18 gm?3. A strong like hood relation was observed between the melting layer height and the LWC, with the LWC reaches peak at the considerable height of about 4160 m which coincides precisely with the freezing height level (rain height of ~4520 m) of the study location. Good correlation was also observed between the LWC and R in most of the heights considered. The results obtained will assist system engineers to assess the level of absorption, reflection and attenuation of electromagnetic signals as a result of precipitable LWC along the transmitting paths. The novelty of the present work is in the area of linking LWC and Z as against usual relation between Z and R.

Molecular dynamics study of room temperature ionic liquids with water at mica surface

Water in room temperature ionic liquids(RTILs) could impose significant effects on their interfacial properties at a charged surface. Although the interfaces between RTILs and mica surfaces exhibit rich microstructure, the influence of water content on such interfaces is little understood,in particular, considering the fact that RTILs are always associated with water due to their hygroscopicity. In this work, we studied how different types of RTILs and different amounts of water molecules affect the RTIL-mica interfaces, especially the water distribution at mica surfaces,using molecular dynamics(MD) simulation. MD results showed that(1) there is more water and a thicker water layer adsorbed on the mica surface as the water content increases, and correspondingly the average location of K^+ ions is farther from mica surface;(2) more water accumulated at the interface with the hydrophobic [Emim][TFSI] than in case of the hydrophilic [Emim][BF4] due to the respective RTIL hydrophobicity and ion size. A similar trend was also observed in the hydrogen bonds formed between water molecules. Moreover, the 2D number density map of adsorbed water revealed that the high-density areas of water seem to be related to K^+ ions and silicon/aluminum atoms on mica surface. These results are of great importance to understand the effects of hydrophobicity/hydrophicility of RTIL and water on the interfacial microstructure at electrified surfaces.

Variations in Composition and Water Use Efficiency of Plant Functional Groups Based on Their Water Ecological Groups in the Xilin River Basin

Major plant species in the Xilin River Basin were grouped into six plant functional groups (PFGs) based on their water ecological groups: xerophytes, mesoxerophytes, xeromesophytes, mesophytes, hygromesophytes and hygrophytes. We surveyed the composition, delta(13)C values and proline concentration of PFGs in eight different plant communities along a soil moisture gradient. Results show that: (1) PFGs occurred variously in eight steppe communities with different soil moisture status. In wetter habitats, hygromesophytes and hygrophytes were more abundant and accounted for the majority of aboveground biomass, whereas xerophytes and mesoxerophytes became more conspicuous in dryer habitats; (2) the numerical order of the mean delta(13)C values of PFGs is as follows: xerophytes (-26.38parts per thousand) = mesoxerophytes (-26.51parts per thousand) > xeromesophytes (-27.02parts per thousand) > mesophytes (-27.56parts per thousand) = hygromesophytes and hygrophytes (-27.80parts per thousand); (3) xerophytes maintained relative higher delta(13)C values and water use efficiency (WUE) in habitats of different water availability, whereas delta(13)C values of xeromesophytes were more sensitive to change in soil water availability; (4) From xerophytes to hygrophytes, their proline content markedly increased. Significantly positive correlations existed between proline and biomass or delta(13)C values of different water ecological groups.

KLWC-5含水量仪原理及在人工增雨中的应用

简要介绍了热线含水量仪的研究进展 ,讨论了目前人工增雨试验中使用的机载KLWC含水量仪的工作原理、显示模块及其在微物理探测中的应用。这些飞机观测数据资料有助于加深人们对云物理结构的了解 ,从而提高人工增雨作业效率。

Aircraft Observations of Liquid and Ice in Midlatitude Mixed-Phase Clouds

ABSTRACT This paper reports airborne measurements of midlatitude altostratus clouds observed over Zhengzhou, Henan Province, China on 3 March 2007. The case demonstrates mixed-phase conditions at altitudes from 3200 to 4600 m （0°C to -7.6°C）, with liquid water content ranging from 0.01 to 0.09 g m-3. In the observed mixed-phase cloud, liquid water content exhibited a bimodal distribution, whereas the maximum ice particle concentration was located in the middle part of the cloud. The liquid and ice particle data showed significant horizontal variability on the scale of a few hundred meters. The cloud droplet concentration varied greatly over the horizontal sampling area. There was an inverse relationship between the cloud droplet concentration and ice particle concentration. A gamma distribution provided the best description of the cloud droplet spectra. The liquid droplet distributions were found to increase in both size and concentration with altitude. It was inferred from the profile of the spectra parameters that the cloud droplet sizes tend to form a quasi-monodisperse distribution. Ice particle spectra in the cloud were fitted well by an exponential distribution. Finally, a remarkable power law relationship was found between the slope （λ） and intercept （No） parameters of the exponential size distribution.

Study of Water Movement in Unsaturated Copper Ore

Leaching is widely applied in the exploitation of depleted ores. In order to discover the law of leachant movement in the leaching process and calculating volumes and time intervals of spraying leachant,experiments and numerical simulation with the TOUGH2/EOS3 module were carried out in order to find out the principle of water movement in unsaturated copper ore. The results show that water volume increases at the same location over time,that copper ore tends to become saturated and that liquid velocity decreases at the same time as the distance from top in-creases. On the other hand,a comparison and analysis of our experimental and simulated results indicate that the EOS3 module could accurately simulate the water movement in an unsaturated state.

Magnitude and Trends of High-elevation Cloud Water Pollutant Concentrations and Modeled Deposition Fluxes

Cloud water samples, LWC （Liquid Water Content） and meteorological data were collected at the Clingmans Dome, Tennessee, high-elevation site in Great Smoky Mountains National Park during the warm season from 1994 through 2011. This paper presents results from 2000 through the conclusion of the study in 2011. Samples were analyzed for SO42＂, NO3, NH4＋ and H＋. These measurements were supplemented by measurements of ambient air and precipitation concentrations to estimate dry and wet deposition. Cloud water concentrations, LWC, cloud frequency, various meteorological measurements and information on nearby forest canopy were used to model cloud water deposition to gauge trends in deposition. Total deposition was calculated as the sum of cloud, dry and wet deposition estimates. Concentrations and deposition fluxes declined over the study period. The decreases in cloud water SO42＂ and NO3 concentrations were 40 percent and 26 percent, respectively. Three-year mean 5042 and NO3 deposition rates decreased by 71 percent and 70 percent, respectively. Trends in concentrations and depositions were comparable with trends in SO2 and NOx emissions from Tennessee Valley Authority power plants and aggregated emission reductions from electric generating units in adjacent states. Back trajectories were simulated with the HYSPLIT model and aggregated over cloud sampling periods from 2000 through 2007 and 2009 through 2011. Trajectories during periods with high H＋ concentrations traveled over local EGU （Electric Generating Unit） emission sources in Tennessee and Kentucky to the Ohio River Valley, Alabama and Georgia with the conclusion that these source regions contributed to acidic cloud water deposition at Clingmans Dome. This work was supported by U.S. Environmental Protection Agency and the Tennessee Valley Authority with infrastructure support provided by the National Park Service.

Yangtze River Delta Aerosol liquid water in PM_(2.5)and its roles in secondary aerosol formation at a regional site of Yangtze River Delta

Aerosol liquid water content(ALWC)plays an important role in secondary aerosol formation.In this study,a whole year field campaign was conducted at Shanxi in north Zhejiang Province during 2021.ALWC estimated by ISORROPIA-Ⅱ was then investigated to explore its characteristics and relationship with secondary aerosols.ALWC exhibited a highest value in spring(66.38μg/m^(3)),followed by winter(45.08μg/m^(3)),summer(41.64μg/m^(3)),and autumn(35.01μg/m^(3)),respectively.It was supposed that the secondary inorganic aerosols(SIA)were facilitated under higher ALWC conditions(RH>80%),while the secondary organic species tended to form under lower ALWC levels.Higher RH(>80%)promoted the NO_(3)^(-)formation via gas-particle partitioning,while SO_(4)^(2-)was generated at a relative lower RH(>50%).The ALWC was more sensitive to NO_(3)^(-)(R=0.94)than SO_(4)^(2-)(R=0.90).Thus,the self-amplifying processes between the ALWC and SIA enhanced the particle mass growth.The sensitivity of ALWC and OX(NO_(2)+O_(3))to secondary organic carbon(SOC)varied in different seasons at Shanxi,more sensitive to aqueous-phase reactions(daytime R=0.84;nighttime R=0.54)than photochemical oxidation(daytime R=0.23;nighttime R=0.41)in wintertime with a high level of OX(daytime:130-140μg/m^(3);nighttime:100-140μg/m^(3)).The self-amplifying process of ALWC and SIA and the aqueous-phase formation of SOC will enhance aerosol formation,contributing to air pollution and reduction of visibility.

长江三角洲地区高空云过程气溶胶——云相互作用的观测研究

气溶胶—云相互作用过程对于评估大气云和气溶胶的寿命及气候效应至关重要。目前关于气溶胶—云相互作用的研究主要以飞机航测、卫星反演和模式模拟为主,地基直接观测由于布置难度大、实验时间长、人力物力耗费等原因开展得较少。当前针对气溶胶—云相互作用机制的理解还比较低,亟需外场观测资料深入认识其过程。本研究以长江三角洲地区高山站点的云雾为背景,利用雾滴谱仪、地用逆流虚拟撞击器、混合凝聚核粒子计数器、扫描电迁移率颗粒物粒径谱仪等仪器,研究了大明山顶(海拔1483 m)7月份多云雾期间云滴和气溶胶的特性,探讨了气溶胶对云形成和发展的影响以及云对气溶胶颗粒物的清除作用。云形成初期对气溶胶颗粒物的清除率约为20%~50%。研究显示水汽过饱和度越高且颗粒物粒径越大,清除率越高,这表明粒径较大的吸湿性颗粒物容易活化为云凝结核。对比同一云雾事件中气溶胶数浓度差异较大的三个阶段,我们发现较低的气溶胶数浓度有利于形成液态水含量高的浓云,此时云团由数量相对较少而粒径大的云滴组成,而大气颗粒物数量增多会使云雾变淡,此时的云团由大量细小的云滴组成。本研究分析了8μm以上云滴的云凝结核数量分布特征,发现大云滴的云凝结核几乎都是100 nm以上的颗粒物;随着气溶胶数浓度升高,8μm以上大云滴的数量减少,且大云滴云凝结核的平均直径变大。这些结果显示气溶胶数浓度升高会促使云滴的数量增多而等效直径变小,在水汽有限的自然环境中,气溶胶数浓度越高,颗粒物的临界活化直径越大。总之,我们发现大气气溶胶的数浓度—粒径分布特性影响着云滴的数量和粒径,云的形成和发展也对气溶胶颗粒物有较强的清除作用。

生物炭施用对冻结期退化黑土水热盐动态变化的影响

[目的]生物炭施用可改变土壤理化性状,研究不同生物炭施用方式对土壤水、热及电导率(EC)分布的影响,可为季节性冻土科学管理提供依据。[方法]利用田间定位试验,通过长期观测,研究东北黑土区不同生物炭施用方式对冻结期的土壤液态水含量、温度及EC的影响差异。生物炭施用方式包括一次性生物炭混施40 t/hm^(2)(HO)、生物炭底施40 t/hm^(2)(HE),空白为0 t/hm^(2)(CK)。[结果]2种生物炭施用方式均增加冻结期土壤平均液态水含量(p<0.05),表现为HO>HE>CK;整个试验周期内生物炭施用均显著增加土壤EC,且HO和HE处理土壤平均EC分别比CK增加17.73%,6.89%;2种生物炭施用方式对土壤温度影响不同,与CK相比,HE处理土壤平均温度提高0.32℃,而HO处理土壤平均温度降低0.46℃。此外,HE处理相较于HO和CK处理减弱冻结期土壤液态水、温度及EC的变化幅度。[结论]生物炭混施和底施均有利于提高冻结期退化黑土液态水含量和EC,特别是生物炭底施还有利于提升冻结期耕层土壤温度,而生物炭混施在同时期还有利于减缓土壤冻结作用,2种生物炭施用方式均可能对冻结期土壤水盐运移和物质转化过程有重要影响,甚至对春季作物出苗和早期生长产生重要影响。

HPLC法同时测定黄花蒿水提浸膏中青蒿素、青蒿乙素、猫眼草黄素和猫眼草酚D的含量

目的建立高效液相色谱(HPLC)法同时测定黄花蒿水提浸膏中青蒿素、青蒿乙素、猫眼草黄素、猫眼草酚D的含量。方法采用Agilent ZORBAX SB-C18(250 mm×4.6 mm,5μm)色谱柱;流动相:乙腈(A)-纯水(B),梯度洗脱;体积流量:0.8 mL·min^(-1);柱温:30℃;进样量:10μL;检测波长:210 nm。结果青蒿素、青蒿乙素、猫眼草黄素和猫眼草酚D进样量分别在1.6088~16.088μg(r=0.9999)、0.0141~0.1414μg(r=1)、0.1851~1.8509μg(r=0.9999)、0.1441~1.4414μg(r=0.9999)范围内与峰面积呈良好的线性关系,平均加样回收率(n=6)分别为102.44%、97.82%、95.07%、95.55%,RSD分别为1.12%、1.44%、1.29%、1.53%。结论该方法简便准确、可靠稳定、重复性好,可用于同时测定黄花蒿水提浸膏中青蒿素、青蒿乙素、猫眼草酚D、猫眼草黄素的含量。

真空作用下高含水率疏浚泥颗粒迁移规律试验研究

研制了高含水率疏浚泥真空固结模型装置,针对两种具有不同液限的疏浚泥,开展不同初始状态下的真空固结试验,探究真空作用下疏浚泥初始状态对细颗粒迁移性状的影响规律。研究结果表明,引入初始含水率与液限比值作为无量纲化的初始状态指标,能够作为确定细颗粒迁移与否的一个临界阈值。当初始含水率与液限比值不大于临界阈值,真空作用下高含水率疏浚泥没有发生颗粒迁移;当初始含水率与液限比值大于临界阈值,真空作用下高含水率疏浚泥发生颗粒迁移,黏粒向排水面附近聚集。一旦发生颗粒迁移,黏粒向排水面附近富集的程度随着初始含水率与液限比值的增大而愈发显著。

Prediction of the undrained shear strength of remolded soil with non-linear regression,fuzzy logic,and artificial neural network

This study aims to predict the undrained shear strength of remolded soil samples using non-linear regression analyses,fuzzy logic,and artificial neural network modeling.A total of 1306 undrained shear strength results from 230 different remolded soil test settings reported in 21 publications were collected,utilizing six different measurement devices.Although water content,plastic limit,and liquid limit were used as input parameters for fuzzy logic and artificial neural network modeling,liquidity index or water content ratio was considered as an input parameter for non-linear regression analyses.In non-linear regression analyses,12 different regression equations were derived for the prediction of undrained shear strength of remolded soil.Feed-Forward backpropagation and the TANSIG transfer function were used for artificial neural network modeling,while the Mamdani inference system was preferred with trapezoidal and triangular membership functions for fuzzy logic modeling.The experimental results of 914 tests were used for training of the artificial neural network models,196 for validation and 196 for testing.It was observed that the accuracy of the artificial neural network and fuzzy logic modeling was higher than that of the non-linear regression analyses.Furthermore,a simple and reliable regression equation was proposed for assessments of undrained shear strength values with higher coefficients of determination.

NUMERICAL STUDY OF REMOTE SENSING OF CLOUD LIQUID WATER CONTENT BY SPACE-BORNE COMBINED RADAR-RADIOMETER

A retrieval method of microwave(MW)space-borne remote sensing of cloud liquid water content by the combined radar-radiometer is suggested.A three-layer cloud model is chosen to represent the typical stratified precipitating cloud.The retrieval method mainly follows our previously suggested scheme with some modifications.Numerical comparative study shows that in space-borne remote sensing of cloud liquid water content by the combined method is much better than by radar only;Also the retrieval accuracy of cloud liquid water content may be improved when using the three-layer cloud model in the combined method.

考虑水盐相变的盐渍土基质吸力的温度效应

基质吸力是引起土体中水分迁移的驱动力,对探究土体中水盐迁移动态具有重要的意义。为研究由温度变化诱发的盐渍土孔隙溶液相变对土体基质吸力的影响,用pF meter测试了不同NaCl和Na_(2)SO_(4)比例的盐渍土在不同温度条件下的基质吸力。试验结果表明:在水盐相变发生前,盐渍土基质吸力随温度的降低呈线性增加;而当降温过程中有水盐相变发生时,土体基质吸力随温度的变化趋势会发生明显突变。NaCl和Na_(2)SO_(4)对土体水盐相变规律影响不同,使得含不同比例NaCl和Na_(2)SO_(4)的复合盐渍土基质吸力呈现较大的区别。2%NaCl+4%Na_(2)SO_(4)的盐渍土在19和-9℃附近发生盐结晶相变和二次相变,而4%NaCl+2%Na_(2)SO_(4)的盐渍土两次相变分别发生在11和-16℃附近。水盐相变导致土体液态含水率明显降低,进而引起复合盐渍土基质吸力在两个相变阶段均有明显增加。NaCl抑制土体中液态水发生冰水相变,Na_(2)SO_(4)容易在正温结晶,故Na_(2)SO_(4)主要影响土体正温时的盐结晶规律,NaCl则主要影响土体在负温条件下的冰晶产生规律;二者比例不同造成土体盐结晶温度和二次相变温度有明显差异,使得复合盐渍土的水盐相变规律更加复杂,其基质吸力随温度的变化更加难以预测。此外,该研究进一步探究了冰、盐结晶量对基质吸力变化的贡献,为深入理解盐渍土的相变过程和基质吸力之间的关系提供了有效参考。

结冰气象探测飞行及数据符合性分析方法研究

结冰气象捕获、最优气象条件选取准则、符合性数据处理方法等一直是飞机自然结冰试飞过程中亟待攻克的难题。通过分析CCAR25部附录C结冰气象标准的形成背景及其局限性,提出一种利用结冰试验研究机开展结冰探测的飞行方法,该方法包括试验研究机的选型、改装、探测目标区域确定、飞行操作策略、飞行安全管理、数据处理等。依据对探测数据的统计分析,确定民用运输机自然结冰试飞的气象条件选取准则,规范云隙、液态水含量、总水收集率、积冰速率、积冰厚度和冰脱落程度等一系列结冰气象的数据处理方法和符合性判据,校验国内结冰气象预测算法,探索自然结冰试飞的安全管控策略和风险降解措施。大量飞行实测表明:该方法通用性强,效果显著,已经成功应用于C919大型客机合格取证试飞工作,并有力支撑了国内结冰适航标准自主。