Airborne Lidar Observations of Water Vapor Variability in Tropical Shallow Convective Environment

An airborne downward-pointing water vapor lidar provides two-dimensional, simultaneous curtains of atmospheric backscatter and humidity along the flight track with high accuracy and spatial resolution. In order to improve the knowledge on the coupling between clouds, circulation and climate in the trade wind region, the DLR (Deutsches Zentrum für Luft- und Raumfahrt) water vapor lidar was operated on board the German research aircraft HALO during the NARVAL (Next Generation Aircraft Remote Sensing for Validation Studies) field experiment in December 2013. Out of the wealth of about 30 flight hours or 25,000 km of data over the Tropical Atlantic Ocean east of Barbados, three ~ 2-h-long, representative segments from different flights were selected. Analyses of Meteosat Second Generation images and dropsondes complement this case study. All observations indicate a high heterogeneity of the humidity in the lowest 4 km of the tropical troposphere, as well as of the depth of the cloud (1–2 km thick) and sub-cloud layer (~ 1 km thick). At the winter trade inversion with its strong humidity jump of up to 9 g/kg in water vapor mixing ratio, the mixing ratio variance can attain 9 (g/kg)², while below it typically ranges between 1 and 3 (g/kg)². Layer depths and partial water vapor columns within the layers vary by up to a factor of 2. This affects the total tropospheric water vapor column, amounting on average to 28 kg/m², by up to 10 kg/m² or 36%. The dominant scale of the variability is given by the extent of regions with higher-than-average humidity and lies between 300 and 600 km. The variability mainly stems from the alternation between dry regions and moisture lifted by convection. Occasionally, up to 100-km large dry regions are observed. In between, convection pushes the trade inversion upward, sharpening the vertical moisture gradient that is colocated with the trade inversion. In most of the water vapor profiles, this gradient is stronger than the one located at the top of the sub-cloud layer. Lidar observations in concert with models accurately reproducing the observed variability are expected to help evaluate the role these findings play for climate.     

Dynamical Climatology of the Upper Mesosphere, Lower Thermosphere and Ionosphere

The main features of upper atmosphere dynamics as an important part of upper atmosphere climatology are presented. The dynamics of the mesosphere and lower thermosphere (MLT) are of special interest. The results are based on the long series of investigations in East Siberia and data from a world-wide network of observatories. We present the regional climatic norms for the prevailing wind and semi-diurnal tide and the main features of the quasi-periodic structure of the wind field. The non-zonality of MLT dynamics is demonstrated as well as regional differences in the response of the wind field to stratospheric disturbances, solar activity variations and geomagnetic storms.     

Diurnal Thermal Stratification and Floc Rising in Clariflocculators of the Tropical Water Works

In four tropical water works there are carried out investigations on the floc rising occurring during the day-hours, and especially in the hot season, in the flocculators. This phenomenon is caused by the great heating of the raw water during the day-hours, due to which between 10.00 a. m. and 10.00 p. m. a temperature difference up to 3.7 K between the influent and the effluent of the flocculators occurs during a retention period of 3.5… 5 h within the flocculators. Even temperature differences of only 1 K result in floc rising, reducing the filter run by four to seven hours. Oversaturation of the raw water with oxygen by the photosynthetic oxygen production constitutes an additional cause. As a measure against the rising and passing-on of flocs we recommend the aeration of the water at the raw water intake point, to prevent a thermal stratification during the day-hours and at the same time to remove the perhaps given oxygen oversaturation.     

Determination of Partition Coefficients of Metals in Natural Tropical Water

The values for the partition coefficient (K_d) were calculated for Ca, Mg, Cd, Cr, Cu, Fe, Mn, Pb, Ni, and Zn at 19 sites in the Capivara hydroelectric reservoir in Brazil. It was found that the relative values of K_d follow the order: Cr > Mn > Fe > Cu > Zn > Ni > Pb > Ca > Cd, differing from the values reported for K_d in aquatic systems in the northern hemisphere. A hierarchical cluster analysis and linear correlations showed that Cr is strongly associated with Fe and Cu, and that Cd is the only metal found in complexation with organic matter, explaining its higher solubility.     

Variability of the Earth's Atmospheric Electric Field and Ion-Aerosols Kinetics in the Troposphere

The paper deals with the mechanism of generating a ground potential gradient electric field in regions of seismic activity and its penetration into the ionosphere. The mechanism is based on the electrode effect of charge separation under the action of the natural atmospheric electric field, A large, non-compensated, space charge is formed following a chain of ion-molecular reactions as a result of the anomalous increase of radon and aerosol emanation from the crust. This space charge leads to anomalous variations of the electric field ground level, which is supported by the experimental observations made in the seismo-active regions. In turn the variations of the strong electric field over the large earthquake areas lead to the modification of ionospheric parameters due to penetration of the anomalous electric field into the ionosphere. A theoretical model of these phenomena is proposed in this paper.     

Emerging Technologies and Synergies for Airborne and Space-Based Measurements of Water Vapor Profiles

A deeper understanding of how clouds will respond to a warming climate is one of the outstanding challenges in climate science. Uncertainties in the response of clouds, and particularly shallow clouds, have been identified as the dominant source of the discrepancy in model estimates of equilibrium climate sensitivity. As the community gains a deeper understanding of the many processes involved, there is a growing appreciation of the critical role played by fluctuations in water vapor and the coupling of water vapor and atmospheric circulations. Reduction of uncertainties in cloud-climate feedbacks and convection initiation as well as improved understanding of processes governing these effects will result from profiling of water vapor in the lower troposphere with improved accuracy and vertical resolution compared to existing airborne and space-based measurements. This paper highlights new technologies and improved measurement approaches for measuring lower tropospheric water vapor and their expected added value to current observations. Those include differential absorption lidar and radar, microwave occultation between low-Earth orbiters, and hyperspectral microwave remote sensing. Each methodology is briefly explained, and measurement capabilities as well as the current technological readiness for aircraft and satellite implementation are specified. Potential synergies between the technologies are discussed, actual examples hereof are given, and future perspectives are explored. Based on technical maturity and the foreseen near-mid-term development path of the various discussed measurement approaches, we find that improved measurements of water vapor throughout the troposphere would greatly benefit from the combination of differential absorption lidar focusing on the lower troposphere with passive remote sensors constraining the upper-tropospheric humidity.     

基于Emardson模型的GNSS-PWV转换系数精化

转换系数(K值)是GNSS气象学中影响GNSS可降水量(Precipitable Water Vapor, PWV)反演精度的关键参数之一.针对中国地区缺乏统一的高精度K值模型, 本文选取2018—2019年均匀分布的42个探空站资料, 分析K值与测站经纬度和高程之间的相关性, 利用2018年K值和多元线性拟合法, 分别建立基于测站纬度和年积日的Emardson-I模型和基于测站纬度、高程和年积日的Emardson-H模型, 并用2019年K值作为真值验证以上两模型的K值预报精度.研究结果表明: (1)K值与测站纬度和高程之间呈负相关, 相关系数分别为0.735和0.941, 而与测站经度的相关性较小; (2)Emardson-H模型预报的K值平均绝对误差(MAE)和均方根(RMS)均值分别为0.00150和0.00182, 均优于Emardson-I模型的0.00221和0.00255, 特别在高海拔地区表现更好; (3)基于Emardson-H模型的GNSS-PWV的MAE和RMS均值分别为0.226 mm和0.283 mm, 均优于Emardson-I模型(0.288 mm和0.360 mm), 在低海拔地区精度提高更为显著.因此, Emardson-H模型的精度优于Emardson-I模型, 在中国西部高海拔地区能取得更好的K值预报效果, 但就PWV反演精度而言, 在低海拔地区效果更好.Emardson模型以其无需实测气象参数的特点使其在地基GNSS气象学中具有更好的实时应用前景.

     

Water Quality Monitoring of Tropical Ponds: Location and Depth Effect in Two Case Studies

The variability in water chemistry of samples taken on a monthly basis (March 1999 to February 2000) from two shallow tropical ponds was studied. The effect of location and pond depth on water chemistry was also examined. The study demonstrated that intraannual variability in nutrient concentration is high. Thus, a high annual sampling frequency is required to provide representative annual mean water quality data. Routine monitoring during the monsoons is important for studies on dissolved oxygen and macrophyte growth. Significant differences were found between the topmost and bottommost points for samples of dissolved oxygen collected from the deepest part of both ponds. For nutrient analysis (nitrogen and phosphorus), sample from any location was found to be representative of the whole pond.     

The Influence of Surface Covers on the Performance of a Soil Vapor Extraction System

This study looks at the influence of surface covers on the performance of a single pumping well system. Pilot tests were conducted on a sandy soil to determine the influence of surface confinement based upon both induced vacuum and pore gas velocity design criteria. The results demonstrate how covering the surface can significantly alter the associated air flow patterns and velocity distribution. Comparison of streamline iso‐contours obtained in covered scenarios reveals that the surface seal tended to prevent air from entering the subsurface near the extraction well and force air to be drawn from a greater distance. Calculated and measured pressure differentials, for open and semi‐confined scenarios, clearly show that adding a clay layer as a surface cover increased the vacuum induced within the soil. Pore gas velocity analysis showed that when the cover clay layer was used, the zone of capture of the soil vapor extraction system increased. The radius of influence of soil vapor extraction (SVE) systems, based on the attainment of a critical vacuum or pore gas velocity, can then be increased by including a surface seal in the design of such systems. The focus of this study is limited to air flow patterns contrasted between covered and uncovered conditions and not on the nuances of a full scale remediation implementation.     

Ionosphere as an Indicator of Processes in the Geospace,Troposphere, and Lithosphere

The possible causes of the strong ionospheric day-to-day variability under the influence of processes in the geospace, troposphere, and lithosphere are considered based on the data of the critical frequency of the F2 layer of the ionosphere at two observation stations. It is shown that even in the absence of powerful events, the ionosphere is influenced both “from above” and “from below”; in this case, the ionosphere can respond to an external action as an open nonlinear dissipative system.     

Biotesting in the Assessment of Environmental and Toxicological State of Water Bodies in Lower Don River Basin

The toxicity of river water in the Lower Don basin was studied using biotesting with different biological objects. Water taken from most examined reaches of the Don and its tributaries was shown to exert toxic effect on crustaceans, algae, protozoa, and Rotifera.     

The Physico-Chemical Characteristics of the Used Filter Sand and its Role in the Seven Water Works Systems in a Tropical Region

The filter-technical equipment of seven water works in a tropical region of India is described. The structure of the filter sand layer, the grain size distribution and the degree of uniformity are compared by means of tables. The uniformity coefficient of a good filter sand is smaller than 1.7. Besides physical properties, also the surface properties of the filter sand grains are of interest. Different analytical methods for determining the incrustation are described. The amount of the filter grain load also depends on age, i.e. on the service life of the filter sand. The efficiency of a filter plant is determined also by the regeneration process, i.e. by back-wash. This includes the methods of scouring with water only and the back-washing with water/air.     

一维河网不稳定流模型在黄河下游枯季水量调度中的应用

随着黄河下游工农业生产的不断发展,人民群众生活质量不断提高,黄河水资源供需矛盾越来越突出.确保黄河不断流必然面临着越来越大的压力,必须提高水量调度的快速反映能力.本文讨论了一维河网不稳定流数值计算模型在黄河下游枯水演进中的数学基础、 实现方法和在此基础上建立的枯季水量调度软件的应用.从对八十年代以来的枯水年份的模拟情况来看,流量拟合结果均能达到乙级以上,这对于水资源短缺的黄河下游的引黄调度具有重要的参考价值.     

大别造山带地壳结构反演及其动力学意义

大别造山带是全球最大的碰撞造山带之一,三叠纪时期,扬子板块深俯冲至地幔的200km处,经历了超高压变质作用。白垩纪早期,该造山带发生了强烈的伸展和垮塌,以及大规模的后造山地幔源岩浆侵入和火山活动。本研究收集了大别造山带及其邻区(29°~34°N、114°~119°E)的震相资料,采用双差层析成像技术,对大别造山带地壳结构进行反演,研究地壳结构与后造山地幔源岩浆侵入和火山活动之间的关系。结果显示,大别造山带中上地壳存在低速结构,该低速结构可能是熔融的幔源侵入物质,由于俯冲板片断裂,或下地壳/岩石圈发生拆沉,导致软流圈物质上涌至地壳底部、侵入地壳中,形成大别造山带地壳中的低速结构;同时,合肥盆地显示为低速区,可能是受浅部沉积层影响。研究中横切大别山的4条剖面显示,该地区下方存在北向倾斜高速结构,该高速结构可能是襄樊-广济断层,或者是扬子板块向华北板块下方俯冲的遗迹。     

Fishery Water Releases to the Lower Pool of the Volgograd Hydroelectric Power Plant

Conditions of fish reproduction in the Volga–Caspian Basin depending on the hydrological regime in the Volga lower reaches, transformed by water withdrawals and regulatory impact of reservoirs are considered.     

Effects Of Geomagnetic Storms – Different Morphology and Origin in the Upper Middle Atmosphere and the Troposphere

Compiling various experimental as well as theoretical results, we find that the effects of geomagnetic storms in the upper middle atmosphere (heights about 60 – 100 km) and the troposphere are of different morphology, origin and nature.     

Small Purge Method to Sample Vapor from Groundwater Monitoring Wells Screened Across the Water Table

Groundwater monitoring wells are present at most hydrocarbon release sites that are being assessed for cleanup. If screened across the vadose zone, these wells provide an opportunity to collect vapor samples that can be used in the evaluation of vapor movement and biodegradation processes occurring at such sites. This paper presents a low purge volume method (modified after that developed by the U.S. EPA) for sampling vapor from monitoring wells that is easy to implement and can provide an assessment of the soil gas total petroleum hydrocarbon (TPH) and O₂ concentrations at the base of the vadose zone. As a result, the small purge method allows for sampling of vapor from monitoring wells to support petroleum vapor intrusion (PVI) risk assessment. The small purge volume method was field tested at the Hal's service station site in Green River, Utah. This site is well‐known for numerous soil gas measurements containing high O₂ and high TPH vapor concentrations in the same samples which is inconsistent with well‐accepted biodegradation models for the vapor pathway. Using the low purge volume method, monitoring wells were sampled over, upgradient, and downgradient of the light nonaqueous phase liquid (LNAPL) footprint. Results from our testing at Hal's show that vapor from monitoring wells over LNAPL contained very low O₂ and high TPH concentrations. In contrast, vapor from monitoring wells not over LNAPL contained high O₂ and low TPH concentrations. The results of this study show that a low purge volume method is consistent with biodegradation models especially for sampling at sites where low permeability soils exist in and around a LNAPL source zone.     

Experience with a Water Detector in the Study of the Permafrost Structure

Geomagnetism and Aeronomy - The results of a study of the geoelectric section of the upper layers of the Earth at observation sites in Yakutia via vertical electrical sounding and surface impedance...