A comparative study of atmospheric conductivity at ground level and at one meter above ground

Summary Observations made at various locations, with portable apparatus, from within New York City to one-hundred miles of the city show the following results: (1) The total conductivities at ground level and at one meter above ground are not equal. In general, the one-meter conductivity is greater than the ground during the day, but at night the ground value is the greater. Also, for high values of conductivity the total one-meter conductivity is greater than that at ground level. For lower values the reverse is the case. This might not be true for all locations. (2) The ratios of the polar conductivities of one sign at ground level to the corresponding values at one meter are not constant, and the ratio of the total conductivity at ground level to that at one meter is not constant. (3) These ratios depend upon wind velocities, the amount of pollution in the air, on the nature of the terrain, and upon the time, i. e., day or night.(4) Under normal conditions, conductivity rises to an early morning maximum, the ground maximum rising more sharply that the one-meter, and remains fairly constant during the day but drops inthe late afternoon or early evening reaching a minimum between 20h and 22h. (5) When variation in conductivity takes place under constant turbulence (wind 0–1), the one-meter conductivities change more rapidly than those at the ground (except at the time of maximum), where terrain is level. Local conditions may alter the above (e. g., smoky air rising from lower ground). Also, under all conditions the one-meter conductivity is more variable than ground conductivity. (6) Our findings do not confirm those ofP. J. Nolan [1] andA. R. Hogg [2] that the unipolar (positive) conductivity at ground is almost equal to the total conductivity at one meter above ground.

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Zusammenfassung Unsere Beobachtungen über die atmosphärische Leitfähigkeit in Bodenhöhe und einen Meter darüber, die mit einem Gerdienschen Aspirator mit Wulf-Elektrometer in der näheren und weiteren Umgebung der Stadt New York (bis 160 km Entfernung) ausgeführt wurden, führten zu folgenden Resultaten: 1. Die totale Leitfähigkeit der Luft nahe dem Erdboden und in 1 m Höhe ist nicht gleich. Im allgemeinen ist bei höheren Werten die Leitfähigkeit in 1 m Höhe während der Tagesstunden größer als am Erdboden, während es in der Nacht umgekehrt ist. Bei niedrigen Werten der Leitfähigkeit kehrt sich dieses Verhältnis um; doch trifft dies möglicherweise nicht für alle Orte zu. 2. Das Verhältnis der polaren Leitfähigkeit je eines Vorzeichens am Boden zu der entsprechenden in 1 m Höhe ist nicht konstant; dasselbe gilt auch für die Gesamtleitfähigkeit. 3. Die numerischen Werte dieser Verhältniszahlen hängen von der Windgeschwindigkeit (Turbulenz), dem Gehalt der Luft an Verunreinigungen, den Terrainverhältnissen und der Tageszeit ab. 4. Normalerweise erreicht die Leitfähigkeit ein Maximum in den frühen Morgenstunden; dabei erfolgt der Anstieg zum Maximum am Boden steiler als in 1 m Höhe. Während des Tages bleibt die Leitfähigkeit ziemlich konstant, fällt dagegen am späten Nachmittag und erreicht ihr Minimum zwischen 20 Uhr und 22 Uhr. 5. Wenn bei konstanten Turbulenzbedingungen (Windstärke 0–1) eine Änderung der Leitfähigkeit erfolgt, so ändert sich die Leitfähigkeit über ebenem Terrain in 1 m Höhe stärker als am Boden (außer zur Zeit des Hauptmaximums). Lokale Verhältnisse (wie z. B. Rauch) können dies ändern. In allen Fällen ist die Leitfähigkeit in 1 m Höhe stärker veränderlich als am Boden. 6. Unsere Ergebnisse bieten keine Bestätigung der Resultate vonP. J. Nolan [1] undA. R. Hogg [2], wonach die positive Leitfähigkeit am Boden fast ebenso groß ist wie die gesamte Leitfähigkeit in 1 m Höhe über dem Boden.

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Résumé Nos mesures de la conductibilité atmosphérique au niveau du sol et à un mètre de hauteur effectuées avec un aspirateur de Gerdien et un électromètre de Wulf aux environs immédiats et lointains de New-York (jusqu'à 160 km de distance) ont conduit aux résultats suivants. 1. La conductibilite totale au niveau du sol n'est pas la même qu'à un mètre. En général pour les valeurs élevées la conductibilité est plus forte à un mètre qu'au sol pendant le jour; l'inverse a lieu la nuit. Pour les valeurs faibles le phénomène s'inverse, mais ce n'est pas nécessairement le cas partout. 2. Le rapport de la conductibilité polaire de chaque signe au sol à celle qui lui correspond à un mètre n'est pas constant; il en est de même pour la conductibilité totale. 3. La valeur numérique de ces rapports dépend de la vitesse du vent, de la teneur de l'air en impuretés, de la configuration du terrain et du moment de la journée.4. La conductibilité atteint normalement un maximum dans les premières heures du jour; l'accroissement est alors plus rapide au sol qu'à un mètre. Pendant la journée la conductibilité reste sensiblement constante, décroît cependant en fin d'après-midi et atteint son minimum entre 20 et 22 heures. 5. Si par turbulence constante (vitesse du vent 0 à 1) il se produit une variation de la conductibilité, celle-ci varie plus fortement à un mètre qu'au niveau du sol en terrain plat (sauf à l'époque du maximum principal). Les conditions locales, comme la fumée par exemple, peuvent ici apporter des modifications. Dans tous les cas la conductibilité varie davantage à un mètre que sur le sol. 6. Nos résultats ne confirment pas ceux deP. J. Nolan [1] et deA. R. Hogg [2] selon lesquels la conductibilité positive au niveau du sol serait presque aussi grande que la conductibilité totale à la hauteur d'un mètre.

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With 12 Figures.     

Influence of Clouds on UV Irradiance at Ground Level and Backscattered Exittance

The influence of various cloud parameters and the interactions with the ground albedo and the solar zenith angle have been studied by means of model simulations. The radiative transfer model suitable for a cloudy atmosphere as well as for a clear atmosphere has been developed on the basis of the Discrete Ordinate Method. This study leads to a general understanding for cloudy atmospheres: in the presence of a uniform cloud, the cloud scattering is dominant to molecular and aerosol scattering, and it is also wavelength-independent; the ratio of transmitted irradiance in a cloudy atmosphere to that in the background clear atmosphere is independent of cloud height and solar zenith angle. That’s to say, the radiation downwelling out of a cloud is quite isotropic; it decreases approximately exponentially with the cloud optical depth at a rate related to the ground albedo; the reflected irradiance at the top of the atmosphere is dependent on cloud optical depth as well as on solar zenith angle, but not on ground albedo for clouds of not very thin optical depth.     

The cell-move-expansion model for the evaluation of ground level pollutant concentration

A model for evaluating pollutant concentrations near the ground is developed. The main advantages of the model are its ability to estimate the distribution and variation of ground concentration under non-uniform or unsteady wind field with minimal computations and the elimination of numerical pesudo-diffusion.     

关于地市级移动气象计量检定系统应用要点的探讨

1地市级移动气象计量检定系统应用的背景根据区域气象监测的需要,黑龙江省将逐步建成覆盖所有气象观测站点的气象计量检测机构。因省级气象计量机构为主体的计量保障体系难以承受全省区域站的计量工作,所以将计量保障体系的主体推进到地市级,形成省级气象计量机构针对国家站网自动气象站开展业务,地市级气象计量机构针对区域站网开展业务的新的气象计量保障模式。地市级气象计量机构的业务配置应采用与省级气象计量机构相近似的模式,即实验室校准和现场移动校准、核查相结合,实现对于区域自动气象站充分、有效、及时的计量保障。     

The role of precursor emissions on ground level ozone concentration during summer season in Poland

Three online coupled chemical transport model simulations were analyzed for three summer months of 2015 in Poland. One of them was run with default emission inventory, the other two with NO_x and VOC emissions reduced by 30%, respectively. Obtained ozone concentrations were evaluated with data from air quality measurement stations and ozone sensitivity to precursor emissions was estimated by ozone concentration differences between simulations and with the use of indicator ratios. They were calculated based on modeled mixing ratios of ozone, total reactive nitrogen and its components, nitric acid and hydrogen peroxide. The results show that the model overestimates ozone concentrations with the largest errors in the morning and evening, which is primarily related to the way vertical mixing is resolved by the model. Better model performance for ozone is achieved in rural than urban environment, as PBL and mixing mechanisms play more significant role in urban areas. Modeled ozone shows mixed sensitivity to precursor concentrations, similarly to other European regions, but indicator ratios have different values than are found in literature, particularly H₂O₂/HNO₃ is larger than in southern Europe. However, indicator ratios often differ between locations and transition values need to be established individually for a given region.     

The investigation of microwave precipitation measurement at 37GHz

In this paper we use a 10-layer radiation transfer model to systematically investigate the relation between brightness temperature and the rainfall rates at 37 GHz, including various viewing of microwave (MW) remote sens-ing and different surface condition, with main focus on the influence of the structure of ice-phase layer. The results show that the quantitative rainfall measurement can not be reliably obtained over the land from spaceborne radiometer at this wavelength and the structures of ice layer are very important in determining the “observed” bright-ness temperature for the spaceborne MW remote sensing.     

The vertical sulfur dioxide distribution at the tropopause level

In 1978–1980 nine aircraft flights to an altitude of up to 15 km were made over western Europe. Sulfur dioxide was measured with a sensitive chemiluminescence method consisting of separate sampling and analysis stages and application of a wet chemical filter procedure (detection limit: 8 pptv SO₂).The measurements performed in the upper troposphere and lower stratosphere lead to some unexpected results: (a) the meteorological conditions at the tropopause level have an important influence on the observed SO₂ mixing ratio; (b) between the 500 mb and the actual tropopause level the SO₂ mixing ratio is found to be <100 pptv, and weak vertical gradients of SO₂ suggest only a small flux of tropospheric SO₂ into the stratosphere; (c) increasing SO₂ mixing ratios within the first kilometers of the stratosphere give strong support to a stratospheric source of SO₂.In the light of improved one-dimensional models considering the vertical distribution of stratospheric sulfur compounds (Crutzen, 1981; Turco et al. 1981) it can be shown that the oxidation of organic sulfur compounds (e.g., OCS, CS₂) seems to be a stratospheric source of SO₂. Furthermore, the flux calculations based on the SO₂ mixing ratios measured at the tropopause level indicate that the contribution of tropospheric (man-made) SO₂ to the stratospheric aerosol layer is of only minor importance.     

The Askervein Hill Project: Mean wind variations at fixed heights above ground

This is one of a series of papers on the Askervein Hill Project. It presents results on the variations in mean wind speed at fixed heights (z) above the ground from linear arrays of anemometer posts and towers. Most of the data are for z = 10 m but some are for z = 3 m. Selected and directionally grouped data from the 55 Mean Flow runs are presented together with mean flow data from Askervein '83 Turbulence runs. Comparisons are made between the data and guideline estimates of fractional speed-up ratio at hilltop locations and between the data and MS3DJH/3 model predictions along the tower lines. There is good agreement in most cases.     

寻呼台基站的防雷与接地

本文着重论述了寻呼台基站系统防雷与接地的重要性。针对接地不当,雷击造成通信设备的损坏,从通信设备接地、交流电源接地、保护地、电话中继线防雷等方面介绍了接地方法与具体措施,可为我省各地市包揽部门寻呼台提供有价值的参考。     

Retrieval of turbulent pressure fluctuations at the ground surface beneath a forest

The relationship between surface pressure fluctuations and the velocity field associated with turbulent coherent structures is examined for flow within and above a deciduous forest. Measurements were taken with tower-mounted sonic anemometer/thermometers at six heights, Lyman-alpha humidiometers at three heights, and a pressure sensor at the forest floor. We find a strong, near-linear relationship between the mean square turbulent velocity and the standard deviation of the high-pass-filtered pressure fluctuations. Lagged cross-correlations between vertical velocity fluctuations and those of pressure show maximum correlations of ± 0.5 but with a phase offset. Examination of surface pressure during the passage of coherent structures, which are characterized by a transition from ejection to sweep, reveals a period of overpressure about 20 s in duration roughly centered on the time of passage of the scalar microfront at the top of the canopy. Pressure patterns associated with coherent structures appear to be largely responsible for the form of the correlations stated above.Pressure patterns calculated from an integrated Poisson equation, using observed velocity and temperature signals during coherent structures, match the main features of the observed pressure. Retrieval of the pressure fluctuations in this manner reveals that the mean wind shear/turbulence interaction term is dominant, but that important contributions arise from two other terms in the equation. Buoyancy effects are negligible. We show that the surface pressure signal is mainly created by the velocity field near the top of the forest, and present evidence to suggest that features of the sub-crown air movement result directly from this pressure field.     

Assessing the state of traditional knowledge at national level

Traditional practices of Indigenous Peoples support the sustainable management of a quarter of the global land area. Yet their traditional knowledge is declining. To date, there has been insufficient focus on the development of participatory and evidence-based processes for assessing the state of traditional knowledge at national levels. We used traditional knowledge indicators and participatory video to evaluate the state of traditional knowledge within three Indigenous groups in Guyana. We find that traditional knowledge is perceived to be ’stable’ and responding and adapting to a diverse set of environmental factors and new circumstances. There are differences amongst Indigenous groups, but also commonalities, which help identify areas of intervention and point towards developing shared and collective narratives at the national level to feed into policy making. The findings have critical implications for the ways in which traditional knowledge should be researched, measured and safeguarded.     

市级灾害性天气应急服务系统

灾害性天气应急服务系统是市级气象台根据实际工作需要,研制开发的灾害性天气监测、预报预警业务系统。系统实现了对灾害性天气的实时监测,预警信息编辑、制作和发布,灾情快速评估及极端灾害性天气预报应急服务等功能。介绍了系统的功能特点和业务应用情况。为市级台站做好灾害性天气监测、预报和预警应急服务等工作提供了可借鉴的思路。     

四川小麦锈病成因及生产对策

小麦锈病是由锈菌生理小种变异，丧失抗性而引发的一种病害。锈菌的越夏、越冬、传播侵染、流行与气象环境条件密切相关。四川麦区作为全国条锈病的重发区近年爆发流行，对小麦生产造成危害，潜在威胁很大。本文从农业气象角度探讨其发病规律并采取相应对策，以期解决这一生产问题，对粮食安全有着实际意义。     

Implementing Europe's climate targets at the regional level

Having agreed upon a binding emissions reduction path by 2020, the EU plays a leading role in international climate policy. The EU currently pursues a dual approach through an Emissions Trading Scheme (ETS) at the EU level and also via national targets in sectors not covered by the ETS. The latter include the buildings sector, transportation, agriculture, and waste. Emissions from these sectors are mainly subject to policies at provincial and local levels. A method is presented for elaborating and implementing a long-term climate policy process up to 2030 for the regional (provincial) level. Building on regional GHG inventory data, a set of indicators for each sector is developed in order to arrive at a target path consistent with the deduced regional GHG reduction requirement. Policy measures and their implementation are then settled subsequent to this process. Quantitative regional targets are found to be a prerequisite for the formation of regional climate policy as they increase participant responsibility and commitment. A five-step process of stakeholder participation ensures effective implementation of regional climate action plans. Insights from an exemplary European region are drawn upon, and policy issues are discussed in both quantitative and institutional terms.     

A climate model intercomparison at the dynamics level

Until now, climate model intercomparison has focused primarily on annual and global averages of various quantities or on specific components, not on how well the general dynamics in the models compare to each other. In order to address how well models agree when it comes to the dynamics they generate, we have adopted a new approach based on climate networks. We have considered 28 pre-industrial control runs as well as 70 20th-century forced runs from 23 climate models and have constructed networks for the 500 hPa, surface air temperature (SAT), sea level pressure (SLP), and precipitation fields for each run. We then employed a widely used algorithm to derive the community structure in these networks. Communities separate “nodes” in the network sharing similar dynamics. It has been shown that these communities, or sub-systems, in the climate system are associated with major climate modes and physics of the atmosphere (Tsonis AA, Swanson KL, Wang G, J Clim 21: 2990–3001 in 2008; Tsonis AA, Wang G, Swanson KL, Rodrigues F, da Fontura Costa L, Clim Dyn, 37: 933–940 in 2011; Steinhaeuser K, Ganguly AR, Chawla NV, Clim Dyn 39: 889–895 in 2012). Once the community structure for all runs is derived, we use a pattern matching statistic to obtain a measure of how well any two models agree with each other. We find that, with the possible exception of the 500 hPa field, consistency for the SAT, SLP, and precipitation fields is questionable. More importantly, none of the models comes close to the community structure of the actual observations (reality). This is a significant finding especially for the temperature and precipitation fields, as these are the fields widely used to produce future projections in time and in space.     

四川小麦锈病成因及生产对策.

小麦锈病是由锈菌生理小种变异,丧失抗性而引发的一种病害.锈菌的越夏、越冬、传播侵染、流行与气象环境条件密切相关.四川麦区作为全国条锈病的重发区近年爆发流行,对小麦生产造成危害,潜在威胁很大.本文从农业气象角度探讨其发病规律并采取相应对策,以期解决这一生产问题,对粮食安全有着实际意义.