Marked changes in the aerosol chemical matrix recently observed at 1780 m a.s.l. (BAPMoN mountain station) and results of first comparisons with samples obtained simultaneously at 740 m a.s.l

Summary Recently we reported on results concerning the structure of the aerosol chemical matrix in samples collected from 1972 to 1982 at a mountain observatory at 1780 m a.s.l. in a clean air region (BAPMoN-station). Trend analyses and parameterizations have been made using the meteorological environmental conditions. Sampling and measurements were continued and show in the recent past for components of mostly anthropogenic origin significant reductions. Moreover, we give for the first time results of synchronous aerosol sampling at the mountain observatory and in the neighboring valley floor at 740 m a.s.l., the horizontal distance being only 6 km. The results are analyzed statistically.

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In jüngster Zeit beobachtete starke Änderungen in der Aerosolchemischen Matrix in 1780 m NN (BAPMoN-Bergstation) und Ergebnisse erster Vergleiche mit simultanen Proben aus 740 m NN

Zusammenfassung Kürzlich wurde über Ergebnisse der Struktur der chemischen Aerosol-Matrix berichtet, welche von 1972 bis 1982 auf einem Bergobservatorium in 1780 m NN in einer Reinluftzone(BAPMoN-Station)gesammelt wurden. Trend-Analysen und Parameterisierungen mit Hilfe der meteorologischen Umweltbedingungen wurden durchgeführt. Die Probenahmen und Messungen wurden fortgesetzt und zeigen im Hinblick auf Komponenten hauptsächlich anthropogenen Ursprungs in jüngster Zeit signifikante Reduzierungen, die dargestellt werden. Außerdem werden erstmals Ergebnisse mitgeteilt aus synchronen Aerosol-Probenahmen am Bergobservatorium in 740 m NN bei nur 6 km horizontaler Distanz. Die Ergebnisse werden statistisch analysiert.

     

Determination of the concentration of chemical main and trace elements (chemical matrix) in the aerosol from 1972 to 1982 at a North-alpine pure air station at 1780 m a.s.l.

Summary Aerosol particles have been separated by filter at a mountain station at 1780 m a.s.l. continuously since 1972. The station (a WMO-BAPMoN station with extended program) is freely exposed to all sides and in no way influenced by local aerosol sources. In the cold seasons it lies almost exclusively above the convection layer (very often over inversions) so that real background data can be acquired in these cases. By means of analytical methods the chemical components are determined on the exposed filters. This includes (apart from crust elements) also cations and anions from man-made and maritime sources as well as some important trace elements (in all, 15 components). Filters are exposed over 1–4 days. Filter exchange is determined by the respective weather situation with due regard to all changes so that the requirements for a reasonable correlation of the measured values with the meteorological conditions are met. Additionally, all meteorological parameters are determined, as well as intensity of the vertical exchange, number density of Aitken nuclei, concentration of natural radioactivity (RaB), and other variables. In the present paper the components of the aerosol chemical matrix are related to the behavior of the parameters below and the results are discussed in detail: Dependence of the individual components on total aerosol mass per volume, type of air mass; representation of two single cases of long-range transport of crust elements (source areas: Sahara, Colorado); vertical exchange coefficient, concentration of natural radioactivity, temperature gradient between valley and mountain station, temperature at the sampling site, relative humidity, precipitation rate, wind direction. occurrence of fog.Zusammenfassung An einer allseitig frei exponierten Bergstation in 1780 m NN werden seit 1982 die Aerosolpartikel auf Filtern gesammelt. Die Station (eine WMO-BAPMoN-Station mit erweitertem Programm) wird nicht durch lokale Aerosolquellen in irgendeiner Weise beeinflußt. Sie liegt in den kalten Jahreszeiten fast ausschließlich über der Konvektionsschicht (sehr oft oberhalb von Inversionen), so daß in diesen Fällen echte Background-Daten erfaßt werden. Mittels analytischer Verfahren werden an den exponierten Filtern alle chemischen Hauptkomponenten (von den Krustenelementen abgesehen auch die Kationen und Anionen sowohl anthropogenen als auch maritimen Ursprungs), sowie einige gewichtige Spurenelemente (insgesamt 15 Komponenten) bestimmt. Die Filter werden 1–4 Tage lang exponiert. Der Filterwechsel wird durch den jeweiligen Wetterzustand bzw. seiner Veränderung gesteuert, so daß eine gute Voraussetzung für eine Zuordnung der Meßwerte zu den meteorologischen Bedingungen gegeben ist. Zusätzlich werden alle meteorologischen Parameter, sowie die Intensität des Vertikalaustausches, Zahl der Aitken-Kerne, Konzentration der natürlichen Radioaktivität (RaB) und andere Größen bestimmt. In der vorliegenden Arbeit werden die Komponenten der chemischen Aerosolmatrix zum Verhalten der folgenden Parameter in Beziehung gesetzt und die Ergebnisse eingehend diskutiert:Abhängigkeit der Einzelkomponenten von: Gesamt-Aerosohnasse pro Volumen; Typ der Luftmasse und Darstellung von zwei Einzelfällen eines Ferntransportes von Krustenelementen (Quellgebiete: Sahara, Colorado); vertikaler Austauschkoeffizient; Konzentration der natürlichen Radioaktivität; Temperaturgradient zwischen Tal- und Bergstation; Temperatur an der Probennahmestelle; relative Feuchte; Niederschlagsintensität; Windrichtung; Auftreten von Nebel.

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Bestimmung der Konzentration chemischer Haupt- und Spurenstoffe (chemische Matrix) im Aerosol von 1972 bis 1982 an einer nordalpinen Reinluftstation in 1780 m NN.Teil II: Parametrische Korrelationsanalyse der chemischen Matrix mit Berücksichtigung meteorologischer Größen

     

Determination of the concentration of chemical main and trace elements (chemical matrix) in the aerosol from 1972 to 1982 at a North-alpine pure air station at 1780 m a.s.l.

Theoretical and Applied Climatology - Aerosol particles have been separated by filter at a mountain station at 1780 m a.s.l. continuously since 1972. The station (a WMO-BAPMoN station with extended...     

Spatial structure of a jet flow at a river mouth

The present work concentrates on the latest data measured in the Jordan river flow in lake Kinneret. Spectral characteristics of fluctuating velocity components have been obtained and processed. The three-dimensional structure of turbulence along the flow has been described. The main features of the jet flow turbulence in the river mouth are: a) The supply of turbulent energy changes due to different mechanisms along the flow. b) The structure of turbulence formed in the river decays rapidly along the flow, and c) In the sand area and beyond it, a significant generation of turbulent energy occurs. Quantitative estimations of the above effects were carried out.     

Small-particle concentration fluctuations at a coastal site

Aerosol size spectra (d=10 nm–10 μm) were measured with an electrical aerosol spectrometer (EAS) at Mace Head on the west coast of Ireland. Several small aerosol particle (diameter 10–32 nm) concentration bursts were observed during the measurement period. Relationships between the events, air mass trajectories, tide height, and meteorological parameters are examined. Series of bursts were observed when a spectral transformation due to subsequent particle growth from 10 to 56–100 nm can be identified in an Eulerian experiment. Particle growth rates of between 1 and 3 nm/h were determined. These bursts appear in cold and comparatively clean arctic or polar air masses with temperature and relative humidity fluctuations, and do not correlate with low tide in some cases. These episodes, similar to those frequently found in the continental boundary layer, are thought to occur over a wide area and, for clear detection, require stable airflow for a few days. Elevated small-particle concentration events are more common during low tide or shortly after, and are typically associated with low wind speeds. Here, the increased shore exposure during low tide is thought to influence the nucleation and the subsequent growth of these aerosol particles. The occurrences of the bursts are found to depend on local wind direction. The highest d=10–32 nm particle concentrations appeared for wind sectors furthest from the tidal regions when the wind direction was 150–160°(south-easterly). Most of the events occurred during daytime when solar irradiation is most intense.     

Evaluation of a land-surface scheme at Cabauw

Summary We study the response of the land-surface to prescribed atmospheric forcing for 31 May 1978 at Cabauw, Netherlands, using the land-surface scheme from the Coupled Atmospheric boundary layer-Plant-Soil (CAPS) model. Results from model runs show realistic daytime surface fluxes are produced using a canopy conductance formulation derived from Cabauw data (for 1987, a different year), and un-tuned parameterizations of root density (near-uniform with depth) and soil heat flux (reduced thermal conductivity through vegetation). Sensitivity of model-calculated surface heat fluxes to initial values of soil moisture is also examined. Results of this study provide the land-surface base state for a coupled land–atmosphere modeling study.     

Tropical climates at the Last Glacial Maximum: a new synthesis of terrestrial palaeoclimate data. I. Vegetation, lake-levels and geochemistry

 Palaeodata in synthesis form are needed as benchmarks for the Palaeoclimate Modelling Intercomparison Project (PMIP). Advances since the last synthesis of terrestrial palaeodata from the last glacial maximum (LGM) call for a new evaluation, especially of data from the tropics. Here pollen, plant-macrofossil, lake-level, noble gas (from groundwater) and δ¹⁸O (from speleothems) data are compiled for 18±2 ka (¹⁴C), 32 °N–33 °S. The reliability of the data was evaluated using explicit criteria and some types of data were re-analysed using consistent methods in order to derive a set of mutually consistent palaeoclimate estimates of mean temperature of the coldest month (MTCO), mean annual temperature (MAT), plant available moisture (PAM) and runoff (P-E). Cold-month temperature (MAT) anomalies from plant data range from −1 to −2 K near sea level in Indonesia and the S Pacific, through −6 to −8 K at many high-elevation sites to −8 to −15 K in S China and the SE USA. MAT anomalies from groundwater or speleothems seem more uniform (−4 to −6 K), but the data are as yet sparse; a clear divergence between MAT and cold-month estimates from the same region is seen only in the SE USA, where cold-air advection is expected to have enhanced cooling in winter. Regression of all cold-month anomalies against site elevation yielded an estimated average cooling of −2.5 to −3 K at modern sea level, increasing to ≈−6 K by 3000 m. However, Neotropical sites showed larger than the average sea-level cooling (−5 to −6 K) and a non-significant elevation effect, whereas W and S Pacific sites showed much less sea-level cooling (−1 K) and a stronger elevation effect. These findings support the inference that tropical sea-surface temperatures (SSTs) were lower than the CLIMAP estimates, but they limit the plausible average tropical sea-surface cooling, and they support the existence of CLIMAP-like geographic patterns in SST anomalies. Trends of PAM and lake levels indicate wet LGM conditions in the W USA, and at the highest elevations, with generally dry conditions elsewhere. These results suggest a colder-than-present ocean surface producing a weaker hydrological cycle, more arid continents, and arguably steeper-than-present terrestrial lapse rates. Such linkages are supported by recent observations on freezing-level height and tropical SSTs; moreover, simulations of “greenhouse” and LGM climates point to several possible feedback processes by which low-level temperature anomalies might be amplified aloft. Received: 7 September 1998 / Accepted: 18 March 1999     

Climate politics at a crossroad: views on building a consensus

The climate change issue faces a big challenge, perhaps the biggest challenge of all—politics. Pakistan has taken many noticeable steps in relation to climate change: (1) it is the only country in which the Prime Minister is heading an inter-ministerial task force on climate change, (2) it is the first developing country to establish a specialized, self-financed scientific centre to research the impact of climate change, and (3) it is the lead country to earmark budgetary funds for a national carbon sequestration programme. Pakistan, together with many developing countries, has much to offer the climate change issues. The author proposes five approaches to build consensus among climate policy negotiators: (1) reinforcing the polluter pays principle and ‘common but differentiated responsibility’, (2) active partnership by developing countries, (3) recognizing the voluntary actions taken by developing countries, (4) reinforcing the issue of adaptation, and (5) considering the option of equal per capita entitlements.     

Boundary-layer effects on cold fronts at a coastline

The present note discusses one physical mechanism which may contribute to cold air channelling, manifest as a frontal bulge on a surface-analysis chart, in the coastal region of Victoria in southeast Australia. This involves the modification of boundary-layer air in both offshore (prefrontal) and onshore (postfrontal) flow, and the effect on cross-frontal thermal contrast. The problem is discussed in terms of a north-south-oriented cold front behaving as an atmospheric gravity current, propagating along an east-west-oriented coastline, in the presence of a prefrontal offshore stream.     

Ozone concentration characteristics at a high-elevation forest site

Summary Atmospheric ozone concentrations have been monitored at a subalpine forest ecosystem site, 3180m above mean sea level (msl), and at a 2680m msl forest-steppe ecotone site 15km to the southeast. Ozone concentrations were monitored at three heights above the ground on a 30m tower at the higher elevation site, and on a 10m tower in a large meadow downwind of this site.The research reported here concentrates on the data for the first six months of 1990–1994. The diel amplitude of ozone concentrations is very small in winter, increasing as the seasons advance to June. Following snowmelt in late May or June, the nighttime minima decrease under the forest canopy. The highest monthly mean ozone concentrations occur in April or May, depending on the year. Episodal high concentrations were recorded during spring months when upper level atmospheric low pressure troughs and cut-off low centers occurred. These contributions peak in May, and add about 10% to normal May background ozone concentrations, varying widely from year to year. Spectral representations of ozone concentrations, illustrate the suppression of the diel peak during spring months, when stratospheric-tropospheric intrusion patterns show no significant diel cycle.With 9 Figures     

青岛一次中到大雪过程的综合分析

2005年2月17～18日，受冷空气和较强暖湿气流共同影响，青岛发生中到大雪降雪过程。对这次过程的环流背景和雷达资料进行综合分析表明，低空暖平流、垂直风切变和高空西风急流提供了有利的动力条件，中空西南气流和近地层从黄渤海海面的水汽输送提供了降水所需的水汽。随着2．0～2．7km高度上，一个以青岛为中心的中尺度气旋性风场的出现，降雪强度迅速达到最强，该风场破坏，降雪强度也迅速减弱；雷达回波首先出现在3．0～5．5km的高度上，然后向上下扩展加强；降雪初期，0．8～3．2km高度上有弱回波区。     

江苏高速公路收费站一次雷击事故分析

本文对2010年8月3日19时30分沿江高速公路张家港收费站一次严重雷击事故的雷暴过程进行诊断分析,并对其防雷工程存在问题进行综合探讨.分析得出:这次雷暴发生在副热带高压边缘环流形势下,虽副热带高压强大,但大幅度东退,面积明显减小,脊线位置和流场也出现调整.江苏上空由西南气流转为西北气流影响,北方有弱冷空气沿西北气流南...     

江苏高速公路收费站一次雷击事故分析

本文对2010年8月3日19时30分沿江高速公路张家港收费站一次严重雷击事故的雷暴过程进行诊断分析,并对其防雷工程存在问题进行综合探讨。分析得出:这次雷暴发生在副热带高压边缘环流形势下,虽副热带高压强大,但大幅度东退,面积明显减小,脊线位置和流场也出现调整。江苏上空由西南气流转为西北气流影响,北方有弱冷空气沿西北气流南下,引发江苏降温,为大气不稳定的增强和触发不稳定能量的释放提供重要条件;本文还分析了雷暴与对流参数关系及演变特征,并探究不稳定参数在雷暴发生中的作用。根据现场调查,分析出这次收费站雷击事故在防雷工程方面存在设备接地、等电位、线路屏蔽、电涌保护器设置、安装和接地电阻等问题,最后针对这些问题提出6点防雷工程整改建议。