共查询到20条相似文献，搜索用时 718 毫秒
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The relationship between 18 O/16 O and 13 C/12 C ratios of ambient CO2 in two Amazonian tropical forests
LEONEL DA S. L. STERNBERG MARCELO Z. MOREIRA LUIZ A. MARTINELLI REYNALDO L. VICTORIA EDELCILIO M. BARBOSA LUIZ C. M. BONATES DANIEL NEPSTAD 《Tellus. Series B, Chemical and physical meteorology》1998,50(4):366-376
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C. C. &#;W. LEE J. H. SAVARINO H. CACHIER M. H. THIEMENS 《Tellus. Series B, Chemical and physical meteorology》2002,54(3):193-200
The recent discovery of an anomalous enrichment in 17 O isotope in atmospheric sulfate has opened a new way to investigate the oxidation pathways of sulfur in the atmosphere. From laboratory investigations, it has been suggested that the wet oxidation of sulfur in rain droplets was responsible for the excess 17 O. In order to confirm this theory, sulfur and oxygen isotope ratios of different primary sulfates produced during fossil fuel combustion have been investigated and are reported. None of these samples exhibits any anomalous oxygen or sulfur isotopic content, as compared to urban sulfate aerosols. These results, in agreement with the laboratory investigations, reinforce the idea of an aqueous origin for the oxygen-17 anomaly found in tropospheric sulfates. 相似文献
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使用京津冀冬半年地面气象站雾的常规观测和自动站风的观测资料进行统计分析,得出太行山地形辐合线位置与华北平原雾的空间分布有一定对应关系,即：冬半年(10-2月)华北平原年平均雾日多发区对应地形辐合线的位置；以2013年1月21-22日华北平原雾为例,辐合线附近的能见度相对较低,即辐合线附近雾的浓度较强。为加强对雾天气的成因认识,提高雾天气的预报能力,在科学规划雾天气监测网时应充分考虑地形的影响(如地形辐合线的位置)。 相似文献
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利用2017-2019年空气质量监测数据，采用HYSPLIT后向轨迹模式、聚类分析、潜在源贡献因子分析法（PSCF）和浓度权重轨迹分析法（CWT），对运城市秋冬季大气PM2.5传输路径、对应重污染的天气形势和潜在源区进行分析。结果表明：（1）运城近地层盛行偏东风时污染频率高，弱的偏东风和西南风时，污染物浓度较大。秋冬季PM2.5后向轨迹西北方向最多达53.53%，偏东方向最少为11.25%，偏西方向和西南方向介于两者之间，分别为16.61%和12.06%。（2）不同轨迹对应天气形势不同，西北和偏西轨迹下，500 hPa高度场上为两槽一脊或偏西气流，700～850 hPa受脊前西北气流影响，地面为高压前底部型或均压场型；西南轨迹下，500 hPa高度场上为偏西气流，700～850 hPa运城处于槽前西南气流，地面气压场为高压前底部（底部）或均压场。（3）运城PM2.5潜在源区主要位于陕西南部、四川东部和新疆东南、甘肃的东南部等地区，说明影响运城秋冬季PM2.5的浓度除了来自汾渭平原西南部的颗粒物区域输送，来自西北方向新疆、甘肃的远距离颗粒物传输也是重要来源。 相似文献
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By Z. KLIMONT J. COFALA J. XING W. WEI C. ZHANG S. WANG J. KEJUN P. BHANDARI R. MATHUR P. PUROHIT P. RAFAJ A. CHAMBERS M. AMANN J. HAO 《Tellus. Series B, Chemical and physical meteorology》2009,61(4):602-617
Estimates of Asian emissions of air pollutants and carbonaceous aerosols and their mid-term projections have been changing significantly in the last years. The remote sensing community has shown that increase in NO x in Central East Asia is much stronger than any of the emission inventories or projections indicated so far. A number of studies reviewing older estimates appeared. Here, we review the key contributions and compare them to the most recent results of the GAINS model application for Asia and to the SRES projections used in the IPPC work. The recent projections indicate that the growth of emissions of SO2 in Asia should slow down significantly towards 2010 or even stabilize at the current level. For NO x , however, further growth is projected although it will be most likely slower that in the last decade, owing to introduction of measures in transport. Emissions of carbonaceous aerosols (black carbon and organic carbon) are expected to decline after 2010, largely due to reduced use of biofuels in residential sector and efficiency improvements. The estimates of these emissions are burdened with significantly larger uncertainties than SO2 and NO x ; even for the year 2000 the differences in estimates between studies are up to a factor of 2. 相似文献
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By TOBIAS NAEGLER 《Tellus. Series B, Chemical and physical meteorology》2009,61(2):372-384
Oceanic excess radiocarbon data is widely used as a constraint for air–sea gas exchange. However, recent estimates of the global mean piston velocity 〈 k 〉 from Naegler et al., Krakauer et al., Sweeney et al. and Müller et al. differ substantially despite the fact that they all are based on excess radiocarbon data from the GLODAP data base. Here I show that these estimates of 〈 k 〉 can be reconciled if first, the changing oceanic radiocarbon inventory due to net uptake of CO2 is taken into account; second, if realistic reconstructions of sea surface Δ14 C are used and third, if 〈 k 〉 is consistently reported with or without normalization to a Schmidt number of 660. These corrections applied, unnormalized estimates of 〈 k 〉 from these studies range between 15.1 and 18.2 cm h−1 . However, none of these estimates can be regarded as the only correct value for 〈 k 〉 . I thus propose to use the 'average' of the corrected values of 〈 k 〉 presented here (16.5 ± 3.2 cm h−1 ) as the best available estimate of the global mean unnormalized piston velocity 〈 k 〉 , resulting in a gross ocean-to-atmosphere CO2 flux of 76 ± 15 PgC yr−1 for the mid-1990s. 相似文献
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Laboratory experiments were carried out to investigate the linear depolarization ratios (LDRs) of crystallized H2O/H2SO4 acid clouds at angles of 45°, 135° and 157° to the forward direction. LDR is the ratio of the returned energies in the planes of polarization perpendicular and parallel to that of the source (Sassen, 1974). Experiments were carried out for different concentrations of aqueous solution of sulfuric acid. A cloud of supercooled droplets is formed inside an experimental chamber kept in a walk-in cold room by heating an aqueous solution of sulfuric acid, and the ice crystal formation is initiated by momentarily introducing a rod dipped in liquid nitrogen into the cloud. A 2-mW polarized He:Ne laser beam is directed through the cloud and a photomultiplier tube measures the scattered intensity. It is found that the scattered energy is higher in the direction of 157° and 135° than that at 45°. Microscopic examination of the crystals formed from acid concentrations above 50% shows dark fuzzy spots on the surface of the ice crystals suggesting that this could be a film of acid drops. This film also alters the shape of the crystals, and the crystal boundaries are no longer sharp and well defined like that observed for pure water clouds and this is found to influence the LDR. 相似文献