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Reconstructed light extinction coefficients using chemical compositions of PM<Subscript>2.5</Subscript> in winter in Urban Guangzhou,China 总被引:8,自引:0,他引:8
The objective of this study was to reconstruct light extinction coefficients (b ext ) according to chemical composition components of particulate matter up to 2.5 μm in size (PM 2.5 ). PM 2.5 samples were collected at the monitoring station of the South China of Institute of Environmental Science (SCIES, Guangzhou, China) during January 2010, and the online absorbing and scattering coefficients were obtained using an aethalometer and a nephelometer. The measured values of light absorption coefficient by particle (b ap ) and light scattering coefficient by particle (b sp ) significantly correlated (R 2 > 0.95) with values of b ap and b sp that were reconstructed using the Interagency Monitoring of Protected Visual Environments (IMPROVE) formula when RH was <70%. The measured b ext had a good correlation (R 2 > 0.83) with the calculated b ext under ambient RH conditions. The result of source apportionment of b ext showed that ammonium sulfate [(NH 4 ) 2 SO 4 ] was the largest contributor (35.0%) to b ext , followed by ammonium nitrate (NH 4 NO 3 , 22.9%), organic matter (16.1%), elemental carbon (11.8%), sea salt (4.7%), and nitrogen dioxide (NO 2 , 9.6%). To improve visibility in Guangzhou, the effective control of secondary particles like sulfates, nitrates, and ammonia should be given more attention in urban environmental management. 相似文献
14.
Mesoscale Vortex Generation and Merging Process: A Case Study Associated with a Post-Landfall Tropical Depression 总被引:5,自引:0,他引:5
An observational analysis of satellite blackbody temperature (TBB) data and radar images suggests that the mesoscale vortex generation and merging process appeared to be essential for a tropical-depression-related heavy rain event in Shanghai, China. A numerical simulation reproduced the observed mesoscale vortex generation and merging process and the corresponding rain pattern, and then the model outputs were used to study the related dynamics through diagnosing the potential vorticity (PV) equation. The t... 相似文献
15.
During the pre-summer rainy season, heavy rainfall occurs frequently in South China. Based on polarimetric radar observations, the microphysical characteristics and processes of convective features associated with extreme rainfall rates(ERCFs) are examined. In the regions with high ERCF occurrence frequency, sub-regional differences are found in the lightning flash rate(LFR) distributions. In the region with higher LFRs, the ERCFs have larger volumes of high reflectivity factor above the freezin... 相似文献
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Valuable dropsonde data were obtained from multiple field campaigns targeting tropical cyclones, namely Higos,Nangka, Saudel, and Atsani, over the western North Pacific by the Hong Kong Observatory and Taiwan Central Weather Bureau in 2020. The conditional nonlinear optimal perturbation(CNOP) method has been utilized in real-time to identify the sensitive regions for targeting observations adhering to the procedure of real-time field campaigns for the first time. The observing system experiments... 相似文献
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Viscoelastic (VE) dampers, with their stiffness and energy dissipation capabilities, have been widely used in civil engineering for mitigating wind-induced vibration and seismic responses of structures, thus enhancing the comfort of residents and serviceability of equipment inside. In past relevant research, most analytical models for characterizing the mechanical behavior of VE dampers were verified by comparing their predictions with performance test results from small-scale specimens, which might not adequately or conservatively represent the actual behavior of full-scale dampers, especially with regard to the ambient temperature, temperature rise, and heat convection effects. Thus, in this study, by using a high-performance testing facility with a temperature control system, full-scale VE dampers were dynamically tested with different displacement amplitudes, excitation frequencies, and ambient temperatures. By comparing the analytical predictions with the experimental results, it is demonstrated that adopting the fractional derivative method together with considering the effects of excitation frequencies, ambient temperatures, temperature rises, softening, and hardening, can reproduce the design performance of full-scale VE dampers very well. 相似文献
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垂直探测台风边界层特征对于认清台风结构具有重要意义。基于1319号台风“天兔”途经的三个边界层风廓线雷达站的观测资料,结合探空数据,本文分析了“天兔”的边界层径向、切向风特征,结果表明:1)最大切向风速出现在眼区附近,在“天兔”稳定维持为强台风级别期间,最大切向风速基本稳定在1800 m高度左右,随着登陆后强度的迅速减弱,最大切向风速减弱、最大切向风速垂直范围缩小;2)最大风速所在高度和台风入流层顶高基本相近,大于依据理查森数或位温梯度所判断出的边界层高度,而基于信噪比(SNR)或其梯度所判断的混合层高度时常偏低;3)“天兔”登陆前边界层高度可以达到2100 m以上,在台风级别及以上时,各站观测到的边界层高度变化不大,基本在1200~1600 m之间,登陆后随着台风强度的减弱,边界层高度迅速减小。 相似文献
19.
安徽省濉溪县邹楼铁矿为接触交代型铁矿床,矿床地质特征与华北地块“邯邢式”铁矿类似,矿体位于燕山期闪长质侵入岩与下奥陶统萧县组碳酸盐岩接触带附近,矿床规模较小,矿体个数多。邹楼铁矿物探异常特征较为明显,处于重力高、磁力高、电阻率等值线低阻扭曲部位。通过对该矿床的地质、物探异常特征进行总结,以期为该区乃至华北地块其他地区寻找类似矿床提供借鉴。 相似文献
20.
This paper presents flume and field observations of a bank-confined braided river. Morphological features, including plan form configuration, channel width, and main channel migration, were examined by a series of experiments. Repeated measurements of channel morphology, provided a basis to estimate the relationship between noncumulative frequency of bars and bar area. Additional results from the Dajia River, located in Central Western Taiwan, were presented to provide a reference data set for comparing the laboratory and field data. The results indicate that the relationship between bar length and width can be predicted by a simple best-fit power function relating to self-similarity characteristics. The Hurst index by Walsh and Hicks (2002) provides acceptable predictions of the bar length and width observed in the experiments and confirmed by the field investigations. Eexperimental and field results both show that large river width yields a uniform distribution of bar areas with the similar discharge, leading to a large value of exponent (β) in the model. The river width is confirmed to be a critical parameter in the main channel shift. A small increase in channel width likely increased rapidly the shift cycle. 相似文献