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H. Plaisance S. Sauvage P. Coddeville R. Guillermo 《Environmental monitoring and assessment》1998,51(3):657-671
The variability in performance of three precipitation sensor types, mounted on three identical wet-only collectors, has been compared for eight months at a single site. The catch efficiencies, determined from the sample volumes, are relatively high for these three apparatuses, since they exceed 89% on average. The recorded data of openings and closings of collector lids reveal that the highest losses of collection efficiency, observed for rainfalls of low intensity and low amount, are largely imputable to design and running characteristics of each sensor. Ionic compositions between the samples of these three collectors are relatively close, although significant differences are especially found for H+, Ca2+, Mg2+ and K+, suggesting that these apparatuses are differently exposed to the dry deposition of soil particles. The RS 85 sensor seems to be the most suitable one of the three, since it ensures a high catch efficiency for all rain types and tends to limit the exposures of funnel to the dry deposition. 相似文献
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吉林省城市大气降水pH值时空分异及成因 总被引:5,自引:0,他引:5
通过对吉林省8个代表城市1992-1997年大气降水观测数据的统计分析,对大气降水PH值的时空分异进行了探讨。结果表明:吉林省中西部城市大气降水基本呈中性;东部的图们,珲春两市大气降水酸化亚得,多年平均降水PH分别为5.12和5.38;全省碱性降水多集中在吉林市。 相似文献
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北京大气中BTEX的观测分析与研究 总被引:13,自引:6,他引:7
采用二步深冷浓缩与气相色谱/质谱联机对北京大气中的苯类物质(BTEX) 进行了长期连续观测.最近4年观测数据表明:日变化有双峰和3峰变化,冬、春季呈现与交通高峰期吻合的双峰变化,即上午08:00至10:00和下午17:00前后各出现一个高值;秋季日变化中,夜间22:00出现第3峰值;夏季日变化呈3峰型,最大峰值在正午前后.2000~2002年BTEX月平均总浓度为(44.1±24.5) nmol/mol(碳单位),季变化峰值出现在夏季.年际变化趋势中,北京大气BTEX的总平均浓度从 1999 年到2002年大幅度下降. 相似文献
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Analysis of Meteorological Drought Pattern During Different Climatic and Cropping Seasons in Bangladesh 下载免费PDF全文
Mahiuddin Alamgir Shamsuddin Shahid Manzul Kumar Hazarika Syams Nashrrullah Sobri Bin Harun Supiah Shamsudin 《Journal of the American Water Resources Association》2015,51(3):794-806
Drought is one of the most frequent natural disasters in Bangladesh which severely affect agro‐based economy and people's livelihood in almost every year. Characterization of droughts in a systematic way is therefore critical in order to take necessary actions toward drought mitigation and sustainable development. In this study, standardized precipitation index is used to understand the spatial distribution of meteorological droughts during various climatic seasons such as premonsoon, monsoon, and winter seasons as well as cropping seasons such as Pre‐Kharif (March‐May), Kharif (May‐October), and Rabi (December‐February). Rainfall data collected from 29 rainfall gauge stations located in different parts of the country were used for a period of 50 years (1961‐2010). The study reveals that the spatial characteristics of droughts vary widely according to season. Premonsoon droughts are more frequent in the northwest, monsoon droughts mainly occur in the west and northwest, winter droughts in the west, and the Rabi and Kharif droughts are more frequent in the north and northwest of Bangladesh. It is expected that the findings of the study will support drought monitoring and mitigation activities in Bangladesh. 相似文献