【摘要】：閃電是一種常見的自然現(xiàn)象,地球上每秒約有30~100次閃電發(fā)生。閃電作為最常見的氣象災(zāi)害之一,直接威脅人類的生命和財(cái)產(chǎn)安全。同時(shí),閃電的高溫、高壓等特點(diǎn)能夠迅速引起多種大氣化學(xué)反應(yīng),進(jìn)而對大氣化學(xué)組分及大氣環(huán)境質(zhì)量乃至氣候產(chǎn)生影響。閃電不僅是大氣中氮氧化物(NO_x)主要的自然源之一,也可以通過直接與間接的方式對大氣臭氧(O_3)濃度產(chǎn)生影響,而O_3濃度又直接影響大氣的氧化能力。此外,閃電也可能誘導(dǎo)大氣中新顆粒物的生成。然而,綜合研究閃電活動及其相關(guān)氣象條件對近地面大氣NO_x及O_3濃度的影響以及閃電過程中顆粒物濃度及其化學(xué)組分變化的研究目前在我國還未見報(bào)道。本研究主要基于香港地區(qū)閃電定位系統(tǒng)所獲取的閃電數(shù)據(jù)、香港空氣質(zhì)量監(jiān)測數(shù)據(jù)、氣象數(shù)據(jù)以及地形數(shù)據(jù),探討香港地區(qū)的地閃活動時(shí)空分布特征以及閃電活動對近地面大氣中NO_x及O_3的影響;同時(shí)基于在廣州從化開展的人工引雷實(shí)驗(yàn),對閃電發(fā)生前后NO,O_3及亞微米級細(xì)粒子濃度和化學(xué)組成進(jìn)行了觀測,探討其可能的大氣化學(xué)機(jī)制。本研究的開展一方面對防雷減災(zāi)以及雷雨季節(jié)大氣環(huán)境質(zhì)量的評估具有一定的指導(dǎo)意義,同時(shí)也為閃電的大氣化學(xué)效應(yīng)及其影響機(jī)制的深入研究提供了新的方法和一定的數(shù)據(jù)基礎(chǔ)。具體研究內(nèi)容及相關(guān)研究成果主要包括以下幾個(gè)方面:(1)香港地區(qū)地閃活動時(shí)空分布特征及其影響因素:通過對香港地區(qū)2006~2012年閃電定位數(shù)據(jù)、氣象參數(shù)和海拔高度等相關(guān)數(shù)據(jù)的統(tǒng)計(jì)及相關(guān)性分析,發(fā)現(xiàn)香港地區(qū)2006~2012年間地閃發(fā)生次數(shù)最多的為2010年,最少為2011年;就月際變化而言,地閃活動的發(fā)生主要集中在4~9月;正、負(fù)地閃回?fù)舸螖?shù)的日變化峰值則均出現(xiàn)在凌晨1點(diǎn)。地閃活動的時(shí)間變化特征主要受到天氣和氣候因素以及海陸熱力差異的綜合影響。在空間分布上,西部地區(qū)的正地閃回?fù)裘芏让黠@高于東部,而負(fù)地閃回?fù)裘芏鹊母咧抵行膭t主要集中在海拔較高的山區(qū)。正、負(fù)地閃回?fù)裘芏染S海拔的升高而有所增加。(2)香港地區(qū)地閃活動及相關(guān)氣象條件對近地面NO_x及O_3濃度的影響:選擇香港地區(qū)三個(gè)代表不同土地利用類型的研究站點(diǎn)(郊區(qū)站塔門、新市鎮(zhèn)站東涌及市區(qū)站葵涌),主要采用主成分分析/絕對主成分得分方法(PCA/APCS)結(jié)合多元線性回歸(MLR)模型對NO_x和O_3濃度、閃電定位數(shù)據(jù)及相關(guān)氣象數(shù)據(jù)進(jìn)行了分析。發(fā)現(xiàn)三個(gè)站點(diǎn)的NO_x濃度在閃電日均有一定增加,增長幅度在4.1%~20.5%之間;而O_3濃度則均在閃電日顯著減少,減少幅度為26.5%~44.4%。對相關(guān)影響因子的研究結(jié)果表明,土地利用類型、閃電活動(如:地閃回?fù)纛l率和平均峰值電流)及其相關(guān)氣象條件(如:風(fēng)向、風(fēng)速、降水、溫度、相對濕度、云量和對流有效位能)等均對近地面NO_x及O_3濃度的變化具有不同程度的影響。(3)基于人工引雷技術(shù)對閃電大氣化學(xué)效應(yīng)的驗(yàn)證:通過對2014年8月19日進(jìn)行的五次成功人工引雷前后NO,O_3及亞微米級細(xì)粒子濃度變化的觀測,發(fā)現(xiàn)NO在引雷前半小時(shí)平均濃度為0.4 ppbv,第一次人工引雷成功后迅速升高,峰值濃度達(dá)到220.5 ppbv,其余四次引雷后NO濃度也都有不同程度的升高。O_3濃度在人工引雷前有所增加,而在第一次引雷成功后迅速降低至谷值16.9 ppbv。O_3濃度在引雷前的增加可能與周邊自然閃電電暈放電所產(chǎn)生的O_3以及下沉氣流所攜帶的濃度相對較高的O_3有關(guān),引雷后O_3濃度的下降則可能是由閃電快速產(chǎn)生的NO對O_3的滴定作用引起的。此外,亞微米級細(xì)粒子濃度在引雷成功后出現(xiàn)快速增長的現(xiàn)象,這可能是由于閃電過程有利于離子誘導(dǎo)成核產(chǎn)生新粒子導(dǎo)致的。(4)基于單顆粒氣溶膠質(zhì)譜儀(SPAMS)對人工引雷前后顆粒物化學(xué)組分的初步研究:人工引雷前、中、后三個(gè)階段的正、負(fù)離子平均譜圖顯示,引雷過程中顆粒物的正、負(fù)離子平均質(zhì)譜圖與引雷前相似,最大的差異在于出現(xiàn)了鐵離子的特征峰。對含鐵顆粒的統(tǒng)計(jì)結(jié)果表明,含鐵顆粒數(shù)在第一次引雷成功后的幾分鐘里顯著高于其他時(shí)間,含鐵顆粒數(shù)峰值的出現(xiàn)略晚于NO峰值濃度的出現(xiàn)時(shí)間。由于引雷過程中的鐵離子主要由人工觸發(fā)閃電導(dǎo)致火箭導(dǎo)線熔化產(chǎn)生,因此引雷過程中含鐵顆粒數(shù)量及占比的顯著增加從側(cè)面反映出閃電通道中化學(xué)組分的改變會對顆粒物化學(xué)組分產(chǎn)生一定影響。對含氮顆粒的分析結(jié)果則顯示,閃電過程可能導(dǎo)致大氣顆粒物中硝酸根的增加。
[Abstract]:Lightning is a common natural phenomenon. Lightning occurs about 30-100 times per second on the earth. Lightning, as one of the most common meteorological disasters, directly threatens the safety of human life and property. Lightning is not only one of the major natural sources of nitrogen oxides (NO_x) in the atmosphere, but also directly and indirectly affects the concentration of atmospheric ozone (O_3). In addition, lightning may also induce the formation of new particles in the atmosphere. However, a comprehensive study of flash The effects of electrical activities and related meteorological conditions on the concentrations of NO_x and O_3 in the near-surface atmosphere and the changes of particulate matter concentrations and their chemical components during lightning have not been reported in China. Based on the topographic data, the temporal and spatial distribution characteristics of the ground lightning activity in Hong Kong and the influence of lightning on NO_x and O_3 in the near-surface atmosphere are discussed. The concentration and chemical composition of NO, O_3 and submicron fine particles before and after lightning occurrence are observed, and the possible atmospheric chemistry is discussed. On the one hand, this study has a certain guiding significance for lightning protection and disaster mitigation as well as the assessment of atmospheric environmental quality in thunderstorm season, on the other hand, it also provides a new method and a certain data basis for the in-depth study of lightning atmospheric chemical effect and its impact mechanism. Several aspects: (1) Spatial and temporal distribution characteristics of ground lightning activity in Hong Kong and its influencing factors: Through statistical analysis and correlation analysis of lightning location data, meteorological parameters and altitude data in Hong Kong from 2006 to 2012, it is found that the most frequent occurrences of ground lightning in Hong Kong from 2006 to 2012 are in 2010, at least in 2011; and on the basis of monthly variation. In terms of geostrophism, the occurrence of positive and negative return strokes mainly occurs from April to September, and the diurnal peak of positive and negative return strokes occurs at 1:00 a.m. The high value centers of negative ground flashback density were mainly concentrated in the mountainous areas with higher altitude. The positive and negative ground flashback density increased with the increase of altitude. (2) The influence of ground flashback activity and related meteorological conditions on the concentration of NO_x and O_3 near the ground in Hong Kong: Three research stations representing different land use types were selected. Principal Component Analysis/Absolute Principal Component Scoring (PCA/APCS) combined with Multivariate Linear Regression (MLR) model was used to analyze the concentration of NO_x and O_3, lightning location data and related meteorological data. It was found that the concentration of NO_x at the three stations increased on the day of lightning. The results show that land use types, lightning activities (e.g. ground flashback frequency and mean peak current) and related meteorological conditions (e.g. wind direction, wind speed, precipitation, temperature, relative humidity, cloud cover and cloud cover) are related to land use types. (3) Based on the verification of the atmospheric chemical effects of lightning induced by artificial lightning, the concentration changes of NO, O_3 and submicron fine particles were observed before and after five successful artificial lightning triggers on August 19, 2014, and it was found that NO was about half an hour before the lightning was triggered. The average concentration was 0.4 ppbv, and the peak concentration was 220.5 ppbv after the first successful lightning, and the NO concentration was also increased in varying degrees after the other four lightning. The concentration of O_3 increased before the artificial lightning, but decreased rapidly to the valley value of 16.9 ppbv. O_3 produced by corona discharge of edge natural lightning is related to the relatively high concentration of O_3 carried by subsidence airflow. The decrease of O_3 concentration after lightning may be caused by the titration of O_3 by NO produced by lightning. In addition, the concentration of sub-micron fine particles increases rapidly after successful lightning induction, which may be due to the rapid increase of O_3 concentration. Lightning process is conducive to the formation of new particles induced by ions. (4) Preliminary study on the chemical composition of particulate matter before and after artificial lightning by single particle aerosol spectrometer (SPAMS): before, during and after artificial lightning, the positive and negative ion average spectra show that the positive and negative ion average mass spectra of particulate matter and the lightning induction process. The statistical results of iron-containing particles show that the number of iron-containing particles in the first few minutes after successful lightning is significantly higher than other times, and the peak number of iron-containing particles appears slightly later than the peak concentration of NO. The number and proportion of iron particles in the lightning channel increase significantly, reflecting that the change of chemical composition in the lightning channel will have a certain impact on the chemical composition of particulate matter. The analysis of nitrogen particles shows that the lightning process may lead to nitrate in the atmospheric particulate matter. The increase.
【學(xué)位授予單位】：中國科學(xué)院廣州地球化學(xué)研究所
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：X51;P427.3

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