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1.
雨云7号卫星上的臭氧总量测绘分光仪(TOMS),11年多以来一直测量着全球臭氧柱总量。最近在资料分析上加以改进,得到一种用以确定并消除定标飘移的技术,使记录尽头处的资料相对于记录开头的资料来说可精确到±1.3%(2σ)。由TOMS总臭氧资料时间序列已拟合得出一个统计模式,其中包括季节变化项、线性趋势项、准2年振荡(QBO)项、太阳活动周项以及二阶自回归噪音项。就这个统计模式拟合于65°N到65°S纬圈之间平均的TOMS资料来看,所得到的线性趋势项为-0.26±0.14%/年,即从1978年11月到1990年5月共11.6年中变化-3%。这种变化趋势在赤道近于零(0.0002±0.2%/年),向两极增加。在50°N年平均趋势为-0.5±0.21%/年。在这11.6年期间50°N的趋势,表现出强烈的季节变化,在冬季和初春(即2、3月份)大于-0.8%/年,在夏季(7、8月份)约为-0.2%/年。 相似文献
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对流层大气环流的甚低频振荡 总被引:3,自引:0,他引:3
对1951—1992共42a500hPa北半球高度场的月平均资料进行了纬圈谐波分析,计算了35°N与55°N超长波振幅及位相,以及35—55°N北半球月平均纬向风距平百分比。对超长波振幅及纬向风距平百分比做了小波转换。结果表明,对流层大气环流变化中存在3种准周期性的甚低频振荡:1.年代际的振荡;2.准2a周期振荡(QBO);3.半年韵律。同时发现对流层QBO和平流层赤道纬向风QBO之间可能没有联系。 相似文献
4.
全球农作物对大气CO2及其倍增的吸收量估算 总被引:15,自引:0,他引:15
根据农作物产量资料(FAO1992年),计算出中国和全球各种作物对CO2的吸收总量分别为5.5×108t/aC和28.9×108t/aC。同时以不同CO2浓度下小麦、玉米、大豆等全生育期光合速率实验数据直接计算的C吸收量为对照,与相应的中国产量资料计算结果比较,两者相差2.6%。从而进一步依据作物对CO2倍增反应诊断实验结果,推算出大气CO2浓度比目前倍增(700ppm)条件下,中国和全球农作物吸收CO2总量将增长21%-26%,分别为6.6×108t/a—6.9×108t/a和34.1×108t/a—36.2×108t/aC。研究还表明,单位面积作物年吸C量全球(3.2t/(hm2·8))比中国(4.2t/(hm2·a))低25.4%,而且C4作物普遍高于同类C3作物。 相似文献
5.
龙凤山大气近地层O3浓度变化及与其它因素的关系 总被引:16,自引:0,他引:16
研究首次在龙凤山区域大气本底站测得的地面O3浓度及其变化的资料表明,中国东北农村地面大气O3浓度总体水平不很高,但在少数特殊的天气条件下,时均浓度可超过国家二级标准。O3浓度存在明显的季节和日变化,其月平均浓度1995年1月最低(27.5ppb),1994年11月最高(43.2ppb)。O3日变化幅度夏季的晴天最大(28ppb),冬季的阴天最小(8ppb)。气象要素(尤其是风速、气温和相对湿度等)和NOx与地面O3浓度有较密切的关系。用多变量分析法探讨了地面O3各指标随气象因子和NOx共同变化的规律,并拟合了寒冷和温暖期里与地面O3日最高浓度、日最低浓度及日变化幅度有关的方程。 相似文献
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农田近地面层CO2和湍流通量特征研究 总被引:11,自引:0,他引:11
利用1985年5月至6月在北京郊区中国科学院农业生态试验研究站的麦田中实测的小麦不同生长期的CO2浓度梯度、光合有效辐射、净辐射、土壤热通量和温度、湿度及风速梯度等量的数据,采用空气动力学方法,计算了CO2通量、感热通量、潜热通量和动量通量。并对观测场地、仪器设备、校准方法及误差分析进行了描述。结果表明:从5月14日到6月15日,在1m,2m和10m处,CO2浓度振幅的日变化分别为103.4到27.5,87.5到27.3和69.8到11.5ppm;光合型和呼吸型的平均CO2浓度分别为345.3,350.6,357.5ppm和373.9,369.7,362.1ppm。在白天,CO2通量和梯度的输送方向是从大气向植被,在中午(11时到13时)输送达到负的最大值。在夜间,CO2通量和梯度输送的方向与白天相反,并且,在早晨(4时到6时)达到正的最大值。CO2通量与净辐射(Rn)、可利用能(H+LE)、光合有效辐射和动量通量之间有较好的相关关系 相似文献
9.
根据Dobson和TOMS资料分析北京和昆明大气臭氧总量变化特征 总被引:11,自引:0,他引:11
用约20年 Dobson和TOMS资料来分析北京(39.93°N,116.40°E)和昆明 (25.02°N,102.68°)两地大气臭氧总量的变化特征,结果表明:(1)在1979-2000年间北京大气臭氧长期变化趋势是-0.642 DU/年,而昆明在1980-2000年间的趋势是-0.009 DU/年;(2)北京和昆明两地大气臭氧都有很强的季节内变化(尤其冬季更强),与季节性变化强度相当;(3)在北京和昆明,由记录较短的大气臭氧资料分析得到的长期变化趋势,与较长记录得到的结果有显著差异;(4)在北京(中纬度)和昆明(低纬度)大气臭氧都有显著的准两年振荡信号;(5)两个站点大气臭氧的年际变化主要由长期趋势项和准两年振荡信号组成;(6)Dobson仪测量得到的臭氧总量与TOMS资料非常一致。 相似文献
10.
温带森林土壤消耗大气CO总量及影响因素研究 总被引:4,自引:1,他引:3
CO虽然不是温室气体,但人为活动释放到大气中的CO可引起对流层中CH4、O3等温室气体含量增加,从而间接的产生温室效应,因此,对全球性CO源和汇的研究应给予重视。本研究利用静态箱式方法,对温带落叶森林土壤年释放CO进行了长时间测定,表明该类型土壤年净消耗大气中CO平均强度为46.3±25.5ng/m2·s-1,对调节大气中CO浓度增加有积极意义。文中详细分析了影响土壤消耗CO的环境因素、土壤消耗CO的强度和释放温室气体CO2、CH4之间的关系等 相似文献
11.
R. R. Reddy K. Rama Gopal L. Siva Sankara Reddy K. Narasimhulu K. Raghavendra Kumar Y. Nazeer Ahammed C. V. Krishna Reddy 《Journal of Atmospheric Chemistry》2008,59(1):47-59
In the present study, an attempt has been made to examine the governing photochemical processes of surface ozone (O3) formation in rural site. For this purpose, measurements of surface ozone and selected meteorological parameters have been
made at Anantapur (14.62°N, 77.65°E, 331 m asl), a semi-arid zone in India from January 2002 to December 2003. The annual
average diurnal variation of O3 shows maximum concentration 46 ppbv at noon and minimum 25 ppbv in the morning with 1σ standard deviation. The average seasonal
variation of ozone mixing ratios are observed to be maximum (about 60 ppbv) during summer and minimum (about 22 ppbv) in the
monsoon period. The monthly daytime and nighttime average surface ozone concentration shows a maximum (55 ± 7 ppbv; 37 ± 7.3 ppbv)
in March and minimum (28 ± 3.4 ppbv; 22 ± 2.3 ppbv) in August during the study period. The monthly average high (low) O3 48.9 ± 7.7 ppbv (26.2 ± 3.5 ppbv) observed at noon in March (August) is due to the possible increase in precursor gas concentration
by anthropogenic activity and the influence of meteorological parameters. The rate of increase of surface ozone is high (1.52 ppbv/h)
in March and lower (0.40 ppbv/h) in July. The average rate of increase of O3 from midnight to midday is 1 ppbv/h. Surface temperature is highest (43–44°C) during March and April months leading to higher
photochemical production. On the other hand, relative humidity, which is higher during the rainy season, shows negative correlation
with temperature and ozone mixing ratio. It can be seen that among the two parameters are measured, correlation of surface
ozone with wind speed is better (R
2=0.84) in compare with relative humidity (R
2=0.66). 相似文献
12.
Lokesh K. Sahu Shyam Lal Valérie Thouret Herman G. Smit 《Journal of Atmospheric Chemistry》2009,62(2):151-174
Tropospheric distributions of ozone (O3) and water vapor (H2O) have been presented based on the Measurements of OZone and water vapor by Airbus In-Service AirCraft (MOZAIC) data over the metro and capital city of Delhi, India during 1996–2001. The vertical mixing ratios of both O3 and H2O show strong seasonal variations. The mixing ratios of O3 were often below 40 ppbv near the surface and higher values were observed in the free troposphere during the seasons of winter
and spring. In the free troposphere, the high mixing ratio of O3 during the seasons of winter and spring are mainly due to the long-range transport of O3 and its precursors associated with the westerly-northwesterly circulation. In the lower and middle troposphere, the low mixing
ratios of ∼20–30 ppbv observed during the months of July–September are mainly due to prevailing summer monsoon circulation
over Indian subcontinent. The summer monsoon circulation, southwest (SW) wind flow, transports the O3-poor marine air from the Arabian Sea and Indian Ocean. The monthly averages of rainfall and mixing ratio of H2O show opposite seasonal cycles to that of O3 mixing ratio in the lower and middle troposphere. The change in the transport pattern also causes substantial seasonal variation
in the mixing ratio of H2O of 3–27 g/kg in the lower troposphere over Delhi. Except for some small-scale anomalies, the similar annual patterns in
the mixing ratios of O3 and H2O are repeated during the different years of 1996–2001. The case studies based on the profiles of O3, relative humidity (RH) and temperature show distinct features of vertical distribution over Delhi. The impacts of long range
transport of air mass from Africa, the Middle East, Indian Ocean and intrusions of stratospheric O3 have also been demonstrated using the back trajectory model and remote sensing data for biomass burning and forest fire activities. 相似文献
13.
This study examines the processes controlling the diurnal variability of ozone (O3) in the marine boundary layer of the Kwajalein Atoll, Republic of the Marshall Islands (latitude 8° 43′ N, longitude 167°
44′ E), during July to September 1999. At the study site, situated in the equatorial Pacific Ocean, O3 mixing ratios remained low, with an overall average of 9–10 parts per billion on a volume basis (ppbv) and a standard deviation
of 2.5 ppbv. In the absence of convective storms, daily O3 mixing ratios decreased after sunrise and reached minimum during the afternoon in response to photochemical reactions. The
peak-to-peak amplitude of O3 diurnal variation was approximately 1–3 ppbv. During the daytime, O3 photolysis, hydroperoxyl radicals, hydroxyl radicals, and bromine atoms contributed to the destruction of O3, which explained the observed minimum O3 levels observed in the afternoon. The entrainment of O3-richer air from the free troposphere to the local marine boundary layer provided a recovery mechanism of surface O3 mixing ratio with a transport rate of 0.04 to 0.2 ppbv per hour during nighttime. In the presence of convection, downward
transport of O3-richer tropospheric air increased surface O3 mixing ratios by 3–12 ppbv. The magnitude of O3 increase due to moist convection was lower than that observed over the continent (as high as 20–30 ppbv). Differences were
ascribed to the higher O3 levels in the continental troposphere and weaker convection over the ocean. Present results suggest that moist convection
plays a role in surface-level O3 dynamics in the tropical marine boundary layer. 相似文献
14.
Hydroxyl and Peroxy Radical Chemistry in a Rural Area of Central Pennsylvania: Observations and Model Comparisons 总被引:2,自引:0,他引:2
Atmospheric hydroxyl (OH), hydroperoxy (HO2), total peroxy (HO2 and organic peroxy radicals, RO2) mixing ratios and OH reactivity (first order OH loss rate) were measured at a rural site in central Pennsylvania during
May and June 2002. OH and HO2 mixing ratios were measured with laser induced fluorescence (LIF); HO2
+ RO2 mixing ratios were measured with chemical ionization mass spectrometry (CIMS). The daytime maximum mixing ratios were up
to 0.6 parts per trillion by volume (pptv) for OH, 30 pptv for HO2, and 45 pptv for HO2 + RO2. A parameterized RACM (Regional Atmospheric Chemistry Mechanism) box model was used to predict steady state OH, HO2 and HO2 + RO2 concentrations by constraining the model to the measured OH reactivity and previously measured volatile organic compound
(VOC) distributions. The averaged model calculations are generally in good agreement with the observations. For OH, the model
matched the observations for day and night, with an average observed-to-modeled ratio of 0.80. In previous studies such as
PROPHET98, nighttime NO was near 0 pptv and observed nighttime OH was significantly larger than modeled OH. In this study,
nighttime observed and modeled OH agree to within measurement and model uncertainties because the main source of the nighttime
OH was the reaction HO2 + NO → OH + NO2, with the NO being continually emitted from the surrounding fertilized corn field. The observed-to-modeled ratio for HO2 is 1.0 on average, although daytime HO2 is underpredicted by a factor of 1.2 and nighttime HO2 is over-predicted by a factor of ∼2. The average measured and modeled HO2 + RO2 agree well during daytime, but the modeled value is about twice the measured value during nighttime. While measured HO2 + RO2 values agree with modeled values for NO mixing ratios less than a few parts per billion by volume (ppbv), it increases substantially
above the expected value for NO greater than a few ppbv. This observation of the higher-than-expected HO2 + RO2 with the CIMS technique confirms the observed increase of HO2 above expected values at higher NO mixing ratios in HO2 measurements with the LIF technique. The maximum instantaneous O3 production rate calculated from HO2 and RO2 reactions with NO was as high as 10–15 ppb h−1 at midday; the total daily O3 production varied from 13 to 113 ppbv d−1 and was 48 ppbv d−1 on average during this campaign. 相似文献
15.
K. Renuka Harish Gadhavi A. Jayaraman Shyam Lal M. Naja S. V. Bhaskara Rao 《Journal of Atmospheric Chemistry》2014,71(2):95-112
We have studied long-term changes in tropospheric NO2 over South India using ground-based observations, and GOME and OMI satellite data. We have found that unlike urban regions, the region between Eastern and Western Ghat mountain ranges experiences statistically significant decreasing trend. There are few ground-based observatories to verify satellite based trends for rural regions. However, using a past study and recent measurements we show a statistically significant decrease in NOX and O3 mixing ratio over a rural location (Gadanki; 13.48° N, 79.18° E) in South India. In the ground-based records of surface NOX, the concentration during 2010–11 is found to be lower by 0.9 ppbv which is nearly 60 % of the values observed during 1994–95. Small but statistically significant decrease in noon-time peak ozone concentration is also observed. Noon-time peak ozone concentration has decreased from 34?±?13 ppbv during 1993–96 to 30?±?15 ppbv during 2010–11. NOX mixing ratios are very low over Gadanki. In spite of low NOX values (0.5 to 2 ppbv during 2010–11), ozone mixing ratios are not significantly low compared to many cities with high NOX. The monthly mean ozone mixing ratio varies from 9 ppbv to 37 ppbv with high values during Spring and low values during late Summer. Using a box-model, we show that presence of VOCs is also very important in addition to NOX in determining ozone levels in rural environment and to explain its seasonal cycle. 相似文献
16.
Jayanarayanan Kuttippurath Armin Kleinböhl Holger Bremer Harry Küllmann Justus Notholt Björn-Martin Sinnhuber Wuhu Feng Martyn Chipperfield 《Journal of Atmospheric Chemistry》2010,66(1-2):41-64
Airborne measurements of stratospheric ozone and N2O from the SCIAMACHY (Scanning Imaging Absorption Spectrometer) Validation and Utilization Experiment (SCIA-VALUE) are presented. The campaign was conducted in September 2002 and February–March 2003. The Airborne Submillimeter Radiometer (ASUR) observed stratospheric constituents like O3 and N2O, among others, spanning a latitude from 5°S to 80°N during the survey. The tropical ozone source regions show high ozone volume mixing ratios (VMRs) of around 11 ppmv at 33 km altitude, and the altitude of the maximum VMR increases from the tropics to the Arctic. The N2O VMRs show the largest value of 325 ppbv in the lower stratosphere, indicating their tropospheric origin, and they decrease with increasing altitude and latitude due to photolysis. The sub-tropical and polar mixing barriers are well represented in the N2O measurements. The most striking seasonal difference found in the measurements is the large polar descent in February–March. The observed features are interpreted with the help of SLIMCAT and Bremen Chemical Transport Model (CTMB) simulations. The SLIMCAT simulations are in good agreement with the measured O3 and N2O values, where the differences are within 1 ppmv for O3 and 15 ppbv for N2O. However, the CTMB simulations underestimate the tropical middle stratospheric O3 (1–1.5 ppmv) and the tropical lower stratospheric N2O (15–30 ppbv) measurements. A detailed analysis with various measurements and model simulations suggests that the biases in the CTMB simulations are related to its parameterised chemistry schemes. 相似文献
17.
B. Ridley J. Walega D. Montzka F. Grahek E. Atlas F. Flocke V. Stroud J. Deary A. Gallant H. Boudries J. Bottenheim K. Anlauf D. Worthy A. L. Sumner B. Splawn P. Shepson 《Journal of Atmospheric Chemistry》2000,36(1):1-22
Measurements of NOx (NO +NO2) and the sum of reactive nitrogenconstituents, NOy, were made near the surface atAlert (82.5°N), Canada during March and April1998. In early March when solar insolation was absentor very low, NOx mixing ratios were frequentlynear zero. After polar sunrise when the sun was abovethe horizon for much or all of the day a diurnalvariation in NOx and NOy was observed withamplitudes as large as 30–40 pptv. The source ofactive nitrogen is attributed to release from the snowsurface by a process that is apparently sensitized bysunlight. If the source from the snowpack is a largescale feature of the Arctic then the diurnal trendsalso require a competing process for removal to thesurface. From the diurnal change in the NO/NO2ratio, mid-April mixing ratios for the sum of peroxyand halogen oxide radicals of 10 pptv werederived for periods when ozone mixing ratios were inthe normal range of 30–50 ppbv. Mid-day ozoneproduction and loss rates with the active nitrogensource were estimated to be 1–2 ppbv/day and in nearbalance. NOy mixing ratios which averaged only295±66 pptv do not support a large accumulation inthe high Arctic surface layer in the winter and springof 1998. The small abundance of NOy relative tothe elevated mixing ratios of other long-livedanthropogenic constituents requires that reactivenitrogen be removed to the surface during transport toor during residence within the high Arctic. 相似文献
18.
Deanne D. Grant Jose D. Fuentes Stephen Chan William R. Stockwell Daniel Wang Seydi A. Ndiaye 《Journal of Atmospheric Chemistry》2008,60(1):19-35
The objectives of this study were to identify species and levels of volatile organic compounds (VOCs), and determine their
oxidation capacity in the rural atmosphere of western Senegal. A field study was conducted to obtain air samples during September
14 and September 15, 2006 for analyses of VOCs. Methanol, acetone, and acetaldehyde were the most abundant detected chemical
species and their maximum mixing ratios reached 6 parts per billion on a volume basis (ppbv). Local emission sources such
as firewood and charcoal burning strongly influenced VOC concentrations. The VOC concentrations exhibited little temporal
variations due to the low reactivity with hydroxyl radicals, with reactivity values ranging from 0.001 to 2.6 s−1. The conditions in this rural site were rather clean. Low ambient NO
x
levels limited ozone production. Nitrogen oxide (NO
x
) levels reached values less than 2 ppbv and maximum VOC/NO
x
ratios reached 60 ppbvC/ppbv, with an overall average of 2.4 ± 4.5 ppbvC/ppbv. This indicates that the rural western Senegal
region is NO
x
limited in terms of oxidant formation potential. Therefore, during the study period photochemical ozone production became
limited due to low ambient NO
x
levels. The estimated ozone formation reactivity for VOCs was low and ranged between −5.5 mol of ozone/mol of benzaldehyde
to 0.6 mol/mol of anthropogenic dienes. 相似文献
19.
Hydrogen peroxide, one of the key compounds in multiphase atmospheric chemistry, was measured on an Atlantic cruise (ANT VII/1) of the German research vessel Polarstern from 15 September to 9 October 1988, in rain and ambient air by a chemiluminescence technique. For gas phase H2O2 cryogenic sampling was employed. The presented results show an increase of gas-phase mixing ratios of about 45 pptv per degree latitude between 50° N and 0°, and a maximum of 3.5 ppbv around the equator. Generally higher mixing ratios were observed in the Southern Hemisphere, with a clear diurnal variation. The H2O2 mixing ratio is correlated to the UV radiation intensity and to the temperature difference between air and ocean surface water. 相似文献
20.
Martin Saliba Raymond Ellul Liberato Camilleri Hans Güsten 《Journal of Atmospheric Chemistry》2008,60(2):117-135
A 10-year study of surface ozone mixing ratios in the Central Mediterranean was conducted based on continuous ozone measurements
from 1997 to 2006 by a background regional Global Atmospheric Watch (GAW) station on the island of Gozo. The mean annual maximum
mixing ratio is of the order of 66 ppbv in April–May with a broad secondary maximum of 64 ppbv in July–September. No long-term
increase or decrease in the background level of surface ozone could be observed over the last 10 years. This is contrary to
observations made in the Eastern Mediterranean, where a slow decrease in the background ozone mixing ratio was observed over
the past 7 years. Despite the very high average annual ozone mixing ratio exceeding 50 ppbv—in fact, the highest average background
ozone mixing ratio ever measured in Europe—, the diurnal O
3 max/O
3 min index of <1.40 indicates that the island of Gozo is a good site for measuring background surface ozone. However, frequent
photosmog events from June to September during the past 10 years with ozone mixing ratios exceeding 90 ppbv indicate that
the Central Mediterranean is prone to long-range transport of air pollutants from Europe by northerly winds. This was particularly
evident during the so-called “August heatwave” of the year 2003 when the overall ozone mixing ratio was 4.6 ppbv higher than
the average of all other 9 months of August since 1997. Air mass back-trajectory analysis of the August 2003 photosmog episodes
on Gozo confirmed that ozone pollution originated from the European continent. Regression analysis was used to analyse the
10-year data set in order to model the behaviour of the ozone mixing ratio in terms of the meteorological parameters of wind
speed, relative humidity, global radiation, temperature, month of year, wind sector, atmospheric pressure, and time of day
(predictors). Most of these predictors were found to significantly affect the ozone mixing ratios. From March to November,
the monthly average of the AOT40 threshold value for the protection of crops and vegetation against ozone was constantly exceeded
on Gozo during the past 10 years. 相似文献