华北平原固城站NO2对流层柱浓度变化特征

基于2008年9月—2010年9月河北固城生态与农业气象试验站多轴差分吸收光谱仪 (multi-axis differential optical absorption spectroscopy, MAX-DOAS) 获得的太阳散射光谱观测,反演计算该地区NO₂对流层柱浓度,分析其季节、日变化特征以及不同来源输送的影响,并与同期NO₂地面观测资料和卫星产品进行对比分析。发现固城站NO₂对流层柱浓度冬高 (5.14×1016 cm-2) 夏低 (1.28×1016 cm-2);日变化形态在四季均呈现中午低、傍晚高的特征,且冬季最明显。与北京城市区域同期的观测相比,冬季固城站观测值略低,而在春、夏季则偏低较显著。地面风玫瑰图分析显示,来自SW, SSW, NE方向及ENE方向的污染输送对其贡献最大。与地面、卫星NO₂观测的对比表明,MAX-DOAS反演的NO₂柱浓度与地面观测浓度具有一致的季节和日变化特征,卫星反演的NO₂对流层柱浓度产品在华北平原农村地区存在系统性低估。     

利用GOME卫星资料分析北京大气NO2污染变化

利用GOME (Global Ozone Monitoring Experiment, 全球臭氧监测实验) 1996年1月—2002年12月NO₂对流层柱浓度月平均卫星遥感资料以及根据北京市2001年1月1日—2002年12月31日NO₂污染指数数据计算出的地面NO₂日均质量浓度值, 分析了北京市城市大气NO₂污染变化的季节变化特征以及年际变化, 并将2001年1月—2002年12月北京上空GOME NO₂对流层柱浓度月平均值变化与北京市地面NO₂日均质量浓度月平均值变化进行了比较, 结果表明两者随时间的变化趋势具有较好的一致性, 据此可以利用GOME NO₂对流层柱浓度月平均卫星遥感资料来分析特定区域大气NO₂的季节变化和年际变化。     

民勤地区紫外辐射的观测与模拟研究

利用2010年春季民勤加强观测实验的地面辐射资料,分析了民勤沙漠干旱区总紫外辐射的变化特征,并对该地区的紫外辐射进行了估算和模拟。结果表明,紫外辐射和太阳总辐射表现出一致的变化特征,层云对两者的反射能力比卷云强。2010年6月紫外辐射的瞬时最大值为55.92 W·m-2,平均日总量为1.07 MJ·m-2,紫外辐射与太阳辐射比例的平均值为4.7%,其变化范围在3%~9%之间。根据晴空指数(Kt)与最大紫外辐射(UV0)及太阳总辐射(G)建立了民勤地区紫外辐射(UV)的估算方程:UV=2.94+1.22×(Kt×UV0)和UV=0.047G,均能较好地估计该地区的地表紫外辐射。由于受输入参数精度的限制,辐射传输模式SBDART低估了晴空条件下的紫外辐射,低估的总平均值为1.12 W·m-2(约5.6%),变化范围在-2.8~0.2 W·m-2之间。     

香河地区光合有效辐射观测分析研究

利用中国科学院大气物理研究所香河大气综合观测实验站(39°47′N,116°57′E)2004年10月至2005年12月共15个月的太阳辐射观测资料,分析了该地区光合有效辐射与太阳总辐射比值的(PAR/Rs)日变化和季节变化特征,得出月平均PAR/Rs值变化范围在1.808~2.048μE.J-1之间,最大值出现在夏季,最小值出现在冬季,年平均值为1.948μE.J-1。提出了一个利用太阳总辐射观测值计算光合有效辐射瞬时值的参数化算式,用该算式计算得到的PAR与实际观测值的均方根误差为19.28μE.m-2.s-1,有96%的计算值与观测值偏差在±10%以内。比较了香河地区与太湖地区、额济纳地区光合有效辐射瞬时最大值、小时累积最大值及日累积最大值的差异。     

三江平原地区光合有效辐射观测研究

利用2005~2011年的太阳辐射观测资料分析三江平原地区光合有效辐射(Qp)的时间变化特征及其与总辐射(Rs)比值(Qp/Rs)的变化规律,结果表明,Qp与Rs具有相同的季节变化特征;Qp日累计值的变化范围为60.47~0.11 mol m-2 d-1,年均值为23.76 mol m-2 d-1。Qp/Rs的变化范围为1.52~2.07 mol MJ-1,年均值为1.91 mol MJ-1。Qp/Rs和Qp季节变化一致,两者都是夏季最大,春秋次之,冬季最小。通过利用2011年的Qp观测数据、大气质量数与晴空指数的相互关系,建立了适合于估量三江地区Qp的经验方程,估算值与观测值的相对误差在5.7%以内。     

INTEX-B NO2排放源在中国地区的应用与检验

将INTEX-B排放源应用到空气质量模型Model3-CMAQ中,对中国地区对流层NO₂的浓度分布进行了数值模拟,并与OMI卫星对流层NO₂资料进行了对比和验证。结果表明：将INTEX-B排放源应用到Model3-CMAQ模式,模拟的NO₂浓度在中国地区的分布、季节变化规律与卫星资料所得结果一致。敏感性试验表明,工业及电厂排放对NO₂的浓度贡献最大,而交通排放的贡献相对较小,两种排放均主要集中在京津、长江三角洲等经济发达地区。     

南京北郊 O3、NO2和 SO2变化特征分析

利用 2008年1-12月南京北郊O₃、NO₂及SO₂质量浓度连续观测资料,分析了南京北郊气体污染物(O₃、NO₂、SO₂) 的质量浓度变化规律。结果表明：南京北郊O₃浓度夏季较高,日变化曲线呈单峰型,NO₂和SO₂浓度夏季较低,日变化曲线呈双峰型,NO₂与O₃的日变化呈现负相关关系,该地区SO₂浓度整体较高,夏季周末效应NO₂和SO₂较O₃更明显。     

闪电产生氮氧化物对青藏高原臭氧低谷形成的影响

为了进一步了解青藏高原闪电的产生氮氧化物（LNO_x）经由光化学反应对O₃浓度变化及夏季O₃低谷形成的可能影响,本文利用2005~2013年由OMI卫星得到的对流层NO₂垂直浓度柱（NO₂ VCD）、O₃总浓度柱（TOC）和O₃廓线以及星载光学瞬变探测器OTD和闪电成像仪LIS获取的总闪电数资料,对青藏高原和同纬度长江中下游地区的TOC和NO₂ VCD月均值时空分布特征、闪电与NO₂ VCD的相关性和O₃的垂直分布特征及其与LNO_x的关系进行了对比分析。结果表明,青藏高原的O₃低谷主要出现在夏季和秋季,其TOC值比同纬度长江中下游地区低约10~15 DU（Dobson unit）。青藏高原NO₂VCD总体较小,表现为夏高冬低的分布特征。青藏高原夏季O₃浓度受南亚高压的影响总体呈减小趋势,但因强雷暴天气导致对流层中上部LNO_x浓度升高,并随强上升气流向对流层顶输送,同时通过光化学反应使O₃浓度增加,缩小了青藏高原和同纬度地区的O₃浓度差,减缓了O₃总浓度的下降,抑制了夏季O₃低谷的进一步深化。     

长波区间太阳辐射对气候模拟的影响

长波区间的太阳辐射在气候模式中往往被忽略。利用国家气候中心BCC_AGCM2.0.1大气环流模式,采用矩阵算子辐射传输算法,研究了长波区间太阳辐射对气候模式辐射通量和温度模拟结果的影响。结果表明,以ISCCP和CERES辐射资料为标准,考虑长波区间太阳辐射后,长波区间晴空大气地表向下辐射通量平均误差减小2.05 W/m2,均方根误差减少1.29 W/m2;长波区间晴空大气模式顶向上辐射通量平均误差减小0.70 W/m2,均方根误差减小0.21 W/m2;长波区间有云大气地表向下辐射通量平均误差减小1.38 W/m2,均方根误差减小1.03 W/m2;长波区间有云大气模式顶向上辐射通量平均误差减小0.99 W/m2,均方根误差减小0.30 W/m2。以ECMWF再分析资料为标准,考虑长波区间太阳辐射后,赤道地区上对流层—下平流层区域温度的冷偏差得到改善,对流层顶温度平均误差减小0.27 K,均方根误差减小0.25 K。     

中国地区闪电和对流层上部NOx的时空分布特征及其相关性分析

为了解闪电对对流层上部NO_x的贡献,本文利用美国全球水资源和气候中心（GHRC）提供的1995年4月~2005年12月的闪电卫星格点资料及高层大气研究卫星 (UARS) 上的卤素掩星试验装置 (HALOE) 1991年10 月~2005 年11月的观测资料,分析了中国地区闪电与对流层上部NO_x体积混合比的时空分布特征及两者的相关性.结果表明:中国地区闪电和对流层上部的NO_x在季节分布、年际分布和空间分布上保持很好的一致性,闪电是对流层上部NO_x的重要来源;NO极值高度在350 hPa左右,云闪直接产生的NO是极值产生的主要原因,NO₂的极值高度在250 hPa左右,因为闪电产生的NO在传输过程中会被氧化成NO₂并通过雷暴的垂直输送作用抬升到更高高度;强对流活动有利于NO_x的传输,而人类活动产生的NO_x一般较难输送到对流层上部,因此闪电多发区的NO_x极值较大,所在的高度也较高.     

Solar eclipse-induced variations in solar flux, j(NO2) and surface ozone at Kannur, India

Surface ozone is mainly produced by the photodissociation of nitrogen dioxide (NO₂) by solar UV radiation. Subsequently, solar eclipses provide one of the unique occasions to explore the variations in the photolysis rate of NO₂ and their significant impact on the production of ozone at a location. This study aims to examine the diurnal variations in the photodissociation rate coefficient of NO₂, (j(NO₂*)), and mixing ratios of surface ozone and NO _X * (NO?+?NO₂*) during the solar eclipse that occurred on 15 January 2010 at Kannur (11.9°N, 75.4°E, 5?m amsl), a tropical coastal site on the Arabian Sea in South India. This investigation was carried out on the basis of the ground level observations of surface ozone and its prominent precursor NO₂*. The j(NO₂*) values were estimated from the observed solar UV-A flux data. A sharp decline in j(NO₂*) and surface ozone was observed during the eclipse phase because of the decreased efficiency of the ozone formation from NO₂. The NO₂* levels were found to increase during this episode, whereas the NO levels remained unchanged. The surface ozone concentration was reduced by 57.5%, whereas, on the other hand, that of NO _X * increased by 62.5% during the solar eclipse. Subsequently a reduction of *% in the magnitude of j(NO₂*) was found here during the maximum obscuration. Reductions in solar insolation, air temperature and wind speed were also observed during the solar eclipse event. The relative humidity showed a 6.4% decrease during the eclipse phase, which was a unique observation at this site.     

华北地区香河站对流层NO_2的MAX-DOAS光谱仪观测及变化特征分析

利用中国科学院大气物理研究所香河大气探测综合试验站2010年3月至2012年2月(2年)的多轴差分吸收光谱仪(MAX-DOAS)观测数据和32 m高塔常规气象资料,反演了华北地区香河站对流层NO2柱浓度,分析了该区域NO2柱浓度的季节变化特征。研究表明:可见光455~485 nm、紫外330~370 nm都可以作为MAX-DOAS工作波段很好地反演NO2;香河地区NO2柱浓度夏季最低,几乎保持在2×1016 cm–2以下,春、秋季次之,在3×1016 cm–2上下小范围浮动,冬季最高,可达4.5×1016 cm–2;月平均最低值出现在7月,最高值出现在11月。NO2柱浓度与风速、风向密切相关:来自东边唐山方向的风,风速越大时NO2浓度越高,因为唐山是NO2的高值区之一;其它方向风速越大,浓度越低。春、夏两季NO2柱浓度日变化趋势比较平缓,秋、冬两季日变化明显,秋季正午偏高,冬季早晚偏高。     

Relationships between photosynthetically active radiation and clearness index at Bloemfontein, South Africa

Summary Relationships between photosynthetically active radiation (PAR) and solar radiation (SR) and between diffuse radiation and global radiation at Bloemfontein, South Africa were investigated. The ratio of PAR to SR (PAR/SR) has been reported from many places in the northern hemisphere, but there were not many PAR/SR measurements documented from the southern hemisphere, including the study region. Based on the present observations, mean PAR/SR in the region (0.48) was not exceptionally different from other reported data (0.45–0.50). The effects of sky condition on PAR/SR were also investigated and confirmed the previous findings. PAR/SR increased as the clearness index (K_T=ratio of global to extraterrestrial SR) decreased, as sky conditions varied from clear to cloudy. Thus, PAR/SR can be a simple function of the clearness index (the global PAR model). In this study, PAR/SR was explained by a quadratic function of K_T. For the relationship between diffuse and global radiation, a simple linear threshold diffuse PAR model, as a linear function of K_T, was proposed for the study region using long-term data of diffuse and global SR. Using the previous findings on the relationship between the ratio of diffuse to global SR (K_SR) and the ratio of diffuse to global PAR (K_PAR), at high K_T, K_PAR can be estimated as 30% higher than K_SR, while at low K_TK_PAR is equivalent to K_SR.     

Calculation of cloud modification factors for the horizontal plane eye damaging ultraviolet radiation

This research examines the influence of cloud on the cataract effective UV (UV_Cat) irradiances on a horizontal plane over an extended period of 12months that included the range of cloud conditions, solar zenith angle (SZA) and ozone conditions experienced over that time. The data were collected at five minute intervals. Cloud modification factors were determined from the influence of clouds on the global broadband solar radiation and these were applied to the cloud free cataract effective UV to evaluate the UV_Cat irradiances on a horizontal plane for all cloud conditions. A comparison of the measured and calculated UV_Cat irradiances for the 2004 data set in the range of SZA of 70° or less provided an R² value of 0.85. The data in the first 6months of 2005 for an SZA of 70° or less that were at a different time to that when the technique was developed provided an R² value of 0.83 for the comparison of the measured and calculated UV_Cat irradiances.     

The characteristics of ultraviolet radiation in arid and semi-arid regions of China

Measurements of the broadband global solar radiation (R _S) and total ultraviolet radiation (the sum of UV-A and UV-B) were conducted from 2005 to 2010 at 9 sites in arid and semi-arid regions of China. These data were used to determine the temporal variability of UV and UV/R _S and their dependence on the water vapor content and clearness index. The dependence of UV/R _S on aerosol optical depth (AOD) and water vapor content was also investigated. In addition, a simple and efficient empirically model suited for all-weather conditions was developed to estimate UV from R _s. The annual average daily UV level in arid and semi-arid areas is 0.61 and 0.59 MJ m^?2 d^?1, respectively. The highest value (0.66?±?0.25 MJ m^?2 d^?1) was recorded at an arid area at Linze. The lowest value (0.53?±?0.22 MJ m^?2 d^?1) was recorded at a semi-arid area at Ansai. The highest daily value of UV radiation was measured in May, whereas the lowest value was measured in December. The monthly variation of the UV/R _s ratio ranged from 0.41 in Aksu to 0.35 in Qira. The monthly mean value of UV/R _s gradually increased from November and then decreased in August. A small decreasing trend of UV/R _s was observed in the arid and semi-arid regions due to recently increasing amounts of fine aerosol. A simple and efficient empirically model suit for all-weather condition was developed to estimate UV from R _s. The slope a and intercept b of the regression line between the estimated and measured values were close to 1 and zero, respectively. The relative error between the estimated and measured values was less than 11.5%. Application of the model to data collected from different locations in this region also resulted in reasonable estimates of UV.     

Comparison of human radiation exchange models in outdoor areas

Results from the radiation components of seven different human thermal exchange models/methods are compared. These include the Burt, COMFA, MENEX, OUT_SET* and RayMan models, the six-directional method and the new Park and Tuller model employing projected area factors (f _p) and effective radiation area factors (f _eff) determined from a sample of normal- and over-weight Canadian Caucasian adults. Input data include solar and longwave radiation measured during a clear summer day in southern Ontario. Variations between models came from differences in f _p and f _eff and different estimates of longwave radiation from the open sky. The ranges between models for absorbed solar, net longwave and net all-wave radiation were 164, 31 and 187?W?m^?2, respectively. These differentials between models can be significant in total human thermal exchange. Therefore, proper f _p and f _eff values should be used to make accurate estimation of radiation on the human body surface.     

Analysis of photosynthetically active radiation and applied parameterization model for estimating of PAR in the North China Plain

As photosynthetically active radiation (PAR) variability and PAR estimating methods play an important role in climate change and ecological process research, PAR variation trends and broadband global solar radiation (R _s ) ratios (PAR/R _s ) in the North China Plain (NCP) are examined using in situ PAR and R _s observed data for 2005 to 2011. The annual average PAR value found in the NCP is 22.9 mol m^?2 d^?1. The highest and lowest values were recorded at Changwu and Luancheng sites, respectively. The highest PAR/R _s value was found in Jiaozhouwan due to large water vapor volumes present in this area. PAR/R _s levels have increased in the NCP due to a decrease in fine aerosols and increase in water vapor concentration. From these analysis results, a parameterization model that can be applied to all sky conditions was checked. Empirical estimation model comparisons for obtaining PAR values indicate that model was least accurate when R _s was used independently. When the model included R _s, the clearness index (K _s) and the solar zenith angle, the model estimated PAR values with acceptable accuracy. A parameterization model was constructed by considering K _s and attenuation factors of PAR under clear weather conditions (ρ _clear). The improved parameterization model more accurately predicts values for local sites and for various observation sites.     

A Seasonal Comparison of the Ozone Photochemistry in Clean and Polluted Air Masses at Mace Head, Ireland

Measurements of the sum of peroxy radicals [HO₂ + RO₂],NO_x (NO + NO₂) and NO_y (the sum of oxidisednitrogen species) made at Mace Head, on the Atlantic coast of Ireland in summer 1996 and spring 1997 are presented. Together with a suite of ancillary measurements, including the photolysis frequencies of O₃ O(¹D)(j(O¹D)) and NO₂ (j(NO₂)), the measured peroxy radicals are used to calculate meandailyozone tendency (defined as the difference of the in-situphotochemical ozone production and loss rates); these values are compared with values derived from the photochemical stationary state (PSS) expression. Although the correlation between the two sets of values is good, the PSS values are found to be significantly larger than those derived from the peroxy radical measurements, on average, in line with previous published work. Possible sources of error in these calculations are discussed in detail. The data are further divided up into five wind sectors, according to the instantaneous wind direction measured at the research station. Calculation of mean ozone tendencies by wind sector shows that ozone productivity was higher during spring (April–May) 1997 than during summer (July–August) 1996across all airmasses, suggesting that tropospheric photochemistry plays an important role in the widely-reported spring ozone maximum in the Northern Hemisphere. Ozone tendencies were close to zero for the relatively unpolluted south-west, west and north-west wind sectors in the summer campaign, whereas ozone productivity was greatest in the polluted south-east sector for both campaigns. Daytime weighted average ozone tendencies were +(0.3± 0.1) ppbv h^–1 for summer 1996 and +(1.0± 0.5) ppbvh^–1 for spring 1997. These figures reflect the higher mixing ratios of ozone precursors in spring overall, as well as the higher proportion of polluted air masses from the south-east arriving at the site during the spring campaign. The ozone compensation point, where photochemical ozone destruction and production processes are in balance, is calculated to be ca. 14 pptv NO for both campaigns.     

Latitudinal variation of measured NO2 photolysis frequencies over the Atlantic Ocean between 50° N and 30° S

Using a filter radiometer, the meridional profile of the NO₂ photolysis frequency, J(NO₂), was measured between 50° N and 30° S during the cruise ANTVII/1 September/October 1988 of the research vessel Polarstern on the Atlantic Ocean. Simultaneously, global broadband irradiance and acrosol were monitored. Clean marine background air with low aerosol loads (b _sp=(1–2)×10^-5 m^-1) was encountered at the latitudes 25° N–30° N and 18° S–27° S, respectively. Under these conditions and an almost cloudless sky J(NO₂) reached 7.3×10^-3 s^-1 (2 sr) for a zenith angle of 30°. Between 30° N and 30° S, the latitudinal variation of the J(NO₂) noontime maxima was less than ± 10%, while the mean value at noon was 7.8×10^-3 s^-1. For the set of all data between 50° N and 30° S, a nearly linear correlation of J(NO₂) vs. global broadland irradiance was found. The slope of (8.24±0.03)×10^-5 s^-1/mW cm^-2 agrees within 10% with observations in Jülich (51° N, 6.2° E).