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1.
A programme of ground-based stratospheric and total NO2 column measurements was instituted at the Laboratory of Atmospheric Physics (40.5° N, 22.9° E) in August 1985. We present here the results of the first two years of measurements with a modified Canterbury filter photometer, details of which are given in the text. The stratospheric NO2 column, obtained at twilight during low local NO2 levels, shows the seasonal variation with monthly mean values of about 6×10-15 molec. cm-2 in the summertime to about 2.2×10-15 molec. cm-2 in the wintertime. These measurements compare well with measurements obtained with different instruments by other groups at similar latitudes (about 40° N) but in different places. Also, the asymmetry of the evening-to-morning stratospheric NO2 over Thessaloniki was found to be on the average equal to 1.58. Total NO2 column over Thessaloniki has a pronounced seasonal variation with amplitude of 0.68 matm. cm which can be explained partly from measured local NO2 sources which discharge in the mixing layer and partly from photolysis of the NO2 reservoir species.  相似文献   

2.
Infrared absorption features due to ClO in the lower stratosphere have been identified from groundbased solar absorption spectra taken from Aberdeen, U.K. (57° N, 2° W) on 20 January 1995. A vertical column abundance of 3.42 (±0.47)×1015 molec cm-2 has been derived from 13 independent absorption features in the P and R branches of the (0–1) vibration-rotation band of 35ClO, spanning the spectral region 817–855 cm-1. The observed absorption features are consistent with very high levels of ClO (approximately 2.6 parts per billion by volume (ppbv)) in the altitude range 16–22 km. A comparison of this profile with a 3D chemical transport model profile indicates the observation was made inside the polar vortex and shows good qualitative agreement but the model underestimates the concentrations of ClO. Simultaneous measurements of other species were made including HCl, HF and ClONO2. These columns yield a value for HCl+ClONO2+ClO of 7.02±0.65×1015 molec cm-2. This is lower than the total inorganic chlorine (ClO y ) column of 10.7±1.6×1015 molec cm-2 estimated from mean measured (HCl+ClONO2)/HF ratios together with in-vortex HF measurements. The discrepancy is probably due to significant amounts of the ClO dimer (Cl2O2) in the lower part of the stratosphere. The measurements of highly elevated levels of ClO are used to estimate O3 loss rates at the 400, 475 and 550 K levels making assumptions about the probable distribution of ClO and Cl2O2. These are compared with loss rates derived from ozone sonde data.  相似文献   

3.
A set of high-resolution IR solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, from 84/06 to 93/06, and at the National Solar Observatory McMath-Pierce solar telescope facility on Kitt Peak, Arizona, U.S.A. from 78/05 to 92/07 have been analyzed to determine the vertical column abundances of hydrogen cyanide, HCN, above the two stations. The analysis was based on least-squares curve fitting of calculated spectra to the observations encompassing the P4 and the P8 lines of HCN respectively located at 3299.5273 and 3287.2483 cm–1. The results obtained for the two stations indicate that no significant long-term trend affects either of the two databases; however, this analysis reveals variable increases during springtime of up to a factor of 2 in the HCN total column above the Jungfraujoch and even up to 3 above Kitt Peak. The calculated mean vertical column abundances, excluding the spring observations, are equal to (2.55±0.30)×1015 molec./cm2 (S.D.) and (2.75±0.30)×1015 molec./cm2 respectively above the Jungfraujoch and the Kitt Peak observatories. Based on a realistic volume mixing ratio profile, these columns translate into mean volume mixing ratios equal to 190×10–12 ppv at the respective altitudes of the stations.  相似文献   

4.
Monthly mean total vertical column abundances of acetylene have been determined from series of infrared solar spectra recorded at the Jungfraujoch station, Switzerland, between June 1986 and April 1991. The data have been obtained by nonlinear least-squares fittings of the 5 band R19 transition of C2H2 at 776.0818 cm-1. The average of 22 monthly mean total vertical columns of C2H2 retrieved during that time interval of almost 5 years was found to be equal to (1.81±0.12)×1015 molec/cm2, which corresponds to an average mixing ratio of (0,22±0.013) ppbv (parts per billion by volume) in a troposphere extending from the altitude of the station (3.58 km), up to 10.5 km. Despite the large variability found from year to year, a least-squares sine fit to the data reveals a seasonal variation with an amplitude of about ±40% of the mean; the maximum occurs during mid-winter and the minimum in the summer. The present results are compared critically with similar in-situ data found in the literature. A sinusoidal fit to all such free troposphere measurements made in-situ between 30°N and 60°N indicates good agreement in shape and phase with the seasonal variation derived above the Jungfraujoch, but their average column abundance, 2.3×1015 molec/cm2, is about 30% higher; this difference is explained on the basis of non-upwelling meteorological conditions generally prevailing during ground-based remote solar observations.  相似文献   

5.
Simultaneous observations for the total column densities of NO2, O3 and H2O were carried on using the porta-ble Spectrometer (438-450 nm and 400-450 nm) and the visible Spectrometer (544.4-628 nm) during premonsoon thunderstorms and embedded hail storm activity at Pune (18o32’N & 73o51’E), India. These observations confirm the fact that there is an increase in O3 and NO2 column densities during thunderstorms. The increase in O3 was observed following onset of thunderstorm, while the increase in NO2 was observed only after the thunder flashes occur. This implies that the production mechanisms for O3 and NO2 in thunderstorm are different. The observed column density of NO2 value (1 to 3 × 1017molecules · cm-2) during thunderstorm activity is 10 to 30 times higher than the value (1 × 1016molecules · cm-2) of a normal day total column density. The spectrometric observations and observations of thunder flashes by electric field meter showed that 6.4 × 1025molecules / flash of NO2 are produced. The increased to-tal column density of ozone during thunderstorm period is 1.2 times higher than normal (clear) day ozone concentra-tion. The multiple scattering in the clouds is estimated from H2O and O2 absorption bands in the visible spectral re-gion. Considering this effect the calculated amount of ozone added in the global atmosphere due to thunderstorm ac-tivity is 0.26 to 0.52 DU, and the annual production of ozone due to thunderstorm activity is of the order of 4.02 × 1037 molecules /year. The annual NO2 production may be of the order of 2.02 × 1035molecules / year.  相似文献   

6.
基于美国宇航局NASA/AURA卫星臭氧监测仪OMI数据,分析了2005—2014年长三角地区及其典型城市对流层O_3、NO_2柱浓度和HCHO大气总柱浓度的时空分布特征。结果表明:10 a间,长三角地区对流层O_3柱浓度和HCHO总柱浓度呈现增长趋势,O_3增量为0.23ppbv/10 a,HCHO增量为0.07×10~(16) mol/(cm~2·10 a),对流层NO_2柱浓度呈现降低趋势,减量为0.06×10~(15)mol/(cm~2·10 a);长三角地区对流层O_3柱浓度最大值出现在3、4、5月,而对流层NO_2柱浓度最大值出现在1、12月,HCHO总柱浓度最大值出现在6、7月;对流层O_3柱浓度的高值区分布在长三角中部、北部区域,对流层NO_2柱浓度高值区分布于长三角中部,HCHO总柱浓度高值区相对分散,且四季的分布各不相同。O_3与NO_2和HCHO在时间和空间上呈现一定的相关性。  相似文献   

7.
The kinetics of the reaction of nitrous acid (HONO) with nitric acid (HNO3), nitrate radicals (NO3) and dinitrogen pentoxide (N2O5) have been studied using Fourier transform infrared spectroscopy. Experiments were performed at 700 torr total pressure using synthetic air or argon as diluents. From the observed decay of HONO in the presence of HNO3 a rate constant of k<7×10-19 cm3 molecule-1 s-1 was derived for the reaction of HONO with HNO3. From the observed decay of HONO in the presence of mixtures of N2O5 and NO2 we have also derived upper limits for the rate constants of the reactions of HONO with NO3 and N2O5 of 2×10-15 and 7×10-19 cm3 molecule-1 s-1, respectively. These results are discussed with respect to previous studies and to the atmospheric chemistry of HONO.  相似文献   

8.
In the first two weeks of May 1981, the research jet of the German Aerospace Research Establishment (DFVLR) was charted to fly a meridional section between 5° and 82°N. A scanning filter photometer, developed at the Max Planck Institut für Aeronomie to measure column content values of atmospheric ozone and nitrogen dioxide, using ultra violet and visible absorption techniques, constituted part of the experimental payload for this campaign that was called SIMOC. The vertical NO2 column content above the aircraft, flying at approximately 10 km, was found to decrease rapidly from 6.9×1015 molecules cm-2 to 2.5×1015 molecules cm-2 around 50°N and then to increase again north of 75°N. A sharp rise in the NO2 content was observed south of the subtropical jet but this could possibly be due to the increased depth of the troposphere above the aircraft in these regions.  相似文献   

9.
The results of an intercomparison campaign of eight different long path UV-visible DOAS instruments measuring NO2, O3 and SO2 concentrations in a moderately polluted urban site are presented. For effective optical path lengths of 230 and 780 m the overall spread of these measurements (±1) are 5×1010, 6×1010 and 1×1010 molec·cm-3 (2.0, 2.4, and 0.4 ppb) for these molecules respectively when all instruments used a common set of absorption cross sections. The remaining differences are not completely random and the systematic differences are attributed to the different retrieval methods used for each instrument.  相似文献   

10.
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).  相似文献   

11.
Measurements of NO2, HCHO, and H2O2 were made by the highly specific method of mid infra-red absorption spectroscopy using tunable diode lasers (TDLAS) during the 1988 Polarstern expedition. The TDLAS data are compared to those obtained during the cruise using less direct methods. Southern Hemisphere NO2 levels suggest nett photochemical destruction of O3 in the boundary layer. Northern Hemisphere HCHO averaged 0.47±0.2 ppbv; the HCHO measurements are used in a simple calculation to estimate OH noontime maxima of 3–6×106 cm-3.  相似文献   

12.
New laboratory measurements of NO2 absorption cross-section were performed using a Fourier transform spectrometer at 2 and 16 cm-1 (0.03 and 0.26 nm at 400 nm) in the visible range (380–830 nm) and at room temperature. The use of a Fourier transform spectrometer leads to a very accurate wavenumber scale (0.005 cm-1, 8×10-5 nm at 400 nm). The uncertainty on the new measurements is better than 4%. Absolute and differential cross-sections are compared with published data, giving an agreement ranging from 2 to 5% for the absolute values. The discrepancies in the differential cross-sections can however reach 18%. The influence of the cross-sections on the ground-based measurement of the stratospheric NO2 total amount is also investigated.  相似文献   

13.
In this study, the chemical and physical losses of nitrogen oxides (NOx) over the Korean peninsula were discussed in order to better understand the effects of the NOx losses on the tropospheric NO2 columns. Initially, it was found that the physical loss processes due to dry and wet depositions had almost negligible impacts on the NOx loss processes over the Korean peninsula. In contrast, the hourly NOx chemical column losses were large at ??1014 molecules cm?2 h?1. The amounts of NOx removed for 1 hour account for approximately 33?C35% of the episode-averaged tropospheric NO2 columns during summer over the Korean peninsula. The NOx chemical column loss rates were 24.1?C70.9 times larger than the NOx physical column loss rates. In a budget analysis of the NOx chemical column losses, HNO3 formation via the reaction of OH + NO2 had the largest contribution toward the NOx chemical losses (42?C55% during fall and winter seasons; 76?C77% during spring; 92?C93% during summer). Large amounts of NOx were also removed by heterogeneous nitrate formation via N2O5 condensation during the cold seasons (42?C56%) over the Korean peninsula. The columnar NOx chemical losses took place mainly due to the two chemico-physical reaction processes, and also showed seasonal variations. PAN (Peroxyacetyl Nitrate) is another NO2 reservoir of potential importance. If the influence of the PAN-related chemistry on the NOx budget is considered, it can result in an approximate 69% increase in the NOx chemical column loss during summer. Such increases in the amounts of NOx removed for 1 hour due to the formation of PAN were equivalent to 56?C58% of the episode-averaged tropospheric NO2 columns during summer over the Korean peninsula. Such active NOx chemical losses during summer are another main factor for the tropospheric NO2 columns exhibiting their smallest values during summer.  相似文献   

14.
The photodissociation coefficient of NO2, J NO 2, has been measured from a balloon platform in the stratosphere. Results from two balloon flights are reported. High Sun values of J NO 2 measured were 10.5±0.3 and 10.3±0.3×10-3 s-1 at 24 and 32 km respectively. The decrease in J NO 2 at sunset was monitored in both flights. The measurements are found to be in good agreement with calculations of J NO 2 using a simplified isotropic multiple scattering computer routine.  相似文献   

15.
Emissions of nitric oxide and other odd nitrogen oxides (NO x ) from a flooded rice field were studied after urea had been broadcast into the floodwater.The NO x flux from the fertilized area was very low (0.2×10-9 g N m-2 s-1) for the first few days after application of urea and was high (0.95×10-9 g N m-2 s-1) in the subsequent period when significant nitrite and nitrate were present in the floodwater. At night, little if any NO x was exhaled but ambient NO2 was absorbed by the floodwater. An uptake velocity for NO2 of 3×10-4 m s-1 was measured during one night. Maximum NO x losses were observed near 1300 h when temperature and solar ultraviolet light were maximum.While the amounts of nitrogen oxides emitted are of little agronomic importance (2×10-3 per cent of the fertilizer nitrogen was lost as NO x during the 10-day study period), they may well be of significance as a source for some gas reactions in the atmosphere and for the global nitrogen cycle.Of the fertilizer nitrogen applied (as urea) approximately 30% was lost to the atmosphere by NH3 volatilization, 15% by denitrification, presumably as N2, and the remainder, less minor losses of NO and N2O, remained in the plant/soil/water system.Now at Forestry Department, Australian National University, G.P.O. Box 4, ACT 2601, Australia.  相似文献   

16.
This study reports comparisonsbetween model simulations, based on current sulfurmechanisms, with the DMS, SO2 and DMSOobservational data reported by Bandy et al.(1996) in their 1994 Christmas Island field study. For both DMS and SO2, the model results werefound to be in excellent agreement with theobservations when the observations were filtered so asto establish a common meteorological environment. Thisfiltered DMS and SO2 data encompassedapproximately half of the total sampled days. Basedon these composite profiles, it was shown thatoxidation of DMS via OH was the dominant pathway withno more than 5 to 15% proceeding through Cl atoms andless than 3% through NO3. This analysis wasbased on an estimated DMS sea-to-air flux of 3.4 ×109 molecs cm-2 s-1. The dominant sourceof BL SO2 was oxidation of DMS, the overallconversion efficiency being evaluated at 0.65 ± 0.15. The major loss of SO2 was deposition to theocean's surface and scavenging by aerosol. Theresulting combined first order k value was estimated at 1.6 × 10-5 s-1. In contrast to the DMSand SO2 simulations, the model under-predictedthe observed DMSO levels by nearly a factor of 50. Although DMSO instrument measurement problems can notbe totally ruled out, the possibility of DMSO sourcesother than gas phase oxidation of DMS must beseriously considered and should be explored in futurestudies.  相似文献   

17.
China’s first carbon dioxide(CO2) measurement satellite mission, TanSat, was launched in December 2016. This paper introduces the first attempt to detect anthropogenic CO2 emission signatures using CO2 observations from TanSat and NO2 measurements from the TROPOspheric Monitoring Instrument(TROPOMI) onboard the Copernicus Sentinel-5 Precursor(S5P) satellite. We focus our analysis on two selected cases in Tangshan, China and Tokyo, Japan.We found that t...  相似文献   

18.
Simultaneous measurements of ozone and ozoneprecursors were made during a field campaign atSchauinsland in the Black Forest and in the valleynorth of Schauinsland that channels the flow ofpolluted air from the city of Freiburg to the site.From the decay of hydrocarbons and NOx between the twomeasuring sites and the known rate coefficients, theconcentration of OH radicals was calculated. From abudget analysis of OH and HOx it is concluded that therelatively high OH concentrations (5–8 ×106cm-3) in the presence of high NO2concentrations cannot be explained by the knownprimary sources. The budget can be closed if efficientrecycling of OH via HO2 is assumed to occur andthat, based on the measured hydrocarbons, 2 HO2molecules are formed for each OH radical that reactswith a hydrocarbon molecule. This assumption is inaccordance with the budget of Ox obtained from ourmeasurements and with results from earliermeasurements of alkylnitrates and peroxy radicals atSchauinsland. A possible conclusion is that the decayof precursors and production of photooxidants in urbanplumes proceeds at a faster rate than is currentlyassumed. The potential role of biogenichydrocarbons for the radical budget is alsodiscussed.  相似文献   

19.
Emissions of N2O, CH4, and CO2 from soils at two sites in the tropical savanna of central Venezuela were determined during the dry season in February 1987. Measured arithmetic mean fluxes of N2O, CH4, and CO2 from undisturbed soil plots to the atmosphere were 2.5×109, 4.3×1010, and 3.0×1013 molecules cm-2 s-1, respectively. These fluxes were not significantly affected by burning the grass layer. Emissions of N2O increased fourfold after simulated rainfall, suggesting that production of N2O in savanna soils during the rainy season may be an important source for atmospheric N2O. The CH4 flux measurements indicate that these savanna soils were not a sink, but a small source, for atmospheric methane. Fluxes of CO2 from savanna soils increased ninefold two hours after simulated rainfall, and remained three times higher than normal after 16 hours. More research is needed to clarify the significance of savannas in the global cycles of N2O, CH4, CO2, and other trace gases, especially during the rainy season.  相似文献   

20.
对临安大气本底站2003-2004年冬、夏季二氧化氮(NO2)、二氧化硫(SO2)、臭氧(O3)进行了分析.结果表明:冬季NO2和SO2平均体积分数分别为19.48×10-9和35.74 x10-9,而夏季的平均体积分数分别为4.81×10-9和8.12×10-9,冬季高于夏季;O3在夏季的平均体积分数为33.55×10-9,略高于冬季的25.44×10-9;夜间NO2和SO2体积分数比白天高,并且NO2呈明显的单峰单谷型分布,O3也呈单峰型但峰值出现在白天.NO2、SO2体积分数存在着明显的“假日效应”,假日比非假日低,周五高于假日和非假日;但O3体积分数没有明显的假日效应.降水对SO2有明显的清除作用,但对NO2的清除作用不明显.与风向对比发现,夏季高体积分数的NO2、SO2都受到NW、WNW风的影响,冬季则分别受NE和SW、SSW风的影响;而O3受风向的影响较复杂,与局地光化学反应有关.  相似文献   

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