Long-term trends in the total columns of ozone and its precursor gases derived from satellite measurements during 2004–2015 over three different regions in South Asia: Indo-Gangetic Plain,Himalayas and Tibetan Plateau

ABSTRACT

Long-term (2004–2015) satellite data over three adjacent yet contrasting regions: Indo-Gangetic Plain, Himalayas and Tibetan Plateau (TP) were used to study the spatiotemporal distribution of total ozone column (TOC) and its precursor gases (such as nitrogen dioxide (NO₂), methane (CH₄) and carbon monoxide (CO)). The ozone precursor emission data and forest fire points were used to explore the findings. Trace gases showed increasing trend probably due to increasing emission from South Asia as supported by the Emission Database for Global Atmospheric Research emission data. Strong seasonal variation in trace gases was observed with the highest value during the pre-monsoon season, over three regions, possibly due to the biomass burning, pollution build-up and also long-range transport of pollution. TOC exhibited the similar seasonal variation as shown by the earlier ground-based studies over the region. The total column of precursor gases (except methane) exhibited strong seasonality with the highest column during the pre-monsoon season. Patterns in the variations of TOC and related precursors over the Himalayas were similar with that of the TP. Seasonal climatological trends also exhibited increasing pattern except for CO. This work provides an overview on the long-term TOC and its precursor gases which are necessary to understand the regional climate variability especially over the Himalayas and Tibetan Plateau region.     

A note on the comparison between total ozone from Oslo CTM2 and SBUV satellite data

The results of a comparison between total ozone amounts derived from solar backscatter ultraviolet (SBUV) satellite observations and those calculated from the chemical transport model Oslo CTM2 are presented for the period 2001–2007. Monthly mean total ozone amounts from improved model simulations were used to compute monthly, seasonal and annual zonal means over 10° latitude zones, and compared with respective satellite retrievals over the northern and southern hemispheres. The results show that the improved model simulations slightly underestimate total ozone over the northern hemisphere when compared with the satellites by 1.4% on average, and slightly overestimate total ozone over the southern extra-tropics, middle and high latitudes by 1.6% on average. The mean difference between the model- and satellite-derived total ozone columns from 75°S to 75°N is estimated to be about ?0.3%. A linear regression analysis between the model- and satellite-derived total ozone data shows statistically significant correlations between the two data sets at all latitude zones (about +0.8 in the tropics and more than +0.9 over all other latitudes). The annual cycle of total ozone is shown to be well reproduced by the model at all latitudes.     

Spatiotemporal variations of tropospheric column nitrogen dioxide over Jing-Jin-Ji during the past decade

Of all anthropogenic pollutants, nitrogen dioxide (NO₂) has the most negative effect on atmospheric chemistry. In this study, measurements of tropospheric column NO₂ obtained from the ozone monitoring instrument (OMI) are used to investigate temporal and spatial dynamics of NO₂. Temporal and spatial distributions of tropospheric NO₂ concentrations obtained from OMI over the Beijing-Tianjin-Hebei (Jing-Jin-Ji) region from 2007 to 2016 are presented, and annual changes and trends in the seasonal cycle are shown. Annual amounts of NO₂ are found to firstly increase then decrease, where after reaching a maximum in 2012 they begin a progressive yearly decline. NO₂ shows significant cyclical seasonal characteristics over Jing-Jin-Ji, with maximum values in winter and minimum in summer. In addition, the spatial distribution is unbalanced, and Beijing-Tianjin-Tangshan and Shijiazhuang-Xingtai-Handan are found to be highly polluted areas. The many complex factors affecting variations in NO₂ are analysed in this article, and the impact of meteorological factors and human activities are emphasized. It is considered that temperature and precipitation are natural factors influencing NO₂ concentration but there is a stronger negative relationship between tropospheric column NO₂ and temperature. Optimization of the energy structure is thus considered to be important and a reduction in energy consumption is required to control the concentration of pollutants. Coal combustion is a major anthropogenic factor in increasing NO₂ concentrations, and there is a strong correlation between higher amounts of NO₂ and coal consumption in the Jing-Jin-Ji region.     

An update on the dynamically induced episodes of extreme low ozone values over the northern middle latitudes

Over the middle latitudes of the Northern Hemisphere (NH), especially during the months of October–December, a number of episodes are observed when the total ozone for more than 2–3 days falls below 220 DU. This value has been introduced as the threshold for the Antarctic ozone hole but also represents ozone deviations of about one-third from the pre-1976 October–November–December monthly mean for the middle latitudes of the NH. Earlier studies have shown that the most common pattern of these events indicates transport of subtropical air from the Atlantic to the northeast frequently reaching Scandinavia and Northern Russia, sometimes combined with upward motions above a tropospheric anticyclone lifting low ozone mixing ratios to higher altitudes. In this study we report on the frequency and spatial extend of such extreme events using the newly available Multi Sensor Reanalysis (MSR) satellite total ozone data set for the period 1978–2008. During the autumn months considered in this study these events result to an ozone mass deficiency (O₃MD) of 5 tonnes km^?2 and their areal extend on a daily basis often exceeds 1.5 million km². More and larger in area events were observed during the 1990s and were possibly influenced by changes in the meridional circulation triggered by the maximum ozone depletion observed then over the middle latitudes of the NH.     

On the variation of the tropospheric ozone over Indian region in relation to the meteorological parameters

Using monthly mean satellite measurements of TOMS/SBUV tropospheric ozone residual (TOR) data and meteorological parameters (tropopause height (TPH), 200 hPa geopotential height (GPH) and outgoing longwave radiation (OLR)) during 1979–2001, seasonal variability of TOR data and their association with meteorological parameters are outlined over the Indian region. Prominent higher values of TOR (44–48 DU, which is higher than the globally averaged 31.5 DU) are observed over the northern parts of the country during the summer monsoon season (June–September). Similar to the TOR variation, meteorological parameters (tropopause height, 200 hPa geopotential height and outgoing longwave radiation) also show higher values during the summer monsoon season, suggesting an in phase relationship and strong association between them because of deep convection present during summer monsoon time. The monthly trends in TOR values are found to be positive over the region. TOR has significant positive correlations (5% level) with GPH, and negative correlations with OLR and TPH for the month of September. The oxidation chains initiated by CH₄ and CO show the enhanced photochemical production of ozone that would certainly become hazardous to the ecological system. Interestingly, greenhouse gases (GHG) emissions were found to have continuously increased over the Indian region during the period 1990–2000, indicating more anthropogenic production of ozone precursor gases causing higher level of tropospheric ozone during this period.     

Satellite remote sensing of total ozone column (TOC) over Pakistan and neighbouring regions

Total ozone column (TOC) obtained from the Ozone Monitoring Instrument (OMI) on board the Aura satellite was utilized to examine the spatio-temporal distribution of atmospheric ozone over Pakistan and adjoining regions of Afghanistan, India, and Iran for October 2004 to March 2014. This region has not yet been evaluated in greater detail. A yearly spatial averaged value of 278 ± 2 DU was found over the region. A decadal increase of 1.3% in TOC value over study region was observed for the first time. Large spatial and temporal variability of TOC was found over the study region. Elevated ozone columns were observed over the regions with high NO₂ and CO concentrations. Analysis indicated that Srinagar city has the highest averaged value of 290 ± 3 DU whereas Jodhpur city showed the highest increasing trend of 1.9% per decade. A monthly averaged maximum value of 289 ± 8 DU and a minimum of 264 ± 5 DU were found during April and November, respectively, over the region. January showed a decreasing trend of ?0.8% and February exhibited the highest increasing trend of 5.1% per decade. Forward trajectory analysis showed the possibility of ozone transport from eastern parts of the study region towards the Indian Ocean (Bay of Bengal) through the subtropical jet stream creating low values at higher meridians in October. TOC data deduced from OMI and the Atmospheric Infrared Sounder were compared to check the level of correlation and the results showed significant correlation (r = 0.75) and an acceptable average relative difference of 4.2%.     

Model study of tropospheric composition response to NOx and CO pollution

The effect of NO_x and CO pollution on other important atmospheric gases from 0–16 km in the northern temperate zonal belt is calculated using a 2-D (altitude–longitude) channel photochemical model with climatic zonal and vertical fixed transport. The geographical inhomogeneities of the NO_x and CO large-scale surface releases are modeled. The distinction between NO_x and CO fluxes from the oceanic and land surfaces and those from areas with various pollution source intensities is considered. NO_x and CO emissions from world transport aviation engine exhausts and the NO source from lightning discharges are also included. Model results are analyzed and compared with observational data for nitrogen compounds, carbon monoxide, and ozone. The dependence of the spatial and temporal hydroxyl distribution on the carbon monoxide (as the main destroyer of OH) concentration field is analyzed and discussed.     

Investigating the impacts of the North Atlantic Oscillation on global vegetation changes by a remotely sensed vegetation index

Large-scale climatic variability may have a critical impact on the vegetation growth at both local and global scales. In this study, a long time-series (1982–2006) monthly normalized difference vegetation index (NDVI) has been used as a proxy of vegetation vigour to investigate the global vegetation responses to the North Atlantic Oscillation (NAO, the dominant mode of atmospheric behaviour in the North Atlantic sector). The spatial distribution of the possible connections between NAO and global NDVI has been analysed by a cross-correlation method. The results reveal that the correlated regions between NAO and NDVI are concentrated in the middle- and high-latitude areas of the northern hemisphere around the N60° belt, the Africa zone around the N15° belt as well as the vast regions of the southern hemisphere around the S10°–30° belt. As expected, owing to geographic proximity, NAO-related regions are spread globally forming five geographical west-eastward modes. Simultaneously, some correlated areas persist at one place over several months without geographic transfer. Our findings show that, besides the northern hemisphere, which has been the focus of previous studies, the vegetation responses to NAO are found across the southern hemisphere, with various time lags in different regions, sometimes even over one and a half years. This suggests the existence of a so far unrecognized mechanism that carries the NAO signal far to the southern hemisphere and even persists for multiple years. The lagged vegetation responses to NAO can provide potential for over one-year crop production prediction and agricultural water resource management in the NAO-related regions, as well as useful information for global terrestrial carbon cycle modelling.     

Comparison of atmospheric CO2 observed by GOSAT and two ground stations in China

The atmospheric carbon dioxide (CO₂) column concentrations observed by the Greenhouse Gases Observing Satellite (GOSAT) and ground stations at Mt Waliguan (36.29° N, 100.90° E) and Lulin (23.47° N, 120.87° E) in China are compared. The data covered time periods from June 2009 to November 2011 for GOSAT and from July 2009 to December 2010 for the ground stations. The GOSAT monthly mean data tend to be generally smaller than those of the ground measurements by 5–10 ppm. The spatial and temporal variations of the atmospheric XCO₂ (dry air, column averaged, molar fraction of CO₂) concentrations, especially in the regions of China, are analysed by using the GOSAT monthly mean data. The variations are more significant in the northern hemisphere than in the southern hemisphere and show relatively high values and obvious fluctuations in the 15° N–45° N latitudinal band. These are generally consistent with the measurements of the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) and Atmospheric Infrared Sounder (AIRS). The satellite data show significant seasonal variations, with maximum in April and May and minimum in September and October. This feature is in general agreement with that of the ground observations and previous reports. In the regions of China, the XCO₂ ranged from 355 ppm to 385 ppm with a mean of 374 ppm, which is in agreement with the global concentration.     

Cover – volcanic ash and airspace closures

Trace gases are important components for climate change process, and Earth’s climate is sensitive to change in their atmospheric concentrations; therefore, proper assessment of trace gases is essential for ongoing global climate simulation. The spatio-temporal variations of four trace gases, namely carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃), and carbon dioxide (CO₂), over Bangladesh during the last decade are analysed using the remote-sensing data sets of the Atmospheric Infrared Sounder (AIRS) and Ozone Monitoring Instrument (OMI). Monthly, seasonal, and annual mean variations of trace gases were assessed. Higher CO, O₃, and CO₂ concentrations show west-to-east gradient, indicating the impact of both local meteorology and emissions on variations in trace gases. On the other hand, total NO₂ concentration increases over Dhaka because of large population density, high traffic emission, larger industrial activities, and highly polluted air. The inter-annual variations of trace gases are mainly due to large-scale climatic phenomena such as El Niño and La Niña conditions. All the trace gases show strong seasonality, with higher levels during pre-monsoon season and lower levels during monsoon season, which are caused by the seasonal variations in biomass burning (BB), long-range transportation, and rainfall in South and Southeast Asia (S–SE Asia). However, O₃ concentration reveals minimum loading during winter season, associated with the reduction of O₃ formation in cold days due to insufficient heat. These findings are important to estimate regional climate variability due to trace gases.     

Temporal and spatial variabilities of total ozone column over Portugal

This paper focuses on the spatial-temporal structure of total ozone column (TOC) over Portugal. This relevant region of southwestern Europe has not been evaluated yet in detail due to the lack of continuous and well-covered ground-based TOC measurements. The data used in this study are derived from the NASA's Total Ozone Mapping Spectrometer (TOMS) for the period 1978-2005. The TOC spatial behavior shows no significant longitudinal variability (smaller than 3%). In contrast, the variation in latitude changes between 3.5% and 6% depending on the calendar month. The TOC in the northern Portugal is, on average, higher than that recorded in the South. The temporal variability was analyzed for three scales: long-term, seasonal and short-term. The long-term TOC changes are analyzed between 1978 and 1999 by means of linear least squares fits. The results show an annual TOC trend of (−2.65 ± 0.70)%/decade which is statistically significant at the 95% confidence level. This TOC decrease is smaller than the trends obtained in other midlatitudes regions which could be partially explained by the compensation due to the observed increase in the tropospheric ozone over the Iberian Peninsula. A trend analysis performed for each individual month shows a statistically significant TOC decline between March and October, with a maximum linear trend value of (−7.30 ± 1.45)%/decade in May. The amplitude of the seasonal TOC cycle over Portugal shows a slight dependence in latitude, varying from 28.6 DU (37.5° N) to 33.6 DU (41.5° N). Finally, the short-term variability showed a notable seasonal behavior, with maximum day-to-day TOC changes in winter (~ 6%) and minimum in summer (~ 3%). In addition, the persistence (characterized by the autocorrelation coefficients) strongly decreases after a few days (except in summer months).     

Ozone dynamics over Greece as derived from satellite and! in situ measurements

A comprehensive analysis of the records of surface ozone available for Athens, Greece ( 38° N, 24° E) for the periods 1901–1940 and 1987–1990 is presented. Both records are analysed to explore the intraseasonal fluctuations and the harmonic components of surface ozone and also compared to other historical surface ozone records. The variation in surface ozone concentration during rainfall is also investigated, using the hourly measurements of the surface ozone concentration obtained by a network of four stations within the Greater Athens area. The results indicate that, during rainfall events which are associated with the passing of a cold front, an important decrease of the surface ozone concentration is observed. Daily measurements of surface ozone and NO_x, from five stations in the Greater Athens Basin overthe period 1986–1990 are also used in order to examine the main features of basin-wide 0₃-HC-NO_x relations. A simple regression model between the surface ozone concentration and the temperature at the 850 hPa level, which was first tested in Los Angeles, gave satisfactory results in reproducing the mean monthly ozone variation in Athens, when coefficients extracted from local data were used in the regression equation. A series of vertical ozone soundings over Athens has been also performed in order to explore the tropospheric ozone variations and to examine further the transport that occurs at the 700hPa level with advection from the north-western sector. The relevant results are discussed. The existing uncertainties concerning the stratosphere-troposphere exchange of ozone which mainly occurs during midlatitude tropopause folding as well as during cut-off low events are also discussed. The examination of the role of the atmospheric circulation in the lower stratosphere in relation to the laminated structure of ozone is also attempted. The data collected during the balloon ascents have been compared with those during the balloon descents. Both profiles are compared with the total ozone measurements derived from the TOMS on the Nimbus-7 satellite and the Dobson spectrophotometer. The data collected for the vertical distribution of ozone and temperature have been compared with the satellite-derived reference models which provide the monthly latitudinal variations of vertical structure of both ozone and temperature. We have also used total ozone measurements obtained with a Dobson spectrophotometer ( No. 118) which has been instituted in Athens from 1989 in order to examine the consistency of data from TOMS with the corresponding Dobson data on a daily basis. Furthermore monthly mean total ozone data were first estimated for the entire period and were then Fourier analysed to obtain the amplitude, phase and percentage contribution to the total variance of the first, second and third harmonics.     

Satellite-sensed tropospheric NO2 patterns and anomalies over Indus,Ganges, Brahmaputra,and Meghna river basins

This study presents trends, seasonality, hot spots, and anomalies of tropospheric NO₂ pollution over four basins of Indus, Ganges, Brahmaputra, and Meghna rivers in South Asia using observations from Ozone Monitoring Instrument (OMI) on-board Aura satellite during 2004–2015. For the first time this area, a highly populated and industrialized region with significant emissions of air pollutants, has been discussed collectively. OMI data reveal significantly elevated NO₂ column over the region averaged at (1.9 ± 0.1) × 10¹⁵ molecules cm^–2 (average ± standard deviation of observations) with an increase of 21.12% (slope (0.036 ± 0.004) × 10¹⁵ molecules cm^–2, y-intercept (1.705 ± 0.024) × 10¹⁵ molecules cm^–2, R² = 0.92) during the study period. According to MACCity anthropogenic emissions inventory transportation, energy, residential, and industrial sectors are the major contributors of high NO_x emissions. NO₂ pollution hot spots are identified and their tendencies have been discussed. The hot spots of megacities Lahore (Pakistan) and Dhaka (Bangladesh) are found to be strengthening and expanding over the time. Eastern Ganges Basin shows the highest NO₂ concentration at (2.63 ± 0.22) × 10¹⁵ molecules cm^–2 and growth rate of 3.22% per year mainly linked to power generation, fossil fuel extraction, mining activities, and biomass burning. NO₂ over Indus–Ganges–Brahmaputra–Meghna Basin exhibits seasonal maximum in winter and minimum in monsoon. The highest seasonality is found over Meghna Basin due to large variations in meteorological conditions and large-scale crop-residue burning. Some anomalies in NO₂ levels have been detected linked to intense crop-residue burning events. During these anomalies, exceptionally high levels of daily NO₂ reaching up to 76.23 × 10¹⁵ molecules cm^–2 have been observed over some places in Indus and Meghna Basins.     

Photon stimulated sensor based on indium oxide nanoparticles I: Wide-concentration-range ozone monitoring in air

Ozone sensors are of great demand for monitoring high-concentration ozone for industrial applications and low-concentration ozone for protecting people's health, although commercial ozone sensors are limited in their detection range. In this work, it is demonstrated that compact energy-saving photostimulated ozone sensors based on indium oxide nanoparticles can detect ozone with a dynamical range over four orders of magnitude at room temperature. The photostimulated ozone sensor shows a very low cross response to NO₂, CO, and CO₂. Furthermore, the sensing signal is very reproducible, and no hysteresis effects were found in repeated measurements.     

Validation of Ozone Monitoring Instrument NO2 measurements using ground based NO2 measurements at Zvenigorod,Russia

We present the results of comparison between Ozone Monitoring Instrument (OMI) data of NO₂ measurements (Collection 3) onboard the NASA EOS-Aura satellite and correlative ground-based twilight measurements at Zvenigorod station in Russia in 2004–2008. Compared quantities are unpolluted column and tropospheric column amounts of NO₂ which are standard products of OMI measurements. The NO₂ columns observed by our ground-based instrument have been interpolated to the time of OMI measurements using a one-dimensional photochemical model. According to our comparison, the OMI unpolluted NO₂ columns underestimate ground-based measurements by (0.084 ± 0.025)?×?10¹⁵ molecules/cm², or (3.2 ± 0.9)%. The correlation coefficient between the OMI and ground-based unpolluted NO₂ columns is 0.92. The tropospheric NO₂ columns derived from OMI measurements are on average by (1.8 ± 0.5)?×?10¹⁵ cm^?2, or approximately 40%, less than those derived from ground-based measurements. The correlation coefficient between these data is about 0.3. Reasons for this discrepancy are discussed.     

Tropospheric ozone variability over the Indian coastline and adjacent land and sea

A tropospheric ozone variability study is carried out to investigate the spatial and temporal distribution over the coastline of the Indian peninsula and adjacent land and sea using NASA Langley Tropospheric Ozone Residual data set for the period 1979–2005. A strong seasonal cycle has been observed with large variation (～ 55%) over the upper eastern coast, followed by the upper and lower western coast, compared to the lower eastern coast (～ 33%). A negative gradient in ozone concentration is observed along eastern and western coasts during summer (slope ～ –0.78 and –0.65) and a positive gradient (slope ～ 0.16 and 0.21) during winter. The same is observed over the adjacent land and sea along the coastline with slight variation. This change in gradient can be attributed to the anthropogenic emission of precursor gases that reinforce localized photochemical production of ozone. In addition, topography, transport, seasonality of emission of precursor gases and the solar insolation cycle play a vital role.     

Observations of urban NOx plume dispersion using mobile and satellite DOAS measurements around the megacity of St.Petersburg (Russia)

Mobile DOAS (Differential Optical Absorption Spectroscopy) circular measurements of tropospheric nitrogen dioxide (NO₂) were performed on a number of days in 2012 and 2014–2016 around St.Petersburg. These observations figured out an evolution of urban pollution plume, released from the megacity. The HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectories) model was configured to simulate the observed NO₂ dispersion, taking into account the municipal inventory database of urban nitrogen oxides (NO_x = NO+ NO₂) emission. The simulation results were found consistent with the data of mobile measurements, allowing to fit an estimate of integral NO_x emission rate from St.Petersburg (about 60 kt year^?1 on the average). Coincident satellite measurements the Aura Ozone Monitoring Instrument (OMI) of tropospheric NO₂ mostly agree with the data of simulation on the days of mobile observations. In general, presented results demonstrate the capabilities of joint interpretation of disparate tropospheric NO₂ data in the vicinity of a megacity.     

Data assimilation of ozone in the atmospheric transport chemistry model LOTOS

Modelled ozone concentrations often differ from measured concentrations quite substantially, partly due to measurement errors, but mainly due to uncertainties in the model. Modelling studies would therefore benefit highly from more reliable model simulations. One way to achieve this is the application of data assimilation, a technique that uses measurement information within the model simulation in a way that is consistent with the model itself. This aim of this paper is to show that this is indeed one way to go with atmospheric transport chemistry models (ATCMs) by presenting results of data assimilation simulations of ozone with the model LOTOS. The assimilation technique used in this study is the Ensemble Kalman Filter. A simulation for a period of 4 weeks has been performed in which ground-level ozone measurements have been assimilated. The necessary noise input consisted of uncertainties in the emissions of NO_x, SO_x, VOC and CO in 17 groups of countries. The main conclusion is that it is possible to improve ATCM simulations of ozone by data assimilation, but that noise inputs other than emissions only are essential for the reduction of the differences between measured and modelled concentrations to acceptable margins.     

Biomass burning and related trace gas emissions from tropical dry deciduous forests of India: A study using DMSP-OLS data and ground-based measurements

Biomass burning is one of the major sources of trace gas emissions in the atmosphere. In India the major sources of biomass burning include deforestation, shifting cultivation, accidental fires, controlled burning, fire wood burning, burning from agricultural residues and burning due to fire lines. Studies on biomass burning practices gain importance due to increasing anthropogenic activities and increasing rates of deforestation. Satellite data have been widely used over the globe to monitor the rates of deforestation and also with respect to biomass burning studies. But, much of the polar orbiting satellites, due to their repetitive cycle, have limitations in observing such events and in the tropics, due to cloud cover, getting a cloud-free image during the daytime is difficult. In this study we used Defence Meteorological Satellite Program Operational Line Scanner (DMSP-OLS) night-time data to study the biomass burning events over a period of 10 years from 1987 to 1998 for the Eastern Ghats region, covering the northern part of Andhra Pradesh, India. Two ground-based experiments were carried out to quantify the emissions from biomass burning practices. The results of the study with respect to trace gases suggested emission ratios for CO, CH4, NOx and N20 during the burning to be about 12.3%, 1.29%, 0.29% and 0.07% at the first site and 12.5%, 1.59%, 0.29% and 0.05% at the second site, suggesting low inter-fire variability between the sites. The variation has been attributed to the fuel load, vegetation characteristics, site conditions and local meteorological parameters affecting the relative amounts of combustion. Using the DMSP OLS derived areal estimates of active fires, the trace gas emissions released from the biomass burning were quantified. The results suggested the emissions of 8.2 2 10 10 g CO 2, 1.8 2 10 8 g CO, 6.0 2 10 6 g N 2 O, 3.0 2 10 6 g NO x and 1.2 2 10 8 8 g CH 4 during March 1987. The emissions increased to 1.0 2 10 11 g CO 2, 2.3 2 10 g CO, 7.8 2 10 6 g N 2 O, 3.9 2 10 7 g NO x and 1.6 2 10 8 g CH 4, over a period of 10 years. The results of the analysis suggest the possible use of monitoring biomass burning events from DMSP-OLS night-time data.     

利用GOME-2卫星数据反演对流层臭氧

基于GOME-2level 1B数据利用最优估计反演算法获得了GOME-2臭氧廓线产品,分析了GOME-2对流层臭氧反演产品的误差和信息量等特征,并对比验证了紫外光谱仪GOME-2与热红外光谱仪TES反演的对流层臭氧柱总量及其敏感性。结果表明:GOME-2对流层臭氧柱总量反演随机误差在10%以内;GOME-2相对TES的对流层臭氧柱总量偏小5%~20%;晴空下GOME-2对流层臭氧反演的敏感性随高度增加而上升,接近TES的敏感性垂直分布;在有云条件下,GOME-2和TES的云下部分信号都被屏蔽,在云顶之上GOME-2臭氧反演敏感性明显高于热红外仪器TES。