articles
A case study on the application of SCIAMACHY satellite methane measurements for regional studies: the Greater Area of the Eastern Mediterranean
Georgoulias A.K., Kourtidis K.A., Buchwitz M., Schneising O., Burrows J.P.
International Journal of Remote Sensing, 32(3), 787-813, doi:10.1080/01431161.2010.517791, 2011.
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Many studies have focused on geological formations, such as mud volcanoes, which abound in the Greater Area of the Eastern Mediterranean (GAEM; 25° N-50° N, 5° E-55° E). This geological source is thought to provide a significant portion of the global methane (CH4) emissions. However, studies in the GAEM have focused on specific locations rather than extensive areas, which has led to a gap in our understanding of the spatial and temporal variability of CH4 atmospheric mixing ratios. Here, we present characteristics of methane loading over land in the GAEM using dry air columnar data (XCH4) retrieved from SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography) satellite measurements with the Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS) version 1.0 algorithm. We defined methane annual, seasonal and monthly spatial patterns over the area using 2003 and 2004 measurements. The annual mean XCH4 levels over the study area were estimated to be 1761 ± 27 ppb for 2003 and 1758 ± 26 ppb for 2004. A seasonal variability with a summer-autumn peak was observed for both 2003 and 2004, August being the month with the highest methane concentrations. The northeastern part of the area exhibits the highest XCH4 values while the high elevation regions defined by the triangle of eastern Turkey, the Persian Gulf and the Caspian Sea and the region of the eastern coast of the Red Sea exhibit the lowest levels. A latitudinal gradient was observed for the area during 2003 and 2004. A comparison of measured XCH4 levels above two of the world's most renowned mud volcano regions situated in the GAEM with anticipated methane columnar concentrations as modelled for eruption cases shows that no mud volcano eruptions were observed from SCIAMACHY during 2003 or 2004. |
AMFIC Web Data Base - A Satellite System for the Monitoring and Forecasting of Atmospheric Pollution
A. K. Georgoulias, I. Kioutsioukis, P. Symeonidis, K. Kourtidis
Journal of Engineering Science and Technology Review (2008)
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In this work we present the contribution of the Laboratory of Atmospheric Pollution and Pollution Control Engineering
of Democritus University of Thrace in the AMFIC-Air Monitoring and Forecasting In China European project. Within
the framework of this project our laboratory in co-operation with DRAXIS company will create and manage a web
satellite data base. This system will host atmospheric pollution satellite data for China and for the whole globe in
general. Atmospheric pollution data with different spatial resolution such as O3 and NO2 total columns and
measurements of other important trace gasses from GOME (ERS-2), SCIAMACHY (ENVISAT) and OMI (EOSAURA)
along with aerosol total load estimates from AATSR (ENVISAT) will be brought to a common spatial and
temporal resolution and become available to the scientific community in simple ascii files and maps format. Available
will also be the results from the validation procedure of the satellite data with the use of ground-based observations and a
set of high resolution maps and forecasts emerging from atmospheric pollution models. Data will be available for two
geographical clusters. The one cluster includes the greater area of China and the other the whole globe. This integrated
satellite system will be fully operational within the next two years and will also include a set of innovative tools that
allow easy manipulation and analysis of the data. Automatic detection of features such as plumes and monitoring of their
evolution, data covariance analysis enabling the detection of emission signatures of different sources, cluster analysis etc
will be possible through those tools. The AMFIC satellite system shares a set of characteristics with its predecessor,
AIRSAT. Here, we present some of these characteristics in order to bring out the contribution of such a system in
atmospheric sciences.
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Change of NO2 column density over Beijing from satellite measurement during the Beijing 2008 Olympic Games
Yu Huan, Wang Pucai, Zong XueMei, Li Xin, and LV DaRen
Chinese Science Bulletin (2009)
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The effect of the air quality ensuring measures for the Beijing 2008 Olympic Games in reducing air pollution during the game period is assessed using the tropospheric NO2 column density retrieved from the Ozone Monitoring Instrument (OMI) onboard the AURA satellite. The basic method of the assessment is the comparison of the NO2 column densities during the game period with that during the corresponding period of 2005-2007 for the Beijing area, and the comparison among Beijing and neighbouring cities Tianjin and Tangshan, which are of simular situation in air pollution of NO2 in recent years. The images of tropospheric NO2 column densities over Northern China during the Beijing 2008 Olympic Games show the remarkable effect of the air quality ensuring measures in reducing NO2 pollution: the tropospheric NO2 column density in Beijing is much lower than that in Tianjin and Tangshan, while there were very simular values in the three large cities during the same period of the last three years. About 40% reduction in tropospheric NO2 column density over Beijing area is obtained from the assessment during July to August, 2008, a key period of air quality ensuring measures for the Beijing Olympic Games.
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Evaluation of the Diurnal Cycle of Trace Gases over Beijing as Modelled by Chimere
Arjan Lampe
Master thesis, University Twente/KNMI. July 2009
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In the framework of the international EU and ESA project "Air quality Monitoring
and Forecasting In China" (AMFIC) an air quality forecast system of
Eastern China is in development.
Chimere is the chemical transport model used for this purpose. It has meteorological
forecasts and emissions as inputs and calculates through advection
and chemical reactions of 44 species their temporal and spatial concentrations
in a computational domain.
The model output of Chimere is compared to in situ measurements of pollutants
in Beijing, showing that the predicted nocturnal concentrations of pollutants
are systematically too high. The objective of the present research is to
find possible causes of this discrepancy. To achieve this goal several sensitivity
studies of parameters in the model have been conducted. These studies show
that the discrepancy is due to the incorrect representation of the atmospheric
boundary layer height. This is due to the absence of the so-called urban heat
island effect in Chimere. The urban heat island is the phenomenon of the air
inside an urban region being warmer than its rural surroundings. This effect is
strongest at night and increases vertical mixing resulting in a higher nocturnal
atmospheric boundary layer. It is shown that incorporating this effect in the
Chimere model leads to a better agreement of the calculated surface pollutant
concentrations with observations.
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Reductions of NO2 detected from space during the 2008 Beijing Olympic Games
Mijling, B., R. J. van der A, K. F. Boersma, M. Van Roozendael, I. De Smedt, and H. M. Kelder
Geophys. Res. Lett. (2009), 36, L13801, doi:10.1029/2009GL038943.
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During the 2008 Olympic and Paralympic Games in Beijing (from 8 August to 17 September),
local authorities enforced strong measures to reduce air pollution during the events.
To evaluate the direct effect of these measures, we use the tropospheric NO2 column observations
from the satellite instruments GOME-2 and OMI. We interpret these data against simulations from
the regional chemistry transport model CHIMERE, based on a 2006 emission inventory, and find a
reduction of NO2 concentrations of approximately 60% above Beijing during the Olympic period.
The air quality measures were especially effective in the Beijing area, but also noticeable
in surrounding cities of Tianjin (30% reduction) and Shijiazhuang (20% reduction).
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Twelve Years of Global Observation of Formaldehyde in the Troposphere Using GOME and SCIAMACHY Sensors
I. De Smedt, J.-F. Müller, T. Stavrakou, R. van der A, H. Eskes, and M. Van Roozendael
Atmospheric Chemistry and Physics, 4947-4963, 2008
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This work presents global tropospheric formaldehyde columns retrieved
from near-UV radiance measurements performed by the GOME instrument
onboard ERS-2 since 1995, and by SCIAMACHY, in operation on ENVISAT since
the end of 2002. A special effort has been made to ensure the coherence and
quality of the CH2O dataset covering the period 1996-2007. Optimised DOAS settings
are proposed in order to reduce the impact of two important sources of error in the
derivation of slant columns, namely, the polarisation anomaly affecting the SCIAMACHY
spectra around 350 nm, and a major absorption band of the O4 collision complex
centred near 360 nm. The air mass factors are determined from scattering weights
generated using radiative transfer calculations taking into account the cloud
fraction, the cloud height and the ground albedo. Vertical profile shapes of CH2O
are provided by the global CTM IMAGES based on an up-to-date representation of
emissions, atmospheric transport and photochemistry. A comprehensive error analysis
is presented. This includes errors on the slant columns retrieval and errors on
the air mass factors which are mainly due to uncertainties in the a priori profile
and in the cloud properties. The major features of the retrieved formaldehyde column
distribution are discussed and compared with previous CH2O datasets over the major
emission regions.
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Trends, seasonal variability and dominant NOx source derived from a ten year record of NO2 measured from space
R.J. van der A, H.J. Eskes, K.F. Boersma, T.P.C. van Noije, M. Van Roozendael, I. De Smedt, D.H.M.U. Peters, E.W. Meijer
J. Geophys. Res., 2008, 113, doi:10.1029/2007JD009021
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For the period 1996-2006 global distributions of tropospheric nitrogen dioxide (NO2) have been derived from radiances measured with the satellite instruments GOME on ERS-2 and SCIAMACHY on Envisat. A statistical analysis is applied to derive trends and seasonal variability for this period on a global scale. The time series of the monthly NO2 columns for these ten years have been fitted with a linear function superposed on an annual seasonal cycle on a grid of 1º by 1º. We see significant reductions (up to 7% per year) in NO2 in Europe and parts of the eastern USA, and a strong increase in Asia, most particularly in China (up to 29% per year) but also in Iran and Russia. By comparing the data with the cloud information derived from the same satellite observations the contribution of lightning to the total column of NO2 is estimated. The estimated NO2 from lightning is, especially in the tropics, in good agreement with observations from the OTD and LIS instruments. The satellite observed seasonal variability of NO2 generally correlates well with independent observations and estimates of the seasonal cycle of specific NOx sources. Source categories considered are anthropogenic (fossil fuel and biofuel), biomass burning, soil emissions and lightning. The seasonal variability has been used to identify the dominant source of NOx emissions on a global scale and on a 1º by 1º grid.
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Variations of CO and NO2 column concentrations of China in 2003 using the TM5 simulation results
Zhang Yan, Zhang Peng, Jeroen Kuenen, Zhang Xingyang, Li Xiaojing, Qiu Hong, Wang Weihe
Remote Sensing Information, 6, 2007 (in Chinese)
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The spatial and temporal characteristics of CO and NO2 simualtions of China in 2003 are analyzed by using TM5 results (The two-way nested global chemistry-transport zoom model). It is shown that the seasonal variations of CO and NO2 are obvious in China, and there are high CO concentrations in eastern China (30-40 degrees) and high NO2 concentrations in eastern China and the Sichuan basin. It is also found that the CO vertical variations are significantly changed with differnet seasons, while the NO2 profile variations of different seasons are very little.
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Trends, seasonal cycle, and sources of tropospheric NO2 over China during 1997-2006 based on satellite
measurement
Zhang XingYing, Zhang Peng, Zhang Yan, Li XiaoJing and Qiu Hong
Sciences in China Series D:Earth Sciences, 50, 1877-1884, 2007
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The characteristics of spatial and temporal distribution of tropospheric NO2 column density concentration
over China are presented, on the basis of measurements from the satellite instruments GOME
and SCIAMACHY. From these observations, monthly averaged tropospheric NO2 variations are determined
for the period of 1997 to 2006. The trend and seasonal cycle are also investigated. The possible
source of tropospheric NO2 over megacity area is discussed in this paper. The results show a large
growth of tropospheric NO2 over eastern China, especially above the industrial areas with a fast economical
growth, such as, Yangtze Rive Delta region and Pearl River Delta region because of the
prominent anthropogenic activity. There is a rapid increase of tropospheric NO2 over megacities in
China. For instance, Shanghai had a linear significant increase in NO2 columns of ~20% per year (reference
year 1997) in the period of 1997-2006, which is the rapidest increase among all the selected
cities. The seasonal pattern of the NO2 concentration shows a difference between the east and west in
China. In the eastern part of China, an expected winter maximum in seasonal cycle is found because of
the prominent anthropogenic activity and meteorological conditions. In the western part this cycle
shows a NO2 maximum in summer time, which is attributed to natural emissions, especially soil emissions
and lightning. A quickly increasing vehicle population may contribute to the increase of tropospheric
NO2 over megacities in China for the remarkable correlation for vehicle population with tropospheric
NO2.
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Detection of the trend and seasonal variation in tropospheric NO2 over China
R.J. van der A, D.H.M.U. Peters, H.J. Eskes, K.F. Boersma, M. Van Roozendael, I. De Smedt, H.M. Kelder
J. Geophys. Res., 2006, 111, doi:10.1029/2005JD006594
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The results of a trend study on the tropospheric NO2 column over China are presented, on the basis of measurements from the satellite instruments GOME and SCIAMACHY. From these observations, monthly averaged tropospheric NO2 distributions are determined for the period 1996 to 2005 on a 1° by 1° grid. A linear model with a seasonal component is used to fit these time series. The variance and the autocorrelation of the noise are used to calculate the significance of the trend. The results show a large growth of tropospheric NO2 over eastern China, especially above the industrial areas with a fast economical growth. For instance, Shanghai had a linear significant increase in NO2 columns of 20% ± 6% per year (reference year 1996) in the period 1996\u20132005. The seasonal pattern of the NO2 concentration shows a difference between east and west China. In the east a NO2 maximum is found during wintertime, because of chemistry and anthropogenic activity. Contrary to this, in the western part of China the NO2 concentration reaches a maximum in summertime. This spatial difference correlates with the population distribution of China. Since there is negligible anthropogenic activity in west China this difference in seasonality of NO2 is attributed to natural emissions in west China.
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Anthropogenic NOx emission estimates for China based on satellite measurements and chemistry-transport modelling
J.J.P. Kuenen
Master thesis, TUE/KNMI. May 2006
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Recent studies have shown that signicant growth in tropospheric NO2 has occurred over
China, especially over its major cities. The main reason for this growth is the increase
in anthropogenic NOx emissions as a result from increasing power consumption and traffic.
The purpose of this study is to improve the anthropogenic NOx emission estimates
in China, with the use of satellite observations from GOME and SCIAMACHY and the
chemistry transport model TM5.
Firstly, the relationship between NO2 columns and anthropogenic NOx emissions is determined.
Thereafter it is applied, in combination with satellite observations of tropospheric
NO2, to estimate the anthropogenic NOx emissions in China. Multiple iterations have been
performed to account for NOx transport and to improve the emission estimates.
This approach has been applied to multiple years of data, whereafter a linear and exponential
model have been used to fit the dataset. The results show that the exponential model
fits better to the dataset and shows an increase of 20% in anthropogenic NOx emissions in
2005.
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