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Fire radiative power (FRP), which is the power radiated by fire within a unit area, is a fundamental component for estimation of fire emissions. Successive information of FRP is provided by instruments on geostationary satellites, such as the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board Meteosat, and the Imager on board Geostationary Operational Environmental Satellite (GOES) for Europe, Africa and America. In East Asia, however, the geostationary satellites such as Multifunctional Transport Satellite, Himawari, Fengyun, and Communication, Ocean and Meteorological Satellite (COMS) do not provide official FRP products yet. This article describes the first retrieval of COMS FRP using the mid-infrared radiance method with an optimal sensor coefficient derived from our experimental simulations. The COMS FRP retrievals were compared with Moderate Resolution Imaging Spectroradiometer (MODIS) FRP products in East Asia for each April during 2011–2014. The mean absolute percentage differ...

A Multiple Regression Method (MRM) is used for the first time with Ozone MonitoringInstrument (OMI) and Moderate Resolution Imaging Spectroradiometer (MODIS) data to estimateformaldehyde (HCHO) Vertical Column Density (VCD). For a 3.5-year period from January 2005 throughJuly 2008, HCHO VCD estimation is investigated in cities over Asia in two categorized areas: (1) Majorcities in Northeast Asia (Beijing, Seoul, and Tokyo), (2) Major cities in Southeast Asia (New Delhi, Dhaka,and Bangkok). In the Major cities in Northeast Asia, there are good agreements between HCHO estimatedby the multiple linear regression method (HCHO MRM ) and HCHO measured by OMI (HCHO OMI ) (0.78

The performance of various empirical linear models to estimate the concentrations of surface-level particulate matter with a diameter less than 10 μm (PM10) was evaluated using Aerosol Robotic Network (AERONET) sun photometer and Moderate-Resolution Imaging Spectroradiometer (MODIS) data collected in Seoul during the Distributed Regional Aerosol Gridded Observation Network (DRAGON)-Asia campaign from March to May 2012. An observed relationship between the PM10 concentration and the aerosol optical depth (AOD) was accounted for by several parameters in the empirical models, including boundary layer height (BLH), relative humidity (RH), and effective radius of the aerosol size distribution (Reff), which was used here for the first time in empirical modeling. Among various empirical models, the model which incorporates both BLH and Reff showed the highest correlation, which indicates the strong influence of BLH and Reff on the PM10 estimations. Meanwhile, the effect of RH on the relationship between AOD and PM10 appeared to be negligible during the campaign period (spring), when RH is generally low in northeast Asia. A large spatial dependency of the empirical model performance was found by categorizing the locations of the collected data into three different site types, which varied in terms of the distances between instruments and source locations. When both AERONET and MODIS data sets were used in the PM10 estimation, the highest correlations between measured and estimated values (R = 0.76 and 0.76 using AERONET and MODIS data, respectively) were found for the residential area (RA) site type, while the poorest correlations (R = 0.61 and 0.68 using AERONET and MODIS data, respectively) were found for the near-source (NS) site type. Significant seasonal variations of empirical model performances for PM10 estimation were found using the data collected at Yonsei University (one of the DRAGON campaign sites) over a period of 17 months including the DRAGON campaign period. The best correlation between measured and estimated PM10 concentrations (R = 0.81) was found in winter, due to the presence of a stagnant air mass and low BLH conditions, which may have resulted in relatively homogeneous aerosol properties within the BLH. On the other hand, the poorest correlation between measured and estimated PM10 concentrations (R = 0.54) was found in spring, due to the influence of the long-range transport of dust to both within and above the BLH.

In this present paper, we, for the first time, calculated SO2 inflow from China to Korea peninsula based on OMI SO2 products and HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) backward trajectory calculations. The major factors used to estimate SO2 flux are long range transported SO2 concentration, transport speed of air mass, and thickness of transported air mass layer. The mean and maximum SO2 fluxes are estimated to be 0.81 and 2.11 g·m-2·h-1, respectively based on OMI products while, those of SO2 fluxes are 0.50 and 1.18 g·m-2·h-1 respectively using insitu data obtained at the surface. For most cases, larger SO2 inflow values were found at the surface than those estimated for the air mass layer which extends from surface up to 1.5 km. However, increased transport speed of air mass leads to the enhanced SO2 flux at the altitude up to 1.5 km at the receptor sites. Additionally, we calculate uncertainties of SO2 flux using error propagation method.

This study introduces a new method of combining Imaging Differential Optical Absorption Spectroscopy (Imaging-DOAS) data and plume dispersion formulas for power plant emissions to determine the threedimensional structure of a dispersing pollution plume and the spatial distributions of trace gas volume mixing ratios (VMRs) under conditions of negligible water droplet and aerosol effects on radiative transfer within the plume. This novel remote-sensing method, applied to a power plant stack plume, was used to calculate the twodimensional distributions of sulfur dioxide (SO2) and nitrogen dioxide (NO2) VMRs in stack emissions for the first time. High SO2 VMRs were observed only near the emission source, whereas high NO2 VMRs were observed at locations several hundreds of meters away from the initial emission. The results of this study demonstrate the capability of this new method as a tool for estimating plume dimensions and trace gas VMRs in power plant emissions.

Surface NO2 volume mixing ratio (VMR) at a specific time (13:45 Local time) (NO2 VMRST) and monthly mean surface NO2 VMR (NO2 VMRM) are estimated for the first time using three regression models with Ozone Monitoring Instrument (OMI) data in four metropolitan cities in South Korea: Seoul, Gyeonggi, Daejeon, and Gwangju. Relationships between the surface NO2 VMR obtained from in situ measurements (NO2 VMRIn-situ) and tropospheric NO2 vertical column density obtained from OMI from 2007 to 2013 were developed using regression models that also include boundary layer height (BLH) from Atmospheric Infrared Sounder (AIRS) and surface pressure, temperature, dew point, and wind speed and direction. The performance of the regression models is evaluated via comparison with the NO2 VMRIn-situ for two validation years (2006 and 2014). Of the three regression models, a multiple regression model shows the best performance in estimating NO2 VMRST and NO2 VMRM. In the validation period, the average correlation coefficient (R), slope, mean bias (MB), mean absolute error (MAE), root mean square error (RMSE), and percent difference between NO2 VMRIn-situ and NO2 VMRST estimated by the multiple regression model are 0.66, 0.41, −1.36 ppbv, 6.89 ppbv, 8.98 ppbv, and 31.50%, respectively, while the average corresponding values for the other two models are 0.75, 0.41, −1.40 ppbv, 3.59 ppbv, 4.72 ppbv, and 16.59%, respectively. All three models have similar performance for NO2 VMRM, with average R, slope, MB, MAE, RMSE, and percent difference between NO2 VMRIn-situ and NO2 VMRM of 0.74, 0.49, −1.90 ppbv, 3.93 ppbv, 5.05 ppbv, and 18.76%, respectively.

The vertical distribution of single scattering albedos (SSAs) of Asian dust mixed with pollutants was derived using the multi-wavelength Raman lidar observation system at Gwangju (35.10°N, 126.53°E). Vertical profiles of both backscatter and extinction coefficients for dust and non-dust aerosols were extracted from a mixed Asian dust plume using the depolarization ratio from lidar observations. Vertical profiles of backscatter and extinction coefficients of non-dust particles were input into an inversion algorithm to retrieve the SSAs of non-dust aerosols. Atmospheric aerosol layers at different heights had different light-absorbing characteristics. The SSAs of non-dust particles at each height varied with aerosol type, which was either urban/industrial pollutants from China transported over long distances at high altitude, or regional/local pollutants from the Korean peninsula. Taking advantage of independent profiles of SSAs of non-dust particles, vertical profiles of SSAs of Asian dust mixed with pollutants were estimated for the first time, with a new approach suggested in this study using an empirical determination of the SSA of pure dust. The SSAs of the Asian dust-pollutants mixture within the planetary boundary layer (PBL) were in the range 0.88–0.91, while the values above the PBL were in the range 0.76–0.87, with a very low mean value of 0.76±0.05. The total mixed dust plume SSAs in each aerosol layer were integrated over height for comparison with results from the Aerosol Robotics Network (AERONET) measurements. Values of SSA retrieved from lidar observations of 0.92±0.01 were in good agreement with the results from AERONET measurements.

Total Vertical Column Density (VCD) of NO 2, a key component in air quality and tropospheric chemistry was measured using a ground-based instrument, Pandora, in Seoul from March 2012 to October 2013. The NO 2 measurements using Pandora were compared with those obtained by satellite remote sensing from Ozone Monitoring Instrument (OMI) where the intercomparison characteristics were analyzed as a function of measurement geometry, cloud amount and aerosol loading. The negative biases of the OMI NO 2 VCD were larger when cloud amount and Aerosol Optical Depth (AOD) were higher. The correlation coefficient between NO 2 VCDs from Pandora and OMI was 0.53 for the entire measurement period, whereas the correlation coefficient between the two was 0.74 when the cloud amount and AOD were low (cloud amount

The diurnal pattern of the vertical distribution of biogenic pollen in the lower troposphere was investigated by LIDAR. Meteorological data were taken at the ground. Pollen concentrations were measured at the surface using a Burkard 7-day-recording volumetric spore sampler. Aerosol extinction coefficients and depolarization ratios at 532 nm were obtained from LIDAR measurements in spring (4 May–2 June) 2009 in Gwangju, South Korea. Linear volume depolarization ratios varied between 0.08 and 0.14 and were observed only during daytime (09:00–17:00 local time (LT)) during days of high pollen concentration (4 to 9 May). Daily average pollen concentrations ranged 1000–2500 cm−3 in the same period. The temporal evolution of the vertical distribution of the linear volume depolarization ratio showed a specific diurnal pattern. Linear volume depolarization ratios of more than 0.06, were measured near the surface in the morning. High depolarization ratios were detected up to 2 km aboveground between 12:00 and 14:00 LT, whereas high depolarization ratios were observed only close to the surface after 17:00 LT. Low values of depolarization ratios (≤0.05) were detected after 18:00 LT until the next morning. During the measurement period, the daily variations of the high depolarization ratios close to the surface showed correlation to number concentration measurements of pollen. This finding suggests that high depolarization ratios could be attributed to enhanced pollen concentrations. The diurnal characteristics of the high values of depolarization ratios are thought to be closely associated with turbulent transport. Diurnal and vertical characteristics of pollen, if measured continuously, could be used to improve the accuracy of pollen-forecasting models via data assimilation studies.

In this paper, we introduce a new method to estimate the change in mean mixing ratio of a target species at a receptor site due to the contribution of the long-range transport (CLRT). We applied our method to determine inter-annual and inter-seasonal variations in the CLRT of SO2 in Seoul, a major megacity in northeast Asia, during the period from 2001 to 2010. The major potential source areas of SO2 for the 2001–2010 period were located in East China according to the potential source contribution function (PSCF) maps. The CLRT of SO2 in Seoul was estimated to range from 0.40 to 1.03 ppb, which accounted for 8–21% of the ambient mean SO2 mixing ratio in Seoul. The inter-annual variations of estimated CLRT of SO2 was well correlated with those of the total emissions in China during the period of 2001–2008 (R = 0.85). We found that both local emissions from around Seoul and long-range transport from East China, especially the Shandong peninsula, affected the SO2 mixing ratio in Seoul throughout the decade of study. The CLRT of SO2 in Seoul increased after 2007 even though the total emissions of SO2 by China have been decreasing since 2006. The CLRT of SO2 in Seoul was high in spring and winter, which can be attributed to enhanced SO2 emissions in East China during these seasons and a dominant westerly wind. The CLRTs of SO2 accounted for 15, 11, 4, and 12% of the seasonal mean SO2 mixing ratio in spring, summer, fall, and winter, respectively. The uncertainty ranged from 24 to 62% of the estimated CLRT values.

Based on an optimal estimation method, an algorithm was developed to retrieve the column-averaged dry-air mole fraction of carbon dioxide (XCO2) using Shortwave Infrared (SWIR) channels, referred to as the Yonsei CArbon Retrieval (YCAR) algorithm. The performance of the YCAR algorithm is here examined using simulated radiance spectra, with simulations conducted using different Aerosol Optical Depths (AODs), Solar Zenith Angles (SZAs) and aerosol types over various surface types. To characterize the XCO2 retrieval algorithm, reference tests using simulated spectra were analysed through a posteriori XCO2 retrieval errors and averaging kernels. The a posteriori XCO2 retrieval errors generally increase with increasing SZA. However, errors were found to be small (

A recently developed aerosol retrieval algorithm based on O4 slant column densities (SCDs) measured at a visible wavelength (476 nm) was utilized to derive aerosol information (e.g., aerosol optical depth (AOD) and vertical distributions of aerosol extinction coefficients (AECs)) in the lower troposphere during a severe Asian dust period. The MAX-DOAS measurements were carried out at Gwangju, Korea for nearly three months from February through May 2008. Comparison with AOD and surface PM10, measured by collocated sunphotometer and beta gauge sampler, were made to validate the retrieved AODs and AECs in the atmospheric layer surface to 1 km height above ground. On the Asian dust days, temporal variations of the AODs retrieved from MAX-DOAS measurements show similar patterns, but with reduced magnitudes, to those measured by sunphotometer whereas similar AOD magnitude and temporal variation was observed between MAX-DOAS and sunphotometer measurements during the non-episodic days. Smaller correlation was obs...

The East Asian countries have been affected by atmospheric gaseous pollutants (in particular SO2) transported from the Asian continent as well as Asian dust storms. For investigation of the impact of these anthropogenic trace gases on local air quality in Korea, ground-based measurements using a Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) system and in situ gas analyzers as well as synoptic meteorological data and scattered sunlight spectra obtained by the satellite-borne instrument, Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) launched on board of Environmental Satellite (ENVISAT) in March 2002, were utilized to retrieve SO2 and trace its transport from the Asian continent to Korea in May 2005. The ground-based measurements were carried out in the region of interest, at Korea Global Watch Observatory (KGAWO) in Korea. Plumes of high SO2 over Chinese industrial areas and their transport to the Korean peninsula were observed in SCIAMACHY data in the period of 21–26 May 2005. Highly increased SO2 was measured by the MAX-DOAS system and in situ gas analyzer in the period of 27–29 May 2005 at KGAWO. These observations are supported by the meteorological results that the air-masses picking up these high SO2 plumes while passing over the Chinese industrial and metropolitan areas were transported to the Korean peninsula. The tropospheric SO2 VCDs over these Chinese industrial and metropolitan areas ranged up to 1.4×1017 mol cm−2 in SCIAMACHY data. These SO2 plumes resulted in increased SO2 surface levels of up to 7.8 ppbv (measured by an in situ gas analyzer) at KGAWO.

We investigate the simultaneous effects of aerosol peak height (APH), aerosol properties, measurement geometry, and other factors on the air mass factor for NO2 retrieval at sites with high NO2 concentration. A comparison of the effects of high and low surface reflectance reveals that NO2 air mass factor (AMF) values over a snowy surface (surface reflectance 0.8) are generally higher than those over a deciduous forest surface (surface reflectance 0.05). Under high aerosol optical depth (AOD) conditions, the aerosol shielding effect over a high-albedo surface is revealed to reduce the path-length of light at the surface, whereas high single scattering albedo (SSA) conditions (e.g., SSA = 0.95) lead to an increase in the aerosol albedo effect, which results in an increased AMF over areas with low surface reflectance. We also conducted an in-depth study of the APH effect on AMF. For an AOD of 0.1 and half width (HW) of 5 km, NO2 AMF decreases by 29% from 1.36 to 0.96 as APH changes from 0 to 2 km. In the case of high-AOD conditions (0.9) and HW of 5 km, the NO2 AMF decreases by 240% from 1.85 to 0.54 as APH changes from 0 to 2 km. The AMF variation due to error in the model input parameters (e.g., AOD, SSA, aerosol shape, and APH) is also examined. When APH is 0 km with an AOD of 0.4, SSA of 0.88, and surface reflectance of 0.05, a 30% error in AOD induces an AMF error of between 4.85% and −3.67%, an SSA error of 0.04 leads to NO2 VCD errors of between 4.46% and −4.77%, and a 30% error in AOD induces an AMF error of between −9.53% and 8.35% with an APH of 3 km. In addition to AOD and SSA, APH is an important factor in calculating AMF, due to the 2 km error in APH under high-SZA conditions, which leads to an NO2 VCD error of over 60%. Aerosol shape is also found to have a measureable effect on AMF under high-AOD and small relative azimuth angle (RAA) conditions. The diurnal effect of the NO2 profile is also examined and discussed.

In East Asia, where aerosol concentrations are persistently high throughout the year, most satellite CO2 retrieval algorithms screen out many measurements during quality control in order to reduce retrieval errors. To reduce the retrieval errors associated with aerosols, we have modified YCAR (Yonsei Carbon Retrieval) algorithm to YCAR-CAI to retrieve X-CO2 from GOSAT FTS measurements using aerosol retrievals from simultaneous Cloud and Aerosol Imager (CAI) measurements. The CAI aerosol algorithm provides aerosol type and optical depth information simultaneously for the same geometry and optical path as FTS. The YCAR-CAI X-CO2 retrieval algorithm has been developed based on the optimal estimation method. The algorithm uses the VLIDORT V2.6 radiative transfer model to calculate radiances and Jacobian functions. The X-CO2 results retrieved using the YCAR-CAI algorithm were evaluated by comparing them with ground-based TCCON measurements and current operational GOSAT X-CO2 retrievals. The retrievals show a clear annual cycle, with an increasing trend of 2.02 to 2.39 ppm per year, which is higher than that measured at Mauna Loa, Hawaii. The YCAR-CAI results were validated against the Tsukuba and Saga TCCON sites and show an root mean square error of 2.25, a bias of -0.81 ppm, and a regression line closer to the linear identity function compared with other current algorithms. Even after post-screening, the YCAR-CAI algorithm provides a larger dataset of X-CO2 compared with other retrieval algorithms by 21% to 67%, which could be substantially advantageous in validation and data analysis for the area of East Asia. Retrieval uncertainty indicates a 1.39 to 1.48 ppm at the TCCON sites. Using Carbon Tracker-Asia (CT-A) data, the sampling error was analyzed and was found to be between 0.32 and 0.36 ppm for each individual sounding.

[1] In order to investigate the optical properties of atmospheric aerosol in the urban area of Beijing, in situ and remote measurements of particulate pollutants were conducted at an urban site (39.98°N, 116.35°E, ∼20 m above ground level) in Beijing during the Campaign of Air Quality Research in Beijing (CAREBeijing) campaign from 16 August to 10 September 2006. During the intensive measurement period, average PM2.5 mass concentration and light extinction coefficient (bext) were measured to be 102.1 ± 55.0 μg m−3 and 880.7 ± 685.9 Mm−1, respectively. Average mass scattering efficiency of PM10 and PM2.5 particle were found to be 2.5 ± 1.1 and 3.4 ± 1.2 m2 g−1, respectively. Average single scattering albedo (SSA) of dry PM10 was characterized to be 0.82 ± 0.09. It was found that SSA decreased to lower values of ∼0.75 during the relatively clean condition while it increased up to ∼0.86 during polluted condition mainly owing to the increases of ammonium sulfate, ammonium nitrate, and organic mass by carbon's contributions to PM mass concentrations. Pollution episodes in Beijing were strongly related to wind speed and wind direction. Stagnant weather conditions with southerly wind and low wind speed accelerated the accumulation of the pollutants in Beijing, which led to severe haze. It has been found that high PM2.5/AOT (aerosol optical thickness) ratio of 228.2 μg m−3 was observed when air mass was transported from western or northern China while significantly lower PM2.5/AOT of 107.6 μg m−3 was observed when it was affected mostly by local air pollutants in Beijing.

During the CAREBEIJING campaign in 2006, imaging differential optical absorption spectroscopy (I-DOAS) measurements were made from 08:00 to 16:00 on September 9 and 10 over Beijing, China. Detailed images of the near-surface NO(2) differential slant column density (DSCD) distribution over Beijing were obtained. Images with less than a 30-min temporal resolution showed both horizontal and vertical variations in NO(2) distributions. For DSCD to mixing ratio conversion, path length along the lines of I-DOAS lines of sight was estimated using the light-extinction coefficient and Angstrom exponent data obtained by a transmissometer and a sunphotometer, respectively. Mixing ratios measured by an in-situ NO(2) analyzer were compared with those estimated by the I-DOAS instrument. The obtained temporal and spatial variations in NO(2) distributions measured by I-DOAS for the two days are interpreted with consideration of the locations of the major NO(x) sources and local wind conditions. I-DOAS measurements have been applied in this study for estimating NO(2) distribution over an urban area with multiple and distributed emission sources. Results are obtained for estimated temporal and spatial NO(2) distributions over the urban atmosphere; demonstrating the capability of the I-DOAS technique. We discuss in this paper the use of I-DOAS measurements to estimate the NO(2) distribution over an urban area with multiple distributed emission sources.

An integrated system approach has been adopted at the Advanced Environment Monitoring Research Center (ADEMRC), Kwangju Institute Science and Technology (KJIST), Korea for the effective monitoring of atmospheric environment utilizing various optical remote sensing methods. A multi-channel LIDAR system has been used since December 2002 to monitor the vertical profile of atmospheric aerosol. Vertical profiles of extinction coefficient, depolarization ratio, and color ratio of atmospheric aerosols are determined from the simultaneous detection of three elastic-backscatter signals and one Raman signal backscattered by atmospheric nitrogen molecules. Ground based sunphotometer measurement provides LIDAR validation and information on the column integrated aerosol optical depth at seven different wavelengths. Optical atmospheric environment monitoring over horizontal path is also made with a Long-path DOAS system and a transmissometer. The GIST long-path DOAS system has been used to measure concentration of trace gases as well as atmospheric extinction at 550 nm. Results of aerosol optical depth determination based on satellite data retrieval are compared with the results of LIDAR and sunphotometer measurements. This paper presents the results of integrated measurements of atmospheric aerosol at Gwangju (35°10`N, 126°53`E), Korea.

The contributions of long range transported aerosol in East Asia to carbonaceous aerosol and particulate matter (PM) concentrations in Seoul, Korea were estimated with potential source contribution function (PSCF) calculations. Carbonaceous aerosol (organic carbon (OC) and elemental carbon (EC)), PM(2.5), and PM(10) concentrations were measured from April 2007 to March 2008 in Seoul, Korea. The PSCF and concentration weighted trajectory (CWT) receptor models were used to identify the spatial source distributions of OC, EC, PM(2.5), and coarse particles. Heavily industrialized areas in Northeast China such as Harbin and Changchun and East China including the Pearl River Delta region, the Yangtze River Delta region, and the Beijing-Tianjin region were identified as high OC, EC and PM(2.5) source areas. The conditional PSCF analysis was introduced so as to distinguish the influence of aerosol transported from heavily polluted source areas on a receptor site from that transported from relatively clean areas. The source contributions estimated using the conditional PSCF analysis account for not only the aerosol concentrations of long range transported aerosols but also the number of transport days effective on the measurement site. Based on the proposed algorithm, the condition of airmass pathways was classified into two types: one condition where airmass passed over the source region (PS) and another condition where airmass did not pass over the source region (NPS). For most of the seasons during the measurement period, 249.5-366.2% higher OC, EC, PM(2.5), and coarse particle concentrations were observed at the measurement site under PS conditions than under NPS conditions. Seasonal variations in the concentrations of OC, EC, PM(2.5), and coarse particles under PS, NPS, and background aerosol conditions were quantified. The contributions of long range transported aerosols on the OC, EC, PM(2.5), and coarse particle concentrations during several Asian dust events were also estimated. We also investigated the performance of the PSCF results obtained from combining highly time resolved measurement data and backward trajectory calculations via comparison with those from data in low resolutions. Reduced tailing effects and the larger coverage over the area of interest were observed in the PSCF results obtained from using the highly time resolved data and trajectories.