scholarly journals Vertical variation of optical properties of mixed Asian dust/pollution plumes according to pathway of air mass transport over East Asia

2015 ◽  
Vol 15 (12) ◽  
pp. 6707-6720 ◽  
Author(s):  
S.-K. Shin ◽  
D. Müller ◽  
C. Lee ◽  
K. H. Lee ◽  
D. Shin ◽  
...  
Keyword(s):  
Optical Properties ◽  
East Asian ◽  
Asian Dust ◽  
Optical Characteristics ◽  
Vertical Position ◽  
Dust Pollution ◽  
Transport Time ◽  
Lidar Measurements ◽  
The Mean ◽  
532 Nm

Abstract. We use five years (2009–2013) of multiwavelength Raman lidar measurements at Gwangju, South Korea (35.10° N, 126.53° E) for the identification of changes of optical properties of East Asian dust depending on its transport path over China. Profiles of backscatter and extinction coefficients, lidar ratios, and backscatter-related Ångström exponents (wavelength pair 355/532 nm) were measured at Gwangju. Linear particle depolarization ratios were used to identify East Asian dust layers. We used backward trajectory modeling to identify the pathway and the vertical position of dust-laden air masses over China during long-range transport. Most cases of Asian dust events can be described by the emission of dust in desert areas and subsequent transport over highly polluted regions of China. The Asian dust plumes could be categorized into two classes according to the height above ground at which these plumes were transported: (case I) the dust layers passed over China at high altitude levels (> 3 km) until arrival over Gwangju, and (case II) the Asian dust layers were transported near the surface and within the lower troposphere (< 3 km) over industrialized areas before they arrived over Gwangju. We find that the optical characteristics of these mixed Asian dust layers over Gwangju differ depending on their vertical position above ground over China and the change of height above ground during transport. The mean linear particle depolarization ratio was 0.21 ± 0.06 (at 532 nm), the mean lidar ratios were 52 ± 7 sr at 355 nm and 53 ± 8 sr at 532 nm, and the mean Ångström exponent was 0.74 ± 0.31 for case I. In contrast, plumes transported at lower altitudes (case II) showed low depolarization ratios (0.13 ± 0.04 at 532 nm), and higher lidar ratio (63 ± 9 sr at 355 nm and 62 ± 8 sr at 532 nm) and Ångström exponents (0.98 ± 0.51). These numbers show that the optical characteristics of mixed Asian plumes are more similar to optical characteristics of urban pollution. We find a decrease of the linear depolarization ratio of the mixed dust/pollution plume depending on transport time if the pollution layer traveled over China at low heights, i.e., below approximately 3 km above ground. In contrast, we do not find such a trend if the dust plumes traveled at heights above 3 km over China. We need a longer time series of lidar measurements in order to determine in a quantitative way the change of optical properties of dust with transport time.

scholarly journals Vertical variation of optical properties of mixed Asian dust/pollution plumes according to pathway of airmass transport over East Asia

2015 ◽  
Vol 15 (3) ◽  
pp. 3381-3413 ◽  
Author(s):  
S.-K. Shin ◽  
D. Müller ◽  
K. H. Lee ◽  
D. Shin ◽  
Y. J. Kim ◽  
...  
Keyword(s):  
Optical Properties ◽  
Asian Dust ◽  
Optical Characteristics ◽  
Vertical Position ◽  
Depolarization Ratio ◽  
Dust Pollution ◽  
Transport Time ◽  
Lidar Measurements ◽  
The Mean ◽  
532 Nm

Abstract. We use five years (2009–2013) of multiwavelength Raman lidar measurements at Gwangju, Korea (35.10° N, 126.53° E) for the identification of changes of optical properties of East Asian dust in dependence of its transport path over China. Profiles of backscatter and extinction coefficients, lidar ratios, and backscatter-related Ångström exponents (wavelength pair 355/532 nm) were measured at Gwangju. Linear particle depolarization ratios were used to identify East Asian dust layers. We used backward trajectory modelling to identify the pathway and the vertical position of dust-laden air masses over China during long-range transport. Most cases of Asian dust events can be described by the emission of dust in desert areas and subsequent transport over highly polluted regions of China. The Asian dust plumes could be categorized into two classes according to the height above ground in which these plumes were transported: (I) the dust layers passed over China at high altitude levels until arrival over Gwangju, and (II) the Asian dust layers were transported near the surface and the lower troposphere over industrialized areas before they arrived over Gwangju. We find that the optical characteristics of these mixed Asian dust layers over Gwangju differ in dependence of their vertical position above ground over China and the change of height above ground during transport. The mean linear particle depolarization ratio was 0.21 ± 0.06 (at 532 nm), the mean lidar ratios were 52 ± 7 sr at 355 nm and 53 ± 8 sr at 532 nm, and the mean Ångström exponent was 0.74 ± 0.31 in case I. In contrast, plumes transported at lower altitudes (case II) showed low depolarization ratios, and higher lidar ratio and Ångström exponents. The mean linear particle depolarization ratio was 0.13 ± 0.04, the mean lidar ratios were 63 ± 9 sr at 355 nm and 62 ± 8 sr at 532 nm, respectively, and the mean Ångström exponent was 0.98 ± 0.51. These numbers show that the optical characteristics of mixed Asian plumes are more similar to optical characteristics of urban pollution. We find a decrease of the linear depolarization ratio of the mixed dust/pollution plume in dependence of transport time if the pollution layer travelled over China at low heights, i.e., below approximately 3 km above ground. In contrast we do not find such a trend if the dust plumes travelled at heights above 4 km over China. We need a longer time series of lidar measurements in order to determine the change of optical properties of dust with transport time in a quantitative way.

scholarly journals Profiling Aerosol Optical Properties at the Central Asian Site of Dushanbe, Tajikistan: Pure Dust Cases

2020 ◽  
Vol 237 ◽  
pp. 02027
Author(s):  
Julian Hofer ◽  
Dietrich Althausen ◽  
Sabur F. Abdullaev ◽  
Abduvosit N. Makhmudov ◽  
Bakhron I. Nazarov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Central Asia ◽  
Asian Dust ◽  
Aerosol Optical Properties ◽  
Central Asian ◽  
The Mean ◽  
Ground Based Lidar ◽  
First Time ◽  
532 Nm

Tajikistan is often affected by atmospheric mineral dust originating from various surrounding deserts. The direct and indirect radiative effects of that dust play a sensitive role in the Central Asian climate system and therefore need to be quantified. The Central Asian Dust Experiment (CADEX) provides for the first time an aerosol climatology for Central Asia based long-term aerosol profiling by ground-based lidar (PollyXT type) in Dushanbe, Tajikistan. For pure dust cases, mean depolarization(lidar) ratios of 0.23±0.03(44±3 sr) at 355 nm and 0.32±0.02(38±3 sr) at 532 nm wavelength have been measured. The mean extinction-related Ångström exponent was 0.18±0.15.

Analysis of aerosol properties at recent (2015-2018) high PM concentration events in two super-mega cities, Seoul and Beijing

2020 ◽  
Author(s):  
Yesol Cha ◽  
Chang-Keun Song
Keyword(s):  
Air Pollution ◽  
Optical Properties ◽  
East Asian ◽  
Optical Characteristics ◽  
High Concentration ◽  
East Asian Region ◽  
Asian Region ◽  
Physical Chemical ◽  
Mega Cities ◽  
Aerosol Properties

&lt;p&gt;To meet public concerns of health caused by the high concentration of PM highly raised, this research has been done to find out unique physical, chemical, and optical characteristics of aerosols in the case of recent four years high PM concentration events over the East Asian region, especially in Korea and China. Severe air pollution over the East Asian region has occurred by the rapid development of urban areas and industrialization. Also, the meteorological conditions in East Asia are strongly correlated with a high concentration of air pollution and seasonal variation of aerosols. There are three types of aerosol properties (physical, chemical, and optical property), and each property is essential to understand the characteristics of regional and seasonal high PM concentrations. This research has been done to find out unique physical, chemical, and optical characteristics of aerosols in the case of high PM concentration events, especially in two super-mega cities (Seoul and Beijing) of Korea and China, by using various observations measured during recent four years. To analyze those characteristics of aerosols at high concentration events occur, various measurement data are used, like ambient surface air monitoring data (for physical properties) from national network in both Korea and China, Intensive Monitoring Data (for chemical properties), AERONET, GOCI satellite (for optical properties), and meteorological data during recent years (2015 &amp;#8211; 2018). This study can provide observational evidence to confirm that each different region has different physical, chemical and optical characteristics of aerosol with the different time periods. The comprehensive results analyzed from this study and integrated methodologies suggested in this study might be useful to make a better in-depth understanding of the relations between various aerosol properties in certain regions and periods.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Key words : &lt;/strong&gt;Aerosol, High concentration events, Physical/Chemical/Optical Properties of aerosols&lt;/p&gt;

scholarly journals Deriving the effect of wind speed on clean marine aerosol optical properties using the A-Train satellites

2011 ◽  
Vol 11 (22) ◽  
pp. 11401-11413 ◽  
Author(s):  
V. P. Kiliyanpilakkil ◽  
N. Meskhidze
Keyword(s):  
Optical Properties ◽  
Wind Speed ◽  
Optical Depth ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Marine Aerosol ◽  
Marine Aerosols ◽  
Aerosol Optical Properties ◽  
The Mean ◽  
532 Nm

Abstract. The relationship between "clean marine" aerosol optical properties and ocean surface wind speed is explored using remotely sensed data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the CALIPSO satellite and the Advanced Microwave Scanning Radiometer (AMSR-E) on board the AQUA satellite. Detailed data analyses are carried out over 15 regions selected to be representative of different areas of the global ocean for the time period from June 2006 to April 2011. Based on remotely sensed optical properties the CALIPSO algorithm is capable of discriminating "clean marine" aerosols from other types often present over the ocean (such as urban/industrial pollution, desert dust and biomass burning). The global mean optical depth of "clean marine" aerosol at 532 nm (AOD532) is found to be 0.052 ± 0.038 (mean plus or minus standard deviation). The mean layer integrated particulate depolarization ratio of marine aerosols is 0.02 ± 0.016. Integrated attenuated backscatter and color ratio of marine aerosols at 532 nm were found to be 0.003 ± 0.002 sr−1 and 0.530 ± 0.149, respectively. A logistic regression between AOD532 and 10-m surface wind speed (U10) revealed three distinct regimes. For U10 ≤ 4 m s−1 the mean CALIPSO-derived AOD532 is found to be 0.02 ± 0.003 with little dependency on the surface wind speed. For 4 < U10 ≤ 12 m s−1, representing the dominant fraction of all available data, marine aerosol optical depth is linearly correlated with the surface wind speed values, with a slope of 0.006 s m−1. In this intermediate wind speed region, the AOD532 vs. U10 regression slope derived here is comparable to previously reported values. At very high wind speed values (U10 > 18 m s−1), the AOD532-wind speed relationship showed a tendency toward leveling off, asymptotically approaching value of 0.15. The conclusions of this study regarding the aerosol extinction vs. wind speed relationship may have been influenced by the constant lidar ratio used for CALIPSO-derived AOD532. Nevertheless, active satellite sensor used in this study that allows separation of maritime wind induced component of AOD from the total AOD over the ocean could lead to improvements in optical properties of sea spray aerosols and their production mechanisms.

scholarly journals Deriving the effect of wind speed on clean maritime aerosol optical properties using the A-Train satellites

2011 ◽  
Vol 11 (2) ◽  
pp. 4599-4630 ◽  
Author(s):  
V. P. Kiliyanpilakkil ◽  
N. Meskhidze
Keyword(s):  
Optical Properties ◽  
Wind Speed ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Sea Salt ◽  
Marine Aerosol ◽  
Marine Aerosols ◽  
Aerosol Optical Properties ◽  
The Mean ◽  
532 Nm

Abstract. Relationship between "clean marine" aerosol optical properties and ocean surface wind speed is explored using remotely sensed data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the CALIPSO satellite and the Advanced Microwave Scanning Radiometer (AMSR-E) on board the AQUA satellite. Detailed data analyses are carried out over 15 regions selected to be representative of different areas of the global ocean for the time period from June 2006 to June 2010. Based on remotely sensed optical properties the CALIPSO algorithm is capable of discriminating "clean marine" aerosols from other types often present over the ocean (such as urban/industrial pollution, desert dust and biomass burning). The global mean optical depth of "clean marine" aerosol at 532 nm (AOD532) is found to be 0.052 ± 0.038. The mean layer integrated volume depolarization ratio of marine aerosols is 0.016 ± 0.012, the value representative of sea salt crystals. Integrated attenuated backscatter and color ratio of marine aerosols at 532 nm were obtained to be 0.003 ± 0.002 sr−1 and 0.530 ± 0.149, respectively. A logistic regression between AOD532 and 10-meter surface wind speed (U10) revealed three distinct regions. For surface winds lower than 4 m s−1, the mean CALIPSO-derived AOD532 is found to be 0.02 ± 0.003 with little dependency on the surface wind speed. For surface winds from 4 m s−1 to 12 m s−1, representing the dominant fraction of all available data, marine aerosol optical depth is linearly correlated with the U10, with a slope of 0.0062 s m−1. In this intermediate wind speed region, the AOD532 vs. U10 regression derived here is comparable to previously reported relationships. At very high wind speed values (U10 > 18 m s−1), the AOD532-wind speed relationship showed a tendency toward leveling off, suggesting the existence of some maximum value for maritime AOD. Results of our calculations suggest that considerable improvements to both optical properties of marine aerosols and their production mechanisms can be achieved by discriminating "clean marine" aerosols (or sea salt particles) from all other types of aerosols present over the ocean.

scholarly journals Comparison of the optical properties of pure and transported anthropogenic dusts measured by ground-based Lidar

2017 ◽  
Author(s):  
Zhijuan Zhang ◽  
Bin Chen ◽  
Jianping Huang ◽  
Jingjing Liu ◽  
Jianrong Bi ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spherical Shape ◽  
Threshold Value ◽  
Dual Band ◽  
Depolarization Ratio ◽  
Color Ratio ◽  
Lidar Measurements ◽  
Ground Based Lidar ◽  
Two Peaks ◽  
532 Nm

Abstract. In this study, the optical properties of pure dust (PDU) and transported anthropogenic dust (TDU) (also defined as polluted dust) are compared by using ground-based Lidar data for the period from October 2009 to June 2013. The total attenuated backscattering coefficient at 532 nm, the linear volume depolarization ratio and the color ratio are derived from the L2S-SM-II dual-band polarization Lidar. We found that the TDU has a spherical shape, a small linear volume depolarization ratio and a large color ratio which representing its large particle sizes. The threshold value delineating PDU and TDU was approximately 0.2, which is the same as the threshold value used in the CALIPSO CAD algorithm. The histogram of the attenuated backscattering coefficients and the color ratios of pure dust shows two peaks, but that for the transported anthropogenic dust shows no significant peak and a nearly uniform distribution. The ground-based Lidar results confirm that both the transported anthropogenic dust and pure dust can be detected by air-borne or ground-based Lidar measurements.

scholarly journals Vertical Variation of Optical Properties of Mixed Asian Dust/Pollution Plumes According to Pathway of Airmass Transport Over East Asia

2016 ◽  
Vol 119 ◽  
pp. 08001
Author(s):  
Sung-Kyun Shin ◽  
Detlef Müller ◽  
K.H. Lee ◽  
D. Shin ◽  
Y. J. Kim ◽  
...  
Keyword(s):  
Optical Properties ◽  
East Asia ◽  
Asian Dust ◽  
Dust Pollution ◽  
Vertical Variation ◽  
Pollution Plumes

scholarly journals Volcanic ash from Iceland over Munich: mass concentration retrieved from ground-based remote sensing measurements

2010 ◽  
Vol 10 (11) ◽  
pp. 26705-26750 ◽  
Author(s):  
J. Gasteiger ◽  
S. Groß ◽  
V. Freudenthaler ◽  
M. Wiegner
Keyword(s):  
Optical Properties ◽  
Extinction Coefficient ◽  
Mass Concentration ◽  
Volcanic Ash ◽  
Inversion Algorithm ◽  
Uncertainty Range ◽  
Particle Properties ◽  
Model Aerosol ◽  
Lidar Measurements ◽  
532 Nm

Abstract. Volcanic ash plumes, emitted by the Eyjafjallajökull volcano (Iceland) in spring 2010, were observed by the lidar systems MULIS and POLIS in Maisach (near Munich, Germany), and by a CIMEL Sun photometer and a JenOptik ceilometer in Munich. We retrieve mass concentrations of volcanic ash from the lidar measurements; spectral optical properties, i.e. extinction coefficients, backscatter coefficients, and linear depolarization ratios, are used as input for an inversion. The inversion algorithm searches for model aerosol ensembles with optical properties that agree with the measured values within their uncertainty ranges. The non-sphericity of ash particles is considered by assuming spheroids. Optical particle properties are calculated using the T-matrix method supplemented by the geometric optics approach. The lidar inversion is applied to observations of the pure volcanic ash plume in the morning of 17 April 2010. We find 1.45 g m−2 for the ratio between the mass concentration and the extinction coefficient at λ = 532 nm, assuming an ash density of 2.6 g cm−3. The uncertainty range for this ratio is from 0.9 g m−2 to 2.3 g m−2. At the peak of the ash concentration over Maisach the extinction coefficient at λ = 532 nm was 0.75 km−1 (1-h-average), which corresponds to a maximum mass concentration of 1.1 mg m−3 (0.65 to 1.7 mg m−3). We compare the lidar inversion results to results from an independent approach using sky radiance measurements of the CIMEL in the aureole of the Sun. We find good agreement.

scholarly journals Properties of biomass burning aerosol mixtures derived at fine temporal and spatial scales from Raman lidar measurements: Part I optical properties

2019 ◽  
Author(s):  
Lucja Janicka ◽  
Iwona S. Stachlewska
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Spatial Scales ◽  
Depolarization Ratio ◽  
Data Set ◽  
Lidar Ratio ◽  
Biomass Burning Aerosol ◽  
The Mean ◽  
Temporal And Spatial ◽  
532 Nm

Abstract. The analysis of the aerosol optical properties derived at fine temporal and spatial scales were performed based on measurements obtained during heat wave event in vicinity of a cold weather front in Warsaw on August 9th–11th, 2015. The signals collected by the PollyXT-UW lidar allowed for the calculation of 23 sets of so-called 3β + 2α + 2δ + wv profiles averaged by 30-minutes periods during 2 nights. The total number of 11 different aerosol types and aerosol mixtures were identified with reference to properties within 116 sub-layers in the profiles and were characterized by the mean values. The statistical sample of various optical properties being in agreement for consecutive profiles allowed to assess the spatio-temporal extent of aerosol/mixture types. The mean lidar ratio values of 53–73 sr (355 nm) and 31–45 sr (532 nm) in the layers dominated by the anthropogenic pollution were found. For the layers dominated by the biomass burning aerosol (fresh, moderately fresh, moderately aged) mean lidar ratio was of 69–114 sr (355 nm) and 57–85 sr (532 nm). The colour ratio of lidar ratio (532 / 355) higher than 1, characteristic for aged biomass burning aerosol, was found only in one scattered layer, accompanying with low value of extinction related Ångström exponent of 0.60 ± 0.32 and low particle depolarization ratio. The maximum of the particle depolarization ratio of 4.8–5.0 % at 532 nm were observed in a layer likely contaminated with pollen and in a layer dominated by fresh biomass burning aerosol. This study provides an excellent data set for exploration of separation algorithms, aerosol typing algorithms and microphysical inversion.

Sign in / Sign up

Export Citation Format

Share Document