scholarly journals Interrelations between surface, boundary layer, and columnar aerosol properties derived in summer and early autumn over a continental urban site in Warsaw, Poland

2019 ◽  
Vol 19 (20) ◽  
pp. 13097-13128 ◽  
Author(s):  
Dongxiang Wang ◽  
Dominika Szczepanik ◽  
Iwona S. Stachlewska
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Atmospheric Boundary Layer ◽  
Aerosol Optical Depth ◽  
Negative Correlation ◽  
Anthropogenic Pollution ◽  
Free Troposphere ◽  
Positive Correlation ◽  
532 Nm ◽  
Aerosol Properties

Abstract. PollyXT Raman polarization lidar observations were performed at the Remote Sensing Laboratory (RS-Lab) in Warsaw (52.2109∘ N, 20.9826∘ E), Poland, in the framework of the European Aerosol Research Lidar Network (EARLINET) and the Aerosol, Clouds, and Trace gases Research Infrastructure (ACTRIS) projects. Data collected in July, August, and September of 2013, 2015, and 2016 were analysed using the classical Raman approach. In total, 246 sets of intact profiles, each set comprising particle extinction (α) and backscatter coefficients (β) as well as linear particle depolarization ratios (δ) at 355 nm and 532 nm, were derived for statistical investigations and stored in the EARLINET/ACTRIS database. The main analysis was focused on intensive optical properties obtained within the atmospheric boundary layer (ABL). Their interrelations were discussed for different periods: the entire day; nighttime, with respect to the nocturnal boundary layer (NL) and the residual boundary layer (RL); at sunrise, with respect to the morning transition boundary layer (MTL); and from late afternoon until sunset, with respect to the well-mixed boundary layer (WML). Within the boundary layer, the lidar-derived optical properties (entire day, 246 sets) revealed a mean aerosol optical depth (AODABL) of 0.20±0.10 at 355 nm and 0.11±0.06 at 532 nm; a mean Ångström exponent (ÅEABL) of 1.54±0.37; a mean lidar ratio (LRABL) of 48±17 sr at 355 nm and 41±15 sr at 532 nm; a mean linear particle depolarization ratio (δABL) of 0.02±0.01 at 355 nm and 0.05±0.01 at 532 nm; and a mean water vapour mixing ratio (WVABL) of 8.28±2.46 g kg−1. In addition, the lidar-derived daytime boundary layer optical properties (for the MTL and WML) were compared with the corresponding daytime columnar aerosol properties derived from the multi-filter rotating shadowband radiometer (MFR-7) measuring within the National Aerosol Research Network (PolandAOD-NET) and the CE318 sun photometer of the Aerosol Robotic NETwork (AERONET). A high linear correlation of the columnar aerosol optical depth values from the two latter instruments was obtained in Warsaw (a correlation coefficient of 0.98 with a standard deviation of 0.02). The contribution of the aerosol load in the summer and early-autumn free troposphere can result in an AODCL value that is twice as high as the AODABL over Warsaw. The occurrence of a turbulence-driven aerosol burst from the boundary layer into the free troposphere can further increase this difference. Aerosol within the ABL and in the free troposphere was interpreted based on comparisons of the properties derived at different altitudes with values reported in the literature, which were characteristic for different aerosol types, in combination with backward trajectory calculations, satellite data, and model outputs. Within the boundary layer, the aerosol consisted of either urban anthropogenic pollution (∼ 61 %) or mixtures of anthropogenic aerosol with biomass-burning aerosol (< 14 %), local pollen (< 7 %), or Arctic marine particles (< 5 %). No significant contribution of mineral dust was found in the boundary layer. The lidar-derived atmospheric boundary layer height (ABLH) and the AODABL exhibited a positive correlation (R of 0.76), associated with the local anthropogenic pollution (most pronounced for the RL and WML). A positive correlation of the AODABL and LRABL and a negative correlation of the ÅEABL and LRABL, as well as the expected negative trends for the WVABL (and surface relative humidity, RH) and δABL, were observed. Relations of the lidar-derived aerosol properties within the ABL and the surface in situ measurements of particulate matter with an aerodynamic diameter less than 10 µm (PM10) and less than 2.5 µm (PM2.5) measured by the Warsaw Regional Inspectorate for Environmental Protection (WIOS) network, and the fine-to-coarse mass ratio (FCMR) were investigated. The FCMR and surface RH showed a positive correlation even at nighttime (R of 0.71 for the MTL, 0.63 for the WML, and 0.6 for the NL), which generally lacked statistically significant relations. A weak negative correlation of the FCMR and δABL (more pronounced at 532 nm at nighttime) and no casual relation between the FCMR and ÅEABL were found. Most interestingly, distinct differences were observed for the morning transition layer (MTL) and the well-mixed layer (WML). The MTL ranged up to 0.6–1 km, and was characterized by a lower AODABL(<0.12), wetter conditions (RH 50–80 %), smaller particles (ÅEABL of 1–2.2; FCMR from 0.5 to 3), and a low LRABL of between 20 and 40 sr. The WML ranged up to 1–2.5 km and exhibited a higher AODABL (reaching up to 0.45), drier conditions (RH 25–60  %), larger particles (ÅEABL of 0.8–1.7; FCMR of 0.2–1.5), and a higher LRABL of up to 90 sr.

scholarly journals Interrelations between surface, boundary layer, and columnar aerosol properties over a continental urban site

2018 ◽  
Author(s):  
Dongxiang Wang ◽  
Dominika Szczepanik ◽  
Iwona S. Stachlewska
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Urban Site ◽  
Surface Boundary ◽  
Backscatter Coefficient ◽  
Surface Boundary Layer ◽  
Lidar Observations ◽  
532 Nm ◽  
Aerosol Properties

Abstract. PollyXT Raman Polarization Lidar observations were performed at the Remote Sensing laboratory in Warsaw (52.2109° N, 20.9826° E), Poland, in the framework of the European Aerosol Research Lidar Network (EARLINET) and the Aerosols, Clouds and Trace gases Research Infrastructure (ACTRIS). Data collected in July, August and September of 2013, 2015 and 2016 were analysed using the classical Raman approach. In total 202 sets of profiles of the particle extinction and backscatter coefficient, and linear particle depolarization ratio at 355 nm and 532 nm were derived for statistical investigations (EARLINET/ACTRIS Data Base). The main analysis was focused on intensive optical properties obtained within aerosol boundary layer (ABL). The interrelationships of different optical properties inside ABL are discussed for different periods: entire day, nocturnal time and sunrise/sunset time. In addition, the lidar derived boundary layer optical properties were compared with the columnar daytime aerosol properties derived from radiometer (MFR-7, PolandAOD-NET) and photometer (C318, AERONET). Relationships of these and surface in-situ measurements of particulate matter with an aerodynamic diameter

scholarly journals Optical properties of Central Asian aerosol relevant for spaceborne lidar applications and aerosol typing at 355 and 532 nm

2020 ◽  
Author(s):  
Julian Hofer ◽  
Albert Ansmann ◽  
Dietrich Althausen ◽  
Ronny Engelmann ◽  
Holger Baars ◽  
...  
Keyword(s):  
Optical Properties ◽  
Full Range ◽  
Anthropogenic Pollution ◽  
Data Set ◽  
Central Asian ◽  
Lidar Ratio ◽  
Ground Based Lidar ◽  
Complex Relationships ◽  
532 Nm ◽  
Depolarization Ratios

Abstract. For the first time, a dense data set of particle extinction-to-backscatter ratios (lidar ratios), linear depolarization ratios, and backscatter- and extinction-related Ångström exponents for a Central Asian site are presented. The observations were performed with a continuously running multiwavelength polarization Raman lidar at Dushanbe, Tajikistan, during an 18-month campaign (March 2015 to August 2016). The presented seasonally resolved observations fill an important gap in the data base of aerosol optical properties used in aerosol typing efforts with spaceborne lidars and ground-based lidar networks. Lidar ratios and depolarization ratios are also basic input parameters in spaceborne lidar data analyses and in efforts to harmonize long-term observations with different space lidar systems operated either at 355 or 532 nm. As a general result, the found optical properties reflect the large range of occurring aerosol mixtures consisting of long-range-transported dust (from the Middle East and the Sahara), regional desert, soil, and salt dust, and anthropogenic pollution. The full range from highly polluted to pure dust situations could be observed. Typical dust depolarization ratios of 0.23–0.29 (355 nm) and 0.30–0.35 (532 nm) were observed. In contrast, comparably low lidar ratios were found. Dust lidar ratios at 532 nm accumulated around 35–40 sr and were even lower for regional background dust conditions (20–30 sr). The reason for these low values may be partly related to the direct emission and emission of re-suspended salt dust (initially originated from numerous desiccating lakes and the Aralkum desert). Detailed correlation studies (e.g., lidar ratio vs. depolarization ratios and Ångström exponent vs. lidar ratio and vs. depolarization ratio) are presented to illuminate the complex relationships between the observed optical properties and to identify the contributions of anthropogenic haze, dust, and background aerosol to the overall aerosol mixtures found within the 18-month campaign.

scholarly journals Simultaneous retrieval of aerosol and cloud properties during the MILAGRO field campaign

2011 ◽  
Vol 11 (13) ◽  
pp. 6245-6263 ◽  
Author(s):  
K. Knobelspiesse ◽  
B. Cairns ◽  
J. Redemann ◽  
R. W. Bergstrom ◽  
A. Stohl
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Droplet Size ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Cloud Droplet Size Distribution ◽  
Distribution Parameters ◽  
Aerosol Properties

Abstract. Estimation of Direct Climate Forcing (DCF) due to aerosols in cloudy areas has historically been a difficult task, mainly because of a lack of appropriate measurements. Recently, passive remote sensing instruments have been developed that have the potential to retrieve both cloud and aerosol properties using polarimetric, multiple view angle, and multi spectral observations, and therefore determine DCF from aerosols above clouds. One such instrument is the Research Scanning Polarimeter (RSP), an airborne prototype of a sensor on the NASA Glory satellite, which unfortunately failed to reach orbit during its launch in March of 2011. In the spring of 2006, the RSP was deployed on an aircraft based in Veracruz, Mexico, as part of the Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign. On 13 March, the RSP over flew an aerosol layer lofted above a low altitude marine stratocumulus cloud close to shore in the Gulf of Mexico. We investigate the feasibility of retrieving aerosol properties over clouds using these data. Our approach is to first determine cloud droplet size distribution using the angular location of the cloud bow and other features in the polarized reflectance. The selected cloud was then used in a multiple scattering radiative transfer model optimization to determine the aerosol optical properties and fine tune the cloud size distribution. In this scene, we were able to retrieve aerosol optical depth, the fine mode aerosol size distribution parameters and the cloud droplet size distribution parameters to a degree of accuracy required for climate modeling. This required assumptions about the aerosol vertical distribution and the optical properties of the coarse aerosol size mode. A sensitivity study was also performed to place this study in the context of future systematic scanning polarimeter observations, which found that the aerosol complex refractive index can also be observed accurately if the aerosol optical depth is larger than roughly 0.8 at a wavelength of (0.555 μm).

scholarly journals Dust Event in the Gobi Desert on 22-23 May 2013: Transport of Dust from the Atmospheric Boundary Layer to the Free Troposphere by a Cold Front

SOLA ◽  
2015 ◽  
Vol 11 (0) ◽  
pp. 156-159 ◽  
Author(s):  
Kei Kawai ◽  
Kenji Kai ◽  
Yoshitaka Jin ◽  
Nobuo Sugimoto ◽  
Dashdondog Batdorj
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Cold Front ◽  
Gobi Desert ◽  
Free Troposphere ◽  
Dust Event

scholarly journals How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

2017 ◽  
Author(s):  
Quentin Bourgeois ◽  
Annica M. L. Ekman ◽  
Jean-Baptiste Renard ◽  
Radovan Krejci ◽  
Abhay Devasthale ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Climate Models ◽  
Convective Transport ◽  
Free Troposphere ◽  
Range Transport ◽  
Aerosol Classification ◽  
The Tropics ◽  
The Vertical Distribution

Abstract. The global aerosol extinction from the CALIOP space lidar was used to compute aerosol optical depth (AOD) over a nine-year period (2007–2015) and partitioned between the boundary layer (BL) and the free troposphere (FT) using BL heights obtained from the ERA-Interim archive. The results show that the vertical distribution of AOD does not follow the diurnal cycle of the BL but remains similar between day and night highlighting the presence of a residual layer during night. The BL and FT contribute 69 % and 31 %, respectively, to the global tropospheric AOD during daytime in line with observations obtained using the Light Optical Aerosol Counter (LOAC) instrument. The FT AOD contribution is larger in the tropics than at mid-latitudes which indicates that convective transport largely controls the vertical profile of aerosols. Over oceans, the FT AOD contribution is mainly governed by long-range transport of aerosols from emission sources located within neighboring continents. According to the CALIOP aerosol classification, dust and smoke particles are the main aerosol types transported into the FT. Overall, the study shows that the fraction of AOD in the FT – and thus potentially located above low-level clouds – is substantial and deserves more attention when evaluating the radiative effect of aerosols in climate models. More generally, the results have implications for process determining the overall budgets, sources, sinks and transport of aerosol particles and their description in atmospheric models.

scholarly journals Combined effects of surface conditions, boundary layer dynamics and chemistry on diurnal SOA-evolution

2012 ◽  
Vol 12 (4) ◽  
pp. 9331-9375 ◽  
Author(s):  
R. H. H. Janssen ◽  
J. Vilà-Guerau de Arellano ◽  
L. N. Ganzeveld ◽  
P. Kabat ◽  
J. L. Jimenez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Land Surface ◽  
Large Scale ◽  
Organic Aerosol ◽  
Layer Growth ◽  
Combined Effects ◽  
Free Troposphere ◽  
Surface Conditions ◽  
Boundary Layer Dynamics

Abstract. We study the combined effects of land surface conditions, atmospheric boundary layer dynamics and chemistry on the diurnal evolution of biogenic secondary organic aerosol in the atmospheric boundary layer, using a model that contains the essentials of all these components. First, we evaluate the model for a case study in Hyytiälä, Finland, and find that it is able to well reproduce the observed dynamics and gas-phase chemistry. We show that the exchange of organic aerosol between the free troposphere and the boundary layer (entrainment) must be taken into account in order to explain the observed diurnal cycle in organic aerosol (OA) concentration. An examination of the budgets of organic aerosol and terpene concentration shows that the former is dominated by entrainment, while the latter is mainly driven by emission and chemical transformation. We systematically examine the role of the land surface, which governs both the surface energy balance partitioning and terpene-emissions, and the large-scale atmospheric process of vertical subsidence. Entrainment is especially important for the dilution of organic aerosol concentrations under conditions of dry soils and low terpene-emissions. Subsidence suppresses boundary layer growth while enhancing entrainment. Therefore it influences the relationship between organic aerosol and terpene-concentrations. Our findings indicate that the diurnal evolution of SOA in the boundary layer is the result of coupled effects of the land surface, dynamics of the atmospheric boundary layer, chemistry, and free troposphere conditions. This has potentially some consequences for the design of both field campaigns and large-scale modeling studies.

scholarly journals Simultaneous retrieval of aerosol and cloud properties during the MILAGRO field campaign

2011 ◽  
Vol 11 (2) ◽  
pp. 6363-6413 ◽  
Author(s):  
K. Knobelspiesse ◽  
B. Cairns ◽  
J. Redemann ◽  
R. W. Bergstrom ◽  
A. Stohl
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Droplet Size ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Field Campaign ◽  
Cloud Droplet Size Distribution ◽  
Aerosol Properties

Abstract. Estimation of Direct Climate Forcing (DCF) due to aerosols in cloudy areas has historically been a difficult task, mainly because of a lack of appropriate measurements. The Aerosol Polarimetry Sensor (APS), on the upcoming NASA Glory mission, has the potential to retrieve both cloud and aerosol properties because of its polarimetric, multiple view angle, and multi spectral observations. The APS airborne prototype is the Research Scanning Polarimeter (RSP), which has similar characteristics and can be used to demonstrate APS capabilities. In the spring of 2006, the RSP was deployed on an aircraft based in Veracruz, Mexico, as part of the Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign. On March 13th, the RSP over flew an aerosol layer lofted above a low altitude marine stratocumulus cloud close to shore in the Gulf of Mexico. We investigate the feasibility of retrieving aerosol properties over clouds using these data. Our approach is to first determine cloud droplet size distribution using the angular location of the cloud bow and other features in the polarized reflectance. The selected cloud was then used in a multiple scattering radiative transfer model optimization to determine the aerosol optical properties and fine tune the cloud size distribution. In this scene, we were able to retrieve aerosol optical depth, the fine mode aerosol size distribution and the cloud droplet size distribution to a degree of accuracy required for climate modeling. This required assumptions about the aerosol vertical distribution and the optical properties of the coarse aerosol size mode. A sensitivity study was also performed to place this case study in the context of the potential for future systematic APS observations of this kind, which found that the aerosol complex refractive index can also be observed accurately if the aerosol optical depth is larger than roughly 0.8 at a wavelength of 0.555 μm.

scholarly journals The role of advective transport mechanism in continental-scale transport of fungal plant epidemics

2020 ◽  
Author(s):  
Nolan Elauria ◽  
Taeah Truong ◽  
Kush Upadhyay ◽  
Oleg Kogan
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Plant Pathogen ◽  
Transport Mechanism ◽  
Short Range ◽  
Free Troposphere ◽  
Advective Transport ◽  
Transport Channel ◽  
Continental Scale

AbstractIn examining the continental-scale plant pathogen spread, we focus on the competition between the short-range stochastic hopping within the atmospheric boundary layer, and the laminar advection by the currents in the free troposphere. The latter is typically ignored, since it is assumed that the population of spores which have reached the troposphere is small, and the fraction of the remaining spores that survived the subsequent journey is negligible due to ultraviolet light and frigid temperatures. However, we claim that it is in fact a crucial mechanism for continental-scale spread. We argue that free tropospheric currents can not be ignored, even as the probability for spores to reach them and to survive within them approaches zero. In other words, models that neglect tropospheric advection are fragile – their predictions change qualitatively if this alternative transport channel becomes accessible – even when the rate at which spores actually make use of this transport channel approaches zero.

scholarly journals How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

2018 ◽  
Vol 18 (10) ◽  
pp. 7709-7720 ◽  
Author(s):  
Quentin Bourgeois ◽  
Annica M. L. Ekman ◽  
Jean-Baptiste Renard ◽  
Radovan Krejci ◽  
Abhay Devasthale ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Climate Models ◽  
Convective Transport ◽  
Free Troposphere ◽  
Range Transport ◽  
Aerosol Classification ◽  
The Tropics ◽  
The Vertical Distribution

Abstract. The global aerosol extinction from the CALIOP space lidar was used to compute aerosol optical depth (AOD) over a 9-year period (2007–2015) and partitioned between the boundary layer (BL) and the free troposphere (FT) using BL heights obtained from the ERA-Interim archive. The results show that the vertical distribution of AOD does not follow the diurnal cycle of the BL but remains similar between day and night highlighting the presence of a residual layer during night. The BL and FT contribute 69 and 31 %, respectively, to the global tropospheric AOD during daytime in line with observations obtained in Aire sur l'Adour (France) using the Light Optical Aerosol Counter (LOAC) instrument. The FT AOD contribution is larger in the tropics than at mid-latitudes which indicates that convective transport largely controls the vertical profile of aerosols. Over oceans, the FT AOD contribution is mainly governed by long-range transport of aerosols from emission sources located within neighboring continents. According to the CALIOP aerosol classification, dust and smoke particles are the main aerosol types transported into the FT. Overall, the study shows that the fraction of AOD in the FT – and thus potentially located above low-level clouds – is substantial and deserves more attention when evaluating the radiative effect of aerosols in climate models. More generally, the results have implications for processes determining the overall budgets, sources, sinks and transport of aerosol particles and their description in atmospheric models.

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