Detection and characterization of birch pollen in the atmosphere using a multiwavelength Raman polarization lidar and Hirst-type pollen sampler in Finland

Bohlmann, Stephanie; Shang, Xiaoxia; Giannakaki, Elina; Filioglou, Maria; Saarto, Annika; Romakkaniemi, Sami; Komppula, Mika

doi:10.5194/acp-19-14559-2019

Cited by 34 publications

(56 citation statements)

References 48 publications

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“…) in Kuopio is a rural location surrounded by boreal forest (Bohlmann et al, 2019). The focus of the campaign in May 2016 was to investigate the capability to characterize the optical properties of airborne pollen with the multiwavelength Raman lidar PollyXT (Bohlmann et al, 2019). Here, we utilise one week of collocated measurements to compare Halo depolarization at 1565 nm to PollyXT during a spruce and birch pollination episode.…”

Section: Methodsmentioning

confidence: 99%

“…At Vehmasmäki, PollyXT was configured with elastic backscatter channels (355, 532 and 1064 nm), Raman-shifted channels at 387, 407 and 607 nm and a cross-polar channel at 532 nm (Bohlmann et al, 2019). Due to the biaxial construction of emission and detection units, complete overlap is reached at 800-900 m a.g.l.…”

Section: Pollyxtmentioning

confidence: 99%

“…(Engelmann, et al, 2016) and thus, only measurements > 800 m a.g.l. are utilized for this study (Bohlmann et al, 2019). The original spatial resolution is 30 m and temporal resolution 30 s for the Vehmasmäki system (Bohlmann et al, 2019).…”

Section: Pollyxtmentioning

confidence: 99%

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Aerosol particle depolarization ratio at 1565 nm measured with a Halo Doppler lidar

Vakkari¹,

Baars²,

Bohlmann³

et al. 2020

Preprint

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Abstract. Depolarization ratio is a valuable parameter for lidar-based aerosol categorization. Usually, aerosol particle depolarization ratio is determined at relatively short wavelengths of 355 nm and/or 532 nm, but some multi-wavelength studies including longer wavelengths indicate strong spectral dependency. Here, we investigate the capabilities of Halo Photonics Stream Line Doppler lidars to retrieve the particle linear depolarization ratio at 1565 nm wavelength. We utilize collocated measurements with another lidar system, PollyXT at Limassol, Cyprus, and at Kuopio, Finland, to compare the depolarization ratio observed by the two systems. For mineral dust-dominated cases we find typically a little lower depolarization ratio at 1565 nm than at 355 nm and 532 nm. However, for dust mixed with other aerosol we find higher depolarization ratio at 1565 nm. For polluted marine aerosol we find marginally lower depolarization ratio at 1565 nm compared to 355 nm and 532 nm. For mixed spruce and birch pollen we find a little higher depolarization ratio at 1565 nm compared to 532 nm. Overall, we conclude that Halo Doppler lidars can provide particle linear depolarization ratio at 1565 nm wavelength at least in the lowest 2–3 km above ground.

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Section: Methodsmentioning

confidence: 99%

Section: Pollyxtmentioning

confidence: 99%

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Aerosol particle depolarization ratio at 1565 nm measured with a Halo Doppler lidar

Vakkari¹,

Baars²,

Bohlmann³

et al. 2020

Preprint

Self Cite

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“…The lidar has been employed under various campaigns and locations over the course of years. Among others, two long-term aerosol experimental campaigns at Gual Pahari, India (Komppula et al, 2012) and Elandsfontein, South Africa (Giannakaki et al, 2015(Giannakaki et al, , 2016Korhonen et al, 2014) and at the permanent measurement site in Vehmasmäki, Finland (Bohlmann et al, 2019;Filioglou et al, 2017) have been conducted. The system is also part of the Finnish lidar network (Hirsikko et al, 2014), the European Aerosol Research Lidar Network (EARLINET) (Bösenberg et al, 2003;Pappalardo et al, 2014) and PollyNET (Baars et al, 2016) which is an independent Raman and polarization lidar network where measurements from all member-stations are visualized through "quick looks", publicly available on the web page of PollyNET (http://polly.tropos.de).…”

Section: The Multi-wavelength Raman Lidar Fmi -Polly Xtmentioning

confidence: 99%

Optical and geometrical aerosol particle properties over the United Arab Emirates

Filioglou¹,

Giannakaki²,

Backman³

et al. 2020

Preprint

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Abstract. One-year of ground-based night-time Raman lidar observations have been analysed under the Optimization of Aerosol Seeding In rain enhancement Strategies (OASIS) project, in order to characterize the aerosol particle properties over a rural site in the United Arab Emirates. In total, 1130 aerosol particle layers were detected during the one-year measurement campaign which took place between March 2018 and February 2019. Several subsequent aerosol layers could be observed simultaneously in the atmosphere up to 11 km. The observations indicate that the measurement site is a receptor of frequent dust events but predominantly the dust is mixed with aerosols of anthropogenic and/or marine origin. The mean aerosol optical depth over the measurement site ranged at 0.37 ± 0.12 and 0.21 ± 0.11 for the 355 and 532 nm, respectively. Moreover, a mean lidar ratio of 43 ± 11 sr at a wavelength of 355 nm and 39 ± 10 sr at 532 nm was found. The average linear particle depolarization ratio measured over the course of the campaign was 15 ± 6 % and 19 ± 7 % at 355 nm and 532 nm wavelengths, respectively. Since the region is both a source and a receptor of mineral dust, we have also explored the properties of Arabian mineral dust of the greater area of United Arab of Emirates and the Arabian Peninsula. The observed Arabian dust particle properties were 45 ± 5 (42 ± 5) sr at 355 (532) nm for the lidar ratio, 25 ± 2 % (31 ± 2 %) for the linear particle depolarization ratio at 355 (532) nm, and 0.3 ± 0.2 (0.2 ± 0.2) for the extinction‑related Ångström exponent (backscatter‑related Ångström exponent) between 355 and 532 nm. This study is the first to report comprehensive optical properties of the Arabian dust particles based on long term observations, using at the fullest the capabilities of a multi wavelength Raman lidar instrument. The results suggest that the mineral dust properties over the Middle East and western Asia, including the observation site, are comparable to those of African mineral dust with regard to the particle depolarization ratios but not for lidar ratios. The smaller lidar ratio values in this study compared to the reference studies are attributed to the difference in the geochemical characteristics of the soil originating in the study region compared to Northern Africa.

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“…This variation implies that the crown surface may not be the only predictor of pollen emission, but it must be combined with other variables, such as phenological or meteorological data, that can explain the year-to-year variation in pollen count [84]. Recently, a terrestrial LiDAR system was also used to measure the pollen emissions from trees [85]. It is likely that it will be possible to estimate pollen emissions at their source by a combination of aerial and terrestrial LiDAR in the future.…”

Section: Limitations Of the Study And Future Workmentioning

confidence: 99%

Lidar-Derived Tree Crown Parameters: Are They New Variables Explaining Local Birch (Betula sp.) Pollen Concentrations?

Bogawski

Grewling

Dziób

et al. 2019

Forests

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Birch trees are abundant in central and northern Europe and are dominant trees in broadleaved forests. Birches are pioneer trees that produce large quantities of allergenic pollen efficiently dispersed by wind. The pollen load level depends on the sizes and locations of pollen sources, which are important for pollen forecasting models; however, very limited work has been done on this topic in comparison to research on anthropogenic air pollutants. Therefore, we used highly accurate aerial laser scanning (Light Detection and Ranging—LiDAR) data to estimate the size and location of birch pollen sources in 3-dimensional space and to determine their influence on the pollen concentration in Poznań, Poland. LiDAR data were acquired in May 2012. LiDAR point clouds were clipped to birch individuals (mapped in 2012–2014 and in 2019), normalised, filtered, and individual tree crowns higher than 5 m were delineated. Then, the crown surface and volume were calculated and aggregated according to wind direction up to 2 km from the pollen trap. Consistent with LIDAR data, hourly airborne pollen measurements (performed using a Hirst-type, 7-day volumetric trap), wind speed and direction data were obtained in April 2012. We delineated 18,740 birch trees, with an average density of 14.9/0.01 km2, in the study area. The total birch crown surface in the 500–1500 m buffer from the pollen trap was significantly correlated with the pollen concentration aggregated by the wind direction (r = 0.728, p = 0.04). The individual tree crown delineation performed well (r2 ≥ 0.89), but overestimations were observed at high birch densities (> 30 trees/plot). We showed that trees outside forests substantially contribute to the total pollen pool. We suggest that including the vertical dimension and the trees outside the forest in pollen source maps have the potential to improve the quality of pollen forecasting models.

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Detection and characterization of birch pollen in the atmosphere using a multiwavelength Raman polarization lidar and Hirst-type pollen sampler in Finland

Cited by 34 publications

References 48 publications

Aerosol particle depolarization ratio at 1565 nm measured with a Halo Doppler lidar

Aerosol particle depolarization ratio at 1565 nm measured with a Halo Doppler lidar

Optical and geometrical aerosol particle properties over the United Arab Emirates

Lidar-Derived Tree Crown Parameters: Are They New Variables Explaining Local Birch (Betula sp.) Pollen Concentrations?

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