the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 21 Mar 2023
Spectral dependence of birch and pine pollen optical properties using a synergy of lidar instruments
Ari Leskinen
Ville Vakkari
Ewan O'Connor
Minttu Tuononen
Pekko Tuominen
Samuli Laukkanen
Linnea Toiviainen
Annika Saarto
Xiaoxia Shang
Petri Tiitta
Mika Komppula
Abstract. Active remote sensors equipped with the capability to detect polarization, a shape relevant parameter, are essential to aerosol particle identification in the vertical domain. Most commonly, the linear particle depolarization ratio has been available at the shorter wavelengths of 355 nm and/or 532 nm. Recently, linear particle depolarization ratios at longer wavelengths (910 nm, 1064 nm and, 1565 nm) have emerged to the lidar aerosol research. In this study, a synergy of three lidars, namely a PollyXT lidar, a Vaisala CL61 ceilometer and a Halo Photonics StreamLine Pro Doppler lidar, and in situ aerosol and pollen observations have been utilized to investigate the spectral dependence of birch and pine pollen particles. We found that regardless of the pollen type, the linear particle depolarization ratio was subject to the amount of pollen and its relative contribution to the aerosol mixture in the air. More specifically, during the birch pollination characteristic linear particle depolarization ratios of 5 ± 2 % (355 nm), 28 ± 6 % (532 nm), 23 ± 6 % (910 nm) and, 33 ± 4 % (1565 nm) were retrieved at the pollen layer. Regarding the pine dominant period, the characteristic linear particle depolarization ratio of 6 ± 2 %, 43 ± 11 %, 22 ± 6 % and, 26 ± 3 %, was determined at 355 nm, 532 nm, 910 nm and, 1565 nm wavelengths, respectively. For birch, the linear particle depolarization ratio at 1565 nm was the highest followed by 532 nm and 910 nm wavelengths, respectively. A sharp decrease at 355 nm was evident for birch pollen. For pine pollen, a maximum at 532 nm wavelength was observed. There was no significant change in the linear particle depolarization ratio at 910 nm for the pollen types considered in this study. Given the low concentration of pollen in the air, the inclusion of the longer wavelengths (910 nm and 1565 nm) for the detection of birch and pine can be beneficial due to their sensitivity to trace large aerosol particles.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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- Final revised paper
Journal article(s) based on this preprint
Maria Filioglou et al.
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-507', Anonymous Referee #1, 04 Apr 2023
Today it is well accepted that the pollen play an important role in the process of aerosol cloud interaction. Still, the pollen optical properties, as well as the dynamic of their spatio – temporal variations are not studied sufficiently. One of the reasons is that pollen are normally mixed with other types of aerosol, and it is difficult to characterize the properties of “pure” pollen. From this point of view, the study presented is very important. The authors use three remote sensing instruments and provide the particle depolarization ratios at four wavelengths, from UV to IR. It is also important that authors consider numerous measurement cases, accumulated during field campaigns, thus allowing to estimate the depolarization ratio of pure birch and pine pollen. The paper is well and clearly written and is suitable for ACP. I have just several technical notes.
Notes:
Decrease of depolarization at 900 nm looks unexpected. But considering uncertainty of the measurements, may be this decrease is inside the uncertainty interval.
I wonder, why in Fig.2a pollen concentration is shown in logarithmic scale. Probably variations would be better seen in linear scale. But this is up to authors.
Fig.2b. I would change scale of backscattering to 0 - 2 Mm-1sr-1, to see details of profiles. The layer looks to be well mixed and backscattering at 532, 910, 1064 does not change with height, while at 355 nm it increases below 1 km. Can it be effect of overlap? This increase correlates with drop of particle depolarization at 355.
Fig.2c. I would change scale of BAE also: -1 – 2.
Fig.3. If dust contribution increase, it should increase also depolarization at 355 nm. Was it observed?
Line 333. Did authors estimate the EAE value?
Citation: https://doi.org/10.5194/egusphere-2023-507-RC1 -
AC3: 'Reply on RC1', Maria Filioglou, 29 May 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-507/egusphere-2023-507-AC3-supplement.pdf
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AC3: 'Reply on RC1', Maria Filioglou, 29 May 2023
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RC2: 'Comment on egusphere-2023-507', Anonymous Referee #2, 07 Apr 2023
The main research content of this paper is the difference in depolarization ratio by wavelength depending on the type of pollen. It is judged to have important value as a paper with high continuity with previously published papers related to pollen. Overall, it is judged to be of excellent quality, but it is judged that it needs some revision.
Please refer to the information below.
Since the PDR value of pollen changes depending on mixing with aerosols other than pollen, such as PM10, it would be good to include this information in the text. In the current thesis, it is indicated in the graph, but it is not separately indicated in the text. It would be better to distinguish the PDR value when it is pure pollen and the value when mixed and indicate the average value in the text.
In line 268~271 and Figure 5, you can see the difference between shang et al (2022), but there is no difference between Bolnmann (2019, 2021) and this study's PDR532, so it would be nice to add it in Figure 5.
line 28, SSPs -> SPPs
line 61, bioaresols -> bioaerosols
line83, Stremline -> Streamline
Citation: https://doi.org/10.5194/egusphere-2023-507-RC2 -
AC2: 'Reply on RC2', Maria Filioglou, 29 May 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-507/egusphere-2023-507-AC2-supplement.pdf
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AC2: 'Reply on RC2', Maria Filioglou, 29 May 2023
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RC3: 'Comment on egusphere-2023-507 'Spectral dependence of birch and pine pollen optical properties using a synergy of lidar instruments'', Anonymous Referee #3, 17 Apr 2023
The authors present both active remote sensing measurements and in situ aerosol observations of birch and pine pollen particles at Vehmasmäki (Kuopio), Finland to analyze the spectral dependence of the particle depolarization ratio (PDR). A special feature of this study is that the concurrent use of three different lidar systems enables measurements of PDR at four different wavelengths. Furthermore, the measurements were conducted at a rural forest site, with typically reduced pollution in the background. This is of great value as it allows the authors to study optical properties of pure pollen which is especially important as pollen have typically low concentrations compared to other atmospheric aerosol types.
Therefore, this study is important and suitable for ACP. Overall, the paper is well written and of good quality. Only some few aspects could be explained further/expressed clearer and several typos should be corrected, which will be addressed in the special comments below.Special comments:
ll. 60-61: Veselovskii et al. (2021) only used a single broadband fluorescence channel in this study. An approach to obtain spectral fluorescence information by several fluorescence channels has just been presented in Veselovskii et al. (2023, preprint).ll. 136-137: I don’t understand what is meant with the statement that NS and OPS aerosol size distributions were combined, but NS size distribution was neglected. If only the OPS size distribution was used, then it wasn’t combined with the NS one, was it? Could you please clarify this?
ll. 206-207: The statement ‘For each pollen type … of that specific pollen alone is studied’ has already been stated in the same way in ll. 185-187 and is thus repetitive and could be removed.
ll. 238-240, Fig. 4: Also, the 532 nm PDR seems similarly correlated to pollen concentration and concentration of other aerosols as the two longest wavelengths. Only the PDR at 355 nm seems less influenced. Why? Do you also relate this to the higher sensitivity of longer wavelengths to the comparably large pollen particles? Please explain your conclusion further here.
Figure 6: Why do you have less PDR values at 910 nm (only 2?) for pine concentrations > 4000 m-3 compared to the other wavelengths? Was there a technical issue with the respective lidar? Maybe you could add a short remark on that, please.
Typos and technical notes:
l. 19: ‘… is closely associated to allergic diseases’ --> is closely associated with allergic diseases
l. 28: ‘SSPs’ --> ‘SPPs’
l. 31: ‘are an effective ice nuclei’ --> are effective ice nuclei (as it is plural)
l. 45: ‘depolarisation’ --> depolarization
l. 60: ‘polarisation’ --> polarization
l. 82: ‘vary from year to another’ --> vary from one year to another
l. 103: ‘can be found at Vakkari et al. (2021)’ --> can be found in Vakkari et al. (2021)
l. 205: ‘Sect.2.6’ --> Sect. 2.6 (missing space)
l. 212, l. 213: don’t forget the point after Fig. …, e. g., ‘Fig 2a’ --> Fig. 2a
l. 213: ‘Fig 2a)’ --> Fig. 2b) (the shaded area is found in panel b)
l. 222: ‘has previously seen’ --> has previously been seen
l. 284: ‘calculations performed’ --> calculations were performed
l. 328: ‘set up’ --> setup (as it is the noun)References:
Veselovskii, I., Kasianik, N., Korenskii, M., Hu, Q., Goloub, P., Podvin, T., and Liu, D.: Multiwavelength fluorescence lidar observations of fresh smoke plumes, Atmos. Meas. Tech. Discuss. [preprint], https://doi.org/10.5194/amt-2023-5, in review, 2023.Citation: https://doi.org/10.5194/egusphere-2023-507-RC3 -
AC1: 'Reply on RC3', Maria Filioglou, 29 May 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-507/egusphere-2023-507-AC1-supplement.pdf
-
AC1: 'Reply on RC3', Maria Filioglou, 29 May 2023
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-507', Anonymous Referee #1, 04 Apr 2023
Today it is well accepted that the pollen play an important role in the process of aerosol cloud interaction. Still, the pollen optical properties, as well as the dynamic of their spatio – temporal variations are not studied sufficiently. One of the reasons is that pollen are normally mixed with other types of aerosol, and it is difficult to characterize the properties of “pure” pollen. From this point of view, the study presented is very important. The authors use three remote sensing instruments and provide the particle depolarization ratios at four wavelengths, from UV to IR. It is also important that authors consider numerous measurement cases, accumulated during field campaigns, thus allowing to estimate the depolarization ratio of pure birch and pine pollen. The paper is well and clearly written and is suitable for ACP. I have just several technical notes.
Notes:
Decrease of depolarization at 900 nm looks unexpected. But considering uncertainty of the measurements, may be this decrease is inside the uncertainty interval.
I wonder, why in Fig.2a pollen concentration is shown in logarithmic scale. Probably variations would be better seen in linear scale. But this is up to authors.
Fig.2b. I would change scale of backscattering to 0 - 2 Mm-1sr-1, to see details of profiles. The layer looks to be well mixed and backscattering at 532, 910, 1064 does not change with height, while at 355 nm it increases below 1 km. Can it be effect of overlap? This increase correlates with drop of particle depolarization at 355.
Fig.2c. I would change scale of BAE also: -1 – 2.
Fig.3. If dust contribution increase, it should increase also depolarization at 355 nm. Was it observed?
Line 333. Did authors estimate the EAE value?
Citation: https://doi.org/10.5194/egusphere-2023-507-RC1 -
AC3: 'Reply on RC1', Maria Filioglou, 29 May 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-507/egusphere-2023-507-AC3-supplement.pdf
-
AC3: 'Reply on RC1', Maria Filioglou, 29 May 2023
-
RC2: 'Comment on egusphere-2023-507', Anonymous Referee #2, 07 Apr 2023
The main research content of this paper is the difference in depolarization ratio by wavelength depending on the type of pollen. It is judged to have important value as a paper with high continuity with previously published papers related to pollen. Overall, it is judged to be of excellent quality, but it is judged that it needs some revision.
Please refer to the information below.
Since the PDR value of pollen changes depending on mixing with aerosols other than pollen, such as PM10, it would be good to include this information in the text. In the current thesis, it is indicated in the graph, but it is not separately indicated in the text. It would be better to distinguish the PDR value when it is pure pollen and the value when mixed and indicate the average value in the text.
In line 268~271 and Figure 5, you can see the difference between shang et al (2022), but there is no difference between Bolnmann (2019, 2021) and this study's PDR532, so it would be nice to add it in Figure 5.
line 28, SSPs -> SPPs
line 61, bioaresols -> bioaerosols
line83, Stremline -> Streamline
Citation: https://doi.org/10.5194/egusphere-2023-507-RC2 -
AC2: 'Reply on RC2', Maria Filioglou, 29 May 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-507/egusphere-2023-507-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Maria Filioglou, 29 May 2023
-
RC3: 'Comment on egusphere-2023-507 'Spectral dependence of birch and pine pollen optical properties using a synergy of lidar instruments'', Anonymous Referee #3, 17 Apr 2023
The authors present both active remote sensing measurements and in situ aerosol observations of birch and pine pollen particles at Vehmasmäki (Kuopio), Finland to analyze the spectral dependence of the particle depolarization ratio (PDR). A special feature of this study is that the concurrent use of three different lidar systems enables measurements of PDR at four different wavelengths. Furthermore, the measurements were conducted at a rural forest site, with typically reduced pollution in the background. This is of great value as it allows the authors to study optical properties of pure pollen which is especially important as pollen have typically low concentrations compared to other atmospheric aerosol types.
Therefore, this study is important and suitable for ACP. Overall, the paper is well written and of good quality. Only some few aspects could be explained further/expressed clearer and several typos should be corrected, which will be addressed in the special comments below.Special comments:
ll. 60-61: Veselovskii et al. (2021) only used a single broadband fluorescence channel in this study. An approach to obtain spectral fluorescence information by several fluorescence channels has just been presented in Veselovskii et al. (2023, preprint).ll. 136-137: I don’t understand what is meant with the statement that NS and OPS aerosol size distributions were combined, but NS size distribution was neglected. If only the OPS size distribution was used, then it wasn’t combined with the NS one, was it? Could you please clarify this?
ll. 206-207: The statement ‘For each pollen type … of that specific pollen alone is studied’ has already been stated in the same way in ll. 185-187 and is thus repetitive and could be removed.
ll. 238-240, Fig. 4: Also, the 532 nm PDR seems similarly correlated to pollen concentration and concentration of other aerosols as the two longest wavelengths. Only the PDR at 355 nm seems less influenced. Why? Do you also relate this to the higher sensitivity of longer wavelengths to the comparably large pollen particles? Please explain your conclusion further here.
Figure 6: Why do you have less PDR values at 910 nm (only 2?) for pine concentrations > 4000 m-3 compared to the other wavelengths? Was there a technical issue with the respective lidar? Maybe you could add a short remark on that, please.
Typos and technical notes:
l. 19: ‘… is closely associated to allergic diseases’ --> is closely associated with allergic diseases
l. 28: ‘SSPs’ --> ‘SPPs’
l. 31: ‘are an effective ice nuclei’ --> are effective ice nuclei (as it is plural)
l. 45: ‘depolarisation’ --> depolarization
l. 60: ‘polarisation’ --> polarization
l. 82: ‘vary from year to another’ --> vary from one year to another
l. 103: ‘can be found at Vakkari et al. (2021)’ --> can be found in Vakkari et al. (2021)
l. 205: ‘Sect.2.6’ --> Sect. 2.6 (missing space)
l. 212, l. 213: don’t forget the point after Fig. …, e. g., ‘Fig 2a’ --> Fig. 2a
l. 213: ‘Fig 2a)’ --> Fig. 2b) (the shaded area is found in panel b)
l. 222: ‘has previously seen’ --> has previously been seen
l. 284: ‘calculations performed’ --> calculations were performed
l. 328: ‘set up’ --> setup (as it is the noun)References:
Veselovskii, I., Kasianik, N., Korenskii, M., Hu, Q., Goloub, P., Podvin, T., and Liu, D.: Multiwavelength fluorescence lidar observations of fresh smoke plumes, Atmos. Meas. Tech. Discuss. [preprint], https://doi.org/10.5194/amt-2023-5, in review, 2023.Citation: https://doi.org/10.5194/egusphere-2023-507-RC3 -
AC1: 'Reply on RC3', Maria Filioglou, 29 May 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-507/egusphere-2023-507-AC1-supplement.pdf
-
AC1: 'Reply on RC3', Maria Filioglou, 29 May 2023
Peer review completion
Journal article(s) based on this preprint
Maria Filioglou et al.
Maria Filioglou et al.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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