Evaluation of aerosol microphysical, optical and radiative properties measured with a multiwavelength photometer

Zheng, Yu; Che, Huizheng; Wang, Yupeng; Xia, Xiangao; Hu, Xiuqing; Zhang, Xiaochun; Zhu, Jun; Zhu, Jibiao; Zhao, Hujia; Li, Lei; Gui, Ke; Zhang, Xiaoye

doi:https://doi.org/10.5194/amt-15-2139-2022

Articles | Volume 15, issue 7

https://doi.org/10.5194/amt-15-2139-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/amt-15-2139-2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 7

Research article

|

08 Apr 2022

Research article |

| 08 Apr 2022

Evaluation of aerosol microphysical, optical and radiative properties measured with a multiwavelength photometer

Yu Zheng, Huizheng Che, Yupeng Wang, Xiangao Xia, Xiuqing Hu, Xiaochun Zhang, Jun Zhu, Jibiao Zhu, Hujia Zhao, Lei Li, Ke Gui, and Xiaoye Zhang

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Final revised paper (published on 08 Apr 2022)
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Preprint (discussion started on 20 Nov 2021)
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Interactive discussion

Status: closed

RC1:
'Comment on amt-2021-365', Anonymous Referee #1, 26 Nov 2021
Review of "A new multispectral photometer for monitoring aerosol microphysical, optical, and radiative properties" by Zheng et al.

The manuscript "A new multispectral photometer for monitoring aerosol microphysical, optical, and radiative properties" mainly describes a new multispectral photometer (CW193) proposed in this study. In this study, the design of multispectral photometer combines the merit of low maintenance requirements and being appropriate for the deployment in remote and unpopulated regions. In general, the paper is well written and presented in a logical way. It is a timely and important piece of work, and of general interest for Atmospheric Measurement Techniques related communities. I therefore recommend publication of this paper in Atmospheric Measurement Techniques after minor revisions. My comments are listed as follows:

Specific Comments:

Line 109-110, In the sentence of “the main pollution sources are derived from urban activities”, the meaning of “source” has been already included in the word “derive”.

Line 111, a description for is needed.

In figure 1, I suggest the authors add the map of China as well as the CAMS location. Otherwise, the readers cannot catch the location information of CAMS.

Line 141, the role of word “respectively” is indistinct in the sentence.

Line 204, Is the meaning of same as ?

Line 301 and Table 4, What is the standard of Level I-III? The corresponding information is needed.

In the bottom description of Figure 7, the sentence “One–one line, linear regression line, and the EE envelopes of ±(0.05 + 10%) are plotted as red dashed, green solid, and black dashed lines” should be changed to “One–one line, linear regression line, and the EE envelopes of ±(0.05 + 10%) are plotted as red dashed, green solid, and black dashed lines, respectively”.

In the calculations of ADRF for CW193 and instruments of CARSNET, and AERONET, does the authors use the same radiation transfer model? If the model is different, the difference of ADRF may not induced by the instrument alone.
Citation: https://doi.org/10.5194/amt-2021-365-RC1
- AC1: 'Reply on RC1', Huizheng Che, 05 Jan 2022
  
  Please find the AC in Supplement PDF
  
  Citation: https://doi.org/10.5194/amt-2021-365-AC1
RC2:
'Comment on amt-2021-365', Anonymous Referee #2, 08 Dec 2021

This paper presents a newly-designed sun photometer for aerosol retrieval. Compared to the widely used CE318 model, the new instrument has the advantage of better portability with similar accuracy. Inter-comparisons are carried out to evaluate the performance, which shows that the CW193 sunphotometer has comparable retrieval accuracy. The new instrument has the potential to be deployed in remote and desert regions, thus expanding the aerosol observation network. Overall, this is a well written paper with good scientific merit. I only have a few minor questions.

Minor comments:

1. The design of CW193 is very similar to that of CE318. The authors indicated that the biggest advantage is CW193's portability. I suggest providing more detailed discription about this. In Figure 2, only the optial head part is shown, or is this the whole system? If latter, I suggest making it clear as this indeed appears much more compact than CE318.

2. Does the retrieval of aerosol optial properties use the same inversion method as AERONET? Please briefly describe the retrieval method.

3. In addition to comparing with AERONET and CARSNET, I think it is also very important to independant evaluate the measurement and retrieval accuracies of CW193. How accuray are the sky and diffuse radiances? How are the errors in these measurements transferred to the retrieved products? Are these accuracy levels comparable, or better than AERONET?

4. Could the authors provide some explanations of the differences between CW193 and AERONET/CARSNET? Based on Figures 7-11, there are still some biases and differences.

Citation: https://doi.org/10.5194/amt-2021-365-RC2
- AC2: 'Reply on RC2', Huizheng Che, 05 Jan 2022
  
  Please find the AC2 in Supplement PDF
  
  Citation: https://doi.org/10.5194/amt-2021-365-AC2
RC3:
'Comment on amt-2021-365', Anonymous Referee #3, 10 Dec 2021
A new multispectral photometer for monitoring aerosol microphysical, optical, and radiative properties

By Zheng et al.

General comments:

Atmospheric aerosols have significant influence on regional air quality, regional climate change, as well as human health. Their loadings have been increased substantially compared with those in Pre-industrial times. A detailed description on the aerosol optical and physical properties is the prerequisites for better evaluating the effects of the aerosols. Unfortunately, uncertainties of the aerosol radiative forcing and climate effects still exist due to a lack of knowledge about the aerosol properties. Therefore, a new highly integrated observation instrument is necessary to be developed to fill the gap of current observation system. This study proposes a new multispectral photometer (CW193) with a highly integrated designing and smart control performance for monitoring aerosol microphysical, optical, and radiative properties. The results indicate that CW193 can well observe and capture the aerosol characteristics by comparing with AERONET products, implying that the instrument may have a wide application prospect in the further. The topic of this study is interesting and novel. Therefore, the paper has a potential for publication in the journal.

Specific comments:

Why the new instrument is named as CW193? The authors can make a detailed introduction.

What is the main difference (or progressiveness) of the CW193 against to the CE-318?

How many observation intervals can be set for CW193?

The authors state that CW193 has a low maintenance requirement. How long and in what conditions does it need to be taken to maintain? I think all the ground-based instruments are needed to have a routine maintenance.

To make the instrument more reliable, more observation and validation works should be carried out in the further. For example, the authors can perform a series observation activities with different pollution levels, in different time scales, in different regions as well as in different seasons.

Conclusion should be more refined instead of repeating the results. An additional discussion on the potential application of the instrument in the future can be involved in this section.

English should be corrected throughout the whole manuscript.
Citation: https://doi.org/10.5194/amt-2021-365-RC3
- AC3: 'Reply on RC3', Huizheng Che, 05 Jan 2022
  
  Please find the AC3 in Supplement PDF
  
  Citation: https://doi.org/10.5194/amt-2021-365-AC3
CC1:
'Comment on amt-2021-365', Philippe Goloub, 27 Dec 2021
A new multispectral photometer for monitoring aerosol microphysical, optical, and radiative properties
by Zheng et al.
A.   General comments
The manuscript presents a system for the monitoring of atmospheric aerosols, based on a new instrument. It is mainly based on a comparison with the AERONET system (based on the CE318 photometer), considered as the reference.
The main claims of the authors are
novelty,

additional functions,

validity of metrology,

validity of data processing chain,

validity for network operations,

simplified maintenance,

low cost.

Having red this paper, I concluded that these claims are not substantiated by scientific and technical evidences:
No conceptual novelty is shown hence the work appears rather like an approximate duplication of the whole AERONET instrument and system.

The comparison of CW193 specifications to the reference CE318 system is not complete and not fair:

         a) First, this comparison should be done with the current AERONET reference instrument CE318T and not with the old version of CE318 as done in the paper
             b) Second, and linked to point a), several important functions present in AERONET are lacking (Lunar measurements, polarized sky radiance option, multiple scenario configurations). Hence, this comparison looks unfair.
             c) Third, the claimed benefits of some new features brought by CW193 are not explained nor proven.
CW193 performances are not characterized nor validated

Long term performance including robustness, sensitivity to weather conditions is not evaluated, therefore not validated.

In the paper, the data quality analysis is limited to a few selected measurement days. The evaluation of the system's quality requires a much more comprehensive experimental plan.

The additional benefits claimed for the improvement of operational observations (robustness, simple maintenance, low cost) are not evidenced.

As conclusion,
The work presented in the paper does not bring new knowledge to the scientific community, as it would expect.

It mainly rather makes a series of technical and commercial statements on claimed advantages of CW193 instrument without providing corresponding evidences.

In summary, these weaknesses and lacks are in opposition/contradiction with the claimed advantages of CW193: novelty, additional functions, validity of metrology, validity for network operations, simplified maintenance, low cost.

B. Detailed and specific comments
Line 83: "wired communication (for example, serial communication via RS-232) between the instruments and a personal computer is still necessary for most CE318-N photometers".

Comment: This statement is NOT correct. AERONET operates a large number of sites at remote locations without wired communication with a PC.
Line 85: "the non-integrated instrument components, such as the control unit, external battery, protection box, and stents platform, not only cause most of the operational problems but also make the deployment and maintenance difficult for staff with inadequate training"

Comment: This opinion is not justified and does not seem fair.
In AERONET, the protection box and simple tripod platform are options that may be very useful for some types of installations, especially in remote places, where trained staff and technical means are not available. The modular design of CE318 is often an advantage in terms of easy replacement of parts.
Lines 92-93: "which makes the whole system efficient, secure, low cost and highly integrated."

Comment: this list of assertions is not justified by the information provided in the paper.
The presented integrated design does not allow local control of the instrument without a PC, which may be a major issue in remote locations.
The low cost should be quantified, including initial and expected maintenance costs, and spread over the proven expected lifetime of the instrument.
Efficiency and security should be quantified over the long term, in terms of uptime of the instrument and proportion of data brought to some defined quality level.
AERONET has proven an unmatched efficiency and service level in producing quality assured atmospheric aerosol products over the long term
Lines 97-99: these assertions are not justified.

Line 125: "largest" should be qualified: probably refers to China

Line 126: "Same algorithm" should be qualified. How has it been validated?

Line 143: Again, comparison with CE318-N is not relevant as this is an old version of CE318. Most of AERONET sites are equipped with the more recent version CE318-T. The table should be corrected to present a fair comparison.

Table 1 - The whole table 1 should be corrected with CE318-T technical specifications

Table 1: what is the type of detector used?

Table 1 - Drift of single band filter's transmission rate < 1% for CW193 :

                  - Sun tracking accuracy: 0.02 °
                  - Temperature range: -30° to 60°
          The characterization of these performances should be described.
Table 1: - Power supply for CW193

          The type and capacity of the battery system should be described.
          The autonomy of the system, in case of operation on the solar generator and absence of direct sun, should be stated.
Table 1: - Gross weight and flycase dimensions are not really relevant, or should be completed with net weight and dimensions, and with all components (solar panel)

Lines 174-175: "the design of CW193 is very robust, ensuring long-term steady operation in a wide range of temperature and humidity, between about −30°C and 60°C and between about 0 and 100%, respectively"

Comment: This assertion is not supported by any evidence.
Lines 189-192: "It is very convenient to receiving data via 4G network when the serial communication is unavailable in some remote regions, and also in this mode, multiple device control is achievable (device 003, 005 and 006 are on-line and controllable in Figure 3). In the data download part, the history data can be easy downloaded by selecting the start and end time via drop-down menu”.

Comment: This is presented as a new function and an advantage, but the AERONET network already operates a large number of remote sites with direct telecommunication link.
In AERONET, full data collection is ensured fully automatically in real time, or even after interruption of communications. This is more convenient than manual control through a software.
Table 2 - The whole table 2 should be corrected with CE318-T functional specifications

Line 211: "five instruments"

Comment: The method and specifics of the calibration of the studied CW193 should be described.
For the whole intercomparison study, Sun calibration should be made on a different set of data. Is it the case?
Line 313-314: "Therefore, in summary, the CW193 shows high stability under both high and low aerosol loadings; hence, the excellent detection ability makes it a reliable instrument for aerosol monitoring."

Comment: This conclusion regarding the reliability of the instrument is not justified in the paper.
Figure 6:

Comment: This figure does not show interruption at nighttime. The observation time per day should be explained.
Line 352: "We set the envelopes as ±(0.05 + 10%)."

Comment: The choice of this criterium should be explained.
It is quite large compared to the AERONET uncertainty.
Line 412: "uncertainty of <10% is acceptable for the discussion"

Comment: This level of uncertainty is much higher than AERONET's.
Lines 568-570

Comment: This conclusion should be expressed as a preliminary only.
It must be checked on long-term and various weather and aerosol conditions.
Lines 582-585: "the highly integrated design and smart control performance make CW193 more convenient and suitable for the aerosol monitoring, providing similar aerosol optical properties to AERONET. In addition, owing to the built-in 4G communication module, CW193 could be used to create networks in an inexpensive and simple way."

Comment: as such, this is a commercial statement, not evidenced by the paper. It should be removed or rephrased.
Citation: https://doi.org/10.5194/amt-2021-365-CC1
- AC4: 'Reply on CC1', Huizheng Che, 19 Jan 2022
  
  Please find the responce to CC1 in Supplement PDF
  
  Citation: https://doi.org/10.5194/amt-2021-365-AC4

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Huizheng Che on behalf of the Authors (27 Jan 2022) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (28 Jan 2022) by Cheng Liu

RR by Anonymous Referee #2 (29 Jan 2022)

RR by Anonymous Referee #1 (06 Feb 2022)

RR by Anonymous Referee #3 (09 Feb 2022)

RR by Anonymous Referee #4 (09 Feb 2022)

RR by Anonymous Referee #5 (14 Feb 2022)

Suggestions for revision or reasons for rejection

This paper presented an evaluation of aerosol microphysical, optical and radiative properties measured from a multiwavelength photometer, named CW193. As introduced by the authors, the instrument has a highly integrated design, smart control performance, and is composed of three parts (optical head, robotic drive platform, and stents system). Then the CW193 product was inter-compared and validated using reference data from the AERONET based on the synchronous measurements. The results of this preliminary evaluation indicated that the CW193 is appropriate for monitoring aerosol microphysical, optical, and radiative properties, characterized by the good agreement of raw digital counts, accurate AOD results and comparable retrievals with AERONET. In summary, this paper is a good work and has lots of general interest for Atmospheric Measurement Techniques and related communities. Therefore, I have no more major comments and have recommended for acceptance after a minor revision. I suggested the following few comments may improve and strengthen the quality of the manuscript.
Specific Comments:
Line no. 61-64: Authors can be mentioned about the limitation of the polar orbiting or lower earth orbiting satellites with relevant references. For example, due to poor spatial and temporal resolution of such satellites, there are about 50% data lost over high-altitude sites mountainous sites in particular at 0.05x0.05 degree spatial resolution of MODIS (Terra) data (e.g. Ningombam et al., 2021).
Line no. 79-80: It is also very important to expand such robotic measurement made at high-altitude and mountainous region where there are limited ground based data available due to harsh climatic condition and lack of manpower support for operating the instruments.
Line no. 134: Please put the unit of water vapor (mm or cm ?) after +/- 0.10. Also, I found several places in the manuscript where the authors did not put the unit.
Line no. 249: Please mention which version of AERONET data is used as a reference in the present work.
Line no. 306-308: Authors may be added few more relevant references about the importance of quality controlled data over high-altitude and clean environments where the estimated aerosol parameters are of the order of measurement uncertainties.
Line no. 315: Table 4: PM10 for Level I on 7 November is found to be high. Please check if there are any issues in the data. Moreover, aerosol measurement on the same day for Figure 6 might have disrupted due to frequently passing cloudy which may be attributed the high AOD.
Line no. 346: Please correct the wavelength range ’70 nm’, I think it must be 870 nm.
Figure 12: Please put the unit of water vapor (mm or cm ?) in the Figure. Also, I found several places where the authors did not put the unit.
References:
Shantikumar S Ningombam, H-J Song, S K Mugil, Umesh Chandra Dumka, E J L Larson, Brijesh Kumar, Ram Sagar, Evaluation of fractional clear sky over potential astronomical sites, Monthly Notices of the Royal Astronomical Society, 2021, Volume 507(3),pp.3745–3760, https://doi.org/10.1093/mnras/stab1971.

Referee Report: PDF

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ED: Publish subject to minor revisions (review by editor) (18 Feb 2022) by Cheng Liu

AR by Huizheng Che on behalf of the Authors (23 Feb 2022) Author's response Author's tracked changes Manuscript

ED: Publish as is (28 Feb 2022) by Cheng Liu

Post-review adjustments

AA: Author's adjustment | EA: Editor approval

AA by Huizheng Che on behalf of the Authors (05 Apr 2022) Author's adjustment Manuscript

EA: Adjustments approved (07 Apr 2022) by Cheng Liu

Short summary

Ground-based observations of aerosols and aerosol data verification is important for satellite and climate model modification. Here we present an evaluation of aerosol microphysical, optical and radiative properties measured using a multiwavelength photometer with a highly integrated design and smart control performance. The validation of this product is discussed in detail using AERONET as a reference. This work contributes to reducing AOD uncertainties in China and combating climate change.