Aerosol Optical Depth Measurements from a Simulated Low-Cost Multi-Wavelength Ground-Based Camera: A Clear Case over a Peri-Urban Area

Round 1

Reviewer 1 Report

In my opinion the manuscript presents work worthy of publication, and the described algorithm is likely to be of interest to the research community. The methodology is reasonable, and the presentation is of a generally high quality. Although some improvements are necessary, none of the items mentioned in my review rise to the level of being a major issue. Please find my specific comments below.

Lines 333-334: It would help to clarify whether the 10 spectra between the 2 calculated ones are obtained using some sort of interpolation.

Lines 350-354: It should be clarified how a single k-value (mentioned in Line 354) is obtained from the set of k-values that satisfy the two criteria mentioned in Lines 351-352.

Lines 470-471: It should be clarified why having data at multiple times can be expected to increase accuracy. (Perhaps because the errors for different times cancel each other out to some degree?)

Line 492: It should be clarified what it means that an image is “taken in a vertical plane”.

Lines 501-511: I believe it would also be important to test and validate WaltRcam-based AOD retrievals for days when the atmosphere is less clean (that is, for higher AOD values).

Somewhere in Section 4, it would be interesting to discuss whether the AOD values retrieved for individual image pixels show some systematic variations. For example, do the retrieved AOD values vary systematically with view direction or with pixel class (using the classes shown in Fig. 5)? 

Lines 39 and 42: The word “platform” should be in plural in both lines. 

Line 54: I recommend changing “nearly aerosol clear” to “nearly aerosol-free”. (This would make the wording less ambiguous (“clear” could potentially refer to the absence of clouds) and would also match the wording “cloud-free” used elsewhere (e.g., in Line 112). The same change is recommended for Line 116. 

Line 66: The word “to” should be replaced by “from”.

Line 69: The words “due to” should be inserted in front of “changes”.

Line 96: The word “The” should be included in front of “Data”. 

Line 107: The words “a about a 130 degree” should be changed to “an about 130 degree wide”.

Line 183: I recommend changing “between both” to “in the two”. 

Line 193: The word “great” should be changed to “greater”. 

Line 269: The word “simple” should be replaced by “single”.

Line 297: The word “was” should be replaced by “were”.

Line 367: The word “dizain” is not used in this context in English and should be replaced, perhaps by “dozen” or “few dozens”. 

Figure 5: It would help to specify what classes are indicated by each of the various colors.

Table 4: The word “relatif” should be replaced by “relative”.

Table 5: The first letter of “june” should be capitalized.

Lines 469-470: The characters “, which” should be deleted.

Line 473: The letter “s” should be deleted from the end of “wavelengths”.

Line 477: I recommend inserting word “data” after “WaltRcam”. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors simulated the characteristics of an economical multi-wavelength ground-based camera (WaltRCam) using data from a hyperspectral camera (HySpex) and investigated the performance of WaltRCam in retrieving AOD for clean environments compared to AERONET and MODIS. This low-cost instrument is of great interest and importance to the environmental and atmospheric community. However, there are some issues in the manuscript that require attention and resolution before the study can be considered for publication.

There are inconsistent spellings of the camera name throughout the manuscript (e.g., WaltRCam, WaltRcam, WalRcam). For clarity, please ensure consistent use of the camera's name in all instances.

Abstract: The authors need to clarify that the camera’s relatively good performance is contingent upon operating in clean environments. This clarification will prevent potential misunderstanding about its applicability in various atmospheric conditions. Additionally, an investigation and discussion of the camera’s performance under polluted conditions would be of great interest and add significant value to the paper.

Line 33: It is misleading to say that higher AOD would mean more aerosol particles. It is important to recognize that  AOD is influenced by several factors, such as particle size and type, not just quantity.

Line 47: The tense does not match, change to proposed.

Line 92 and 141: Since the WaltRCam is still under development and there is no available data, the authors have degraded the measurements from HySpex and added 10 % random noise to those data to mimic the characteristics of WaltRCam observation. It is crucial for the authors to justify this approach more convincingly. Specifically, the rationale behind choosing a 10 % of noise needs clarification. Is there any literature or data to support this choice? If not, how does the noise value affect the results? The paper would benefit from a discussion on this, possibly including sensitivity studies to validate the reliability and consistency of these simulated WaltRCam images.

Line 111: A lower level of the precision of latitude and longitude might be more appropriate and sufficient.

Line 290: Change incertainties to uncertainties.

Line 393-394: Please revise to ensure the subject-verb agreement for grammatical accuracy.

Table 4: Change Relatif to Relative.

Line 410: Change beetween to between.

Line 428-429: the saying that scattering by aerosols is more efficient at shorter wavelengths is generally correct but too absolute. Strictly speaking, scattering by particles is the most efficient when the wavelength and the size of particles are comparable. I recommend that the authors refine this statement.

Table 5 and Line 449: The values presented in Table 5 and the corresponding textual description in Line 449 do not match. Please address this for clarity and accuracy.

Figure 8: The caption of Figure 8 needs to be revised, e.g. Comparison of the AOD values of WaltRCam and AERONET.

The quality of English in the document is commendable. However, certain aspects such as spelling and tenses need attention. In addition, the Oxford comma is used inconsistently. Some sentences use the Oxford comma while others do not. For the sake of consistency and clarity, please ensure that these elements of language are used consistently throughout the document.

Author Response

Please see the attachment

Author Response File: Author Response.pdf