Black Carbon Evolution at WMO/GAW Station Mt. Waliguan China and Contribution Area from 1994 to 2017
Round 1
Reviewer 1 Report
The manuscript is revised thoroughly, well written, and addresses all the concerns raised in my earlier review.
Author Response
Dear Editor and Reviewer,
We would like to thank the reviewer for your valuable comments and constructive suggestions. The point-to-point response to the reviewer’ comments are listed as below. We hope that the revised manuscript is now suitable for publication. Thank you very much for your time and consideration.
Yours sincerely,
Hao Wu
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This is the second submission of this manuscript that deals with a (precious) long-term database of Black Carbon concentrations. This new version improved significantly when compared to the previous (first version) submission.
In the attached file I added several fixings for the text. It still needs several corrections in the body text with respect to english writting, and I strongly suggest to hire a professional of english language to make a final work.
As pointed by authors in their reply to the first round, it is a technical note and not a scientific paper. However, even for a technical paper, the text uses a too descriptive approach. For example, it uses 70 lines to describe a figure when most of the information is obtained just looking to the wind rose. IMHO, the most important thing is to discuss and not describe the measurement. The authors indeed do the discussion but it could be shortened significantly in several parts of the manuscript.
Comments for author File: Comments.pdf
Author Response
Dear Editor and Reviewer,
We would like to thank the reviewer for your valuable comments and constructive suggestions. The point-to-point response to the reviewer’ comments are listed as below. We hope that the revised manuscript is now suitable for publication. Thank you very much for your time and consideration.
Yours sincerely,
Hao Wu
Please see the attachment.
Author Response File: Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The manuscript entitled “Long-Term Variation of Black Carbon Aerosol from 1994 to 2017 at Mt. Waliguan” by Rongqian Meng and colleagues aims to describe the variations of concentration of atmospheric Black carbon in a background measurement station in China over a 23-year period, at different time scales.
While the manuscript contains interesting data, I have several concerns that would require extensive revision.
My main concerns regard the material&methods and presentation of the results.
The material and methods are clearly insufficiently detailed, with incomplete phrases. The name of the instruments, their type (likely different aethalometers?) and change over the years should be stated. The calculations and a bit of theory about how to convert absorption at different wavelengths into concentrations should be explained. The site of Mount Waliguan should be more described with latitude/longitude and a bit of context (in a forest? Where are the nearest indusrtries? What are those industries? What about traffic?), for example with an informative map of Mount Waliguan and its surroundings that could explain the black carbon concentrations. Also more information of the setting of the instruments are needed.
The method by which the authors obtained backward trajectories should be described in the material and methods.
The results and their presentation should be revised. The figures contain apparently averages and standard deviations, but more information should be provided (eg Figure 1, Figure 3) about whether the average is daily, moving, etc. Figure 1 shows a Y-axis stating a concentration in µg/m3 while it seems to be ng/m3 in the rest of the text. Figure 6 shows four directions (NE, NW, SE, SW) while saying “all directions” and these directions do not match the text. Also it’s unclear what the x-axis is.
Finally, since the authors analyze a time series and speak of trends, they could perform a real time-series analysis with appropriate statistical tools, and conduct statistical analyses that could take into account the changes in the methods (apparently three subperiods before October 2006, between October 2006 and November 2007, and after November 2007, with different wavelengths) to strengthen their descriptive analysis.
Reviewer 2 Report
The manuscript titled "Long-Term Variation of Black Carbon Aerosol from 1994 to 2017 at Mt. Waliguan" by Meng et al. is aimed at presenting the diurnal, seasonal, and annual variation of black carbon (BC) concentration at Mt. Waliguan using continuous observations covering 23 years. Also, the effects of meteorological factors (wind speed and wind direction) on the distribution of BC concentration and corresponding transport characteristics are examined. However, the current version of the manuscript needs to be thoroughly revised in many aspects.
Abstract:
- Usage of acronyms may be avoided in abstract when used first time.
Introduction:
Lines 55-57: Do you mean that Mt. Waliguan station alone has continuous measurements in comparison to the Lin'an Regional Background station, Beijing city, Xi'an city etc.? Clarity is missing in the statement.
Is Mt. Waliguan station located on Qinghai Plateau? (or) How is Waliguan station affected with the Qinghai plateau? Clarity is missing. Better to include a topography map with position of Mt. Walguan station and Qinghai plateau.
Materials and Methods:
Which detection instruments are referred in this section? What is the measurement principle? Clarity about instrumentation, principle of measurement, time resolution of observations, accuracy/uncertainty etc. are missing.
How is the "polluted" data identified and marked? Do mean "polluted" data for spurious/outlier data?
Lines 78-79: It was indicated that the "drift" was found regularly (monthly) by checking the data detected at zero point (or zero air) of the instrument. How is this drift used in the continuous observations? What factors caused this drift? It would be nice if you include a figure showing the changes in drift was for 23 years of observations.
Lines 79-80: How is the abnormal data detected?
Line 80: How are the negative values treated? What is the reason for observing negative values?
Results and Discussion
All figures and labels are not visible clearly. Quality of the figures need to be improved.
Figures 1, 2, 3 and 6: On y-axis, BC is given in µg/m3. In the text, BC mass concentration is represented in terms of ng/m3. Check the units!
In Figure 1, there is no legend to provide information on what those different lines indicate.
Line 93: '... relatively low and significantly lower ...'. Not clear about what the author wants to convey with the usage of 'relatively low' and 'significantly lower'.
Section 3.1.1: There is no mention about why there is high annual variation of BC mass concentration between 2007 and 2010 all of a sudden. What are the possible reasons for this sudden enhancement?
Table 1: Monthly/annual averages may differ with the number of observations. There is no clarity whether these averages are obtained on daily mean values within the month or all the measurements obtained during that particular month. I suggest you to include standard deviation (or) error along with the number of observations considered to calculate the same.
Figure 2: X-axis labels are not understandable. Seems they are in a different language.
Lines 133-134: How do you differentiate high and low values?
What is the scientific relevance of differences in the diurnal variation of BC concentration? Why the peaks and troughs occur? What factors control this peak or trough occurrence?
On what basis the seasonal classification is done? No clarity.
Section 3.2: What do you mean by 'Aerosol Delivery'?
Line 181: Which are those 'other sites'?
Lines 188-191: 'When wind speeds are less than 2 m/s, the BC concentration is higher' --> If this is true, then it means that there are sources in close proximity.
Line 206: Which season correspond to 'heating season'?
Figure 7: Why 96-h back trajectories were shown? Why not for a higher time? What is the rationale for choosing this time frame?
Line 298: '... ratio of black carbon aerosol ...'. Not clear!
Lines 322-324: Is BC generated by human activities alone? How is this attributed?
Line 332: 'The easterly flow in summer is equal to the westerly flow'. Unclear statement.
Reviewer 3 Report
My decision with respect to this manuscript is to reject it.
There are several problems.
First, there are severe problems with the English style. Many fragments seem more like a google translation than original written English.
Second, the subject of the manuscript resembles more a technical report than a scientific paper. It lacks scientific soundness. It makes a purely descriptive treatment of a single chemical component of the atmosphere (in this case, black carbon), which is poor content for a scientific document.
Third, the graphic quality is very low. In the worst case, authors were so careless that used mandarin characters in the axis of a plot.
The manuscript really looks carelessly written given the huge amount of problems.
Due to all these problems, I do not recommend the manuscript for publication.
