Characterisation and Field Test of a Simple AvaSpec Array Spectroradiometer for Solar Irradiance Measurements at an Alpine Site
Round 1
Reviewer 1 Report
The manuscript aims to provide a first comprehensive characterization of the AvaSpec ULS2048-LTEC CCD array-based spectroradiometer acquired by the ARPA institution. It presents an exhaustive description of the different calibration and measurement correction steps followed to obtain reliable values. The study investigates the performance obtained with different calibration references: Bentham spectroradiometer calibration transfer, 200 W lamps and 1000 W lamps; and compares their performance in three different mini-campaigns. It investigates the capabilities of the instrument to provide UVI and GHI values in comparison with the integrated UVI from Bentham spectra and with measurements from a CMP21 pyranometer, respectively.
The topic discussed in this article is of great interest to the field. CCD-array spectrometers are a very promising alternative to conventional scanning spectroradiometers, and should be studied in depth in order to advance in the standardization of the characterization and calibration procedures that can guarantee the quality of their measurements and, therefore, favor their wider use in the future. In this sense, the work represents a substantial contribution to the understanding and correction of the issues of the AvaSec spectrometer. This type of instrument is quite novel and there are no established standard calibration protocols. Therefore, the description of the processes carried out and the results obtained by the authors are of great value. It is noteworthy that the authors address the difficulties of the novelty of the instrument, whose issues are not sufficiently studied, and deal with them satisfactorily.
The main problems of the study refer to some issues shown by the performance of the instrument, which hinder its regular use, such as artifacts and non-real peaks (which the authors suggest to be related to condensation inside the cooling box), and instability in the response. However, these issues are well described and some solutions are suggested and applied, turning them into interesting contributions to the knowledge of the instrument's capabilities.
The methodology is adequate, sound and well supported by previous studies. The references cited are appropriate, up to date and well selected. The article is very well structured and written. The problems encountered are described in great detail, followed by a thorough and interesting discussion of each problem. These discussions are clear and well supported by current knowledge on the subject. The detailed description allows reproducibility by other authors. In addition, the figures clearly show the data and are of great help to the reader in understanding the research. The conclusions are well supported by the data and by the discussions throughout the manuscript.
Author Response
We would like to thank the reviewers for taking the time and effort necessary to review the manuscript. We are very grateful for the positive comments from reviewer 1, who recognised the efforts leading our research.
Reviewer 2 Report
The manuscript is very well written and all aspects of such complex research are highlighted. Two recommendations are considered for the improvement of this manuscript:
1.A comparative analysis of the results obtained by this study of this array spectroradiometer with other published results of similar devices presented in the literature in the last years
2 More details regarding the implementation analysis of this array spectroradiometer for industrial applications.
At the same an English proof reading has to be introduced especially regarding the English style and grammar of the article text.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 3 Report
This paper presents Characterisation and field test of a simple AvaSpec array
Spectroradiometer for solar irradiance measurements at an Alpine site. The presentation of the
submitted manuscript requires minor improvements. This reviewer would like to see the effort
of the authors to revise the paper and addressing the following questions:
1. The authors should revise the discussion in literature review. In particular, this reviewer
cannot distinguish that how the new equipment discussed in this paper is better as
compared to existing methods/approaches in the literature.
2. The literature review section need to be extended by including recent applications of
Spectroradiometer systems and their implementation in solar systems.
3. Add aims and objectives to introduction section.
4. Schematic Diagram of the proposed equipment needs to be included.
5. The conclusion is very lengthy. This reviewer strongly suggest to reduce conclusion
section and highlight the main points.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
