The manuscript aims to describe the data collection, quality control and organization during YOPP at seven sites located in the Arctic. The motivation is to have a database that is organize in a manner to facilitate the evaluation of numerical weather prediction (NWP) models. The manuscript is well-written, but some information is missing, and some should be clarified. For the database, most of the databases seemed to still be under development are not available yet to be used for publications.

Major comments:

1. The abstract contains long sentences (ex: Lines 30-33; line 37-42) and the aim of improving numerical weather prediction (NWP) is also mentioned twice. The abstract should be improved for clarity and to summarize the material presented in the manuscript.
2. The goal of the study should be clarified. While reading the manuscript, I thought that the dataset also included the model outputs, but it is only the field measurements. To improve this, the paragraph starting at line 89, could be divided into 2. One paragraph about the MODF files and a shorter paragraph stating the goal of the manuscript. Also, is a little long and could be shorten. The first few sentences 107-111 seemed to be out of place. Should it be justifying the need to describing such database and, therefore, placed before stating the goal of the study. Additionally, when reading the conclusion, it seems that the authors are doing 2 things: 1) describing a new database and 2) describing a new way to organize/compress data. The goal should probably reflect this because there is a section in the manuscript describing the type of file.
3. Description of the sites (section 2). I suggestion to use a standard structure for the description of each site. For example, the first sentence of the Whitehorse site is about the platform and instruments while not other site description has this information, at least at the beginning of the section. For each site, 1) there should be a photo of the site with the instruments used, 2) short geographical description, 3) the climatology and 4) other relevant information about the site. Since that the manuscript describe field data, photos of the sites/instruments should come before the grid points used by NWP.
4. Figure 2 should probably be later in manuscript when the authors describe the structure of the datasets in sections 4 and 5 to not confuse the field data and the model data.
5. The authors should carefully double check the use of full name/acronyms. These are most of the minor comments below.

Minor comments:

1. Line 119: The sentence can start with “To properly...” and “It is important” can be deleted.
2. Line 177: Add DOE in parenthesis after “Department of energy” and one can use the acronym later.
3. Line 178: Define NOAA here and use the acronym later.
4. Line 193: Use NOAA instead of the full name.
5. Line 194: FMI is already defined.
6. Line 271: I wonder if the author should add a Table to describe these. Then, the reader does not have to download the data to get the information.
7. Lines 338 and 339: Use "m" instead of “meters”.
8. Line 340: Add commas between “respectively”.
9. Line 341: Change “2” for “two”.
10. Line 347: The beginning of the sentence is awkward. Just start the sentence with “The present phase...” and add “used” after “concept”?
11. Line 385: DOE/ARM already defined no need to write the full name.
12. Line 464: I suggest removing “excellent”.
13. Line 522: Use the acronym because they are already defined.
14. Line 549: Delete “see” in front of Figures 3 to 6 and use e.g. instead? One can also delete “as an example”.
15. Line 550: Delete “see”.