of the Paper “ A 10 – year climatology of globally distributed ice cloud properties inferred from the CALIPSO observations ”

Abstract. The present study analyzes the climatology of spatiotemporal and vertical distribution characteristics of ice clouds, including the ice cloud fraction (ICF), ice water content (IWC), and ice cloud optical depth (ICOD) for three ice cloud categories (sub-visual, thin, and opaque). Newly released level 3 ice cloud data observed from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) instrument is used for the period 2007–2016. The results revealed that the global means of ICF and IWC were found to be ~ 10 % and ~ 0.0017 g/m3, respectively. On the other hand, the latitude-and-altitude mean distributions of ICF and IWC were found unimodal in all the seasons. During summer, the peak in the ice cloud formation occurred over the equatorial region of the northern hemisphere (NH) which extended further to higher altitudes over the NH equator than the southern hemisphere (SH). However, the opposite was observed in the cold season. This is mainly related to the strong convective activities in tropical areas, variation in the distribution of land and ocean between NH and SH, and the seasonal migration of the inter-tropical convergence zone (ITCZ). Furthermore, the ice clouds detected during the nighttime in summer occurred at high frequency over the SH high-latitude regions, owing to the polar stratospheric clouds (PSCs). The occurrence of sub-visual ice clouds (ICOD 


Due to the concerns expressed in the Specific comments section of this review, the paper falls in the "Good" category. Revision is necessary prior to publication.

Specific comments
Though the calculations are useful, I do not know a) How the calculations compare to previous published calculations, and b) What is "new and innovative" in the results presented in the paper.
For these two reasons, the paper is problematic. The authors need to address these issues prior to acceptance of the paper.
In the Introduction (line 92, page 4) the authors state that previous studies (6 studies, see lines 89-90) "are not sufficient". Why are those papers "not sufficient"? What does the current paper achieve that was not achieved by previous papers? Please answer these questions without stating an unsubstantiated negative value judgement.
In the Summary and Conclusions section, there are no references to the previous literature. What are the commonalities (and differences) between the current calculations and the previous literature? Add a paragraph or two, with references, to address this concern in the Summary and Conclusions section. The use of the phrase "On the other hand" is confusing, since it is commonly used to make a contrast, and the sentence if it is used in (line 42) does not make a contrast to the previous sentence.
Though the English in the text is generally good, there are several lines in the text which should be revised: Line 47, page 2: change "strong convective activities" to "strong convective activity" This comment also applies to lines 192 and 213.
Line 111, page 5: change to the "A-train" constellation of satellites Line 131-136, page 6: change to The Level 1 CALIOP data file contains 532 nm parallelpolarized and 532 nm perpendicular-polarized attenuated backscatter coefficients. The attenuated backscatter coefficient at 1064 nm is also used to produce the level 2 data file products, given the CALIOP measurements and several algorithms. Line 189, page 9: change to storm activity Lines 206-209, page 10: change to coverage of ICF generally exhibited a vertical profile with a single peak, with the peak under the latitude-independent tropical tropopause altitude, followed by a peak decreasing in altitude steadily towards both the SH and NH polar regions.
When I first looked at Fig. 3, I asked myself the question: "Why are the nighttime ICF larger than the daytime values?" Though there is discussion later in the text (lines 248 and 373), it would be good to tell the reader that a discussion of this matter is discussed later in the text. Is the nighttime and daytime differences a measurement artifact or a cloud microphysics issue? Are nighttime temperatures less than daytime temperatures? Some reference to the previous literature would be helpful.
For Figure 1, page 31, the color scale goes up to 0.5, while the data is mainly from 0 to 0.3. The authors should consider redoing the graph with a color scale from 0 to 0.3 For Figure 2, page 31, the color scale goes up to 0.01, while the data is mainly from 0 to 0005. The authors should consider redoing the graph with a color scale from 0 to 0.005 Line 232, page 11: Use the same g/m 3 units in the text as in Figure 5.
Line 235, page 11: I did not understand what the "spike-shaped structure" refers to. From previous CALIPSO papers, this structure is likely identified with a physical feature. Refer to the literature to make the structure less mysterious. (Is it related to the melting-band lidar backscatter feature, or something else?) Line 238-240, page 11: The sentence is not clear. Please revise. The term "we excluded the maximum" is not clear.
Line 328, page 15: change to during night compared to day.
In Figure 8 (page 37), it may be better to graph 100 (# night observations -# day observations) / # night observations instead of # night observations -# day observations. Line 387, page 18: The phrase "the values of these parameters were obtained from the CALIPSO platform" implies that the RH and temperature profiles are measured by the CALIPSO experiment. It would be better to state that auxiliary files specify these profiles. Please specify the origin of the auxiliary files.