|The manuscript “WHU-SGCC:A novel approach for blending daily satellite (CHIRP) and precipitation observations over Jinsha River Basin” by Shen et al. describes an approach to blend and homogenize daily satellite (CHIRP) and precipitation surface observations over Jinsha River Basin. The approach is named WHU-SGCC.|
The manuscript “WHU-SGCC: A novel approach for blending daily satellite (CHIRP) and precipitation observations over Jinsha River Basin” by Shen et al. describes an approach to blend and homogenize daily satellite (CHIRP) and precipitation surface observations over Jinsha River Basin. The approach is named WHU-SGCC.
The manuscript is quite well written though sometimes it is too schematic and should be instead, to my opinion, more discursive. The manuscript is in the scope of ESSD. However, I suggest below a few potential major revisions of the manuscript along with specific line-by-line suggestions or corrections.
1. The introduction of the dataset underlines the central role of the observations used as the “reference dataset” to build up the homogenized dataset with the needed bias adjustment. Nevertheless, surface rain gauge observations at present have a very low level of metrologic and uncertainty characterization, therefore the manuscript can benefit from a more accurate description of the real and potential limitations due to the use of rain gauge observations as the reference for the homogenization of other rain gauge data.
2. Table 6 and 7 allows the reader to quantify the better performances WHU-SGCC dataset compared to CHIRP and CHIRPS for rain event included in the class 0-10 mm, the moderate improvement for the in 10-25 mm class, while, as the authors themselves discussed in the manuscript, performances are negative for rain events larger than 25 mm. Though this class of rain events contains a minor number of events, the authors should discuss in the manuscript if this might indicate that extreme rain events in the Jinsha River Basin are attenuated in their intensity by the adopted homogenization approach.
3. The authors should comment more on the effect of and the reason why the pixel spatial autocorrelation (and the temporal autocorrelation only within the same season of the same year) is not considered and how its study can help to improve the quality of their results.
4. Table 6 shows that most of the data belongs to C4 pixel category (55-60% of the total dataset), given that these data are homogenized using the IDW technique based on the neighboring observations, the authors should clarify if the application of this technique on the majority of the dataset can smooth out extreme events (very low or very amount) due to the smoothing introduced at the C4 pixels. Moreover, it could be helpful to the highlight the position of C1-C3 pixels in Figure 4 to allow the reader to check the position of that part of the dataset where data homogenization is likely more robust.
5. In Figure 4, the spatial distribution of those statistical indicators used to study the WHU-SGCC performances is shown. It would be interesting to compare the results in Figure 4 with a similar figure showing the statistics for CHIRP. Though it is true that several table already summarizes the results of the statistics for WHU-SGCC, CHIRP and CHIRPS, a comparison of the reported statistics at the spatial level is missing.
6. The statistical analysis shows that CHIRPS is worse than CHIRP in terms of variability but similar in terms of bias: the authors should clarify what is the role of the representativeness uncertainty in the merging of gridded and in-situ point observations as happens in CHIRPS.
Line 11: please here and throughout the manuscript you cannot state that random errors are “removed”. I also encourage to have a consistent use of the terms “error” and “uncertainty”.
Line 21: replace “the” with “a”.
Line 62: it looks clear that the Jinsha River Basin is a region of interest for monitoring precipitation, not only for the authors; however, in order to justify the relevance of the dataset presented in the manuscript, it could be appropriate for the authors to say something more general about Jinsha River Basin and the interest to focus on this region as a special place to monitor monsoon precipitations.
Line 71: gauge-satellite fusing means “combined gauge-satellite products”?
Line 76: please check the style to report citation in the text.
Line 102: please add “weather and climate variations” instead of only climate.
Line 117-118: Discuss in more detailed the limitation of your “reference” dataset, here in the text.
Line 131: what does it indicates the word “strict” here? Please be more specific because this is critical to learn more about the data quality used as “reference” in your approach.
Line 159: “longer length” instead of “longer-term”
Line 195: This sentence should be supported by metadata, a reference, maps, or photos.
Line 196: Are you assuming that there are no outliers? Please explain more.
Line 219-220: these seems to be a repetition of previous text, please check.
Line 246: can the authors validate their cluster analysis with a GIS map, for example, showing the terrain features?
Line 295-296: “Excluding the C1, C2 and C3 pixels, the number of remaining pixels, called C4 pixels which are adjusted by Inverse Distance Weighted (IDW)” there is something in this sentence.
Line 321-322: the word strength here is incorrect. SCC measures if a process is linear or not, you cannot infer more than this.
Line 350: To perform the accuracy evaluation, did you use the 30% of in-situ observation mentioned at the beginning? From this section, this is not clear and how this fraction of observation was selected, is it nor clear as well.