Dear authors

Thank you for providing your responses to the reviewer comments. Please implement these changes in a revised manuscript. I will send it to refrees for another review round.

Kenny Matsuoka
TC/TCD Editor

Dear authors,

This manuscript was reviewed by two referees who requested a major revision. The revised version was reviewed by one referee who judged that the revised version addressed their concerns adequately. However, I would like to request another revision to improve clarity and readability of the manuscript. Surface melt of Greenland is a highly interesting topic for a broad range of scientists, and satellite remote sensing examined in this manuscript is one of the key observational tools over the entire ice sheet for a historic period with a high temporal resolutions.

I would like to use Table 5 as an example to explain my point. This table includes M (most left column), T, LWC1m and LWC5 cm (second column from left), and C+O on the top row. This table is cited at p.12, whereas M is defined as the January-February mean brightness temperature at p.6 (why “M”, by the way, and is it different from Twinter) and it is not cited in the main text where Table 5 is cited. T is not defined, and AWS-measured temperature is defined as Tair at P12L356. LWC is not defined but used many times. I guess “C+O” refers “total error including commission and omission” but it is not defined in the manuscript. I would add headers such as “satellite threshold” and “AWS threshold”. In this way, even if M for example is not defined in the text where this table is cited, the readers can develop good understanding of this table. And I would expand the caption to something like “Performance of surface melt detection examined with AWS data. Six thresholds (rows) are used to determine satellite-detected surface melt. For each case, algorithm performance was examined using AWS data with five thresholds to determine surface melt. Commission and omission errors are shown in percentage of the total number of days considered averaged over all the selected AWS. [add explanations for C+O and C+O mean]” For the broad TC’s readership, this level of description is necessary.

I echo reviewers’ view; this manuscript presents highly interesting and valuable science. However, my own evaluation is that readability and clarify of this manuscript should be improved otherwise the broad readership of TC cannot get the valuable science that you are presenting here.

In general, I request following changes.
1. Remove most of acronyms that do not use so often. Such terms include GrIS, SLR, CDRs, MRF, T-B, E-D, and LTOD (this is not a comprehensive list, and I request the authors to check the entire manuscript carefully).
2. When defined, use acronyms consistently and do not define other acronyms for the same term. Such terms include MAR5cm vs. LWC5cm, M vs. Twinter, and Tair vs T. These terms may refer different values; if it is the case define them more clearly and use them consistently.
3. Add definitions of all acronyms. For example, LWC, C+O.
4. Section 3.3 define many acronyms, such as MD, MMD, MMS, MI, MOD, MED, and MMS. If these acronyms are widely used in passive microwave remote sensing and use of these acronyms improves the clarify of this paper for specialists, you can keep using them in the tables and figures, but define them in the captions and minimize their use in the main text.

I made some notes below, but please carefully check the entire manuscript to fully improve the manuscript in this round. I expect comprehensive revision to improve readability, and just responding to following specific points does not constitute adequate revision that warrants the acceptance of this manuscript.

All page/line numbers refer those in the mark-up version.

Title: change to “derived from”

P1L12 and L14: do you need to define PMW? Is it better to define PMW as passive microwave at 37GHz vertical polarization?

P1L22-L24: present these numbers in a consistent manner. If you indicate the number of days to the first decimal point (e.g. 2.5 days), please do so for the both cases, instead of about 4 days and 2.5 days.

P2L2: Unit for the ice volume in Greenland is km3, not m3.

P2: Many acronyms are defined in an inefficient manner in this paper. Defined acronyms in the first few pages are GrIS, SLR, SMB, PMW, rSIR, CDRs, MRF, GC-Net. Please critically review the manuscript and remove unnecessary acronyms. For example, I don’t think following acronyms are necessary: GrIS, SLR, CDRs. Also, once it is defined please use it consistently. I see many sentences that do not use these acronyms (e.g. P3L94, P3L97, P5L141).

P3L75: Spellout MeASURes (like you did in Abstract).

P3L94-95: Revise. I cannot get the point.

P4L100: Does “estimates of surface melting” refer melting timing, duration and/or amount?

P5L130: remove coordinates of the Swiss Camp. It appears here and also Fig. 2 caption, while it is shown in Table 1.

P6L174: LWC is not defined

P6L177: T-B and E-D are defined but not used. I don’t think you need to define them.

P6L189: What’s the difference between M and Twinter? Also, Twinter is defined so please use it consistently (e.g. P7L198 says winter Tb).

P7L214: MEMLS refers the microwave emission model of layered snowpack in general, so it is confusing if MEMLS is used in two different ways. Indeed, the authors write MEMLS (LWC = 0.2%) later, which is much better to refer MEMLS for a specific case. However, P7L219 uses MEMLS(0.2% LWC). Again, please use these terms consistently. The current manuscript is very hard to read and consistent use of terms will improve readability significantly.

P8L224 and P8L234: What do you mean with “novel nature” and “novelty”?

P12L367, P12L373, P13L380: air temperature or surface temperature?

P13L385 and L387: It was defined as Delta T, not Delta T_b (P6L189).
(I stop commenting editorial issues in the main text here, but request the authors to carefully review the current manuscript and make serious efforts to increase readability of the manuscript).

Table 1: change to “…. Used to validate the results in this study.” If the table includes the sites not used in this work, remove such sites.

Table 2: Do you mean “ the sensors used for this work.”? “Selected” can be interpreted in many ways and thus confusing. Spell out IFOV in the table or at least define it in the caption.

Figure 2: Add Tb after “Brightness temperature” in the y axis label in panel a. The label April 3rd 2012 points to more than 10 days. Use an arrow, instead of circle to specify the date.  and  are not used often, so I suggest removing them and spell out mean and standard deviation every time. If it is the case, remove these values from the panel and add them to the caption. Remove Swiss Camp coordinates.

Figure 3: Is the data density (colorbar) normalized? A clarification is needed, what does the value 1 mean?

Table 3: the left top cell says platforms, but they are sensors (keep Tables 2 and 3 consistent). Spell out PMW (or at least maintain the same style whether caption uses acronyms or spell-outed full terms). Clarify whether “the difference” is T_(high-ress) – T_(low-ress) or vice versa.

Figure 4: clarify “Distance” in the caption.

Figure 5: M+DT should use symbol D. Do you need define epsilon to refer emissivity here? Also it is confusing that epsilon is used to define emissivity and the label has the upper bar to show that it is a mean value. Please minimize the use of acronyms. Remove one unnecessary arrow in panel a.

Figure 7: Add labels to all y axis. The labels show LWC in percent. If so, it is better to show y axis in percent too.

Table 6: What is “245K (MEMLS)” algorithm? Also, the table includes MAR1m MAR5cm, which should be changed to clearer acronyms. They are explained in the caption, but please use the acronyms consistently throughout the paper.

Figure 8: check the year collected these data. Caption says 1984 and 2006, but the table labels say 1983 and2005.

Figure 9: Explain solid and dashed lines in the panel. Also consider spelling out all y label terms, or at least define them in the caption. Does panel b show the values in percentage? If so, clarify it in the y axis label.

Thanks for submitting the revised version. Readability and clarify of the manuscript are largely improved, though my final reading found following issues that need to be considered as technical corrections in the final stage. If any of the following points are unclear, please contact me. Otherwise, the manuscript is accepted subject to technical corrections.

Kenny Matsuoka
TC/TCD Editor

All page/line numbers refer the marked manuscript.

P4L111: Change the current Table 2 to Table 1 and cite the new Table 1 here.

P5L130: remove blue and red (explained in the figure caption, which is enough)

P5L134: remove the reference to Figure 2.

P5L150: Because of swapping the order of Table 1 and Table 2, here it should be “… in Table 2”.

P5L157: non-capitalize Soil/Ice Vegetation Atmosphere Transfer.

P6L169: “…. Along the vertical profile of snow from the surface to 5 cm or to 1 m”

P6L191: “LWC, snow density”

P7L221: Change Table 2 to Table 1

P11L323: “the sum of the two Commission and Omission errors”

P11L331: “0oC”

P13 – P14: Improve clarify. I think NSE values (L416), values of NSE (L417), Nash-Sutcliffe Efficiency coefficient (L444) refer the same value and then it is always write it down as NSE coefficient.

P14L421: remove “(ME)”

P14L441: apostrophe after timeseries?

P14L444: change Nash-Sutcliffe Efficiency to NSE

P15L461: remove “(MOD)”

P15L463: Supplemental figures S2, S3, S4 and S5 are cited altogether. Please cite individual supplemental figures, with a short description what each figure presents.

P16L488-489: is it in Figure 9d or Figure 11?

P16L493: Change to “MEMLS between 1979-2017 …. And MEMLS between 1998-2012”

P17L526: change Figure 12 to Figure 11 (there is no Fig. 12)

P17L531: Change Fig. 12 to Fig. 11

P17L545 cite Fig. S5 after “in August”

P18L547 and L549: does “autocorrelation” refer the range specifically or more generally the autocorrelation features? If the former is the case, please change it to range.

P18L573: change to LWC

P18L562ff: it is confusing to see enhanced dataset, high resolution dataset etc in this section. Define the term at L532 (e.g. “3.125 km resolution 37 GHz horizontal polarization PMW Tb, called higher-resolution dataset”) and use this term consistently.

P19L581-582 and 591, 595: reverse changes to MOD, MED, MMD, MMS and MD (some readers read conclusions first and extensive use of these terms does not help such readers).

Table 1 and Table 2: swap the order.

Figure 2 caption: at the very ends “mean equals …. Standard deviation equals to….”

Table 3: in the top row, change “SMNR vs F08”, “F11 vs. F13 (Evening)” or such like Table 4.

Figure 4: Add the unit of distance (m?). Also, change first, second and third rows to left, center and right.

Table 6 caption: change to “Nash-Sutcliffe Efficienty (NSE) coefficients” and change MOTE to Mote, 2014.

Figure S5: add “Table 7 reports range, sill, nugget and R2 values of these semi variograms.”