Concept Development and Risk Reduction for MISTiC Winds, A Micro-Satellite Constellation Approach for Vertically Resolved Wind and IR Sounding Observations in the Troposphere

Round 1

Reviewer 1 Report

The manuscript describes the development and testing of a satellite system designed to observe atmospheric thermodynamics and wind structure, developed to address inadequacies in current satellite retrievals (cost, resolution and sampling limitations of measurements) through the use of constellations of multiple small satellites. The authors provide enough background material to illustrate how their design addresses specific goals for improving these satellite retrievals, and they provide a substantial amount of information about the design and testing results, including results from a version of the instrument modified to be tested aboard an aircraft.

The manuscript is largely well-written. It is dense with information, but generally the text presents the material understandably. Some suggestions are given below to add clarity to various sections, but the text should be publishable with only minor changes. However, the figures are the primary area where some additional work is needed - some are confusingly presented, and many are lacking in details (both in the figures themselves and their captions) which would substantially help them to support the material in the text. Specific details in both areas are given below.

Title - Suggest expanding the phrase "an Iip Summary" or rewording to eliminate it, as it is not an acronym that every reader will immediately recognize.

Line 37 - Similarly, "OSSE" should probably be clarified here, as it is later in the main text.

It's also noted that "MISTiC" is used multiple times throughout the title, abstract, and main text before it is defined. More generally, the text is very dense with acronyms, some specific to this project and many related to the field in general. It would be worth considering a table summarizing the ones used most commonly throughout the main text to avoid confusion for the reader.

Lines 171-173 - Unclear if some text is missing from the first sentence or if the two sentences are intended to be combined.

Lines 199-203 - The sentence describing the "Optical Flow" method is ambiguous as to whether it is only briefly mentioned in passing or if it is more fundamentally related to the measurements and strategies mentioned subsequently, and should be clarified.

Lines 234-235 - Suggest editing the text so it more directly corresponds to the SWAP-C acronym (or this could just be removed unless there is a specific point in referencing it, since it does not seem to be referred to again).

Line 677 - Note that the text refers to Figure A1 well before the appendix itself.

Lines 716, 731 - Please double-check the figure references in general, e.g. the references to Figures 6 & 8 in these lines.

Figure 1 - This figure is rather confusing, aside from generally representing several constellations of satellites in orbit. I believe it's indicating specific groups of satellites for the wind and thermodynamic measurements, but the labels and arrows are confusingly ambiguous.

Figure 2 - The text on the figure is a bit difficult to read. Additionally, it would be worth expanding the caption to more clearly indicate what the figure shows, and that it is an illustrative example from an existing satellite instrument.

Figure 3 - The arrow indicator at the top left is missing a caption. Additionally the inset image to the right side is nearly impossible to read.

Figure 4 - The figure overall is overly complicated with multiple sets of labels and bullet points. The overlaid labels alone are readable, but the material in the list of points to the right would be conveyed better in the caption and main text, as appropriate. Additionally, perhaps something such as "Spectral Frequency" for the x-axis label would be less ambiguous, since "Frequency" alone often indicates a temporal frequency. Finally, for this and subsequent technical figures, I'd suggest that the captions would better be focused on the specific parameters shown in the figure, rather than a descriptive sentence.

Figure 5 - Similarly, this figure would be more readable if the summary analyses were confined to the main text, and the caption focused on describing what is presented in the figure. The label showing the spectral ranges for each line color with larger text are appreciated, the additional text and numbers present in each figure are too small to read so it is unclear if they are relevant. Additionally, the caption should explicitly include the source used for "Truth" in these comparisons.

Figure 6 - The figure caption should more explicitly describe what instrument is in each panel.

Figure 7 - There are extraneous pieces of text at the bottom of each figure and in the upper label for the left panel. The captions within each panel are also a bit messy to read - a larger and/or thinner font style would help.

Figure 12 - The figures themselves are nearly at the limit of readability, suggest trimming down the amount of text and expanding the data plots.

Figure 13 - Similarly, the upper plot in particular is small enough that text and details are nearly impossible to decipher. Providing more distinct axis labels on both plots, and a more detailed description of the two inset sweeps would substantially help the reader to interpret this figure.

Figure 15 - The material in this figure is confusingly presented. It would likely work better as a longer text description or flowchart rather than another list of bullet points.

Figures 15, 17 and 18 - The hyperspectral imagery would substantially benefit from more contextual information in the plot labels and captions - some of this is given in Figure 15, but it is very simple and generalized.

Author Response

Our response to Review 1 is in the separately attached document.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors, in the attached files, you can find some specific comments on your manuscript.

Apart from them, I encourage you to shorten the current version of your article as it is very long and hard to read. Focus on the most important things that you want to present and avoid unnecessary figures and paragraphs.

Comments for author File: Comments.docx

Author Response

Response to Reviewer 2 provided in the attached document, which embeds our response with theirs, in a separate color.

Author Response File: Author Response.docx

Reviewer 3 Report

Major comments:

With the emphasis on this type of mission in the Decadal Survey and the Weather Focus Area Workshop, this is an important paper to be published.

Most of Sec. 4 (Risk Reduction) on the hardware should be removed, or moved to an appendix. However, Sec. 4.4 should remain in the main text (especially the first half on deriving the cloud motion). May want to move L737 to L785 to an appendix as it has little to do with the AMVs.

L809-810, L824: Not convinced that < 2 m/s RMS compared to sondes is attainable based on (a) height assignment error in Table 2; (b) spatial resolution on orbit (1.38 km at nadir) should result in a much larger AMV RMS compared to tracking a feature from the ER-2 altitude (what is the spatial resolution? Perhaps, I missed it in the text). Some related questions below in minor comments.

Minor comments:

Many acronyms are not defined, or not defined when first used:

NWP, MISTiC, IASI, CrIS, IFOV, ABI, GIFTS, HES, ESPA, s/c, JPSS, MMV, CMV, LWIR, VLWIR, IIP

Should ‘-‘ and ‘--' be replaced by commas? Dashes seem non-standard.

Should be consistent with ‘space craft’ vs ‘spacecraft’

Many figure captions have the first letter in each word capitalized.

L98: AQUA or should it be Aqua

L167: AMV

L172: LIDAR,

L192: Orbit period for NOAA polar satellites, Terra, Aqua is closer to 99-100 minutes

Fig. 4: Many details on right side of figure with no explanation; perhaps crop that out.

L268: Superscript 20 apparently not used

Fig. 5: Text in upper half of figure is not readable

Table 1: Heading has ‘Characteristics’, caption has ‘Requirements’. Are they really the same?

Table 2: Very interesting requirements; is there a reference(s) for the table? Can MISTiC meet those requirements, because in Table 1 there is a 1km vertical resolution, which corresponds to 70 hPa in the mid-troposphere; so can you get < 30 hPa height assignment accuracy? Also, one AMV per 6 km square seems like a very high density, especially if there is only one sounding every 6 km square. Additional explanation in these areas would help.

L335: temperature

L403-404: The URL to reference 21 is not valid. I was able to find the document elsewhere, but couldn’t find mention of the 2 m/s RMS. Could that be from another reference? Also, given the temperature and humidity errors in table 1, is the height assignment error going to be significantly better than from cloud tracking in imagers?

L491: Office is last letter in GMAO

Fig. 15: From the description, I conclude the cloud motion is 13.2 m/s at an altitude of 2.7 km. Then, when I look in the upper-left panel of Fig. 16, the rawinsonde wind speed at 2.7 km is < 5 m/s. Or, since the ground is at 0.7 km, should the speed be compared with sonde at 2.0 km, which is about 11 m/s?

Fig. 16: I see one dot at 0.7 km and 9 m/s in the upper-left; two dots in the upper-right: 0.7km at 70 deg., 2.7 km at 350 deg. Can those dots be made a different color and labeled, or described in the figure caption?

L731: Reference to Fig. 8 does not seem correct.

L760-761: Break in sentence?

Author Response

Author response to review 3 in the attached document, with our response in red font.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

All of my remarks have been incorporated, and I'm happy with the changes. In my opinion the manuscript is now ready to be published. 

Author Response

Thank you for the careful review.

Reviewer 3 Report

It’s good to see a lot of the hardware details are moved to an appendix

There are still several typos:

L187: AVM should be AMV

L241-243: I assume this is the Fig. 1 caption; it still contains each word beginning with capitals.

L254: “that available”, perhaps should be ““than available”

L270: “, (or optical flow methods),” shouldn’t have both commas and parentheses

L307-313: The bulleted statements have capitalized words throughout. Why?

L325: “illustratess”

L363: “An important requirements” shouldn’t be plural

L375: VLWIR first used, but not defined until L1026

Author Response

Reply is found in the attached document.

Author Response File: Author Response.docx