Near-surface temperature inversion during summer at Summit, Greenland, and its relation to MODIS-derived surface temperatures

Adolph, Alden C.; Albert, Mary R.; Hall, Dorothy K.

doi:https://doi.org/10.5194/tc-12-907-2018

Articles | Volume 12, issue 3

https://doi.org/10.5194/tc-12-907-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/tc-12-907-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 12, issue 3

Research article

|

14 Mar 2018

Research article |

| 14 Mar 2018

Near-surface temperature inversion during summer at Summit, Greenland, and its relation to MODIS-derived surface temperatures

Alden C. Adolph, Mary R. Albert, and Dorothy K. Hall

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Final revised paper (published on 14 Mar 2018)
Supplement to the final revised paper
Preprint (discussion started on 23 Oct 2017)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Review of "Near-surface thermal stratification during summer at Summit, Greenland, and its relation to MODIS-derived surface temperatures"', Anonymous Referee #1, 07 Dec 2017
RC2: 'Review of ‘Near-surface thermal stratification during summer at Summit, Greenland, and its relation to MODIS-derived surface temperatures’ by Adolph et al.', Anonymous Referee #2, 12 Dec 2017
AC1: 'Author Response', Alden Adolph, 16 Jan 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Alden Adolph on behalf of the Authors (16 Jan 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (18 Jan 2018) by Michiel van den Broeke

RR by Anonymous Referee #2 (22 Jan 2018)

RR by Anonymous Referee #1 (30 Jan 2018)

Suggestions for revision or reasons for rejection

General comments:

The revised manuscript answers satisfactorily to my previous comments and is now clear and nicely structured. I have just few more comments regarding the writing or elements that are still missing the analysis.

Specific comments:

It should be mentioned somewhere that this study does not include surface temperatures close to melting point. It means that the timing and duration of melt detected by MODIS LST is still not validated with surface measurements. Potentially, it was done with 2m air temperatures as proxy in previous studies, but your study shows that this proxy is not performing well.

l. 24 “during summer months”: You do not have enough data to conclude on ‘summer’ conditions in general or even for summer 2015. Please consider more conservative ‘during our study period’ or similar.

l.24 “after additional cloud masking”: Please also give the performance with standard MODIS cloud masking as it is the one future users of MODIS LST will use.

l.42 “Furthermore, the energy balance ….” The following sentences are unclear and fail to link the general context given previously to your studied topic: surface temperature. L.48 In the same way you state that surface temperature is a critical variable but do not go into details. Consider being more specific about how and why surface temperature is important (tracking melt, heat exchange with atmosphere, firn warming/cooling …) to show better the motivations of the study.

l.65 “is defined by…” very bad definition of the process at the core of your study: Inversion is not defined by measurements. It can be detected with them (and not only at two levels). The sign of the temperature difference also matters. Please rephrase.

l.74 “… these two temperatures generally agree well …” seems like Good (2016) did not find any inversion over snow? Is that right? Then more explanation about why some studies detect inversion and some do not would be useful.

l.76 This paragraph is redundant as it defines again thermal inversions and its drivers (l.61 “In the polar regions…”), but in a much better way than previously. Consider merging with previous paragraph.

l.100 In the previous paragraph you already listed studies that detected and measured near-surface thermal inversion on the Greenland ice sheet. This paragraph shows that the same was done for Arctic sea ice which is less relevant for your application at Summit. Could be removed or relocated. As a general rule, it is clearer to go from the general (definition of inversion; measurements on land, seasonal snow and sea ice) to the specific (previous study of thermal inversion at Summit). Consider rearranging accordingly.

l. 321 “As these variables …” Out of all the assumptions that were made (atmospheric conditions and compositions, bandwidth used by MODIS vs. bandwidth used by IR sensor ...) why would cloud masking and non-synchronicity be the main source of divergence? You stated that non-synchronicity would act as random noise, why would it now explain a small negative bias? From your result it is indeed visible that imperfect cloud masking is responsible for part of the negative bias. But why is that? Can you please explain and interpret?

l.338 “This indicates ….” More discussion/interpretation is needed from this comparison. Are these numbers satisfactory? Would you recommend changing the MOD35 threshold? Or would that lead to too much false negative. How to choose?

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ED: Publish subject to technical corrections (30 Jan 2018) by Michiel van den Broeke

AR by Alden Adolph on behalf of the Authors (06 Feb 2018) Author's response Manuscript

Short summary

In our studies of surface temperature in Greenland, we found that there can be differences between the temperature of the snow surface and the air directly above, depending on wind speed and incoming solar radiation. We also found that temperature measurements of the snow surface from remote sensing instruments may be more accurate than previously thought. Our results are relevant to studies of climate change in the remote sensing community and in studies of the atmospheric boundary layer.