A revisiting of the parametrization of downward longwave radiation in summer over the Tibetan Plateau based on high-temporal-resolution measurements

Liu, Mengqi; Zheng, Xiangdong; Zhang, Jinqiang; Xia, Xiangao

doi:https://doi.org/10.5194/acp-20-4415-2020

Articles | Volume 20, issue 7

https://doi.org/10.5194/acp-20-4415-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Study of ozone, aerosols and radiation over the Tibetan Plateau...

https://doi.org/10.5194/acp-20-4415-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 20, issue 7

Technical note

|

16 Apr 2020

Technical note |

| 16 Apr 2020

A revisiting of the parametrization of downward longwave radiation in summer over the Tibetan Plateau based on high-temporal-resolution measurements

Mengqi Liu, Xiangdong Zheng, Jinqiang Zhang, and Xiangao Xia

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Final revised paper (published on 16 Apr 2020)
Preprint (discussion started on 06 May 2019)

Interactive discussion

Status: closed

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

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RC1: 'Review of acp-2019-397', Anonymous Referee #1, 13 Jun 2019
- AC1: 'Reply to the first reviewer', Xiangao Xia, 03 Aug 2019
RC2: 'Liu et al 'A revist...'', Anonymous Referee #2, 23 Jun 2019
- AC2: 'Reply to the second reviewer', Xiangao Xia, 03 Aug 2019

Peer-review completion

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

AR by Xiangao Xia on behalf of the Authors (03 Aug 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 Aug 2019) by Yan Yin

RR by Anonymous Referee #3 (25 Aug 2019)

Suggestions for revision or reasons for rejection

General Comment：The change of land-atmosphere interaction on the Tibetan Plateau has a significant impact on the climate of China and even the whole world. However, due to the high altitude and harsh climate condition, there are few observations and a poor applicability for the empirical models parameterized in other regions. This paper used the measurements with the high temporal resolution to calibrate the parameterization of empirical models for downward longwave radiation, to improve their applicability in the Tibetan Plateau. This paper is expected to provide a useful reference for scientists working on the land surface energy balance over the Tibetan Plateau. To make this paper suitable for publication, please address satisfactorily the specific comments I have appended below.
Major Comments:
(1) The biggest flaw in this article is the lack of validation. The author used observation data to optimize the parameterization of the data, but did not use other observation data to conduct effective verification. The dataset used to optimize models were not independent from the dataset to verified models, which seriously affected the credibility of the validation.
(2) The change of cloud cover during the day is analyzed based on the downward shortwave radiation, but the change of cloud cover at night is not involved. The authors should examine whether there are significant differences in the amount of cloud cover over the Tibetan plateau between day and night.
(3) The main content of this paper is to adjust the parameters of the empirical model so as to improve its performance in the Tibetan Plateau. However, the process of parameter optimization is not introduced in detail in this paper. We want to guide whether there is some physical significance to the parameters adjustment, or what is the selection criteria for you to finally choose those parameters, and whether those parameters are optimal or not.
Minor Comments:
(1) Table 4 and table 5 should be combined into one table for easy comparison.
(2) Equation 5 is a very interesting highlight of this paper. In previous studies, it was believed that the cloud base height had a very significant impact on the change of downward long-wave radiation, but most empirical models did not consider the cloud base height due to the lack of observation. However, there are limited introduction and verification for the Equation 5. Therefore, I hope the author can add some graphs and tables to introduce this part in detail.
(3) Fig 3 shows that, compared with Zhu's research results, the two are mainly the difference in intercept, which mainly depends on the calibration of initial value and has no great significance for the study of variabilities of DLW.

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RR by Anonymous Referee #4 (05 Sep 2019)

ED: Reconsider after major revisions (02 Nov 2019) by Yan Yin

AR by Anna Wenzel on behalf of the Authors (05 Dec 2019) Author's response

ED: Referee Nomination & Report Request started (31 Jan 2020) by Yan Yin

RR by Anonymous Referee #5 (03 Mar 2020)

RR by Anonymous Referee #6 (13 Mar 2020)

Suggestions for revision or reasons for rejection

The manuscript evaluated and locally calibrated 11 clear-sky and 4 cloudy DLR parameterizations using high temporal resolution radiation measurements over TP in summer months. Three methods were combined to discriminate clear sky from clouds, which play an important role in improving the accuracy of parameterizations. The influence of CBH on DLR under overcast conditions was analyzed and a parameterization considering CBH was introduced. The topic is of sufficient interest to the communities of study on solar modelling and climate change. I recommend this paper for publication after revision.
Comments:
1. “W•m-2”, “Wm-2”, and “W/m2” appear in the manuscript and they should be unified.
2. Line32: Is the overestimation of clear-sky DLR found in one pervious study or some studies? The statement should be changed to “in one previous study” or “in previous studies”.
3. Line 56: If “those remote regions” refer to some particular regions?
4. The abbreviation “T” refers to screen-level temperature in Line 64 and air temperature in Line 295. Different abbreviations should be used.
5. Line 97: Two predicate verbs appear in one sentence.
6. Line 105: Change “of highly significance” to “of high significance” or “highly significant”.
7. Line 120: Change “root mean square” to “root mean square error”.
8. Line 151: Change “make it having” to “make it have”.
9. Line 157: If you want to express “side-by-side”?
10. Line 161: What does “the dataset” refer to?
11. Line 187-188: The machine model of Cimel sunphotometer is usually expressed as “CE-318”.
12. Line 188-189: Why did the authors adopt the same Angstrom wavelength exponent and Angstrom turbidity in NQ as that in AL? Please confirm the rationality. In addition, the rationality of adopting mean SSA in Lhasa should also be explain.
13. Line 189: Units of latitude and longitude should be added.
14. Line 228: Change “an abruptly changes” to “an abrupt changes”.
15. Line 262: Change “Previous studies suggests” to “Previous studies suggest”.
16. Line 283-285: It is suggested to explain the bad performance of parameterization proposed by Swinbank (1963) and Idso and Jackson (1969).
17. Line 371: References are needed.
18. Line 388-289: Change “introduce” to “introduction” and “significance” to “significant”.

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ED: Publish subject to minor revisions (review by editor) (13 Mar 2020) by Yan Yin

AR by Xiangao Xia on behalf of the Authors (16 Mar 2020) Author's response Manuscript

ED: Publish as is (19 Mar 2020) by Yan Yin

AR by Xiangao Xia on behalf of the Authors (20 Mar 2020) Author's response Manuscript

Short summary

This study uses 1 min radiation and lidar measurements at three stations over the Tibetan Plateau (TP) to parametrize downward longwave radiation (DLR) during summer months. Clear-sky DLR can be estimated from the best parametrization with a RMSE of 3.8 W m^-2 and R² > 0.98. Additionally cloud base height under overcast conditions is shown to play an important role in cloudy DLR parametrization, which is considered in the locally calibrated parametrization over the TP for the first time.