the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 08 Dec 2023
Air temperature changes in SW Greenland in the second half of the 18th century
Abstract. The thermal conditions of south-western Greenland in the second half of the 18th century were estimated using two unique series of meteorological observations. The first series (Neu-Herrnhut, 1st Sep 1767 to 22nd Jul 1768, hereinafter 1767–68) is the oldest long-term series of instrumental measurements of air temperature available for Greenland. The second (Godthaab, Sep 1784 to Jun 1792) contains the most significant and reliable data for Greenland for the study period. The quality controlled and corrected data were used to calculate daily, monthly, seasonal and yearly means. The daily means were further used to calculate day-to-day temperature variability (DDTV), thermal seasons, growing degree days (GDD), air thawing index (ATI), positive-degree days (PDD) and air-freezing-index-degree days (AFI).
Air temperature in Godthaab (now Nuuk) was, on average, warmer than the present day (1991–2020) in 1767–68 and colder in 1784–92. Compared to the Early Twenty Century Arctic Warming (ETCAW) period, the data for the two sub-periods show that the late 18th century was as warm or even warmer. Except winter 1767/68, winters and springs in the study period were longer, while summers and autumns were shorter than at present. The analysed climate indices usually do not exceed the maximum and minimum values from 1991–2020. Mean daily air temperature in studied historical periods rarely exceed ±2 SD of the long-term mean calculated for the contemporary period. Their distribution was usually close to normal, both in historical and contemporary periods.
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RC1: 'Comment on cp-2023-95', Anonymous Referee #1, 28 Dec 2023
In this work, the sub-daily temperature records of two periods in southwest Greenland, 1767.9.1-1768.7.22h and 1784.9-1792.6 respectively, were used to analyses the climate conditions in the second half of the 18th century. The results were displayed through various statistical and visual methods, combined with some weather and climate indexes. It is important to increase the understanding of the climate in this region of high latitudes at an earlier time. This work has significant implications for increasing the understanding of earlier climate in this region of high latitude.
The manuscript has a detailed narrative with rich results and in-depth discussion. However, we still recommend that the readability of the paper be improved through minor revisions and adjustments. Here are a few specific suggestions.1. Here are 2 minor fallacies in the formulas and charts:
- On page 6, line 139, in equation (4), is there a missing T in front of 21?
- In the picture in Figure 7, the letter numbers are in upper case, and in the name of the figure, they are in lower case.2. We suggest a more detailed, systematic and independent description of the sources of the data, the way they are observed, the form in which they are recorded, etc, which are rather scattered and abbreviated in the current text. (Such as the data sources are in the remarks to the figure, the means of observation and missing measurements are briefly mentioned in paragraph 4.) Thus, we recommend a separate subsection in Part 2 to display them, as well as, a basic presentation of the data through statistics and visualization, including time periods of valid data, etc. This will be more visual than a text description. We believe that this will allow readers from different professional backgrounds to be more aware of the observation record and increase the credibility of the analysis results.
3. How the records were further analyzed could also be a separate section in Part 2. In this section, we think it would have been better to give the reasons for the selection of each climate or weather indices (Table 2). Because it seems that from the results alone, these indices do not give some new and interesting insights other than adding to the richness of the presentation. Therefore, we believe it would be better if the purpose of selecting these indices for analysis was mentioned in the methodology section to help the reader understand the purpose and results, also better echo what would be discussed in part 4.
4. We would also like to see more inferences or insights in the discussion that are closely related to the results or conclusion of this paper. For example, we are curious if the results of 1767-68 being warmer than now and 1784-92 being colder than now are reliable, over what range, and whether there is similar corroboration in other regions. As well, is this phenomenon just indicating exceptional years, or is it actually somewhat indicating that the climate becoming colder during 20 years (which means the end of the warm period in 18th century). We believe that such issue to be discussed can enhance the significance of the whole study.
We sincerely hope that our suggestions can better improve the quality of manuscripts, which we believe to be of great scholarly value.
Citation: https://doi.org/10.5194/cp-2023-95-RC1 -
AC1: 'Reply on RC1', Przemyslaw Wyszynski, 01 Feb 2024
The comment was uploaded in the form of a supplement: https://cp.copernicus.org/preprints/cp-2023-95/cp-2023-95-AC1-supplement.pdf
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AC1: 'Reply on RC1', Przemyslaw Wyszynski, 01 Feb 2024
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RC2: 'Comment on cp-2023-95. Air temperature changes in SW Greenland in the second half of the 18th century', Anonymous Referee #2, 24 Feb 2024
This is a rigorous and deep work, well organized in general, done by authors with ample experience in the study of Arctic climatology, who, by delving into historical data, try to obtain the maximum information available. They are aware of the testimonial value of the original data and of the possibility that they could be used as a reference for subsequent local and regional climate reconstruction studies.
This study presents the results of an analysis of historical climate data referring to the second half of the 18th century in Greenland. It covers two groups of years: 1767-68 and 1784-1792. The analysis is focused especially on the second of these groups, because it contains the most data. Although there is no complete information for all the years and months included in the latter group, the results obtained are in line with those of other studies in Greenland and the Arctic which demonstrates both the quality of the data used and the reliability of the analysis. The temporal sequence analyzed is also a significant contribution, because no data as old as these exist for the Arctic area to date and, as in all historical data prior to contemporaneous observations, there is no option but to study what is available.
The general guidelines I followed for the review were the following: Control of the general structure of the work and the contents of the different sections. Proposals to maximize the value of the analysis carried out and to enhance the results. Proposals to expand interest in the work in non-specialist readers along with reaching other related scientific fields
The statistical treatment performed is based on the comparison of historical data with current data from the 1991-2020 series by referencing historical data to the 1991-2020 series and checking deviations from normal value. This is a type of analysis that fits well with the nature of the data and is accompanied by numerous graphs and tables.
- SPECIFIC COMMENTS
Area and method section
This section is too short considering the interest and the complexity of the study’s reconstructions, methods used, or motivations to start this analysis. To complete it and help readers to assimilate the text rationally and fluently, the following is proposed:
The text would improve by including some comment on the study area, considering its geographical singularity in relation to the meteorology, climatology, and natural environment.
For both historical and statistical interest, it would be quite convenient to include more information about the methodology used to obtain the original data as well as its preparation and correction.
Even though the statistical methods selected fit well with the typology of the original data, please add some comments to justify, in climatic or/and environmental terms, why the indexes in table 2 were selected.
Discussion section
The comparison of the results with the previous references is intense and complete. However, it is focused on contrasting it with other authors’ results, relegating other interesting findings. Considering that the study is based on historical data not contained in any previous work, and that unusual statistical indices have been used, this section should also include an interpretation of the complete statistical work that has been done, as well as its climatic, environmental, and human implications. Consequently, these should be reflected in the conclusions section.
Conclusion section
A part of the paragraph between lines 439 and 450 in page 21 could be moved to section 2.
- TECHICAL CORRECTIONS
Section numbering
The Discussion section numbering should be 4 and, consequently, the Conclusion section 5.
Repeated paragraphs
Page 12, paragraph 2, lines 245-255 is repeated, as well as pages 14-15, lines 274-282.
References missed in the Reference list.
Bertrand et al. (2002)
Born et al. (2021)
Kaufman et al. (2009)
Houghton et al (1990)
Overpeck et al. (1997)
3. TYPING ERRORS
Lines 339-340: delete space between; and Kobashi.
Line 340: Publication year in Crespin et al. no coincidence between text and reference list. In line 349: Crespin et al. (2012), in line 378 Crespin et al. (2009) and Crespin let al. (2014), in line 380Crespin et al. (2009), but in the reference list: Crespin et al. (2014) (2013) and (2019).
Lines 395 correct year 1021 by 1921
Line 460 The Author contribution section name is repeated and wrong in this place.
Line 471: Delete , after Corne
Line 478. Does [et]. c. means [etc.]?
Line 486: delete point after Ebers
Line 550: replace the year 2012 by 2021
Line 551: delete , after . in Lüdecke, C.
Line 606: add publication year
Citation: https://doi.org/10.5194/cp-2023-95-RC2 -
AC2: 'Reply on RC2', Przemyslaw Wyszynski, 01 Mar 2024
The comment was uploaded in the form of a supplement: https://cp.copernicus.org/preprints/cp-2023-95/cp-2023-95-AC2-supplement.pdf
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