the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 13 Nov 2024
Multi-year precipitation characteristics based on in-situ and remote sensing observations at Ny-Ålesund, Svalbard
Abstract. Accurate precipitation data are essential for understanding the Arctic climate, yet estimates from satellite, re-analysis, or climate models remain uncertain. Ground-based observations, which are sparse in the Arctic, are needed for a better understanding of precipitation processes and, as reference points, can help to characterize uncertainties and improve precipitation estimates. We present extended precipitation measurements at the Arctic research station AWIPEV in Ny-Ålesund, Svalbard, consisting of a Pluvio precipitation gauge, a Parsivel disdrometer, and a micro rain radar. Analyzing four years of data (August 2017–December 2021), we characterized precipitation by amount, type, and frequency and also focused on extreme events. Monthly precipitation at Ny-Ålesund varied widely, from 1 to 155 mm. We also associated the contribution of weather systems, i.e., of atmospheric rivers (ARs), cyclones, and fronts, to precipitation amount. Though ARs (separated or co-located with other weather systems) occur only 8 % of the time at Ny-Ålesund, 43 % of the total precipitation amount is measured during these events and 22 % when only ARs are present. Cyclones contributed 40 % (21 %) of the total precipitation amount if all (separated) cyclone events are considered. Extreme precipitation events were largely associated with ARs, i.e. in 11 out of 12 cases. Determining precipitation occurrence depends very much on the observation method and the temporal resolution, from 1 % (Pluvio at 1-minute resolution) to 21 % (micro rain radar) and increased to 38 % with daily resolved Pluvio data. Identifying precipitation type solely through Parsivel remains challenging, and a more detailed evaluation using in-situ methods is needed.
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RC1: 'Comment on egusphere-2024-3368', Anonymous Referee #1, 13 Dec 2024
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The manuscript entitled “Multi-year precipitation characteristics based on in-situ and remote
sensing observations at Ny-Ålesund, Svalbard”, present precipitation detection and measurements by several methods in the period 2017-2021 in Ny Alesund and show how atmospheric circulation (AR, cyclones, front) impacts the precipitations events. I think the paper addresses very important questions in an area of rapid change in the context of global warming. The paper is generally well written and the figures are clear and of good quality. However, I think the quality of the paper can be greatly improved by focusing on more specific questions, reorganizing a bit the different parts and expending on the discussions.
First, the introduction is very informative with a lot of cited literature. You introduce well the need of improving ground based observations. However, the connection between the previous studies, the need of new observations for precipitation in Ny Alesund, and the new measurements that you describe is not clear. What are exactly the measurements that were missing before the instruments were installed and how these new measurements can improve our knowledge on Ny Alesund precipitation? the questions that you mention in the introduction: “How much precipitation falls at Ny-Ålesund, and how is it related to the previously mentioned weather systems? What type of precipitation occurs? How often does it precipitate?” have been already addressed in previous studies. You need to point out what these new measurements are adding to the previous answers to these questions and what is new in your way of relating the precipitation events to weather systems. In summary, you need to be more specific on how these new measurements can help answer your research questions.
Second, I suggest reorganizing the manuscript, because in the present form, the flow of ideas is a bit confusing. I really like the part on explaining the weather patterns origins of precipitation events, but it comes too early in the manuscript. I suggest first introducing the results of the measurements (quantity of precipitation, types, frequency), and then the large-scale weather patterns. The advantage of this organization would be that you can use your previous results on separating snow and rain to study the role of weather patterns on rain and snow events. Summer rain, winter rain (rain and snow) and snow, have very different implications for other research studies and local communities, so it would be extremely interesting to use the pluvio and parsivel measurements to study the specific origins of rain and snow. This analysis would be an application of your method of separating rain and snow. Regarding the part on frequency and the use of MRR, I don’t really see the benefit on this study. It needs to be better explained or to be removed from the analysis.
Finally, your article lacks a discussion part where you talk about previous studies and show how the new measurements may improve the previous studies. Many articles are already cited in the introduction but they don’t serve your discussion in the current version of your manuscript. You have some discussion spread in the manuscript, but it would be good to write a specific discussion section and expend on them.
I think this manuscript have a great potential to get published after major revision, and is a very important step in improving our precipitation knowledge in Ny Alesund.
Here are some specific comments:
I suggest changing the title to “Multi-year precipitation characteristics based on in-situ and ground-based remote sensing observations at Ny-Ålesund, Svalbard”.
l.11 «Cyclones contributed 40% (21%) of the total precipitation amount if all
(separated) cyclone events are considered ». This sentence is not clear to me.
l.13-14: I am not sure this is needed. Of course the occurrence is lower when the resolution is 1 minute compared to daily. What is the resolution of micro rain radar?
l. 32-40 maybe separate what is observed in the past and what is modeled in the future, it is bit mixed up here. There is already literature on past increase of precipitation and rain in the Arctic that you can include.
l. 60-61 «melt days in winter in Svalbard and the associated precipitation sums have increased» not sure I understand what are precipitation sums and how it is associated to melt.
l. 61 «These rain-on-snow events». I would say «the rain on snow events» since you don’t talk about rain-on-snow events previously.
l.77-78: this sentence can be simplified. you say three time the same thing: «model data» «from numerical weather prediction models»and «climate simulations».
l.104: operated by?
l.140 What is the resolution of parsivel?
l.164: what is the horizontal resolution of the MRR?
l.188-189: you can just say june to september
l.231 it seems that the underestimation of your pluvio data compared to MET norway is larger in winter months. It would be interesting to also show the average difference per month.
l. 232-23 you can use the precipitation correction of the MET Norway time series by several methods here https://www.easydata.earth/#/public/metadata/a3d7b9e6-9626-4d43-bb83-623900eb1053. It would be good to include them in table 1 and figure 2. I suggest also to show a scatter plot with corrected MET norway vs corrected pluvio for daily values.
l.257: methodology of?
Table 2: AR-CY not AR-CA. The results are strongly dependent on the occurrence of these weather patterns. It would be good if overall occurrences appear somewhere.
l.259: you mean a monthly maxima?
Figure 4: it also seems that the combined AR-CY don’t happen frequently but are associated to a lot of precipitation. I think this needs to be discussed.
l.264-266: I think you should discuss the specific months after discussing the general behavior.
Figure 5: it would be better to write the bins in th x axis: [-0.5-0.5], [0.5-1.5], [0.5-1.5]… because I am not sure what bin corresponds to each point here. For example, does 0 corresponds to [-0.5-0.5]?
l.276: I question the choice of including hail in solid precipitation as snow and hail are driven by very different processes and may not occur in the same season.
l. 280 I think MET Norway also gives the type of precipitation: snow, liquid, mixed. It may be good to compare with this. And also to compare with snow-rain separation done by Champagne et al. 2024 using a threshold of 1°c (dataset above). I think your study as the potential to determine more precisely a threshold for solid vs liquid precipitations that can validate previous datasets or be used in future studies. It is great and can be emphasize in your manuscript.
l.283 «this makes sense» is a bit familiar. Temperature is mostly used because there is no alternative and because temperature and precipitations are often long records measured together. In my opinion, what is very relevant your study is that the temperature threshold can be validated.
l.285: When you say 2°c you mean the 1.5c-2.5°c bin? Since you use a 1minute resolution, with a lot of data available, I would suggest using more bins, at least for critical temperature between 0 and 3°c (0.1°c wide bins?). You can then arrive with a suggestion of thresholds (or a ranged threshold) separating solid, liquid and mixed precipitation.
l.293-294: Not sure I understand when you say «during periods when solid precipitation has been detected by Parsivel as well (not shown)». parsivel have shown mixed precipitation during these events then?
l.294: what the size of particle infers for the type of precipitation? Expend on that.
l.314-315: I think the thresholds for mixed precipitation can be refined. Looking at figure 5, more than 90 % of precipitation is only solid below 0°c and only liquid above 3°c. Keep in mind that for most studies mixed precipitation is a useless variable. For most fields, we must know if snow is falling and sticking to the ground or if the precipitation are liquid (or almost liquid at the surface). The Parsivel is a very powerful tool that should be used at its best capacity to refine the temperature threshold between liquid and solid precipitation.
Figure 6: why for mixed phase the fraction of precipitation occurrence is way lower than the fraction of precipitation amount?
You could also look at the dataset from Champagne et al. 2024 https://www.easydata.earth/#/public/metadata/a3d7b9e6-9626-4d43-bb83-623900eb1053 and validate if a simple way of separating snow and rain (temperature threshold) can be done. your study can be very useful to validate such dataset.
l.323: «Since the mixed-phase precipitation type, as detected by Parsivel, only seldom occurs» awkward wording.
l.326: I think you can reduce the number of unknown cases by narrowing down the threshold [-2-4°c].
l. 333 i don’t see any analysis on ROS events.
l.345: >0mm or 1mm ?
l.348-349 «To understand which rain or snowfall rate a value of -5 or -10 dBZ actually represents, Ze − R and Ze − S relationships must be applied » Not clear. Reformulate.
l.370: Even though these frequencies serve different purposes, I think you still need to discuss a bit if these frequencies are plausible or not. The MRR frequency seems very high, but pluvio rather low. what causes the overestimation in MRR and Parsival? Also expend on the purpose of these different measurements (maybe in a separate discussion part).
Table 4: I assume these are data from pluvio? Are these raw or corrected data? It would be nice also to see the data from corrected Norway MET data.
l.375-386: What is the main benefit of this MRR for precipitation detection? I don’t really see it here. You are not really describing the vertical variability of the results and how it can be used. This needs to be discuss more.
l.393 not clear. You mean you need to have at least 30 minutes with a Ze < -10dBZ (no precipitation) between two events?
l.394: an event interrupted by for example 12h without precipitation is also likely from the same weather system. So the 30 minutes needs to be better justified.
l.395 discussed later in another paper you mean? I don’t see this discussion.
l.396-397 «Here, we extended the considered period by ±10 min due to the spatial distance of the Pluvio and MRR measurements» you mean that rain may take 10 minutes to reach one site to another? This needs to be better explained.
l.403-406 I don’t really understand the goal of figure 9.
l 410: «maximally contribute to the total precipitation amount with 11%» not clear
l.407-421: The results are interesting but I question what is the end goal of showing all these results. The longer and stronger events of course are more rare but give more precipitation amounts. What is new about it? What are the implications of these results? More generally I have hard time to see the benefit of using MRR here.
l.424 A follow up study would be very interesting as your article leads to lot of new questions. I think it would be very interesting to separate the type of extreme events (summer rain, snow, rain on snow) and to focus on ROS events. It can be done here and would show a good application of pluvio-parsivel.
l.464-472 I would first summarize your main results before introducing what may be done in the future
l.473 replace small by low
l.483-485 I think from your results you can already give approximate temperature threshold for rain, snow and mixed precipitation at Ny Alesund. This is extremely useful for future studies and this needs to be higlighted in your article.
I suggest adding a discussion section and the conclusion needs also to be rewritten with more emphasis on very important results. In the current form the conclusion repeats a lot of previous results but it is hard to see what are the main conclusions.
Citation: https://doi.org/10.5194/egusphere-2024-3368-RC1
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