the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Local spatial variability in the occurrence of summer precipitation in the Sør Rondane Mountains, Antarctica
Alfonso Ferrone
Étienne Vignon
Andrea Zonato
Abstract. During the austral summer 2019/2020, three vertically-pointing K-band Doppler profilers (MRR-PRO) have been deployed along a transect across the Sør Rondane Mountains, directly south of the scientific base Princess Elisabeth Antarctica. The MRR-PRO have been placed at locations corresponding to different stages of the interaction between the complex terrain and the typical flow associated with precipitating systems. The radar measurements, alongside information from the ERA5 reanalysis and a set of high-resolution WRF simulations, have been used to study the spatial variability of snowfall across the transect. Radar observations reveal differences in the frequency of occurrence of virga and surface precipitation above the transect. An analysis of the WRF outputs reveals the presence of a relatively dry layer above the radar locations, reaching a constant altitude of 3.5 km above mean sea level. Due to the complex terrain, the depth of the layer varies across the transect, affecting sublimation and the occurrence of virgae. Combined information from the ERA5 reanalysis, the WRF simulations, and ground-level measurements suggest that orographic lifting enhances precipitation above the highest mountain peaks. Finally, the analysis of the succession of virga and surface precipitation above the sites shows that, in most cases, they represent different stages of the same large-scale events. This study reveals the significant spatial variability in the occurrence of precipitation in a region of complex terrain, emphasizing the importance of collecting snowfall measurements in the mountainous regions of the Antarctic continent.
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Alfonso Ferrone et al.
Status: final response (author comments only)
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RC1: 'Comment on egusphere-2023-490', Anonymous Referee #1, 28 Jun 2023
Review comment on “Local spatial variability in the occurrence of summer precipitation in the Sør Rondane Mountains, Antarctica“ by Ferrone et al, 2023.
In this study the authors analysed the local special variability of snow observed in Antarctica along a transect of three micro-rain radars (MRR-PRO). They found events with precipitating snow reaching the surface but also snow sublimating (virga) on their fall. WRF model simulations were used to find differences in the meteorological conditions between surface precipitation events and virga events. Era5 model output were used to account for large scale conditions (passing low pressure systems).
The study is well written and to the point. One can easily follow each analysis and interpretation. A red thread is recognizable at all times. The authors illuminate the subject sufficiently with literature and emphasize the importance of observations of snow in the mountains of Antarctica.
Both the scientific quality and the quality of the presentation are very good and the explanations are a pleasure to read.
The topic of this publication is within the scope of The Cryosphere and I recommend publication after integrating some minor questions, suggestion and comments listed below:
Line 218: you write: “0.25◦ × 0.25◦ horizontal grid”. How many kilometers are these in Antarctica? Please add this information.
Line 316: Here you use a fixed delay in 15-minute increments. Why didn't you use autocorrelation to find the delay with the highest correlation on a better resolution?
Line 331: Here you write: “at least 5 levels”. What is the vertical resolution of the wrf model or how many levels does it have? Please mention somewhere (i.e. in the WRF section)
Line 341: I think it would be beneficial if you would mention the comparison between MRR and WRF output earlier in this section.
Line 360: Please say a few words about the supersaturation (values above 100%). Are these real or typical values or is it model uncertainty?
Line 394: “MRR06” should be “MRR-PRO 06”, right? Please change.
Line 417: Here, I suggest to summarize the section with one sentence. Why the wind direction analysis is important. Or what was expected?
Citation: https://doi.org/10.5194/egusphere-2023-490-RC1 - AC1: 'Reply on RC1', Alfonso Ferrone, 12 Sep 2023
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RC2: 'Comment on egusphere-2023-490', Anonymous Referee #2, 03 Aug 2023
In this paper the variability in precipitation occurrences is characterized along a transect instrumented with 3 micro rain radars. This dataset is used in combination with reanalyses and modelling products to describe the synoptic conditions that lead to the partial or complete sublimation of precipitation as it passes through the atmosphere. The objectives are clearly exposed, the paper is well written, nicely structured and very pleasant to read. I particularly appreciated the recurrent discussion of the limitations of the (thorough) methodology and the assumptions made in interpreting the results, as well as the effort to summarise the main results in the form of a conceptual diagram given in the conclusion.
Overall this article is well suited for The Cryosphere. I don't have much to add, except for the very few minor comments below, which may help to make a modest improvement to an already very accomplished article. Once they have been addressed, I recommend the publication without further iteration.
L86: The main results of this analysis (as outlined in Appendix A with “These results suggest that precipitation was significantly more frequent than usual during the period of deployment of the MRR-PRO transect. This frequency of occurrence, however, did not correspond to a similarly exceptional total accumulation”) could be recalled here in one brief sentence, as they put the peculiar conditions of your period of interest in a broader climatic perspective.
Fig.2 you may want to specify that contours are shown every 200 m here.
L180-187: Does uncertainty could be quantify using WRF simulations? For instance, looking at the distribution of the the ratio of modelled precipitation rates at the atmospheric level closest to 300 m and at the surface, could be a first attempt, from a modelling perspective, to quantify the uncertainty introduced when considering precipitation at 300 m as surface precipitation.
Section 2.2: How many levels are used to represent the atmosphere? How are they discretized along the atmospheric column? This must be added to Section 2.2 for exhaustivity.
L259: correct “on one hand”
L275-276: Is this analysis procedure also shared with Jullien et al. (2020)? If yes, you should mention it so the complementarity between all these different studies can be strengthen.
L375: Is 1 m/s a typical sedimentation velocity for solid hydrometeors? Any reference to support your choice?
Fig. 7: Maybe specify that the Height in the vertical axis is given in km above sea level
Citation: https://doi.org/10.5194/egusphere-2023-490-RC2 - AC2: 'Reply on RC2', Alfonso Ferrone, 12 Sep 2023
Alfonso Ferrone et al.
Data sets
Radar and ground-level measurements collected during the POPE 2020 campaign at Princess Elisabeth Antarctica Alfonso Ferrone, Alexis Berne https://doi.org/10.5281/zenodo.7428690
Alfonso Ferrone et al.
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