Corrections of Precipitation Particle Size Distribution Measured by a Parsivel OTT2 Disdrometer under Windy Conditions in the Antisana Massif, Ecuador
, Jean Carlos Ruiz-Hernández 3,4, Marcos Villacís 1 and Thomas Condom 3Round 1
Reviewer 1 Report
General Comments
This is an interesting work on the difficult subject about the accuracy of DSD measured with disdrometers and specifically with a laser disdrometer. In the way that results are presented (time series of accumulated rainfall), a clear conclusion on the improvement of DSD and the estimation of precipitation with the proposed method cannot be made. Scatter plots should be included to get more definite conclusions.
Specific Comments
l. 306-309: It is a common hydrometeor type classification for all bins of a DSD and not separately for each bin, right? This is not well understood.
Fig. 4: Fig. 4 and other figures, as well as the discussion of results, imply that liquid precipitation (based on meteorological parameters) may include DSDs classified (based on fall velocity type) as snow, graupel or hail and solid precipitation may include rain. This should be mentioned in the definition of classification in liquid and solid precipitation to avoid confusion of the readers. Also, it looks like too many original measurements were removed after the filtering procedure. Some information about this should be given in the text.
Fig. 6: Does fall velocity in Fig. 6 agree with Fig. 5, e.g. at large diameter bins?
Fig. 9: It should be mentioned that the uncorrected precipitation is "Parsivel measured". The same for Figs. 10 and 11. Also, a scatter plot of e.g. the best model against TPB precipitation would show a lot more clearly the degree of improvement after DSD correction instead of the accumulation vs. observations plots.
l. 647-656: The authors mention that actually the methodology presented in this paper for solid precipitation cannot be verified, which is a significant issue of the paper. This should mentioned in the abstract, too. Also, the finding of Wagnon et al., (2009), which is included in Discussion and Conclusions, should be mentioned here.
Author Response
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Reviewer 2 Report
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Comments for author File: Comments.pdf
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Reviewer 3 Report
This manuscript seeks to evaluate corrections of drop size distributions measured by Parseval disdrometer under windy conditions.
In general, I found the manuscript difficult to follow due to the quality of English. For example, in section 3.3.1 it seems that 'maximum' refers to maximum concentration, though it is unclear what 'concentration' refers to. It seems to be the diameter at which the concentration falls below an arbitrary value (the minimum scale on the y-axis). Though this is not discussed.
The manuscript suggests that gauge observations are not suitable in windy conditions, although this is not adequately contrasted with the accuracy of the disdrometer measurements. In fact, it seems that the disdrometer approach can only reliably identify rainfall in very light winds (<3m/s). It would be better to quantify the anticipated gauge losses due to wind for comparison. I also disagree with the work presented in the Guo et al (2001) reference. Although the apparent size of the gauge orifice changes with fall angle, the sampling volume is unchanged. Consider a cylinder above a gauge as the sampling volume with no horizontal wind. That cylinder gets sheared sideways by a horizontal wind though its volume remains unchanged. The calculations in Guo et al are not correct. It is the flow over the gauge orifice (not the fall angle) that results in under catch. For example, see
Rodda J. C. & Dixon H. 2012 Rainfall measurement revisited.Weather 67(5),131–136 https://doi.org/10.1002/wea.1884.Greater care could be taken with the Figure captions. Figure 2 is labelled Fig 1. Fig 1 has (f) instead of (e). Fig 2 has no reference to (c).
I think that the manuscript could be made clearer and more concise by focussing more on addressing the question of if more reliable precipitation estimates can be made with the disdrometer rather than a gauge in these conditions, and how this is affected by wind speed.
Author Response
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Round 2
Reviewer 1 Report
The authors made sufficient corrections-additions to the paper in response to the comments.
Regarding the comment about Fig. 6, the correct figure for comparison was Fig. 4 (fall velocity vs. diameter) and not Fig. 5 as by error was mentioned in the comment or Fig. 7 which the authors mention in their reply. More specifically, at diameters larger than 10 mm the measured fall velocity according Fig. 4 is a lot higher than the values <2 m/s shown in Fig. 6, which should be explained.
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