Study of the Algorithm for Wind Shear Detection with Lidar Based on Shear Intensity Factor
Round 1
Reviewer 1 Report
This is a very interesting manuscript aiming to improve wind shear detection using a lidar. The results are very relevant, especially from an operational perspective. I have only to minor comments
(1) I think that the authors could include more numerical experiments for the wind shear detection and explore some of the experiments included in the manuscript.
(2) Even if the title of the manuscript refers to lidar, the authors have not included any ideas or specifications of how this algorithm can be implemented operationally.
(3) Moderate English changes are required to improve readability.
Author Response
Please see the attachment. Thank you so much.
Author Response File: 
Author Response.docx
Reviewer 2 Report
General comment
The manuscript “Study on the algorithm for wind shear detection with lidar-based on shear intensity factor” has been reviewed in detail. The manuscript deals with a very interesting and important topic. The document is well structured and also generally well written, although some editing are required to clarify some basic concepts (see detailed comments for authors). The main concern in this paper is about the use (if there was any) of on-site measurements to initialize and/or validate the numerical simulations. In most of the sections, the authors does not clearly state what has been carried out with the lidar and how these numerical simulations have been validated. The comparison with others algorithm results was the only sort of “validation” performed, but this cannot be considered a proper validation stage. In addition, although the present manuscript does not really focus on the characterization of wind conditions, it might be important to describe more deeply the specific meteorological conditions simulated. On these grounds, the reviewer would really appreciate if the authors could also explain how the wind direction is accounted in such algorithms and if not why this is not considered. Actually, the wind shear is not only a function of the wind speed gradient at different locations, but it might be also a function of the wind direction. This and all the above mentioned points must be carefully clarified in the revised version.
Comments/suggestions about different sections of the manuscript are reported in detail below. The points below raised should not be considered as negative comments.
Abstract
At line 10: the statement “low-level wind shear” might be misleading, because the “low-level” in this case is referring to the “wind shear” and not to the altitude. Therefore, the reviewer suggest correcting this statement throughout the whole manuscript whenever necessary, since the problem is actually due to high-levels of wind shear at low altitudes, due for example to downburst winds.
At lines 14-16: the sentence “In this paper … two locations” is redundant and should be rephrased.
At line 16
At line 17: “simulation experiments” is a bit weird as definition, since simulation usually refers to “numerical simulation” weather “experiments” refers to “laboratory tests” or as in such a case to “on-site measurements”. The same comment applies to “simulated results”; is this referring to the on-site measurements of LiDAR?
Introduction
The number of this section cannot be “0”.
At line 48: is the “8 domain algorithm” a proper name/noun? Please clarify.
At lines 59-60: the sentence “The conventional single ramp detection was improved to double ramps detection for the ramp detection algorithm” is quite redundant and unclear for the reader.
At lines 62-63: the sentence “The improved algorithm can effectively improve …” is redundant.
At line 64: “have not been improved”.
At line 67: what do authors mean with small-scale wind shear”?
At line 71: temporal adaptive scales, spatial adaptive scales or both? This is unclear for the reader.
At lines 84-86: the sentence “The results .. wind shear” doesn’t belong to this section. Introduction should not report results. Conversely, at the end of this section authors should describe the structure of the paper by briefly introducing the next sections.
- Methods
2.1 Conventional single ramp wind shear detection algorithm
At lines 89-91: the first sentence of this section is a repetition, it has already been mentioned in the introduction.
At lines 98-104: in this piece of text the authors should clarify what they mean with “average” (1-min, 3-min, 10-min average?) and also with “wind profile” (vertical, horizontal, both?).
2.2 Improvement of ramp length extension and contraction strategy
At line 132, but also in other points of the manuscript: the wind shear is not only function of the wind speed but also of rotation of the wind (the wind direction) over a certain distance. Therefore, the wind direction is important parameter to be considered in case of wind shear gradients. LiDAR measurements/analysis have demonstrated that even on undisturbed positions, like in port areas and airports, the wind direction might suddenly change as the wind speed and turbulence intensity. Hereby a possible reference paper: “Simulation of urban boundary and canopy layer flows in port areas induced by different marine boundary layer inflow conditions”.
In addition, could the authors explain how the directionality (and the turbulence) of the wind is taken into account in the present algorithm?
At line 145: “the variation” instead of “the variation value”.
At line 148: “Equation 3” instead of “formula 3”.
2.3 Technical Process
At line 181: what do authors mean with “constructed simulated wind field”?
At lines 181-188: the piece of text “First, construct the three-dimensional simulated … and disadvantages of each.” is unclear. Could the authors explain:
1) how measurements have been carried out exactly (LiDAR or other stations used, type of outputs, statistical analysis, map of the place + LiDAR, etc.);
2) how measurements have been simulated, the reviewer still does not understand what authors mean with “simulated”;
3) what kind of averaged data have been used for this new algorithm and what kind of data have been used by the other algorithms considered for comparison.
Regarding (3), it is very important to stress in this section whether possible deviations might rise from the different temporal averages considered by the different algorithms (for example).
About Figure 4:
1) could the authors clarify how these 4 weather conditions have been detected and categorized? More in detail:
- is the “frontal wind field” the neutral atmospheric boundary layer (ABL) wind?
- is the “downdraft wind field” the lower part of a microburst or downburst?
- is the “low-level jet vertical wind speed profile” very similar to a downburst wind?
- turbulent wind field is very vague, since any kind of wind field might has a certain level of turbulence that can vary from 0.1% to 50% or even more in case.
2) The 4th row (“location and intensity of wind shear”) might be re-grouped in one cell since they are identical.
Finally, the reviewer would not title this “technical process”, but rather “framework of the project” for example.
- Test of the improved algorithm based on simulated experiment
Title: also here, the authors must distinguish “simulated” and “experiment”. In the present form the title generates confusion.
At lines 196-202: the piece of text “Therefore … is necessary” should be reported (if not) in the introduction, where the authors motivate the present investigation stressing possible knowledge gaps in practice as well as in the scientific literature.
At line 202: the paper does not simulate, the paper shows or presents …
At lines 202-206: the piece of text “This paper … wind fields” explaining the procedure is really unclear. The authors must explain once and for all, what kind of measurements have been carried out, and what kind of measured data have been used for simulations eventually.
At lines 207-209: the sentence “Notably … slide path” is unclear, please clarify.
3.1 Frontal wind field
Same issues:
1) It is unclear how this wind field has be reconstructed/simulated.
2) it is unclear what kind of meteorological event has been detected/measured or simulated based on measurements.
3.2 Downdraft wind field
In the last years a large number of papers has enriched the phenomenological understanding of thunderstorm downbursts, starting from the research/observations of Fujita (1981). A very extensive research (experimental, numerical and theoretical analysis) has been conducted by prof. Solari and his research group to gain more insights about the transient and unsteady nature of such extreme events. Although the present paper does not mainly focuses on downbursts, it is important to support and justify the available knowledge here reported with through some important key publications.
Figure 7:
1) (left and right), how is it possible that the impinging jet height is of 10 km? The authors should carefully check the scientific literature. Although
2) (right) do authors mean vertical wind speed profile? This is unclear once again.
3.3 Low-level jet wind field
The vertical profile of a low-level jet actually should look very similar to a downburst, with an emphasized nose near the ground surface and lower wind speed at higher levels. However, in Figure 8 it seems that authors used a constant vertical wind speed. Is that correct?
3.4 Turbulent wind field
As mentioned above, also a downburst, a low-level jet or even a neutral ABL is turbulent. The only thing that may differ among these winds is the “level” of turbulence (i.e. 1%, 10%, 20%, etc.). In ABL winds the turbulence is expected to be higher near the ground surface and lower with the increasing altitude, and vice versa for downbursts. Therefore, also here the authors should explain how such turbulence has been defined and whether is assumed constant for the whole height (10 km).
Author Response
Please see the attachment. Thank you so much!
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The reviewer would like to thank the authors for the effort made to implement the suggested comments/corrections. The manuscript can be accepted for publication.
