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https://doi.org/10.5194/egusphere-2025-2955
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2025-2955
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
06 Nov 2025
| 06 Nov 2025
Precursor dynamical factors in the local lower atmosphere of Warm-Sector Heavy Rainfall over South China: Evidences from Wind Profiler Observations
Abstract. The Warm Sector Heavy Rainfall (WSHR) is one of the most typical weather events during the early summer monsoon season in South China with instantaneous torrential rain with high locality and complex atmospheric conditions, which results in difficulties in nowcasting and hazard warning. Four dynamical and thermodynamical indices within the lower atmosphere are employed as precursor signals of WSHR over South China in 2019, including the Low-Level Jet Index (LLJI), the Vertical Wind Shear (VWS), the Atmospheric Lifting Intensity (ALI), and the Boundary Layer Height (BLH), by utilizing wind profiler radar and high-density surface observations. Regional heterogeneity in precursor signals are detected 1–4 hours preceding WSHR onset. Significant ALI and WVS signals in western regions are concentrated at approximately 1.5 km height, which is affected by warm, moist advection and orographic lifting. The central region, dominated by urban agglomerations, exhibited complex precursor signal interactions, where anomalies of LLJI and BLH are significant due to combined effects of urban heat island and the presence of the double LLJ at 1 km and 2.5 km, respectively. In contrast, precursor signals are moderated by the upper-level jet and moisture transport. In addition, monsoon activities and geographical factors play important roles in the spatiotemporal distribution of precursor signals. Urbanization effects on wind field at the boundary layer have significantly changed the features of dynamical precursor signals. The urban heat effect makes the low-level wind field more unstable. This research provides fundamental insights to enhance nowcasting and hazard warning for WSHR in South China.
How to cite. Li, W., Sheng, L., Bi, X., Huang, Z., Luo, Y., Xiao, S., Liu, C., Yang, Y., Wang, J., Yang, Y., and Lolli, S.: Precursor dynamical factors in the local lower atmosphere of Warm-Sector Heavy Rainfall over South China: Evidences from Wind Profiler Observations, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2025-2955, 2025.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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RC1: 'Comment on egusphere-2025-2955', Anonymous Referee #1, 28 Nov 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-2955/egusphere-2025-2955-RC1-supplement.pdfCitation: https://doi.org/
10.5194/egusphere-2025-2955-RC1 -
RC2: 'Comment on egusphere-2025-2955', Anonymous Referee #3, 21 Jan 2026
General Comments:
The authors investigated the precursor dynamical factors in the local lower atmosphere of Warm-Sector Heavy Rainfall (WSHR) over South China. There are four dynamical and thermodynamical indices within the lower atmosphere, retrieving from wind profile radars and high-density AWSs, are employed as precursor signals of WSHR over China in 2019. These dynamical and additional environmental factors (i.e., water vapor flux and CAPE) were explored to reveal the physical mechanisms, which contributing to the WSHR events; and to suggest potential indicators for forecasting or warning WSHR onset. The scientific issue of this study is interesting, and the authors introduced the wind profile radar observations into discussing the dynamics before WSHR onset is particularly noteworthy. However, this paper should be improved with much more work, including clarifying the data quality of wind profile radar observations, explaining some confusing issues, and determining the mechanisms contributing to the WSHR from the results in this study. Notably, this article requires through proofreading.
Specific comments:
- Line 61: How to define the onset of WSHR events? And the “vertical profiles” is unclear. Please clarify.
- Lines 65‒67: Please consider rewriting this sentence, as it is overly long and difficult to read. Many sentences in this paper are recommended to be rewritten as short, simple sentences (e.g., lines 17‒22).
- Line 71: “lower level” is an unclear description. Please clarify.
- Line76: “BLH”. The abbreviation should be defined at its first occurrence.
- Line82: How did the authors to combine the observations from wind profile radars and automatic weather stations? Please clarify. Pleases consider evaluating the data quality of the wind profile radars. It is vital to understand the limitations/flaws of such data.
- Line 83: “the f electromagnetic”. What is meaning of “f”?
- Line 100: The caption of Figure 1. Profile or profiler? Please check this carefully throughout the paper.
- Line 101: “subsurface” should be “impermeable subsurface”.
- Line 111: The limitations and sources of potential error in these calculations should be stated.
- Line 123: Please clarify the meaning of “D”.
- Lines 126‒127: What did the authors want to explain via this description “thereby allowing the hydrometeors in the updraft to separate from the updraft.”? If authors want to describe the tilted updrafts, I suggest to rewrite this sentence.
- Line 162: Please check these terms.
- Lines 206‒208: The authors should note that the described phenomenological characteristics should be accompanied by corresponding figures.
- Table 1: The meanings of number in first row should be explained.
- Figure 4: The information in this figure is difficult to discern; it is recommended that the figure be redrawn and zoomed in.
- Lines 239‒240: The authors are encouraged to explain how did you get the Figure 7. And more details should be clarified for this sentence.
- Lines 240‒242: “There is strong… onset of precipitation.” The authors should clarify where the information comes from.
- Lines 245‒246: “Wind speed … WSHR events”. How to explain the differences between Figures 6b, e, g, h and Figures 6a, c, d?
- Lines 246‒247: The corresponding wind direction is southerly in Figure 6g but that is southwester in Figure 6h.
- Figure 7: This Figure is difficult to understand. Please provide more details for clarification.
- Line 267: Why do authors select this range, 0.5‒1.5 km? As they shown, the maximum values occurred at 0-1 km height. Please clarify.
- Figure 8: The authors should carefully check their results (e.g., the 25%–75% quantiles are presented, but the mean values are absent), and the median values are encouraged to be shown in this figure.
- Line 298: “2 hours”. Why did authors use the 2 hours before the onset of WSHR? Please clarify.
- Lines 316‒317: Including the 95% confidence interval in Figure 11 would improve the clarity of the figure.
- Lines 318‒319: “VWS values…before the onset.”. Where is the information from? Figure 11d and e did not show this feature. In addition, the higher VWS is absent from Figure f. Following above context, the “0.5‒1 km” should be “0.5‒1.5 km”.
- Lines 321‒322: The increased ALI over central region is true but the trend of ALI over western region is unclear.
- Lines 330‒332: A question: Is the trend of VWS significant or not?
- Lines 333‒335: “The ALI…formation.”. Which region did authors describe?
- Line 335: “BLH, LLJI…the onset are positively.”. It should be negative.
- Lines 338‒339: How did authors get the information about convergence of wind speed here? And why the convergence of wind speed will inhibit lifting? Please clarify.
- Lines 341‒342: “Overseeing…to precipitation.”. This is not convinced enough, especially for the 2-3 hours leading time.
- Lines 344‒345: The trend of VWS is unclear during this period, i.e., the VWS decreased during 90‒120 minutes.
- Figure 12 caption: For avoiding the confusing, this lag time should be a negative value.
- Lines 350‒351: “the water vapor fluxes oner the three regions are compared” should be "the water vapor fluxes over the three regions are compared".
- Line 357: The authors should not ignore the magnitude of water vapor in the lower altitude (i.e., 1000-800 hPa).
- Line 374: “radiation” should be “divergence”.
- Line 375: “which may be related to the …jets.”. Please further explaining the mechanisms.
- Lines 375‒376: “There is…stronger convection;”. If the CAPE value is got from the moment of rainfall onset, it cannot be used to indicate the convection intensity right now.
- Line 377: “there is sufficient water vapor”. I am not sure whether the authors mean that there is sufficient water vapor throughout the vertical zone or not.
- Lines 380‒384: How did the authors conclude these results? Where is the evidence? Please clarify.
- Figure 14 caption: The authors are encouraged to describe more details to clarify this Figure.
- Line 403: “70 minutes”. The authors need to describe more about the X-axis in Figure 15.
- Line 404: “The ALI…”. The Figure15c shows it is named "ARI". It is confused.
- Lines 405‒406: “The maximum…the subsurface.”. I think the causal link here is reversed.
- Figure 15: The authors should note that the boxes of these figures are not appropriate.
- Lines 418‒419: “there is…SLJ”. Is this feature for each panel in Figure 16?
- Figure 16: For each Figure, it is recommended that the information for the X- and Y-axes be described.
- Figure 17: Please clarify more information about this Figure.
- Lines 439‒441: “The vorticity…urban area.”. Where did the authors define the urban area in the caption of Figure 18?
- Section 5 and 6 should be combined, which named “Conclusion and discussion”.
- Author contributions: According to the list of authors, the contributions of all authors are not fully listed here.
Technical corrections:
- Line 23: “WVS” should be “VWS”. Please carefully check it throughout the paper.
- Line 65: “minutes. (Lolli et al, 2013)” should be “minutes (Lolli et al., 2013)”.
- Line 86: “Th” should be “The”.
- Lines 92‒94: “Observations from…etc.”. Grammatical mistake.
- Line 97: “(CAPE) water” should be “(CAPE), water”.
- Line 105: “Daily” should be “daily”.
- Line 106: “At” should be “at”.
- Line 133: Missing period.
- Lines 150‒151: Formatting issue.
- Line 176: Formatting issue.
- Line 222: Formatting issue.
- Line 287: WVS, again.
- Figure 9 caption: Formatting issue.
- Line 319: WVS, again.
- “Author contributions.s” should be “Author contributions”.
Citation: https://doi.org/10.5194/egusphere-2025-2955-RC2
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Latest update: 27 Jan 2026
Wanju Li
College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao, China
Guangzhou Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China
Lifang Sheng
College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao, China
Xueyan Bi
Guangzhou Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China
Zehao Huang
State Key Laboratory of Climate System Prediction and Risk Management, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China
State Key Laboratory of Climate System Prediction and Risk Management, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China
Shiqi Xiao
School of Atmospheric Sciences and Key Laboratory of Tropical Atmosphere-Ocean System, Ministry of Education, Sun Yat-Sen University, Zhuhai, China
Chao Liu
State Key Laboratory of Climate System Prediction and Risk Management, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China
Yang Yang
State Key Laboratory of Climate System Prediction and Risk Management, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China
Jiandong Wang
State Key Laboratory of Climate System Prediction and Risk Management, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China
Yuanjian Yang
CORRESPONDING AUTHOR
State Key Laboratory of Climate System Prediction and Risk Management, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China
Simone Lolli
CNR-IMAA, Contrada S. Loja, 85050 Tito Scalo (PZ), Italy
Short summary
This study investigated the precursor factors of Warm-Sector Heavy Rainfall (WSHR) events in South China, which existed challenges in nowcasting and hazard warning. Four dynamical and thermodynamical indices were explored and tracked as precursor signals of WSHR, showing anomalous values in precursor signals are detected 1–4 hours preceding WSHR onset with regional heterogeneity. This research provides fundamental insights to enhance nowcasting and hazard warning for WSHR in South China.
This study investigated the precursor factors of Warm-Sector Heavy Rainfall (WSHR) events in...