the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 04 May 2026
Measurement Report: Aircraft-Ground Observation Study of a Spring Snowstorm Event in the North China Plain: Cloud Microphysical Characteristics and Precipitation Vertical Structure
Abstract. Studies on the characteristics of snowfall cloud systems contribute to understanding the mechanisms of snow formation and development. In this study, based on observations from King Air 350 and ground–based radar, the microphysical characteristics and vertical structure of precipitation during a spring snowstorm with thunderstorm on March 16, 2023 in the North China Plain are investigated. High concentrations of ice crystals (up to 131.1 L-1) and limited small-scale cloud droplets (less than 10 cm-3) was observed in the stratiform cloud area. In regions with heavy snowfall and elevated thunderstorm, the liquid water content in the upper cloud layer (∼-18 °C) is significantly higher than in other areas. Precipitations in these regions exhibited a vertical structure of aggregates and vertical ice crystals above, supercooled water in the middle, and graupel below. During the mid-phase of precipitation in Shangqiu, snow particles partially melted within the warm layer (1.8–2.4 km), increasing the equivalent reflectance factor (Ze) and doppler velocity (V). And then it refreeze in the sub-zero temperature zone and finally completely melt into liquid droplets below 0.7 km. In the early and late stages, snow melting into wet snowflakes below 0.5 km significantly enhanced the Ze, V and spectrum width (W). During the late stage, updrafts promoted ice crystal growth and accumulation at 1.5–2.3 km, leading to a peak in Ze and positive value of V. The vertical structure and phase evolution of precipitation revealed here are significant for understanding the microphysical processes during hydrometeors falling, providing insights to improve precipitation type prediction accuracy.
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2026-1706', Anonymous Referee #1, 29 May 2026
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RC2: 'Comment on egusphere-2026-1706', Anonymous Referee #2, 30 May 2026
Recommendation: Reject
1) Scientific significance
Does the manuscript represent a substantial contribution to scientific progress within the scope of this journal (substantial new concepts, ideas, methods, or data)?The paper does not present any findings that are new or generalizable. There is no evidence presented that the data shown are representative of a specific type of storm in this region of China. The paper reads like a report for a class exercise. It describes what the graphs show and then relates those descriptions to well-known findings from the literature with which they are consistent. For example, when an elevated warm layer is present in a winter storm, different precipitation types occur at the surface depending on the temperature profile characteristics of the warm layer aloft and the colder layer at the surface.
The paper examines small samples of data from a spring storm on 16 March 2023 with varying surface precipitation types in two different regions of a larger storm. Region with airborne data--3 usable flight segments of 22 min (B-D), 55 min (E-G) and 9 min (H-I) using aircraft in situ data and airborne Ka-band radar. Segments starting at E had a clear melting layer at ~ 2km altitude. Segment A-B not usable see below. These data are put in context of S-band dual pol radar (location ZZ in Fig 1). Region with ground based observations including vertically pointing MicroRainRadar and S-band radar data (location SQ, Figure 1b) had an elevated warm layer with colder air below. Surface precipitation at SQ for a period of ~9 hours (Fig. 10).
Finding of a specific Ze-SR relationship (Kulie and Bennartz) that happens to work better for this specific storm and location within the storm is not generalizable as it well known that Ze-Sr relations vary a lot even within the same storm (Rasmussen et al. 2003).
Not showing Doppler velocity data from airborne KPR radar is a big problem (lack of evidence). Rather vertical air motions are inferred from Z spatial pattern and in situ data. This does not work since microphysical characteristics are a time-integrated characteristic. For example, irregular particles detected by aircraft could have been formed 10s of minutes earlier and then transported to location where the aircraft found them.
2) Scientific Quality
Key missing reference is Rasmussen et al. (2003, JAMC) which makes the point that snowfall rate can vary up to two orders of the magnitude for the same radar reflectivity.Aircraft in situ data especially from particle probes are not reliable in ascents and descents. Any discussion of data and results from flight segment A-B (shown in Fig. 2) needs to be removed from the paper (text, Table 2, several figures).
“vertical ice crystals” are mentioned several times (including in Abstract) but this term is not a standard term of ice crystal shape and it is not defined.
Figure 5b shows mean Doppler velocity values close to 3 m/s which appear to be unrealistically high. There are also several spikes in the profiles between 4.5 and 7 km that are unexplained. The corresponding KPR Doppler velocity and spectral width data are needed explain this. My concern is that the airborne KPR is not pointing exactly vertically and aircraft motions and/or horizontal winds are incorporated into the Doppler velocity values. There is a big discrepancy between Figure 5b mean values and distribution of velocity values from MRR (which are dominated by near zero and negative values) shown in Figure 8 middle row.
3) Presentation QualityIn Figure 6 showing ground-based S-band data, locally higher Z values up to 45 dBZ look more like melting layer or rain than convective cells in snow.
Lack of details would prevent reproducibility. For example line 422 mentions precipitation phase retrieval method but does not specific what the input data are.
Coarse vertical resolution ERA5 data will not be able to resolve shallow warm layers. Soundings mentioned (paragraph starting on line 431) are not shown. Fuyang and Xuzhou stations (LY and NY in Figure 1) where soundings are available are quite far to the west (~112.5 E longitude) compared to SQ (~115 E longitude) from study area SQ where the ground-based radars including MRR are. Radar data shown in paper demonstrates that temperature profile conditions are not uniform across the storm.
Transitions from sleet to rain and then sleet to snow are mentioned on lines 527-528. But their specific time periods are not shown. Hence not possible to see evidence for findings in paragraph starting on line 527. Figure 9 shows classification of "mixture" and "rain" at surface not sleet.
There are numerous errors in tense and word choice throughout the paper. Paper needs to a comprehensive edit to bring it up to journal standard English.
Citation: https://doi.org/10.5194/egusphere-2026-1706-RC2
Data sets
Dataset for a snowfall event C. Song https://doi.org/10.5281/zenodo.19329115
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The manuscript entitled "Measurement Report: Aircraft-Ground Observation Study of a Spring Snowstorm Event in the North China Plain: Cloud Microphysical Characteristics and Precipitation Vertical Structure" by Song et al. details the microphysical and remote sensing measurements of a springtime convective system with occasionally intense snowfall and rainfall at the surface. The authors provide a thorough presentation of the results from the available airborne and ground-based instrumentation and attempt to relate the observations to microphysics processes occurring in the mixed-phase clouds. However, work still needs to be done to more clearly contextualize the findings to the figures and to past literature before it meets the standards for publication in the journal Atmospheric Chemistry and Physics. As such, I recommend Major Revision to the manuscript. The associated comments can be found in the supplement PDF.