the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Evaluation of hygroscopic cloud seeding in warm rain process by a hybrid microphysics scheme on WRF model: a real case study
Kai-I Lin
Sheng-Hsiang Wang
Li-Hsin Chen
Yu-Chieng Liou
Pay-Liam Lin
Wei-Yu Chang
Hsien-Jung Chiu
Yi-Hui Chang
Abstract. To evaluate the hygroscopic cloud seeding in reality, this study develops a hybrid microphysics scheme on WRF model, WDM6–NCU, which involves 43 bins of seeded cloud condensation nuclei (CCN) in the WDM6 bulk method scheme. This scheme can describe the size distribution of seeded CCNs and explain the process of the CCN imbedding, cloud and raindrop formation in detail. Furthermore, based on the observational CCN size distribution applied in the modelling, a series of tests on cloud seeding was conducted during the seeding periods of 21–22 October, 2020 with stratocumulus clouds. The model simulation results reveal that seeding at in-cloud regions with an appropriate CCN size distribution can yield greater rainfall and that spreading the seeding agents over an area of 40–60 km2 is the most efficient strategy to create a sufficient precipitation rate. With regard to the microphysical processes, the main process that causes the enhancement of precipitation is the strengthening of the accretion process of raindrops. In addition, hygroscopic particles larger than 0.4 μm primarily contribute to cloud-seeding effects. The study results could be used as references for model development and warm cloud seeding operations.
Kai-I Lin et al.
Status: open (until 01 Jun 2023)
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RC1: 'Comment on egusphere-2023-573', Anonymous Referee #1, 05 May 2023
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This research incorporates a bin method into a bulk microphysical scheme (WDM) to calculate the warm rain process and uses this scheme to investigate the warm rain seeding effect through several sensitivity experiments. I suggest that the authors should provide more information about this new scheme.
- Line 625: “The WRF model employs … the third-order Runger-Kutta numerical method for solving the time split integration of the governing equation”. In fact, the third Ruger-Kutta method is just an option in the namelist. input, you can also choose the fifth-order one, so it is not “The WRF model employs”, but you choose this third-order method. Please reword.
- Line 98: “the bins of CCNs whose size extends the critical radius will be able to activate the corresponding liquid bins”, How to understand “corresponding liquid bins”? I feel that the WDM-NCU scheme has not been introduced in detail in this manuscript. What is the size range of the 43 bins? Which microphysics processes are calculated in this bin scheme? Can this scheme reflect the fact that large CCN becomes large cloud droplets? How does the scheme deal with the coupling of the bin part and bulk part?
- Line 102: “After the number concentration and mixing ratio of the liquid bins is calculated, they are used in the calculation of the mixing ratio and number concentration of cloud and rain, and the microphysics processes continue as is the case in the original WDM6”. Do you mean that the bin part of the WDM-NCU scheme only calculates the nucleation process? How do you separate the cloud and rain categories from the liquid bins? The authors have to provide more information.
- Fig. 5 The simulated accumulated precipitation comes from which domain? Is the horizontal space resolution close to the observed data?
- Fig. 6 What is RCWF and RCSL? They have not been explained in the manuscript. And which are observed data and which are simulated results?
- Fig. 7, I suggest to depict the simulated results using dashed lines and put them over the observed data. So that only three 3 subplots are needed. And the Dongyan Mountain site should be plotted in Fig. 3 (or 5, 6).
- Fig. 8: Observation or simulation?
- Where are the seeding points or areas when you seed in 1km2, 10km2, and 100km2? These seeding points should be plotted. The seeding effects should also be shown in horizontal shadow figures, not just be plotted in lines as in Figs 9 and 10. And how much sea salt is seeded?
- Line 240: Why do you say seeding in such large area (100 km2) at 500 m is “impractical and ineffective” but at the same time seeding in 100 km2 at 1300 m is “more suitable”? I think both of them are impractical.
- Fig. 13, Why Praut increases in seed_500(100 km2) but Qr does not increase as shown in Fig.11 g, h.
- Fig. 15, Why the units of dN/dlog(D) is %？
- Line 261: Why do you think when the seeding area is larger than 64km2, the Shihmen region no longer has plenty of cloud water to transform to precipitation？ Is there any evidence supporting your conclusion？ Didn’t you say that seeding leads to an increase in Qc in 10 min?
Citation: https://doi.org/10.5194/egusphere-2023-573-RC1 -
AC1: 'Reply on RC1', Kao-Shen Chung, 19 May 2023
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We greatly appreciate the care taken by the reviewer in evaluating the manuscript. We believe the actions we have taken to address the comments have substantially strengthened the revision of the manuscript. Our bolded responses appear below the reviewer comments.
Kai-I Lin et al.
Kai-I Lin et al.
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