the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Technical note: Theoretical and experimental investigation of isotopic exchange between water vapour and droplets under isothermal saturation conditions
Abstract. Water cycle process will deeply affect water vapour isotope composition, in addition to the evaporation and condensation processes, the exchange process is also a crucial process that influences isotopic variations. To explore the mechanism of isotope exchange under isothermal saturation conditions, we developed an isotope exchange calculation equation for water vapour (IECEWV) based on the conservation of exchange quantity and conducted indoor trials with 100 control groups to validate the IECEWV. The experimental findings demonstrated that the isotopic values of water vapour exhibited enrichment, depletion, and stabilisation during the exchange process when the droplet size first increased and then stabilised, because of the interaction between the exchange state, isotopic gradients, and specific surface area of the droplets according to IECEWV. The variation trend of IECEWV calculated isotopes in water vapour was consistent with experimental value, with average maximum relative errors of 1.66 % for δ2H and 3.19 % for δ18O, and IECEWV analysis further indicates isotopes exchange can lead to the hydrogen and oxygen isotope line of water vapour deviate from the origin. Furthermore, the linear relationship between hydrogen and oxygen isotopes in water vapour after exchanged can be characterised by linear clusters with the same slope, the d-excess of water vapour remains essentially constant. Future studies may combine the IECEWV with the Rayleigh fractionation model to explore the coordinated changes in precipitation and atmospheric water vapour isotopes.
- Preprint
(2062 KB) - Metadata XML
- BibTeX
- EndNote
Status: final response (author comments only)
-
RC1: 'Comment on acp-2024-4', Anonymous Referee #1, 21 Jun 2024
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2024-4/acp-2024-4-RC1-supplement.pdf
-
RC2: 'Comment on acp-2024-4', Anonymous Referee #2, 30 Jun 2024
Exchange processes between precipitation and water vapor isotopes are critical to the interpretation of isotopic signatures. In particular, with the increasing availability of isotope data from high-resolution observations, microphysical processes are becoming increasingly important in explaining isotope variations on the intra-event scale. Isotopic exchanges between water vapor and droplets under isothermal saturation conditions were investigated by theoretical calculations and experimental methods by Bai et al. This has important applications for explaining the isotopic variations of raindrops and water vapor during the actual precipitation processes.
Major comments
(1) Lines 206-207: What is the source of the water vapor that generates droplets here? Is it atmospheric water vapor in the laboratory environment?
(2) Line 251: What standard water vapor sample was utilized in the experiment? In general, liquid water standard samples are usually utilized in experiments.
(3) Line 274: Were these liquid water samples measured for isotopic values? Variations in the isotopic values of liquid water can help explain the exchange processes.
(4) Line 309: Figure 4 shows the water vapor isotopes within the exchange chamber, where is the water vapor coming from? Is it atmospheric water vapor inside or outside the lab? Have any comparison measurements been done to observe water vapor isotopes that have not been subjected to the exchange process?
(5) Line 331: Are the isotopic variations shown in Figure 4 randomly selected from within the results of multiple experiments?
(6) Lines 369-370: The actual observations refer to the data at 0s?
(7) Line 400: Managave et al. (2016) indicated when the raindrops isotopically equilibrate with water vapor, the smaller drops more readily inherit higher d-excess. What is the difference between this study, which found d-excess remained constant, and previous studies?
Reference
Managave et al. Intra‑event isotope and raindrop size data of tropical rain reveal effects concealed by event averaged data. Clim Dyn (2016) 47:981–987.
Citation: https://doi.org/10.5194/acp-2024-4-RC2
Viewed
HTML | XML | Total | BibTeX | EndNote | |
---|---|---|---|---|---|
383 | 44 | 18 | 445 | 11 | 13 |
- HTML: 383
- PDF: 44
- XML: 18
- Total: 445
- BibTeX: 11
- EndNote: 13
Viewed (geographical distribution)
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1