Assessing raindrop evaporation over northern Western Ghats from stable isotope signature of rain and vapour

Nimya, Sheena Sunil; Rajaveni, Sundara Pandian; Sengupta, Saikat; Bhattacharya, Sourendra Kumar; Ananthavel, Nandhini

doi:10.5194/acp-26-9061-2026

Articles | Volume 26, issue 12

https://doi.org/10.5194/acp-26-9061-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-26-9061-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 26, issue 12

Research article

|

26 Jun 2026

Research article |

| 26 Jun 2026

Assessing raindrop evaporation over northern Western Ghats from stable isotope signature of rain and vapour

Sheena Sunil Nimya, Sundara Pandian Rajaveni, Saikat Sengupta, Sourendra Kumar Bhattacharya, and Nandhini Ananthavel

Supplement

https://doi.org/10.5194/acp-26-9061-2026-supplement

Data sets

ERA5 hourly data on pressure levels from 1940 to present H. Hersbach et al. https://doi.org/10.24381/cds.bd0915c6

OCO-2 Level 2 bias-corrected XCO2 and other select fields from the full-physics retrieval aggregated as daily files v11.0 OCO-2/OCO-3 Science Team et al. https://doi.org/10.5067/5Q8JLZL1VD4A

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Short summary

Isotopic analysis of rainwater and vapour samples from Pune, evaluated using a Below-Cloud Interaction Model (BCIM), reveals that rainwater is not in isotopic equilibrium with surface vapour. The surface vapour is significantly modified by a secondary source—likely raindrop evaporation and differs from the ambient vapour that generates condensation aloft. Furthermore, the BCIM indicates that, on a daily scale, an average of 23% of the falling raindrops evaporate before reaching the surface.