19 Oct 2023
 | 19 Oct 2023
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Precipitation in the mountains of Central Asia: isotopic composition and source regions

Zarina Saidaliyeva, Maria Shahgedanova, Vadim Yapiyev, Andrew J. Wade, Fakhriddin Akbarov, Mukhammed Esenaman uulu, Olga Kalashnikova, Vassiliy Kapitsa, Nikolay Kasatkin, Ilkhomiddin Rakhimov, Rysbek Satylkanov, Daniiar Sayakbaev, Eleonora Semakova, Igor Severskiy, Maxim Petrov, Gulomjon Umirzakov, and Ryskul Usubaliev

Abstract. Isotopic composition of precipitation in the mountains of four Central Asian countries (Kazakhstan, Kyrgyzstan, Tajikistan and Uzbekistan) was measured using 908 event-based precipitation samples collected at eight sites in 2019–2021, and 7 monthly samples from Dushanbe (Tajikistan) thereby filling a gap in stable isotope data for the region. Regional and seasonal patterns of δ18O, δD and D-excess were investigated. Local Meteoric Water Lines (LMWL) derived using seven regression methods using both non-weighted and weighted precipitation. It is recommended that the non-weighted Ordinary Least Squares Regression (OLSR) and Reduced Major Axis Regression (RMA) methods can be applied across the region except in summer, when the Precipitation-Weighted Least Squares Regression (PWLSR) method is recommended. An atmospheric back trajectory analysis and a mixing model were applied in combination for the first time, using the δ18O, δD and D-excess data, to identify the atmospheric moisture source regions and quantify the relative importance. The main distant sources were the Black and Caspian Seas region, Iran – eastern Mediterranean, and northern Kazakhstan – Siberia. The recycled moisture from the irrigated lower reaches of the Amu Darya and Syr Darya rivers, and from the study catchments, accounted for 29–71 % of the atmospheric moisture reaching the observation points. In spring, summer and winter, in the Chon-Kyzyl-Suu catchment, up to 85 % of the precipitation was estimated to be derived from local re-evaporation, most likely from Lake Issyk Kul. These findings highlight the importance of moisture from terrestrial sources, especially irrigated land, in precipitation formation in Central Asia.

Zarina Saidaliyeva et al.

Status: open (until 04 Jan 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'General and specific comments to egusphere-2023-2030', Anonymous Referee #1, 13 Nov 2023 reply

Zarina Saidaliyeva et al.

Zarina Saidaliyeva et al.


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Short summary
Ratios of stable isotopes of oxygen and hydrogen in precipitation are used to trace source regions and pathways of atmospheric moisture. A database of these measurements was developed for the mountains of Central Asia and analysed in the context of atmospheric trajectories. Over 50 % of precipitation formed from moisture re-evaporated from the regional terrestrial sources including the irrigated land in the Aral Sea basin highlighting its support of the water tower function of the mountains.