5:15 PM - 6:30 PM
[ACC26-P08] The origin of moisture inferred from water stable-isotopes of an ice-core drilled in the Pamir-Alay Mountains in Central Asia
Keywords:Central Asia, Pamir-Alay mountains, ice-core, stable isotope, moisture
Central Asia is located in the central part of the Eurasia Continent and is characterized by arid climate. Precipitation occurs mostly in the alpine area and forms glaciers, which are important water resources in this region. To evaluate the mass balance of such alpine glaciers, understanding of the moisture sources of the central Asia is important. In this study, water stable isotopes of ice-core drilled in the Pamir-Alay Mountains in western Central Asia were analyzed to assess the origin and its variations of the moisture transported to this region.
An ice-core was drilled in August 2016, at the top of an ice cap in the Pamir-Alay Mountains at the elevation of 5300 m a.s.l. The mean of δ18O, δD, and d-excess of the ice core were -10.0‰, -58.0‰ and 22.3‰, respectively. The stratigraphy of the ice-core suggests that significant melting and refreezing occurred in the most of layers, and thus the stable isotope records of this ice-core appear to be disturbed. The mean stable isotope of the upper parts of the ice-core (above 15 m) was higher than those of the lower part (below 25 m), suggesting the recent warming trend. As the mean isotopes of ice-core was compared with those of river water and precipitation around the mountain range, the isotope of ice-core cannot be explained by elevation effect of river water and precipitation of the southern side of the mountains, while it is close to the isotope of river water and precipitation of the northern side of the mountains. The mean isotope of the ice-core was further compared with those of other ice cores obtained in Central Asia. The isotope of this ice-core is significantly higher than that of the ice-core from Pamir located in the southern side of the mountains, but is close to those of ice-cores from Tien Shan located in the northern side of the study site. Results suggest that the water vapor transported to the Pamir-Alay mountains is different from that of the southern side of Pamir-Alay mountains, which is originally from Indian Ocean, but is similar to that of the Tien Shan Mountains, which is transported from the Mediterranean.
An ice-core was drilled in August 2016, at the top of an ice cap in the Pamir-Alay Mountains at the elevation of 5300 m a.s.l. The mean of δ18O, δD, and d-excess of the ice core were -10.0‰, -58.0‰ and 22.3‰, respectively. The stratigraphy of the ice-core suggests that significant melting and refreezing occurred in the most of layers, and thus the stable isotope records of this ice-core appear to be disturbed. The mean stable isotope of the upper parts of the ice-core (above 15 m) was higher than those of the lower part (below 25 m), suggesting the recent warming trend. As the mean isotopes of ice-core was compared with those of river water and precipitation around the mountain range, the isotope of ice-core cannot be explained by elevation effect of river water and precipitation of the southern side of the mountains, while it is close to the isotope of river water and precipitation of the northern side of the mountains. The mean isotope of the ice-core was further compared with those of other ice cores obtained in Central Asia. The isotope of this ice-core is significantly higher than that of the ice-core from Pamir located in the southern side of the mountains, but is close to those of ice-cores from Tien Shan located in the northern side of the study site. Results suggest that the water vapor transported to the Pamir-Alay mountains is different from that of the southern side of Pamir-Alay mountains, which is originally from Indian Ocean, but is similar to that of the Tien Shan Mountains, which is transported from the Mediterranean.