| 1. |
- An, Wenling, et al.
(författare)
-
Enhanced Recent Local Moisture Recycling on the Northwestern Tibetan Plateau Deduced From Ice Core Deuterium Excess Records
- 2017
-
Ingår i: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 122:23, s. 12541-12556
-
Tidskriftsartikel (refereegranskat)abstract
- Local moisture recycling plays an essential role in maintaining an active hydrological cycle of the Tibetan Plateau (TP). Previous studies were largely limited to the seasonal time scale due to short and sparse observations, especially for the northwestern TP. In this study, we used a two-component mixing model to estimate local moisture recycling over the past decades from the deuterium excess records of two ice cores (i.e., Chongce and Zangser Kangri) from the northwestern TP. The results show that on average almost half of the precipitation on the northwestern TP is provided by local moisture recycling. In addition, the local moisture recycling ratio has increased evidently on the northwestern TP, suggesting an enhanced hydrological cycle. This recent increase could be due to the climatic and environmental changes on the TP in the past decades. Rapid increases in temperature and precipitation have enhanced evaporation. Changes of land surface of plateau have significantly increased evapotranspiration. All of these have intensified local moisture recycling. However, the mixing model used in this study only includes a limited number of climate factors. Some of the extreme values of moisture recycling ratio could be caused by large-scale atmospheric circulation and other climatic and weather events. Moreover, the potential mechanisms for the increase in local recycling need to be further examined, since the numeric simulations from climate models did not reproduce the increased contribution of local moisture recycling in precipitation.
|
|
| 2. |
- Pang, Hongxi, et al.
(författare)
-
The Dominant Role of Brewer-Dobson Circulation on 17O-Excess Variations in Snow Pits at Dome A, Antarctica
- 2022
-
Ingår i: Journal of Geophysical Research: Atmospheres. - 2169-897X .- 2169-8996. ; 127:13
-
Tidskriftsartikel (refereegranskat)abstract
- Recent studies have suggested that water isotopologues in snow pits from remote East Antarctica can be influenced by the input of stratospheric water, which has anomalously high 17O-excess values. However, it remains unclear whether the 17O-excess records preserved in snow and ice from this region can be used to reconstruct stratosphere-troposphere exchange (STE). In this study, we present high-resolution 17O-excess records from two snow pits at Dome A, the highest point of the Antarctic ice sheet. The 17O-excess records show a significant positive correlation with the strength of the Brewer-Dobson circulation (BDC), the hemispheric-scale troposphere-stratosphere overturn circulation. Stronger BDC leads to more stratospheric water input over Antarctica and higher 17O-excess, and vice versa. In addition, the 17O-excess records also have a significant positive correlation with the Southern Annular Mode (SAM) index, because SAM modulates Antarctic precipitation, which has a dilution effect on the stratospheric water input. The 17O-excess records do not show significant correlations with local temperature and relative humidity in the moisture source region. These results suggest the dominant effect of BDC on 17O-excess and indicate the potential for using 17O-excess records in ice cores from remote sites in East Antarctica for reconstructing long-term variations of STE, and understanding their mechanisms and climate effects.
|
|
