Westerly Variations in the Eastern Tibetan Plateau since the Last Interglacial Revealed by the Grain-Size Records of the Ganzi Loess
The westerlies play an important role in driving climate change in the Tibetan Plateau (TP). However, little is known about the history of the westerlies in the TP owing to limited observations and a lack of robust reconstructions. The widely distributed eolian loess in the eastern TP is one of the...
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MDPI AG
2023-01-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/14/2/238 |
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| author | Shengli Yang Jiantao Zhou Zixuan Chen Pushuang Li Chen Wen Xuechao Xu Qiong Li |
| author_facet | Shengli Yang Jiantao Zhou Zixuan Chen Pushuang Li Chen Wen Xuechao Xu Qiong Li |
| author_sort | Shengli Yang |
| collection | DOAJ |
| description | The westerlies play an important role in driving climate change in the Tibetan Plateau (TP). However, little is known about the history of the westerlies in the TP owing to limited observations and a lack of robust reconstructions. The widely distributed eolian loess in the eastern TP is one of the ideal materials to retrieve the intensity history for the westerlies. A detailed grain-size and endmember model analysis (EMMA) on the Ganzi loess sequence located in the eastern TP revealed that the EMMA decomposed the loess grain-size components into four endmembers: EM1 (modal size 1.42 μm) is related to pedogenesis, and EM2 (modal size 7.10 μm) is transported by the westerlies. Silt modes (EM3 and EM4) are transported by the TP winter monsoon or near-surface airflows. The mass accumulation rate (MAR) of EM2 indicated the westerly variations. Combined with the MAR, we reconstructed the history of westerly intensity since the last interglacial period from the Ganzi loess sequence. We found that the intensity of the westerlies showed typical glacial/interglacial variations since the last interglacial period in the eastern TP. The westerly intensity was strong with large fluctuations during the glacial period, whereas it was weak and stable during the Holocene and the last interglacial. The temperature gradient between high and low latitudes caused by changes in insolation and ice volume in the northern hemisphere were the dominant forcing mechanisms for the westerly intensity variations. |
| first_indexed | 2024-03-11T09:11:02Z |
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| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-11T09:11:02Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-6b64f137a4a340c5be85f4f4fd82a3852023-11-16T19:02:01ZengMDPI AGAtmosphere2073-44332023-01-0114223810.3390/atmos14020238Westerly Variations in the Eastern Tibetan Plateau since the Last Interglacial Revealed by the Grain-Size Records of the Ganzi LoessShengli Yang0Jiantao Zhou1Zixuan Chen2Pushuang Li3Chen Wen4Xuechao Xu5Qiong Li6Key Laboratory of Western China’s Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, ChinaKey Laboratory of Western China’s Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, ChinaKey Laboratory of Western China’s Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, ChinaKey Laboratory of Western China’s Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, ChinaKey Laboratory of Western China’s Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, ChinaKey Laboratory of Western China’s Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, ChinaKey Laboratory of Western China’s Environmental System (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, ChinaThe westerlies play an important role in driving climate change in the Tibetan Plateau (TP). However, little is known about the history of the westerlies in the TP owing to limited observations and a lack of robust reconstructions. The widely distributed eolian loess in the eastern TP is one of the ideal materials to retrieve the intensity history for the westerlies. A detailed grain-size and endmember model analysis (EMMA) on the Ganzi loess sequence located in the eastern TP revealed that the EMMA decomposed the loess grain-size components into four endmembers: EM1 (modal size 1.42 μm) is related to pedogenesis, and EM2 (modal size 7.10 μm) is transported by the westerlies. Silt modes (EM3 and EM4) are transported by the TP winter monsoon or near-surface airflows. The mass accumulation rate (MAR) of EM2 indicated the westerly variations. Combined with the MAR, we reconstructed the history of westerly intensity since the last interglacial period from the Ganzi loess sequence. We found that the intensity of the westerlies showed typical glacial/interglacial variations since the last interglacial period in the eastern TP. The westerly intensity was strong with large fluctuations during the glacial period, whereas it was weak and stable during the Holocene and the last interglacial. The temperature gradient between high and low latitudes caused by changes in insolation and ice volume in the northern hemisphere were the dominant forcing mechanisms for the westerly intensity variations.https://www.mdpi.com/2073-4433/14/2/238Tibetan Plateauloessgrain sizeendmember modelthe westerlieslast interglacial |
| spellingShingle | Shengli Yang Jiantao Zhou Zixuan Chen Pushuang Li Chen Wen Xuechao Xu Qiong Li Westerly Variations in the Eastern Tibetan Plateau since the Last Interglacial Revealed by the Grain-Size Records of the Ganzi Loess Atmosphere Tibetan Plateau loess grain size endmember model the westerlies last interglacial |
| title | Westerly Variations in the Eastern Tibetan Plateau since the Last Interglacial Revealed by the Grain-Size Records of the Ganzi Loess |
| title_full | Westerly Variations in the Eastern Tibetan Plateau since the Last Interglacial Revealed by the Grain-Size Records of the Ganzi Loess |
| title_fullStr | Westerly Variations in the Eastern Tibetan Plateau since the Last Interglacial Revealed by the Grain-Size Records of the Ganzi Loess |
| title_full_unstemmed | Westerly Variations in the Eastern Tibetan Plateau since the Last Interglacial Revealed by the Grain-Size Records of the Ganzi Loess |
| title_short | Westerly Variations in the Eastern Tibetan Plateau since the Last Interglacial Revealed by the Grain-Size Records of the Ganzi Loess |
| title_sort | westerly variations in the eastern tibetan plateau since the last interglacial revealed by the grain size records of the ganzi loess |
| topic | Tibetan Plateau loess grain size endmember model the westerlies last interglacial |
| url | https://www.mdpi.com/2073-4433/14/2/238 |
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