Drying–Wetting Changes of Surface Soil Moisture and the Influencing Factors in Permafrost Regions of the Qinghai-Tibet Plateau, China
Soil moisture (SM), an important variable in water conversion between the atmosphere and terrestrial ecosystems, plays a crucial role in ecological processes and the evolution of terrestrial ecosystems. Analyzing and exploring SM’s processes and influencing factors in different permafrost regions of...
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MDPI AG
2022-06-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/14/12/2915 |
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| author | Hongying Li Fenggui Liu Shengpeng Zhang Chaokun Zhang Cungui Zhang Weidong Ma Jing Luo |
| author_facet | Hongying Li Fenggui Liu Shengpeng Zhang Chaokun Zhang Cungui Zhang Weidong Ma Jing Luo |
| author_sort | Hongying Li |
| collection | DOAJ |
| description | Soil moisture (SM), an important variable in water conversion between the atmosphere and terrestrial ecosystems, plays a crucial role in ecological processes and the evolution of terrestrial ecosystems. Analyzing and exploring SM’s processes and influencing factors in different permafrost regions of the Qinghai-Tibet Plateau (QTP) can better serve the regional ecological security, disaster warning, water management, etc. However, the changes and future trends of SM on the QTP in recent decades are uncertain, and the main factors affecting SM are not fully understood. The study used SM observations, the Global Land Evapotranspiration Amsterdam Model (GLEAM) SM products, meteorological and vegetation data, Mann–Kendall test, Theil–Sen estimation, Ensemble Empirical Mode Decomposition (EEMD), and correlation methods to analyze and explore the characteristics and influencing factors of SM change in different permafrost regions of the QTP. The results show that: (1) At the pixel scale, GLEAM SM products can better reflect SM changes in the QTP in the warm season. The seasonal permafrost region is closer to the real SM than the permanent region, with a median correlation coefficient (<i>R</i>) of 0.738, median bias of 0.043 m<sup>3</sup> m<sup>−3</sup>, and median unbiased root mean square errors (ubRMSE) of 0.031 m<sup>3</sup> m<sup>−3</sup>. (2) The average SM in the QTP warm season increased at a rate of 0.573 × 10<sup>−3</sup> m<sup>3</sup> m<sup>−3</sup> yr<sup>−1</sup> over the recent 40 years, and the trend accelerated from 2005–2020. In 64.31% of the region, the soil was significantly wetted, mainly distributed in the permafrost region, which showed that the wetting rate in the dry region was faster than in the wet region. However, the wetting trend does not have a long-term continuity and has a pattern of “wetting–drying-wetting” on interannual and decadal levels, especially in the seasonal permafrost region. (3) More than 65% of the SM wetting trend on the QTP is caused by temperature, precipitation, and vegetation. However, there is apparent spatial heterogeneity in the different permafrost regions and vegetation cover conditions, and the three factors have a more substantial explanatory power for SM changes in the seasonal permafrost region. With the global climate change, the synergistic SM–Climate–Vegetation effect on the QTP tends to be more evident in the seasonal permafrost region. |
| first_indexed | 2024-03-09T22:35:29Z |
| format | Article |
| id | doaj.art-18c0cd3ce7f04c5fb1e532d4f4451b6a |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-09T22:35:29Z |
| publishDate | 2022-06-01 |
| publisher | MDPI AG |
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| series | Remote Sensing |
| spelling | doaj.art-18c0cd3ce7f04c5fb1e532d4f4451b6a2023-11-23T18:48:52ZengMDPI AGRemote Sensing2072-42922022-06-011412291510.3390/rs14122915Drying–Wetting Changes of Surface Soil Moisture and the Influencing Factors in Permafrost Regions of the Qinghai-Tibet Plateau, ChinaHongying Li0Fenggui Liu1Shengpeng Zhang2Chaokun Zhang3Cungui Zhang4Weidong Ma5Jing Luo6College of Geographical Sciences, Qinghai Normal University, Xining 810008, ChinaCollege of Geographical Sciences, Qinghai Normal University, Xining 810008, ChinaCollege of Geographical Sciences, Qinghai Normal University, Xining 810008, ChinaBig Data Center of Geospatial and Nature Resources of Qinghai Province, Xining 810008, ChinaTourism College, Qinghai Nationalities University, Xining 810007, ChinaCollege of Geographical Sciences, Qinghai Normal University, Xining 810008, ChinaCollege of Geographical Sciences, Qinghai Normal University, Xining 810008, ChinaSoil moisture (SM), an important variable in water conversion between the atmosphere and terrestrial ecosystems, plays a crucial role in ecological processes and the evolution of terrestrial ecosystems. Analyzing and exploring SM’s processes and influencing factors in different permafrost regions of the Qinghai-Tibet Plateau (QTP) can better serve the regional ecological security, disaster warning, water management, etc. However, the changes and future trends of SM on the QTP in recent decades are uncertain, and the main factors affecting SM are not fully understood. The study used SM observations, the Global Land Evapotranspiration Amsterdam Model (GLEAM) SM products, meteorological and vegetation data, Mann–Kendall test, Theil–Sen estimation, Ensemble Empirical Mode Decomposition (EEMD), and correlation methods to analyze and explore the characteristics and influencing factors of SM change in different permafrost regions of the QTP. The results show that: (1) At the pixel scale, GLEAM SM products can better reflect SM changes in the QTP in the warm season. The seasonal permafrost region is closer to the real SM than the permanent region, with a median correlation coefficient (<i>R</i>) of 0.738, median bias of 0.043 m<sup>3</sup> m<sup>−3</sup>, and median unbiased root mean square errors (ubRMSE) of 0.031 m<sup>3</sup> m<sup>−3</sup>. (2) The average SM in the QTP warm season increased at a rate of 0.573 × 10<sup>−3</sup> m<sup>3</sup> m<sup>−3</sup> yr<sup>−1</sup> over the recent 40 years, and the trend accelerated from 2005–2020. In 64.31% of the region, the soil was significantly wetted, mainly distributed in the permafrost region, which showed that the wetting rate in the dry region was faster than in the wet region. However, the wetting trend does not have a long-term continuity and has a pattern of “wetting–drying-wetting” on interannual and decadal levels, especially in the seasonal permafrost region. (3) More than 65% of the SM wetting trend on the QTP is caused by temperature, precipitation, and vegetation. However, there is apparent spatial heterogeneity in the different permafrost regions and vegetation cover conditions, and the three factors have a more substantial explanatory power for SM changes in the seasonal permafrost region. With the global climate change, the synergistic SM–Climate–Vegetation effect on the QTP tends to be more evident in the seasonal permafrost region.https://www.mdpi.com/2072-4292/14/12/2915Qinghai-Tibet Plateausoil moisturepermafrost regionvegetationprecipitationdrying–wetting |
| spellingShingle | Hongying Li Fenggui Liu Shengpeng Zhang Chaokun Zhang Cungui Zhang Weidong Ma Jing Luo Drying–Wetting Changes of Surface Soil Moisture and the Influencing Factors in Permafrost Regions of the Qinghai-Tibet Plateau, China Remote Sensing Qinghai-Tibet Plateau soil moisture permafrost region vegetation precipitation drying–wetting |
| title | Drying–Wetting Changes of Surface Soil Moisture and the Influencing Factors in Permafrost Regions of the Qinghai-Tibet Plateau, China |
| title_full | Drying–Wetting Changes of Surface Soil Moisture and the Influencing Factors in Permafrost Regions of the Qinghai-Tibet Plateau, China |
| title_fullStr | Drying–Wetting Changes of Surface Soil Moisture and the Influencing Factors in Permafrost Regions of the Qinghai-Tibet Plateau, China |
| title_full_unstemmed | Drying–Wetting Changes of Surface Soil Moisture and the Influencing Factors in Permafrost Regions of the Qinghai-Tibet Plateau, China |
| title_short | Drying–Wetting Changes of Surface Soil Moisture and the Influencing Factors in Permafrost Regions of the Qinghai-Tibet Plateau, China |
| title_sort | drying wetting changes of surface soil moisture and the influencing factors in permafrost regions of the qinghai tibet plateau china |
| topic | Qinghai-Tibet Plateau soil moisture permafrost region vegetation precipitation drying–wetting |
| url | https://www.mdpi.com/2072-4292/14/12/2915 |
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