Role of Indian Summer Monsoon and Westerlies on glacier variability in the Himalaya and East Africa during Late Quaternary: Review and new data

Kumar, Om; Ramanathan, Alagappan; Bakke, Jostein; Kotlia, Bahadur Singh; Shrivastava, J. P.; Kumar, Pankaj; Sharma, Rajveer; Kumar, Pramod

doi:10.1016/j.earscirev.2020.103431

Cited by 28 publications

(5 citation statements)

References 162 publications

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“…In recent years, due to global warming, the glaciers in these areas have retreated dramatically, which could cause the sea‐level rise and influence hydrological processes within glacier basins (Downs & Johnson, 2022). The glaciers in these surrounding areas involve an overall state of imbalance, with strong glacier ablation and increased instability of the dynamical system, making the probability of glacial disasters significantly increased (Kumar et al, 2021; Q. Liu & Liu, 2016; Remya et al, 2022). More specifically, we choose glaciers near the Duku highway as the training glaciers, and use continental glaciers in the western section of the Nyainqentanglha to test the generalization level of our deep learning‐based approach (Bolch et al, 2010; Wu et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

“…In recent years, due to global warming, the glaciers in these areas have retreated dramatically, which could cause the sea-level rise and influence hydrological processes within glacier basins (Downs & Johnson, 2022). The glaciers in these surrounding areas involve an overall state of imbalance, with strong glacier ablation and increased instability of the dynamical system, making the probability of glacial disasters significantly increased (Kumar et al, 2021;Q. Liu & Liu, 2016;Remya et al, 2022).…”

Section: Study Areasmentioning

confidence: 99%

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Accurate and automatic mapping of complex debris‐covered glacier from remote sensing imagery using deep convolutional networks

Lin

Mei

2022

Geological Journal

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Debris‐covered glacier mapping for monitoring glacier fluctuations is necessary to prevent geohazards caused by glaciers. Recently, deep learning‐based methods have been widely utilized for the identification of debris‐covered glaciers. Compared with conventional geospatial methods, deep learning‐based approaches have the advantage of large‐scale coverage and outstanding accuracies in identifying glaciers. However, there are two main difficulties when using deep learning‐based approaches: (1) object misclassification, which causes the misclassifications of the surrounding bedrock, snow, and mountain‐shadowed areas as glaciers; and (2) the inaccurate segmentation of boundaries. In addition, the sample sets for training deep learning models are generally insufficient, which leads to unsatisfactory results. To address the above problems, a deep learning‐based approach is proposed for accurate and automatic mapping of the complex debris‐covered glacier from remote sensing imagery for glacial hazard prevention. First, high‐quality remote sensing imagery is acquired and pre‐processed. Second, we adopt a weight‐optimized glacier semantic segmentation model to our approach. Then, the post‐processing procedures can be used to obtain the glacier outline. Finally, an accurate and automatic mapping of complex debris‐covered glaciers can be achieved. To demonstrate the effectiveness, our approach is applied to observe spatiotemporal changes in the glacier outline in the Nyenchen Tanglha region. Results show that most evaluation metrics of our model are higher than 90%, which demonstrates that it is reasonable for the glacier boundary extraction. We also verify that the proposed approach can be used to observe the changes in glaciers to prevent and control glacial hazards in high‐mountain regions.

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Section: Methodsmentioning

confidence: 99%

Section: Study Areasmentioning

confidence: 99%

Accurate and automatic mapping of complex debris‐covered glacier from remote sensing imagery using deep convolutional networks

Lin

Mei

2022

Geological Journal

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“…Phartiyal et al (2003) established the climatic implications of the magnetic clusters and zones from Late Quaternary lacustrine sediments at Pithoragarh palaeolake, Kumaun Lesser Himalaya, India, with the correlations of pollen results. Kumar et al (2020Kumar et al ( , 2021 first portrayed the moisture sources based on the highresolution multi-proxy analyses (including environmental magnetism) from India and nearby regions. Their results indicated that the ISM controlled the glacier fluctuations in the Western Himalaya during Late Quaternary.…”

Section: Studies In the Indian Monsoon Regionsmentioning

confidence: 99%

Variability of indian monsoon and its forcing mechanisms since late quaternary

et al. 2022

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The Indian monsoon is an important part of the global monsoon system, allowing important transfers of moisture at a large geographical scale and deeply affecting human populations and economic prosperity of regions. The tropical summer monsoon in the Northern Hemisphere is generally considered to be driven by low latitude solar radiation. Therefore, the summer monsoon strength is near zero-phase to the maximum of Northern Hemisphere Summer Insolation (NHSI). However, records from the Arabian Sea and some other parts of the Indian Ocean (e.g., Andaman Sea) show that a ∼8 kyr phase difference exists between the Indian summer monsoon (ISM) strength and the northern Hemisphere Summer Insolation maxima, which is obviously different from the records of stalagmites in the East Asia and other marine sediments (e.g., Bay of Bengal). This leads to the “sea-land precession phase paradox” in indian summer monsoon research. This paper systematically summarizes the Indian monsoon variability on orbital scale indicated by various records from the Indian monsoon regions (including oceans and continents) since the late Quaternary. The orbital forcing of Indian monsoon, the potential phase difference between indian summer monsoon and northern Hemisphere Summer Insolation and its possible forcing mechanism(s) are further discussed. The observed phase lag between indian summer monsoon and northern Hemisphere Summer Insolation may be controlled by the Atlantic Meridional Overturning Circulation (AMOC), latent heat transfer between the southern Indian Ocean and the Asian continent, or caused by the lack of tightly coupling between the Arabian Sea summer monsoon proxies and the monsoon intensity. In addition, it is still unclear whether previous monsoon proxies can provide a strong constraint on the intensity of summer monsoon. Environmental magnetism has been widely used in high-resolution dating and the analysis of paleoclimate variabilities in marine and terrestrial sediments, due to its high sensitivity on the rainfall and temperature. Therefore, in order to solve these issues, it is necessary to combine magnetic parameters with geochemical and paleontological parameters for more systematic work in the future.

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“…On the other hand, the accurate quantification of oceanic evaporation contributions can also benefit the interpretation of water isotopes and paleoclimate archive records (i.e., ice core, tree ring, lake sediments and stalagmites) gathered in the TP over the past several decades (Tian et al, 2007;Joswiak et al, 2013;Yao et al, 2013;Zhu et al, 2015;Kumar et al, 2021). Water isotopes -the stable isotopic compositions of hydrogen and oxygen -have been widely used to examine the climate and water cycle over the TP, including their paleoclimate history (Joswiak et al, 2013;.…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution of oceanic moisture contributions to precipitation over the Tibetan Plateau

Wang

Huang

et al. 2022

Hydrol. Earth Syst. Sci.

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Abstract. Evaporation from global oceans is an important moisture source for glaciers and headwaters of major Asian rivers in the Tibetan Plateau (TP). Although the accelerated global hydrological cycle, the altered sea–land thermal contrast and the amplified warming rate over the TP during the past several decades are known to have profound effects on the regional water balance, the spatial distribution of oceanic moisture contributions to the vast TP remains unclear. This hinders the accurate quantification of regional water budgets and the reasonable interpretation of water isotope records from observations and paleo archives. Based on historical data and moisture tracking, this study systematically quantifies the absolute and relative contributions of oceanic moisture to long-term precipitation in the TP. Results show that the seasonal absolute and relative oceanic contributions are generally out of phase, revealing the previously underestimated oceanic moisture contributions brought by the westerlies in winter and the overestimated moisture contributions from the Indian Ocean in summer. Quantitatively, the relative contribution of moisture from the Indian Ocean is only ∼30 % in the south TP and further decreases to below 10 % in the northernmost TP. The absolute oceanic contribution exhibits a spatial pattern consistent with the dipole pattern of long-term precipitation trends across the Brahmaputra Canyon region and the central-northern TP. In comparison, relative oceanic contributions show strong seasonal patterns associated with the seasonality of precipitation isotopes across the TP.

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Role of Indian Summer Monsoon and Westerlies on glacier variability in the Himalaya and East Africa during Late Quaternary: Review and new data

Cited by 28 publications

References 162 publications

Accurate and automatic mapping of complex debris‐covered glacier from remote sensing imagery using deep convolutional networks

Accurate and automatic mapping of complex debris‐covered glacier from remote sensing imagery using deep convolutional networks

Variability of indian monsoon and its forcing mechanisms since late quaternary

Spatial distribution of oceanic moisture contributions to precipitation over the Tibetan Plateau

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