Global and Planetary Change最新文献

{"title":"Diversity of the climatological seasonal march of East Asian summer monsoon rainfall among the CMIP6 models","authors":"Tiantian Yu ,&nbsp;Wen Chen ,&nbsp;Hainan Gong ,&nbsp;Xiaoqing Lan ,&nbsp;Chaofan Li","doi":"10.1016/j.gloplacha.2024.104558","DOIUrl":"10.1016/j.gloplacha.2024.104558","url":null,"abstract":"<div><p>We investigated the reproducibility of the observed seasonal march of the East Asian summer monsoon (EASM) in the climate models participating in Phase 6 of the Coupled Model Inter-comparison Project (CMIP6). Overall, the multi-model ensemble of 24 CMIP6 models captured the major characteristics of the seasonal march of the monsoon, but large intermodel diversity was seen. Most of the models simulated a much weaker pre-summer rainy season over South China in May, with the main rainband shifting north. We paid special attention to the Meiyu season in June and the North China rainy season in July, which varied greatly among individual models. The diversity of the seasonal march of the monsoon from June to July in the CMIP6 models is largely modulated by the simulated evolution of the western North Pacific subtropical high (WNPSH), which is closely tied to the sea surface temperature in both the western North Pacific and tropical Atlantic Ocean. Weaker warming in the western North Pacific and stronger warming in the tropical Atlantic favors strong air-sea interaction and the resultant realistic WNPSH, which brings more water vapor to support abundant rainfall, thus resulting in a more realistic seasonal march of the EASM rainfall in the CMIP6 models.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"241 ","pages":"Article 104558"},"PeriodicalIF":4.0,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142097055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Middle Pleistocene weakening of the Indian summer monsoon driven by global cooling","authors":"Zhaoying Ma ,&nbsp;Jinbo Zan ,&nbsp;Xiaomin Fang ,&nbsp;Genhou Wang ,&nbsp;Weilin Zhang ,&nbsp;Maohua Shen","doi":"10.1016/j.gloplacha.2024.104550","DOIUrl":"10.1016/j.gloplacha.2024.104550","url":null,"abstract":"<div><p>The Indian Monsoon profoundly impacts the climate, agriculture, and economy of the Indian subcontinent and southwestern China. However, the long-term variability of the Indian summer monsoon (ISM) and its forcing mechanism in the context of the stepwise Pleistocene cooling trend are poorly understood, due to the lack of high-quality terrestrial paleoclimate records. Quaternary loess and paleosol deposits in SW China provide the opportunity to study the long-term evolution of the ISM. Based on analyses of magnetic properties and chemical weathering indices, we found that decreased chemical weathering and pedogenic intensity occurred in SW China since the Middle Pleistocene. Comparison of our results with published paleoclimate records from the Indian Ocean and SW China suggest that substantial ISM weakening occurred after ∼0.7–0.6 Ma, coincident with the Mid-Pleistocene climatic transition. We conclude that decreasing global surface temperatures associated with the major growth of Northern Hemisphere ice sheets caused the Middle Pleistocene weakening of the ISM, leading to changes in precipitation regimes in the southern Asian continent and SW China. Our results suggest that global cooling is strongly linked with the South Asian monsoon climate system, and they provide clues for predicting future climate changes in its area of influence.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"241 ","pages":"Article 104550"},"PeriodicalIF":4.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142089648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Primary productivity recovery and shallow-water oxygenation during the Sturtian deglaciation in South China","authors":"Xubin Wang ,&nbsp;Lin Dong ,&nbsp;Haoran Ma ,&nbsp;Xianguo Lang ,&nbsp;Ruimin Wang","doi":"10.1016/j.gloplacha.2024.104546","DOIUrl":"10.1016/j.gloplacha.2024.104546","url":null,"abstract":"<div><p>The Cryogenian Period (ca. 720–635 Ma) marks a key node in Earth's history, characterized by two global glaciations when the paleo-tropical regions were covered by glaciers, namely the Sturtian and Marinoan Snowball Earth events. Within the Cryogenian, the evolution of primary producers persisted, evidenced by the worldwide discovery of diverse microfossils and the proliferation of algae in the interglacial oceans. The Cryogenian radiation of algae facilitated the emergence and evolution of early eumetazoan animals. However, the paleoredox reconstruction of the interglacial Cryogenian presents more challenges. The open oceans were predominantly and permanently ferruginous throughout the Cryogenian Period, and persistently euxinic conditions developed in restricted basins, such as the Nanhua Basin. Some of the studies suggested a possible fully‑oxygenated interval in the aftermath of the Sturtian glaciation. Therefore, a knowledge gap lies between the biological prosperity and severe habitability in the interglacial oceans. In order to fill this gap, we report a newly discovered interglacial deposition – the Datangpo Formation – of shallow water depth from the Guitouwan section, Shennongjia area, South China. A combination of iron speciation, total organic matter (TOC), and pyrite sulfur isotopes (δ³⁴S_py) analyses are conducted, along with numerical simulations, for reconstructions of paleoredox conditions and paleoproductivity level. Additionally, we collected Fe chemistry, TOC, and pyrite sulfur data from multiple successions of the Datangpo Formation in South China to reconstruct the paleoredox landscape. The spatial TOC comparison suggests that the interglacial interval is marked by a TOC increase at the base, and the Guitouwan succession represents the early deposition during the wake of Sturtian deglaciation. Fe speciation suggests locally (dys)oxic-ferruginous condition in the Shennongjia area, while the δ³⁴S_py systematics indicate a transition from ferruginous to euxinic condition and a sharp increase in primary productivity during the Sturtian deglaciation. With respect to the high δ³⁴S_py values, the observed discrepancy suggests that the iron proxy might be inapplicable during fast environmental changes, especially during the deglaciation episodes. The comparison of Fe chemistry and pyrite sulfur isotopes between different water-depth settings informs a redox-stratified ocean in the Nanhua Basin. The newly discovered interglacial deposition fills the blank in understanding the shallow-water oxygenation in the Sturtian glacial aftermath, recording the transition from (dys)oxic-ferruginous to ferruginous-euxinic and from low to high productivity levels. These findings shed new light on the interpretation of Fe chemistry and δ³⁴S_py in the geological past, and provide a novel perspective on investigating productivity levels.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"241 ","pages":"Article 104546"},"PeriodicalIF":4.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Ediacara Biota of the Wood Canyon formation: Latest Precambrian macrofossils and sedimentary structures from the southern Great Basin","authors":"Scott D. Evans ,&nbsp;Emily F. Smith ,&nbsp;Prescott Vayda ,&nbsp;Lyle L. Nelson ,&nbsp;Shuhai Xiao","doi":"10.1016/j.gloplacha.2024.104547","DOIUrl":"10.1016/j.gloplacha.2024.104547","url":null,"abstract":"<div><p>Fossils of the Ediacara Biota preserve the oldest indisputable evidence of macroscopic animal life. Although new finds continue to expand the near global distribution of such organisms, relatively abundant and diverse populations of these primarily soft-bodied taxa are known from just a handful of localities. More commonly, reports of late Precambrian fossils consist of comparably lower diversity assemblages (less than ∼10 genera), with a limited number of total specimens (less than ∼1000 reported macrofossils over a broad geographic area). Determining the factors responsible for such differences can help to fully appreciate preserved patterns of Ediacaran biodiversity.</p><p>The lower member of the Wood Canyon Formation in the Death Valley region of the southern Great Basin, USA contains fossils of the Ediacara Biota. Here we redescribe previously recovered specimens based on new data from 3D surface scans and report several new finds from this unit. Although this allows the addition of two Ediacara taxa (<em>Pteridinium</em> and <em>Charnia</em>?) to the known diversity in the region, most potential macrofauna consist of amorphous, irregular forms with minimal preserved structures wherein an abiotic origin cannot be ruled out. A combination of factors – including variable taphonomic conditions, difficulty of identification and an original depauperate community – contribute to the observed diversity of this assemblage. Many biases that impact this record are either common (e.g., age, preservation requirements, difficulty of recognition) or comparable (e.g., paleoenvironmental and taphonomic controls) to known occurrences of Ediacara macrofauana. Thus, we argue this fossil record at least partially reflects the original community composition, suggesting that fossils of the lower Wood Canyon record a signal of relatively low diversity of the Ediacara Biota in the lead up to the Ediacaran-Cambrian boundary.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"241 ","pages":"Article 104547"},"PeriodicalIF":4.0,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142097056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Significance testing for cross correlation: A critical examination of correlations between ENSO and GRACE-derived terrestrial water storage variabilities","authors":"Chunchun Gao ,&nbsp;Benjamin F. Chao ,&nbsp;Bing Tan ,&nbsp;Xudong Wu","doi":"10.1016/j.gloplacha.2024.104549","DOIUrl":"10.1016/j.gloplacha.2024.104549","url":null,"abstract":"<div><p>The cross correlation has a wide range of applications in geophysical fields for measuring linear connections or relationships among physical quantities. Nonetheless, there remains a dearth of comprehensive discourse regarding its statistical significance testing, which is crucial for differentiating meaningful outcomes from those merely stemming from fortuity or pure randomness. Conventional theoretical methods for significance testing, commonly used in statistical analysis tools such as SPSS and MATLAB, are only applicable when dealing with idealized circumstances such as white noise. In discretionary application of these methods to analyze geophysical signals with, say, red noise may result in potentially unjustified conclusions. This study aims to develop a comprehensive approach based on the <span><math><mi>t</mi></math></span>-distribution within a rigorous statistical context, aiming to facilitate significance tests of cross correlation for general signals with specified time shifts or ranges. Extensive Monte Carlo experiments substantiate its robustness, thereby paving the way for accurate and expeditious identification of statistically (hence potentially physically) meaningful correlations in general. As an example, we examine critically the previously purported significant correlations between ENSO (El Niño Southern Oscillation) and global terrestrial water storage variations derived from the GRACE (Gravity Recovery and Climate Experiment) satellite mission, demonstrating that they are subject to questioning in the absence of complete significance testing.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"241 ","pages":"Article 104549"},"PeriodicalIF":4.0,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142097057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Melting of Totten Glacier, East Antarctica since the Last Glacial Maximum Revealed by Beryllium Isotope Ratios of Marine Sediment","authors":"Zihan Huang ,&nbsp;Bethany C. Behrens ,&nbsp;Yosuke Miyairi ,&nbsp;Takahiro Aze ,&nbsp;Stephen Obrochta ,&nbsp;Takato Takemura ,&nbsp;Reisuke Kondo ,&nbsp;Alexandra Post ,&nbsp;Leanne K. Armand ,&nbsp;Philip O'Brien ,&nbsp;Amy Leventer ,&nbsp;Yusuke Yokoyama","doi":"10.1016/j.gloplacha.2024.104548","DOIUrl":"10.1016/j.gloplacha.2024.104548","url":null,"abstract":"<div><p>The Totten Glacier of East Antarctica drains a basin containing about 3.5 m of sea-level rise equivalent ice. While Totten Glacier is generally considered somewhat more stable than the rapidly retreating sectors of the West Antarctic Ice Sheet, such as the Amundsen Sea Embayment and Getz Ice Shelf, our understanding of its intricate dynamics and interaction with the Southern Ocean since the Last Glacial Maximum remains incomplete. Situated in a precarious position grounded below sea level, Totten Glacier represents a critical yet enigmatic component of East Antarctic ice dynamics. Its susceptibility to marine ice sheet instability raises concerns, as positive feedback from grounding line retreat could trigger irreversible ice discharge or even complete collapse. A meticulous reconstruction of the retreat history of the Totten Glacier is imperative to comprehensively grasp the glacier's response to present and future climate changes.</p><p>Here, we present a beryllium isotope ratio analysis of marine sediment from the continental slope proximal to Totten Glacier, the first such record from this location, supplemented by grain size data from the same sediment core. The results, when evaluated together with nearby proxy records, reveal that the initial deglaciation of the Totten Glacier sector of the East Antarctic Ice Sheet began at ca. 21 ka BP. The rapid deglaciation from ca. 7 ka BP that followed is determined to be caused by the intrusion of modified Circumpolar Deep Water, leading to melting at the grounding zone of the Totten Glacier and causing instability of the glacier system. The southward shift and intensification of Antarctic easterlies may be one of the causes of this intrusion. These results contribute to the body of knowledge regarding the dynamical response of marine-terminating glaciers to climate variability during the last deglaciation.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"241 ","pages":"Article 104548"},"PeriodicalIF":4.0,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0921818124001954/pdfft?md5=ae3748751886f1c26293209ee887da2d&pid=1-s2.0-S0921818124001954-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The necessity of coupling the legacy effect with temperature response in crop phenology models","authors":"Dingrong Wu ,&nbsp;Jing Gao ,&nbsp;Peijuan Wang ,&nbsp;Jianying Yang ,&nbsp;Yuping Ma ,&nbsp;Zhiguo Huo ,&nbsp;Qiang Yu","doi":"10.1016/j.gloplacha.2024.104545","DOIUrl":"10.1016/j.gloplacha.2024.104545","url":null,"abstract":"<div><p>Global climate change has changed vegetation phenology substantially around the world. However, the necessity of coupling legacy effects with temperature responses in phenological models remains unclear. The objective of this study was to demonstrate that legacy effects [based on day of year (DOY) of phenology events] have substantial positive impacts on crop phenology. Data from 1883 crop×site combinations across Germany and China were analyzed. DOY was found to be a temperature-independent factor for both vegetative (VGP) and reproductive growth periods (RGP) (based on variance inflation factor values). Partial correlation analysis suggested that DOY explained almost the same variability in date of phenology events as temperature. Akaike information criterion showed the cost-effectiveness of coupling DOY with temperature in 71.2% and 59.1% of sites in VGP and RGP, respectively. A model that coupled a linear legacy effect and a temperature response mechanism (LETM) improved fitting efficiency by an average of 57%. LETM was observed to outperform the well-calibrated WOFOST and WE models in VGP and RGP for all crops. Averaged over all crops, root mean square errors for WOFOST, WE, and LETM were 4.0, 3.9, and 3.7 d in VGP, respectively, and are 5.3, 4.6, and 4.0 d in RGP, respectively. Our results verified the necessity of coupling the legacy effect with temperature responses in phenology models. Given that the results were consistent for all of the crops investigated, we believe that our conclusions can apply to other field crops. Results of this study expand the knowledge of crop phenology responses to environment, and are helpful for accurately predicting crop growth and development responses under future global climate change.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104545"},"PeriodicalIF":4.0,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141985184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of mountain orientation on precipitation isotopes in the westerly belt of Eurasia","authors":"Longhu Chen ,&nbsp;Guofeng Zhu ,&nbsp;Qin Qin Wang ,&nbsp;Linlin Ye ,&nbsp;Xinrui Lin ,&nbsp;Siyu Lu ,&nbsp;Yinying Jiao ,&nbsp;Rui Li ,&nbsp;Gaojia Meng ,&nbsp;Yuhao Wang ,&nbsp;Jiangwei Yang ,&nbsp;Chen Jia","doi":"10.1016/j.gloplacha.2024.104543","DOIUrl":"10.1016/j.gloplacha.2024.104543","url":null,"abstract":"<div><p>Mountains have a significant impact on the transport path of water vapour and local meteorological variations. Therefore, understanding the influence mechanism of mountains on stable isotopes of precipitation is essential. In this study, we analyzed the precipitation stable isotope data within the Westerlies in the Eurasian continent. The results indicate the following: (1) East-west-oriented mountain ranges and plains play a “channelling role” in facilitating the inland penetration of westerly moisture, with this effect being more pronounced in the northern part of the Alps. Conversely, north-south-oriented mountain ranges and plateaus act as a “barrier” to westerly moisture. (2) Mountains influence stable isotopes of precipitation primarily by altering the water vapour movement paths and regulating local meteorological factors. (3) The “altitude effect” is the most common mechanism through which mountains affect local meteorological elements reflected in stable isotopes of precipitation. Furthermore, we anticipate that with global climate warming, the interaction and feedback between mountains and climate will become even more complex. This aspect deserves consideration in future research.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104543"},"PeriodicalIF":4.0,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141986349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Miocene climate cooling and aridification of Antarctica may have enhanced syn-extensional magmatism in the western Ross Sea","authors":"Marco Fioraso ,&nbsp;Pietro Sternai ,&nbsp;Valerio Olivetti ,&nbsp;Maria Laura Balestrieri ,&nbsp;Massimiliano Zattin ,&nbsp;Gianluca Cornamusini","doi":"10.1016/j.gloplacha.2024.104538","DOIUrl":"10.1016/j.gloplacha.2024.104538","url":null,"abstract":"<div><p>Continental rift systems are commonly characterized by volcanism with parental basaltic magmas sourced from the mantle. Erosion of the rift shoulders and sedimentation in the adjacent basins can affect the stress and thermal fields at depth, thereby affecting partial mantle melting. However, the sensitivity of magmatic activity to such surface forcing is elusive. Geological observations from the western Ross Sea, Antarctica, suggest rift onset in the Cretaceous with a transition from wide-rifting to narrow-rifting at the boundary between the Antarctic craton and the Transantarctic Mountains. Miocene climate cooling during rifting in the western Ross Sea, in addition, leads to an abrupt decrease in sedimentation rate, synchronous to the emplacement of the McMurdo Volcanic Group. This represents the largest alkali province worldwide, extending both inland and offshore of Transantarctic Mountains and western Ross Sea, respectively. Here, we use coupled thermo-mechanical and landscape evolution numerical modeling to quantify melt production in slowly stretching rift basins due to changes in erosion/deposition rates. The model combines visco-elasto-plastic deformation of the lithosphere and underlying mantle during extension, partial rock melting, and linear hillslope diffusion of the surface topography. The parametric study covers a range of slow extension rates, crustal thicknesses, mantle potential temperatures and diffusion coefficients. Numerical simulations successfully reproduce the ∼150–200-km-wide extension of western Ross Sea and Miocene-to-present asthenospheric melt production (McMurdo Volcanic Group). Results further show that slow rifts magmatism is highly sensitive to sediment deposition within the basin, which inhibits mantle decompression melting and delays the crustal breakup. Regional climate-driven sedimentation rate changes are thus likely to have affected the <em>syn</em>-rift magmatic history of the western Ross Sea, Antarctica, supporting the relevance of interactions between surface and deep-seated processes across extensional settings.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104538"},"PeriodicalIF":4.0,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0921818124001851/pdfft?md5=cf18ccb541c6c53551b1abeed1eba9f7&pid=1-s2.0-S0921818124001851-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141993128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Excess topography and outburst flood: Geomorphic imprint of October 2023 extreme flood event in the Teesta catchment of Eastern Himalayas","authors":"Abhishek Kashyap,&nbsp;Mukunda Dev Behera","doi":"10.1016/j.gloplacha.2024.104540","DOIUrl":"10.1016/j.gloplacha.2024.104540","url":null,"abstract":"<div><p>The 2023 South-Lohnak Lake outburst flood event across the upstream Teesta catchment triggered short-lived, high-magnitude flooding and substantial socioeconomic disruption downstream. We performed landscape analysis across the Teesta catchment using topographic metrics to understand the geomorphic response to this extreme flood event. We estimated the various topographic metrics such as k_sn anomaly (normalized channel steepness index) (∼500–2500 m^0.9), SL-index (stream-length gradient index) (∼5000–7000 m), and K_snQ (channel steepness-weighted discharge) along the trunk channel draining through the South-Lohnak Lake, which shows high magnitude in flooded regions and numerous spikes in their longitudinal profiles across mass-wasting regions downstream. We used the K_snQ metric as an event characteristic to investigate the changes in the channel morphology due to high-magnitude flooding. There was a sudden increase in the magnitude of the K_snQ metric when the river traversed through the Chungthang dam over the high ranges of excess topography (∼0–1700 m). This shows that the downstream channel morphology changes rapidly during this flood event, and K_snQ is a significant indicator of geomorphic change. To understand the spatial relationship between the physical drivers that trigger this outburst flood, we quantified the causal relationship between glacial-hydrological drivers over the upstream Zemu-sub catchment. Our observations suggest that precipitation intensity and surface temperature had a significant direct causal influence on snowmelt and snow depth (in terms of water equivalent) over the event duration with a 5-day and 1-day lag composite. Through the inclusion of lagged composites and causal linkages, the drivers across the glaciated landscape serve as event anomalies, which trigger the glacier hillslope failure and subsequent high-magnitude outburst flooding. Therefore, we suggest that the interaction of topographic discontinuity with hydrological extremes and their causal interdependencies influences this outburst event in the upper reaches, followed by high-magnitude flooding in the downstream reaches of the Teesta River. However, the long-term geomorphic consequences of such events on the evolution of the regional landscape remain unclear.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104540"},"PeriodicalIF":4.0,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142022287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}