Pub Date : 2024-03-07DOI: 10.1186/s40562-024-00321-1
G. K. Pavur, H. Kim, B. Fang, V. Lakshmi
Accurate and timely inland waterbody extent and location data are foundational information to support a variety of hydrological applications and water resources management. Recently, the Cyclone Global Navigation Satellite System (CYGNSS) has emerged as a promising tool for delineating inland water due to distinct surface reflectivity characteristics over dry versus wet land which are observable by CYGNSS’s eight microsatellites with passive bistatic radars that acquire reflected L-band signals from the Global Positioning System (GPS) (i.e., signals of opportunity). This study conducts a baseline 1-km comparison of water masks for the contiguous United States between latitudes of 24°N-37°N for 2019 using three Earth observation systems: CYGNSS (i.e., our baseline water mask data), the Moderate Resolution Imaging Spectroradiometer (MODIS) (i.e., land water mask data), and the Landsat Global Surface Water product (i.e., Pekel data). Spatial performance of the 1-km comparison water mask was assessed using confusion matrix statistics and optical high-resolution commercial satellite imagery. When a mosaic of binary thresholds for 8 sub-basins for CYGNSS data were employed, confusion matrix statistics were improved such as up to a 34% increase in F1-score. Further, a performance metric of ratio of inland water to catchment area showed that inland water area estimates from CYGNSS, MODIS, and Landsat were within 2.3% of each other regardless of the sub-basin observed. Overall, this study provides valuable insight into the spatial similarities and discrepancies of inland water masks derived from optical (visible) versus radar (Global Navigation Satellite System Reflectometry, GNSS-R) based satellite Earth observations.
{"title":"Spatial comparison of inland water observations from CYGNSS, MODIS, Landsat, and commercial satellite imagery","authors":"G. K. Pavur, H. Kim, B. Fang, V. Lakshmi","doi":"10.1186/s40562-024-00321-1","DOIUrl":"https://doi.org/10.1186/s40562-024-00321-1","url":null,"abstract":"Accurate and timely inland waterbody extent and location data are foundational information to support a variety of hydrological applications and water resources management. Recently, the Cyclone Global Navigation Satellite System (CYGNSS) has emerged as a promising tool for delineating inland water due to distinct surface reflectivity characteristics over dry versus wet land which are observable by CYGNSS’s eight microsatellites with passive bistatic radars that acquire reflected L-band signals from the Global Positioning System (GPS) (i.e., signals of opportunity). This study conducts a baseline 1-km comparison of water masks for the contiguous United States between latitudes of 24°N-37°N for 2019 using three Earth observation systems: CYGNSS (i.e., our baseline water mask data), the Moderate Resolution Imaging Spectroradiometer (MODIS) (i.e., land water mask data), and the Landsat Global Surface Water product (i.e., Pekel data). Spatial performance of the 1-km comparison water mask was assessed using confusion matrix statistics and optical high-resolution commercial satellite imagery. When a mosaic of binary thresholds for 8 sub-basins for CYGNSS data were employed, confusion matrix statistics were improved such as up to a 34% increase in F1-score. Further, a performance metric of ratio of inland water to catchment area showed that inland water area estimates from CYGNSS, MODIS, and Landsat were within 2.3% of each other regardless of the sub-basin observed. Overall, this study provides valuable insight into the spatial similarities and discrepancies of inland water masks derived from optical (visible) versus radar (Global Navigation Satellite System Reflectometry, GNSS-R) based satellite Earth observations.","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140055123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-05DOI: 10.1186/s40562-024-00325-x
Yanan Liu, Qiong Wu, Yizhi Zhang, Lujun Jiang
The rainy season in South China is divided into two phases, the pre- and postrainy seasons, according to the seasonal progression of the East Asian summer monsoon. The precipitation prediction skills for the two rainy seasons are investigated using subseasonal-to-seasonal (S2S) hindcast data from the European Centre for Medium-Range Weather Forecasts (ECMWF) for 2001–2019. The precipitation prediction skills and biases differ between the two rainy seasons, although some similar characteristics exist regarding circulation patterns and their influence on precipitation. During the two rainy seasons, the prediction ability of circulation at 850 hPa in key areas is relatively high, and the influence of circulation on precipitation is well captured; additionally, the relationship between circulation in key areas at 500 hPa and precipitation is less accurately constrained. Moreover, the precipitation prediction skill in the prerainy season is higher than that in the postrainy season. The main bias is that the 200 hPa westerly winds provide favorable divergence conditions for prerainy season precipitation (preprecipitation), while the postrainy season precipitation (postprecipitation) displays almost no correlation with the circulation in the reanalysis product; however, the simulated circulation at 200 hPa is closely connected to the precipitation in both rainy seasons; therefore, the lower prediction skill in the postrainy season is likely associated with overestimation of the complex physical mechanism of the upper-level circulation in the model.
{"title":"Evaluating precipitation prediction skill for the pre- and postrainy seasons in South China in ECMWF subseasonal forecasts","authors":"Yanan Liu, Qiong Wu, Yizhi Zhang, Lujun Jiang","doi":"10.1186/s40562-024-00325-x","DOIUrl":"https://doi.org/10.1186/s40562-024-00325-x","url":null,"abstract":"The rainy season in South China is divided into two phases, the pre- and postrainy seasons, according to the seasonal progression of the East Asian summer monsoon. The precipitation prediction skills for the two rainy seasons are investigated using subseasonal-to-seasonal (S2S) hindcast data from the European Centre for Medium-Range Weather Forecasts (ECMWF) for 2001–2019. The precipitation prediction skills and biases differ between the two rainy seasons, although some similar characteristics exist regarding circulation patterns and their influence on precipitation. During the two rainy seasons, the prediction ability of circulation at 850 hPa in key areas is relatively high, and the influence of circulation on precipitation is well captured; additionally, the relationship between circulation in key areas at 500 hPa and precipitation is less accurately constrained. Moreover, the precipitation prediction skill in the prerainy season is higher than that in the postrainy season. The main bias is that the 200 hPa westerly winds provide favorable divergence conditions for prerainy season precipitation (preprecipitation), while the postrainy season precipitation (postprecipitation) displays almost no correlation with the circulation in the reanalysis product; however, the simulated circulation at 200 hPa is closely connected to the precipitation in both rainy seasons; therefore, the lower prediction skill in the postrainy season is likely associated with overestimation of the complex physical mechanism of the upper-level circulation in the model.","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140036379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this research, we explore the application of artificial neural networks, specifically the vector-quantized temporal associative memory (VQTAM) and VQTAM coupled with locally linear embedding (VQTAM-LLE) techniques, for simulating 2-D magnetotelluric forward modeling. The study introduces the concepts of VQTAM and VQTAM-LLE in the context of simulating 2-D magnetotelluric responses, outlining their underlying principles. We rigorously evaluate the accuracy and efficiency of both VQTAM variants through extensive numerical experiments conducted on diverse benchmark resistivity and real-terrain models. The results demonstrate the remarkable capability of VQTAM and VQTAM-LLE in accurately and efficiently predicting apparent resistivity and impedance phases, surpassing the performance of traditional numerical methods. This study underscores the potential of VQTAM and VQTAM-LLE as valuable computational alternatives for simulating magnetotelluric responses, offering a viable choice alongside conventional methods.
{"title":"Simulating 2-D magnetotelluric responses using vector-quantized temporal associative memory artificial neural network-based approaches","authors":"Phongphan Mukwachi, Banchar Arnonkijpanich, Weerachai Sarakorn","doi":"10.1186/s40562-024-00328-8","DOIUrl":"https://doi.org/10.1186/s40562-024-00328-8","url":null,"abstract":"In this research, we explore the application of artificial neural networks, specifically the vector-quantized temporal associative memory (VQTAM) and VQTAM coupled with locally linear embedding (VQTAM-LLE) techniques, for simulating 2-D magnetotelluric forward modeling. The study introduces the concepts of VQTAM and VQTAM-LLE in the context of simulating 2-D magnetotelluric responses, outlining their underlying principles. We rigorously evaluate the accuracy and efficiency of both VQTAM variants through extensive numerical experiments conducted on diverse benchmark resistivity and real-terrain models. The results demonstrate the remarkable capability of VQTAM and VQTAM-LLE in accurately and efficiently predicting apparent resistivity and impedance phases, surpassing the performance of traditional numerical methods. This study underscores the potential of VQTAM and VQTAM-LLE as valuable computational alternatives for simulating magnetotelluric responses, offering a viable choice alongside conventional methods.","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140018310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-27DOI: 10.1186/s40562-024-00322-0
Kim-Anh Nguyen, Yuei-An Liou
Stringent measures, such as lockdowns, were implemented to curb the virus's spread, leading to reduced pollution levels and environmental improvements at various geographic scales, from cities to regions and nations. Such positive effects have been found and reported for regional scales, but not for a global scale till nowadays. This study aims to fill the gap by uncovering the modifications of global spatiotemporal eco-environmental vulnerability patterns between pre-pandemic (2016) and amid-pandemic (2020) periods. By analyzing various factors influencing the eco-environmental health or geo-health, such as human activities, climate change, and ecological dynamics, we seek to understand the intricate relationships and dynamics within these influential factors. We examined six categories of environmental vulnerability, which encompassed socioeconomics, land resources, natural hazards, hydrometeorology, and topography, using a five-dimensional stressor framework. Our analysis revealed a significant decrease in vulnerability levels across all categories, except for the very low level increased by 78.5% globally. These findings emphasize the detrimental impact of human activities on the global environment. They underscore the urgency of implementing spatial management strategies that prioritize sustainable geo-health development and foster a more resilient Earth.
{"title":"Rethinking our world: a perspective on a cleaner globe emerging from reduced anthropogenic activities","authors":"Kim-Anh Nguyen, Yuei-An Liou","doi":"10.1186/s40562-024-00322-0","DOIUrl":"https://doi.org/10.1186/s40562-024-00322-0","url":null,"abstract":"Stringent measures, such as lockdowns, were implemented to curb the virus's spread, leading to reduced pollution levels and environmental improvements at various geographic scales, from cities to regions and nations. Such positive effects have been found and reported for regional scales, but not for a global scale till nowadays. This study aims to fill the gap by uncovering the modifications of global spatiotemporal eco-environmental vulnerability patterns between pre-pandemic (2016) and amid-pandemic (2020) periods. By analyzing various factors influencing the eco-environmental health or geo-health, such as human activities, climate change, and ecological dynamics, we seek to understand the intricate relationships and dynamics within these influential factors. We examined six categories of environmental vulnerability, which encompassed socioeconomics, land resources, natural hazards, hydrometeorology, and topography, using a five-dimensional stressor framework. Our analysis revealed a significant decrease in vulnerability levels across all categories, except for the very low level increased by 78.5% globally. These findings emphasize the detrimental impact of human activities on the global environment. They underscore the urgency of implementing spatial management strategies that prioritize sustainable geo-health development and foster a more resilient Earth.","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140001787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-26DOI: 10.1186/s40562-024-00326-w
Yonghan Choi, Joo-Hong Kim, Sang-Yoon Jun, Taejin Choi, Xiangdong Zhang
To compensate for the lack of conventional observations over the Arctic Ocean, ship-borne radiosonde observations have been regularly carried out during summer Arctic expeditions and the observed data have been broadcast via the global telecommunication system since 2017. With these data obtained over the data-sparse Arctic Ocean, observing system experiments were carried out using a polar-optimized version of the Weather Research and Forecasting (WRF) model and the WRF Data Assimilation (WRFDA) system to investigate their effects on analyses and forecasts over the Arctic. The results of verification against reanalysis data reveal: (1) DA effects on analyses and forecasts; (2) the reason for the year-to-year variability of DA effects; and (3) the possible role of upper-level potential vorticity in delayed DA effects. The overall assimilation effects of the extra data on the analyses and forecasts over the Arctic are positive. Initially, the DA effects are the most apparent in the temperature variables in the middle/lower troposphere, which spread to the wind variables in the upper troposphere. The effects decrease with time but reappear after approximately 120 h, even in the 240-h forecasts. The effects on forecasts vary depending on the proximity of the radiosonde observation locations to the high synoptic variability. The upper-level potential vorticity is known to play an important role in the development of Arctic cyclones, and it is suggested as a possible explanation for the delayed DA effects after about 120 h.
为弥补北冰洋常规观测数据的不足，在夏季北极考察期间定期开展了船载无线电探空仪观测，并自2017年起通过全球电信系统播发观测数据。利用在数据稀缺的北冰洋上空获得的这些数据，使用极地优化版天气研究与预报（WRF）模式和WRF数据同化（WRFDA）系统开展了观测系统实验，以研究它们对北冰洋上空分析和预报的影响。根据再分析数据进行验证的结果揭示了：(1)DA 对分析和预报的影响；(2)DA 影响年际变化的原因；(3)高层位势涡度在延迟 DA 影响中可能发挥的作用。额外数据对北极地区分析和预报的总体同化效果是积极的。最初，DA效应在对流层中/低层的温度变量中最为明显，然后扩散到对流层高层的风变量。这种效应随着时间的推移而减弱，但在大约 120 小时后再次出现，甚至在 240 小时的预报中也是如此。对预报的影响因无线电探空仪观测点是否靠近高同步变率而异。众所周知，高层位涡在北极气旋的发展过程中起着重要作用，这也是在大约 120 小时后出现延迟 DA 效应的可能原因。
{"title":"Multi-year assessment of the impact of ship-borne radiosonde observations on polar WRF forecasts in the Arctic","authors":"Yonghan Choi, Joo-Hong Kim, Sang-Yoon Jun, Taejin Choi, Xiangdong Zhang","doi":"10.1186/s40562-024-00326-w","DOIUrl":"https://doi.org/10.1186/s40562-024-00326-w","url":null,"abstract":"To compensate for the lack of conventional observations over the Arctic Ocean, ship-borne radiosonde observations have been regularly carried out during summer Arctic expeditions and the observed data have been broadcast via the global telecommunication system since 2017. With these data obtained over the data-sparse Arctic Ocean, observing system experiments were carried out using a polar-optimized version of the Weather Research and Forecasting (WRF) model and the WRF Data Assimilation (WRFDA) system to investigate their effects on analyses and forecasts over the Arctic. The results of verification against reanalysis data reveal: (1) DA effects on analyses and forecasts; (2) the reason for the year-to-year variability of DA effects; and (3) the possible role of upper-level potential vorticity in delayed DA effects. The overall assimilation effects of the extra data on the analyses and forecasts over the Arctic are positive. Initially, the DA effects are the most apparent in the temperature variables in the middle/lower troposphere, which spread to the wind variables in the upper troposphere. The effects decrease with time but reappear after approximately 120 h, even in the 240-h forecasts. The effects on forecasts vary depending on the proximity of the radiosonde observation locations to the high synoptic variability. The upper-level potential vorticity is known to play an important role in the development of Arctic cyclones, and it is suggested as a possible explanation for the delayed DA effects after about 120 h.","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139969334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-25DOI: 10.1186/s40562-024-00327-9
Zhaoxiang Chu, Yiming Wang, Yukun Ji, Xiaozhao Li
The findings of the major strategic consulting project of Chinese Academy of Engineering ‘Research on the strategy of coal mine safety and abandoned mine resources development and utilization in China’ suggest that almost 13,000 discarded collieries in China will provide abundant surface lands and massive underground heritages to not only develop but also store renewable energy within the Earth’s Critical Zone, thus helping attain its net-zero energy goal.
{"title":"China: legacy collieries versus renewable energy","authors":"Zhaoxiang Chu, Yiming Wang, Yukun Ji, Xiaozhao Li","doi":"10.1186/s40562-024-00327-9","DOIUrl":"https://doi.org/10.1186/s40562-024-00327-9","url":null,"abstract":"The findings of the major strategic consulting project of Chinese Academy of Engineering ‘Research on the strategy of coal mine safety and abandoned mine resources development and utilization in China’ suggest that almost 13,000 discarded collieries in China will provide abundant surface lands and massive underground heritages to not only develop but also store renewable energy within the Earth’s Critical Zone, thus helping attain its net-zero energy goal.","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139969684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-25DOI: 10.1186/s40562-024-00324-y
Suqin Zhang, Xia Qu, Gang Huang
Victoria mode (VM), the second dominant mode of North Pacific sea surface temperature variability, has been identified as one of the important factors influencing the Indian summer monsoon (ISM) onset. The positive phase of the May VM delays the ISM onset by both tropical and extratropical pathways. Here, we found a significant interdecadal enhancement of their relationship since the early 1990s, which is mainly attributed to the structure changes and increased variance of the VM. In recent decades, the VM has shown more significant warm SST anomalies in the tropical central Pacific, which drive the large-scale divergent circulation more effectively. This enhanced divergent circulation leads to low-level divergence and reduced rainfall in the tropical Asian summer monsoon region. The reduced rainfall excites equatorial Rossby wave response and anomalous easterly winds in the northern Indian Ocean, delaying the ISM onset. Besides, the increased variance of the VM after 1992/1993 stimulates a stronger extratropical Rossby wave train. This stationary Rossby wave train induces a stronger cooling to the northwest of India, which weakens the land-sea thermal contrast and leads to the delayed ISM onset. This finding should be taken into account to improve short-term predictions of the monsoon onset.
维多利亚模式（VM）是北太平洋海面温度变化的第二主导模式，已被确定为影响印度夏季季风（ISM）开始的重要因素之一。五月 VM 的正相位通过热带和外热带路径延迟了 ISM 的开始。在这里，我们发现自 20 世纪 90 年代初以来，它们之间的关系出现了显著的年代际增强，这主要归因于 VM 的结构变化和方差增大。近几十年来，VM 在热带中太平洋表现出更显著的暖 SST 异常，更有效地驱动了大尺度发散环流。这种增强的发散环流导致热带亚洲夏季季风区的低层发散和降雨量减少。降雨量的减少激发了印度洋北部的赤道罗斯比波响应和异常东风，推迟了国际海洋气象机制的发生。此外，1992/1993 年后增加的 VM 变异激发了更强的外热带罗斯比波列。这个静止的罗斯比波列引起印度西北部更强的降温，从而削弱了陆海热对比，导致国际海洋气象机制推迟出现。应考虑这一发现，以改进对季风开始的短期预测。
{"title":"Enhanced impacts of the North Pacific Victoria mode on the Indian summer monsoon onset in recent decades","authors":"Suqin Zhang, Xia Qu, Gang Huang","doi":"10.1186/s40562-024-00324-y","DOIUrl":"https://doi.org/10.1186/s40562-024-00324-y","url":null,"abstract":"Victoria mode (VM), the second dominant mode of North Pacific sea surface temperature variability, has been identified as one of the important factors influencing the Indian summer monsoon (ISM) onset. The positive phase of the May VM delays the ISM onset by both tropical and extratropical pathways. Here, we found a significant interdecadal enhancement of their relationship since the early 1990s, which is mainly attributed to the structure changes and increased variance of the VM. In recent decades, the VM has shown more significant warm SST anomalies in the tropical central Pacific, which drive the large-scale divergent circulation more effectively. This enhanced divergent circulation leads to low-level divergence and reduced rainfall in the tropical Asian summer monsoon region. The reduced rainfall excites equatorial Rossby wave response and anomalous easterly winds in the northern Indian Ocean, delaying the ISM onset. Besides, the increased variance of the VM after 1992/1993 stimulates a stronger extratropical Rossby wave train. This stationary Rossby wave train induces a stronger cooling to the northwest of India, which weakens the land-sea thermal contrast and leads to the delayed ISM onset. This finding should be taken into account to improve short-term predictions of the monsoon onset.","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139945763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-30DOI: 10.1186/s40562-024-00319-9
Fei Xin, Yichen Shen, Chuhan Lu
Under the proposal of “seamless forecasting”, it has become a key problem for meteorologists to improve the skills of subseasonal forecasts. Since the launch of the subseasonal-to-seasonal (S2S) plan by WMO, the precision of model predictions has been further developed. However, when we are focusing on the practical applications of models in the South China (SC) in recent years, we found that large disagreements appear between forecast members. Some of the members predicted well in this area, while others are not satisfactory. To improve the accuracy of subseasonal forecast in the SC, new methods making full use of different forecast models must be proposed. In this passage, we introduced a weighted ensemble forecasting method based on online learning (OL) to overcome this difficulty. As the state-of-the-art forecast models in the world, three models from China Meteorological Administration, European Centre for Medium-Range Weather Forecasts and National Centers for Environmental Prediction provided by the S2S prediction dataset are used as ensemble members, and an ensemble weight is trained through the aforementioned OL model for the predictions of temperature and precipitation in subseasonal timescale in the SC. The results show that the forecast results produced under the OL method are better than the original model predictions. Compared with the three model ensemble results, the weighted ensemble model has a good ability in depicting the temperature and precipitation in the SC. Furthermore, we also compared this strategy against the climatology predictions and found out that the weighted ensemble model is superior in 10–30 days. Thus, the weighted ensemble method trained thorough OL may shed light on improving the skill of subseasonal forecasts.
在 "无缝预报 "的建议下，如何提高副季节预报的技能已成为气象学家面临的关键问题。自世界气象组织（WMO）推出 "从副季到季"（S2S）计划以来，模式预报的精度得到了进一步提高。然而，当我们关注近年来模式在华南地区的实际应用时，我们发现预报成员之间出现了较大的分歧。有些成员在这一地区的预报效果很好，而有些则不尽如人意。为了提高华南副季节预报的精度，必须提出充分利用不同预报模式的新方法。本文介绍了一种基于在线学习（OL）的加权集合预报方法，以克服这一困难。以S2S预报数据集提供的中国气象局、欧洲中期天气预报中心和美国国家环境预报中心的三个预报模式作为世界上最先进的预报模式，通过上述OL模式训练出一个集合权重，用于预报南极洲副季节尺度的气温和降水。结果表明，OL 方法产生的预报结果优于原始模式的预报结果。与三种模式的集合结果相比，加权集合模式对南极洲气温和降水的描述能力更强。此外，我们还将这一策略与气候学预测结果进行了比较，发现加权集合模式在 10-30 天内的预测结果更优。因此，经过 OL 训练的加权集合方法可能有助于提高副季节预报的技能。
{"title":"Application of a weighted ensemble forecasting method based on online learning in subseasonal forecast in the South China","authors":"Fei Xin, Yichen Shen, Chuhan Lu","doi":"10.1186/s40562-024-00319-9","DOIUrl":"https://doi.org/10.1186/s40562-024-00319-9","url":null,"abstract":"Under the proposal of “seamless forecasting”, it has become a key problem for meteorologists to improve the skills of subseasonal forecasts. Since the launch of the subseasonal-to-seasonal (S2S) plan by WMO, the precision of model predictions has been further developed. However, when we are focusing on the practical applications of models in the South China (SC) in recent years, we found that large disagreements appear between forecast members. Some of the members predicted well in this area, while others are not satisfactory. To improve the accuracy of subseasonal forecast in the SC, new methods making full use of different forecast models must be proposed. In this passage, we introduced a weighted ensemble forecasting method based on online learning (OL) to overcome this difficulty. As the state-of-the-art forecast models in the world, three models from China Meteorological Administration, European Centre for Medium-Range Weather Forecasts and National Centers for Environmental Prediction provided by the S2S prediction dataset are used as ensemble members, and an ensemble weight is trained through the aforementioned OL model for the predictions of temperature and precipitation in subseasonal timescale in the SC. The results show that the forecast results produced under the OL method are better than the original model predictions. Compared with the three model ensemble results, the weighted ensemble model has a good ability in depicting the temperature and precipitation in the SC. Furthermore, we also compared this strategy against the climatology predictions and found out that the weighted ensemble model is superior in 10–30 days. Thus, the weighted ensemble method trained thorough OL may shed light on improving the skill of subseasonal forecasts.","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The China Seismo-Electromagnetic Satellite (CSES), with a sun-synchronous orbit at 507 km altitude, was launched on 2 February 2018 to investigate pre-earthquake ionospheric anomalies (PEIAs) and ionospheric space weather. The CSES probes manifest longitudinal features of four-peak plasma density and three plasma depletions in the equatorial/low-latitudes as well as mid-latitude troughs. CSES plasma and the total electron content (TEC) of the global ionosphere map (GIM) are used to study PEIAs associated with a destructive M7.0 earthquake and its followed M6.5 and M6.3/M6.9 earthquakes in Lombok, Indonesia, on 5, 17, and 19 August 2018, respectively, as well as to examine ionospheric disturbances induced by an intense storm with the Dst index of − 175 nT on 26 August 2018. Anomalous increases (decreases) in the GIM TEC and CSES plasma density (temperature) frequently appear specifically over the epicenter days 1–5 before the M7.0 earthquake and followed earthquakes, when the geomagnetic conditions of these PEIA periods are relatively quiet, Dst: − 37 to 19 nT. In contrast, TEC and CSES plasma parameter anomalies occur globally in the southern hemisphere during the storm days of 26–28 August 2018. The CSES ion velocity shows that the electric fields of PEIAs associated with the M7.0 earthquake are 0.21/0.06 mV/m eastward and 0.11/0.10 mV/m downward at post-midnight/post-noon on 1–3 August 2018, while the penetration electric fields during the storm periods of 26–28 August 2018 are 0.17/0.45 mV/m westward/downward at post-midnight of 02:00 LT and 0.26/0.26 mV/m eastward/upward at post-noon of 14:00 LT. Spatial analyses on CSES plasma discriminate PEIAs from global effects and locate the epicenter of possible forthcoming large earthquakes. CSES ion velocities are useful to derive PEIA- and storm-related electric fields in the ionosphere.
{"title":"Spatial analyses on pre-earthquake ionospheric anomalies and magnetic storms observed by China seismo-electromagnetic satellite in August 2018","authors":"Jann-Yenq Tiger Liu, Xuhui Shen, Fu-Yuan Chang, Yuh-Ing Chen, Yang-Yi Sun, Chieh-Hung Chen, Sergey Pulinets, Katsumi Hattori, Dimitar Ouzounov, Valerio Tramutoli, Michel Parrot, Wei-Sheng Chen, Cheng-Yan Liu, Fei Zhang, Dapeng Liu, Xue-Min Zhang, Rui Yan, Qiao Wang","doi":"10.1186/s40562-024-00320-2","DOIUrl":"https://doi.org/10.1186/s40562-024-00320-2","url":null,"abstract":"The China Seismo-Electromagnetic Satellite (CSES), with a sun-synchronous orbit at 507 km altitude, was launched on 2 February 2018 to investigate pre-earthquake ionospheric anomalies (PEIAs) and ionospheric space weather. The CSES probes manifest longitudinal features of four-peak plasma density and three plasma depletions in the equatorial/low-latitudes as well as mid-latitude troughs. CSES plasma and the total electron content (TEC) of the global ionosphere map (GIM) are used to study PEIAs associated with a destructive M7.0 earthquake and its followed M6.5 and M6.3/M6.9 earthquakes in Lombok, Indonesia, on 5, 17, and 19 August 2018, respectively, as well as to examine ionospheric disturbances induced by an intense storm with the Dst index of − 175 nT on 26 August 2018. Anomalous increases (decreases) in the GIM TEC and CSES plasma density (temperature) frequently appear specifically over the epicenter days 1–5 before the M7.0 earthquake and followed earthquakes, when the geomagnetic conditions of these PEIA periods are relatively quiet, Dst: − 37 to 19 nT. In contrast, TEC and CSES plasma parameter anomalies occur globally in the southern hemisphere during the storm days of 26–28 August 2018. The CSES ion velocity shows that the electric fields of PEIAs associated with the M7.0 earthquake are 0.21/0.06 mV/m eastward and 0.11/0.10 mV/m downward at post-midnight/post-noon on 1–3 August 2018, while the penetration electric fields during the storm periods of 26–28 August 2018 are 0.17/0.45 mV/m westward/downward at post-midnight of 02:00 LT and 0.26/0.26 mV/m eastward/upward at post-noon of 14:00 LT. Spatial analyses on CSES plasma discriminate PEIAs from global effects and locate the epicenter of possible forthcoming large earthquakes. CSES ion velocities are useful to derive PEIA- and storm-related electric fields in the ionosphere. ","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139508785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-19DOI: 10.1186/s40562-023-00318-2
Kaya Iwamoto, Nobuaki Suenaga, Shoichi Yoshioka, Francisco Ortega-Culaciati
In southern Chile, the Nazca plate is subducting beneath the South American plate. This region was struck by megathrust earthquakes in 1960 and 2010 and is characterized by the existence of a volcanic chain. In this region, we modeled a three-dimensional thermal structure associated with the subduction of the Nazca plate by using numerical simulations. Based on the obtained temperature distribution, we determined the updip and downdip limit temperatures for the region ruptured by these two megathrust earthquakes. In addition, the distributions of water content and dehydration gradient were calculated by using appropriate phase diagrams and compared with the location of the volcanic chain. As a result, we infer that the coseismic slip of the 2010 Mw8.8 Maule earthquake occurred only at temperatures lower than and around the 350 °C isotherm that resembles the beginning of the brittle‒ductile transition. We also deduce that the rupture of the 1960 Mw9.5 Valdivia earthquake propagated up to the 450 °C isotherm because the magnitude was considerably large and the young hot plate subducted near the Chile Ridge. In addition, the hydrous minerals in the turbidites, MORB and ultramafic rocks released fluids via dehydration reactions, and dehydrated water migrated upward almost vertically, decreasing the melting point of the mantle wedge and contributing to the formation of the volcanic chain.
在智利南部，纳斯卡板块正在向南美板块下方俯冲。该地区曾在 1960 年和 2010 年发生过特大推力地震，其特点是存在火山链。在这一地区，我们通过数值模拟建立了与纳斯卡板块俯冲相关的三维热结构模型。根据得到的温度分布，我们确定了这两次大地壳地震断裂区域的上升和下降极限温度。此外，我们还利用适当的相图计算了含水量和脱水梯度的分布，并与火山链的位置进行了比较。因此，我们推断 2010 年 Mw8.8 莫尔地震的共震滑动只发生在低于 350 °C 等温线及其附近的温度下，而该等温线类似于脆性-韧性转变的起点。我们还推断，1960 年 Mw9.5 瓦尔迪维亚地震的断裂传播温度高达 450 ° C 等温线，因为震级相当大，年轻的热板块俯冲到智利海脊附近。此外，浊积岩、MORB和超基性岩中的含水矿物通过脱水反应释放出流体，脱水后的水几乎垂直向上迁移，降低了地幔楔的熔点，促进了火山链的形成。
{"title":"3D thermal structural and dehydration modeling in the southern Chile subduction zone and its relationship to interplate earthquakes and the volcanic chain","authors":"Kaya Iwamoto, Nobuaki Suenaga, Shoichi Yoshioka, Francisco Ortega-Culaciati","doi":"10.1186/s40562-023-00318-2","DOIUrl":"https://doi.org/10.1186/s40562-023-00318-2","url":null,"abstract":"In southern Chile, the Nazca plate is subducting beneath the South American plate. This region was struck by megathrust earthquakes in 1960 and 2010 and is characterized by the existence of a volcanic chain. In this region, we modeled a three-dimensional thermal structure associated with the subduction of the Nazca plate by using numerical simulations. Based on the obtained temperature distribution, we determined the updip and downdip limit temperatures for the region ruptured by these two megathrust earthquakes. In addition, the distributions of water content and dehydration gradient were calculated by using appropriate phase diagrams and compared with the location of the volcanic chain. As a result, we infer that the coseismic slip of the 2010 Mw8.8 Maule earthquake occurred only at temperatures lower than and around the 350 °C isotherm that resembles the beginning of the brittle‒ductile transition. We also deduce that the rupture of the 1960 Mw9.5 Valdivia earthquake propagated up to the 450 °C isotherm because the magnitude was considerably large and the young hot plate subducted near the Chile Ridge. In addition, the hydrous minerals in the turbidites, MORB and ultramafic rocks released fluids via dehydration reactions, and dehydrated water migrated upward almost vertically, decreasing the melting point of the mantle wedge and contributing to the formation of the volcanic chain.","PeriodicalId":48596,"journal":{"name":"Geoscience Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139500798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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