Pub Date : 2021-01-01DOI: 10.3319/tao.2021.10.18.01
Ting Wang, Daowei Zhou, Xiangjin Shen
The classification of Köppen climate type has been widely used to identify regional climate change. This study investigated the changes of Köppen climate type over China during 1964 2015. On average, the arid climate was located in the northwest, tropical climate, temperate climate, and cold climate were distributed in the east from south to north along the latitude, and polar climate was concentrated on the Tibetan Plateau. Comparing Köppen climate types during 1964 1989 and 1990 2015, we found that cold climate with dry winter was replaced by a cold steppe climate in Northeast China and North China, warm summer was replaced by cold summer in Northeast China and the Tibetan Plateau, tundra climate was substituted by cold climate in the Tibetan Plateau, and cold climate was replaced by temperate climate in Central China and East China. Our results showed that the arid climate expanded eastward and southward, which may have resulted from a decrease in precipitation. Owing to the increase in temperature, the climate zones moved northward. This study provides valuable insights for government decision-makers in formulating crop planting systems, water resource management, and land use planning. Article history: Received 21 June 2021 Revised 15 September 2021 Accepted 18 October 2021
{"title":"Spatial-temporal variations of Köppen climate types in China","authors":"Ting Wang, Daowei Zhou, Xiangjin Shen","doi":"10.3319/tao.2021.10.18.01","DOIUrl":"https://doi.org/10.3319/tao.2021.10.18.01","url":null,"abstract":"The classification of Köppen climate type has been widely used to identify regional climate change. This study investigated the changes of Köppen climate type over China during 1964 2015. On average, the arid climate was located in the northwest, tropical climate, temperate climate, and cold climate were distributed in the east from south to north along the latitude, and polar climate was concentrated on the Tibetan Plateau. Comparing Köppen climate types during 1964 1989 and 1990 2015, we found that cold climate with dry winter was replaced by a cold steppe climate in Northeast China and North China, warm summer was replaced by cold summer in Northeast China and the Tibetan Plateau, tundra climate was substituted by cold climate in the Tibetan Plateau, and cold climate was replaced by temperate climate in Central China and East China. Our results showed that the arid climate expanded eastward and southward, which may have resulted from a decrease in precipitation. Owing to the increase in temperature, the climate zones moved northward. This study provides valuable insights for government decision-makers in formulating crop planting systems, water resource management, and land use planning. Article history: Received 21 June 2021 Revised 15 September 2021 Accepted 18 October 2021","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69524470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2021-01-01DOI: 10.3319/tao.2021.09.16.02
Ya-Chih Mao, Cissi Y. Lin
{"title":"VHF scintillations and plasma drifts observed in southern Taiwan during the declining phase of solar cycle 24","authors":"Ya-Chih Mao, Cissi Y. Lin","doi":"10.3319/tao.2021.09.16.02","DOIUrl":"https://doi.org/10.3319/tao.2021.09.16.02","url":null,"abstract":"","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69524522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2021-01-01DOI: 10.3319/tao.2021.12.15.02
T. Feng, Tao Zheng
{"title":"A statistical study of the monsoon trough and associated tropical cyclogenesis over the western North Pacific","authors":"T. Feng, Tao Zheng","doi":"10.3319/tao.2021.12.15.02","DOIUrl":"https://doi.org/10.3319/tao.2021.12.15.02","url":null,"abstract":"","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69525023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2021-01-01DOI: 10.3319/tao.2021.12.26.01
H. Chao, C. You, I. Lin, Hsueh-Yu Lu, Hou-Chun Liu, C. Chung
Mud volcano (MV) is one of the most important passageways for deep seated volatile materials to migrate back to Earth’s surface in sedimentary basins and subduction zones. Waters of MV fluid emitted from 18 mud pools in MV Luo-Shan (LS) in eastern Taiwan were sampled from the year 2002 to the year 2021. Major and trace components as well as H, triple O (δ18O and Δ17O) and triple Sr isotopes (87Sr/86Sr and δ88Sr) were measured. The results show that major components of water are Cl-, Na and Ca. Compared with seawater, water of MV LS reveals similar chemical characteristics with low-temperature ridge-flank hydrothermal spring and marine pore water in reducing condition. Limited spatial and temporal variation of major components as well as H, triple O and 87Sr/86Sr indicates waters emitted by mud pools come from the same source regionally. Slightly radiogenic 87Sr/86Sr at southern mud pools and before the year 2003 denotes different fluid reservoir from northern ones. Small 87Sr/86Sr variation in waters of northern mud pools indicates near surface mixing from 2 fluid reservoirs. The correlation among all components reveals sediment component addition is the major factor and evaporation is the key factor for conservative elements. In summary, waters expelled by MV LS mud pools originate from the same regional source, and their trace element composition such as Mg, K, Sr as well as 87Sr/86Sr slightly varies, depending on the location of the reservoir they are hosted. A stable source with small vibration of fluid reservoir of MV LS is indicated during the 19-years investigation period.
{"title":"Water of eastern Taiwan mud volcanoes. Part I. H, triple O, triple Sr isotopes, and trace elements of Lo-Shan mud volcano","authors":"H. Chao, C. You, I. Lin, Hsueh-Yu Lu, Hou-Chun Liu, C. Chung","doi":"10.3319/tao.2021.12.26.01","DOIUrl":"https://doi.org/10.3319/tao.2021.12.26.01","url":null,"abstract":"Mud volcano (MV) is one of the most important passageways for deep seated volatile materials to migrate back to Earth’s surface in sedimentary basins and subduction zones. Waters of MV fluid emitted from 18 mud pools in MV Luo-Shan (LS) in eastern Taiwan were sampled from the year 2002 to the year 2021. Major and trace components as well as H, triple O (δ18O and Δ17O) and triple Sr isotopes (87Sr/86Sr and δ88Sr) were measured. The results show that major components of water are Cl-, Na and Ca. Compared with seawater, water of MV LS reveals similar chemical characteristics with low-temperature ridge-flank hydrothermal spring and marine pore water in reducing condition. Limited spatial and temporal variation of major components as well as H, triple O and 87Sr/86Sr indicates waters emitted by mud pools come from the same source regionally. Slightly radiogenic 87Sr/86Sr at southern mud pools and before the year 2003 denotes different fluid reservoir from northern ones. Small 87Sr/86Sr variation in waters of northern mud pools indicates near surface mixing from 2 fluid reservoirs. The correlation among all components reveals sediment component addition is the major factor and evaporation is the key factor for conservative elements. In summary, waters expelled by MV LS mud pools originate from the same regional source, and their trace element composition such as Mg, K, Sr as well as 87Sr/86Sr slightly varies, depending on the location of the reservoir they are <Ac cept ed M anu scrip t> hosted. A stable source with small vibration of fluid reservoir of MV LS is indicated during the 19-years investigation period.","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"91 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69525142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2021-01-01DOI: 10.3319/tao.2021.12.30.01
C. Hwang, W. Shen, Xiaopeng Li, Ami Hassan Md Din
This special issue (SI) includes papers related to some recent efforts on geoid modeling in the Asia-Pacific region. In total, twelve papers were submitted to this SI, covering geoid models in Australia, mainland China, India, Indonesia, South Korea, Malaysia, Nepal, the Philippines, Taiwan and Thailand. The methods for geoid modeling are rather diversified, with different considerations in gravity data processing and terrain effects. It is suggested that a mechanism for gravity data sharing should be developed and software packages can be freely distributed to geoid modelers. Observed GNSS/leveling along a route over varying terrains across Taiwan are released for testing geoid modeling methods and for accuracy assessments.
{"title":"Introduction to the special issue on Gravity and geoid in the Asia Pacific","authors":"C. Hwang, W. Shen, Xiaopeng Li, Ami Hassan Md Din","doi":"10.3319/tao.2021.12.30.01","DOIUrl":"https://doi.org/10.3319/tao.2021.12.30.01","url":null,"abstract":"This special issue (SI) includes papers related to some recent efforts on geoid modeling in the Asia-Pacific region. In total, twelve papers were submitted to this SI, covering geoid models in Australia, mainland China, India, Indonesia, South Korea, Malaysia, Nepal, the Philippines, Taiwan and Thailand. The methods for geoid modeling are rather diversified, with different considerations in gravity data processing and terrain effects. It is suggested that a mechanism for gravity data sharing should be developed and software packages can be freely distributed to geoid modelers. Observed GNSS/leveling along a route over varying terrains across Taiwan are released for testing geoid modeling methods and for accuracy assessments.","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69525167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2021-01-01DOI: 10.3319/tao.2021.03.03.01
Robb P. Gile, John Carlo S. Sugui, Juanito S. Galang, E. Cayanan, Hsiao-Chung Tsai, Yung-Lan Lin, Ai-Mei Chia, Ping-Yu Lin, Kuo-Chen Lu, B. Jou
The tropical cyclone (TC) intensity forecast from the Weighted Analog Intensity Prediction (WAIP) was evaluated using 63 Philippine TC cases from 2014 to 2017 to determine its applicability as baseline intensity forecast guidance of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA). The method generates a rank-weighted average of intensity evolutions of 10 historical analogs from the 1945 to 2014 Joint Typhoon Warning Center best tracks that closely resemble the PAGASA official forecast track and initial intensity at the time the forecast is generated. WAIP proved to be more skillful in providing intensity forecast at 12 to 96 h and less skillful at 120 h relative to persistence. Verification revealed that WAIP had significantly smaller mean absolute error and consistently smaller intensity biases up to 96 h. However, the small sample size at 96 h due to the limitations in the extent of the observed track and reference track forecast from PAGASA suggests that the result may not fully represent the model performance within the Philippine Area of Responsibility at 96 h. The probability distribution of intensities at 36, 72, and 96 h predicted by the model showed that the statistical model may not fully capture the full range of the observed intensities or the extreme values, with the model struggling to predict lower range of intensity values with increasing forecast intervals. Three TC cases are presented to emphasize the model dependence on the accuracy of the reference track forecast and the number and representativeness of available historical analogs for a particular forecast scenario.
{"title":"Application of Weighted Analog Intensity Prediction (WAIP) guidance on Philippine tropical cyclone events","authors":"Robb P. Gile, John Carlo S. Sugui, Juanito S. Galang, E. Cayanan, Hsiao-Chung Tsai, Yung-Lan Lin, Ai-Mei Chia, Ping-Yu Lin, Kuo-Chen Lu, B. Jou","doi":"10.3319/tao.2021.03.03.01","DOIUrl":"https://doi.org/10.3319/tao.2021.03.03.01","url":null,"abstract":"The tropical cyclone (TC) intensity forecast from the Weighted Analog Intensity Prediction (WAIP) was evaluated using 63 Philippine TC cases from 2014 to 2017 to determine its applicability as baseline intensity forecast guidance of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA). The method generates a rank-weighted average of intensity evolutions of 10 historical analogs from the 1945 to 2014 Joint Typhoon Warning Center best tracks that closely resemble the PAGASA official forecast track and initial intensity at the time the forecast is generated. WAIP proved to be more skillful in providing intensity forecast at 12 to 96 h and less skillful at 120 h relative to persistence. Verification revealed that WAIP had significantly smaller mean absolute error and consistently smaller intensity biases up to 96 h. However, the small sample size at 96 h due to the limitations in the extent of the observed track and reference track forecast from PAGASA suggests that the result may not fully represent the model performance within the Philippine Area of Responsibility at 96 h. The probability distribution of intensities at 36, 72, and 96 h predicted by the model showed that the statistical model may not fully capture the full range of the observed intensities or the extreme values, with the model struggling to predict lower range of intensity values with increasing forecast intervals. Three TC cases are presented to emphasize the model dependence on the accuracy of the reference track forecast and the number and representativeness of available historical analogs for a particular forecast scenario.","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69523653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2021-01-01DOI: 10.3319/TAO.2020.11.24.01
Xuemin Zhang, Yalu Wang, Yongxin Gao, Jing Liu
In this study, three magnetometer stations in China and four co-located magnetometers and geoelectric field detectors in Japan were primarily used for observing co-seismic signatures excited by nuclear explosions conducted in North Korea between 2006 2017. The observations in Japan did not measure considerable magnitudes of the co-seismic electromagnetic (EM) signals corresponding to the geomagnetic and geoelectric fields at large distances from the explosion source. However, the geomagnetic field detectors in northeast China detected clear co-seismic signatures, shortly after the arrival time of the seismic waves. On the day of the most powerful blast on 3 September 2017, the horizontal component of the geomagnetic field with a maximum amplitude of ±5 nT was measured at the Changchun station in China, located at a distance of less than 500 km from the explosion source. In order to understand the measured signals, three mechanisms that can induce these signals were simulated. The electrokinetic and dynamo effects were observed to primarily contribute to the formation of the surface-wave-related EM signals, whereas the shaking and vibration of the instrument caused the continuous oscillation seen in the geomagnetic observations. Article history: Received 3 January 2020 Revised 29 September 2020 Accepted 24 November 2020
{"title":"Electromagnetic disturbances induced by nuclear tests in North Korea","authors":"Xuemin Zhang, Yalu Wang, Yongxin Gao, Jing Liu","doi":"10.3319/TAO.2020.11.24.01","DOIUrl":"https://doi.org/10.3319/TAO.2020.11.24.01","url":null,"abstract":"In this study, three magnetometer stations in China and four co-located magnetometers and geoelectric field detectors in Japan were primarily used for observing co-seismic signatures excited by nuclear explosions conducted in North Korea between 2006 2017. The observations in Japan did not measure considerable magnitudes of the co-seismic electromagnetic (EM) signals corresponding to the geomagnetic and geoelectric fields at large distances from the explosion source. However, the geomagnetic field detectors in northeast China detected clear co-seismic signatures, shortly after the arrival time of the seismic waves. On the day of the most powerful blast on 3 September 2017, the horizontal component of the geomagnetic field with a maximum amplitude of ±5 nT was measured at the Changchun station in China, located at a distance of less than 500 km from the explosion source. In order to understand the measured signals, three mechanisms that can induce these signals were simulated. The electrokinetic and dynamo effects were observed to primarily contribute to the formation of the surface-wave-related EM signals, whereas the shaking and vibration of the instrument caused the continuous oscillation seen in the geomagnetic observations. Article history: Received 3 January 2020 Revised 29 September 2020 Accepted 24 November 2020","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69523867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2021-01-01DOI: 10.3319/tao.2021.09.16.01
Natalia Limones
Flash droughts are defined as fast and intense dryings of the land system. In these episodes, declines in precipitation deficits are often accompanied by rapid intensifications of evaporative demand, leading to sharp soil moisture decreases and noticeable agricultural and environmental impacts. This research presents a straightforward framework for global historical characterization of precipitation-deficit-related flash droughts, examining the extent to which this type of hazard can be described using only pentad rainfall data. The Drought Exceedance Probability Index was applied to global gridded high-resolution rainfall data for 1979 2020. Sharp upsurges in the pentad index series were detected and counted to analyze the occurrence of precipitation-deficit flash droughts. The precipitation characteristics associated to flash drought incidence were explored to learn if some rainfall regimes or times of the year are more prone to the phenomenon, which could help societies become more prepared for the risk. It was observed that climates with marked inter-annual and intra-annual rainfall variability record more flash droughts, especially when that variability is significant during the local wet seasons. This is the case of regions with erratic rainfall generation mechanisms such as Mediterranean climates or monsoon climates. The episodes mainly occur during what is expected to be the humid time of the year, when they can produce greater impact. The methodology used was able to detect the most intense events described in previous studies that used variables associated to soil moisture dryness, confirming the role of acute precipitation deficits in triggering them. Article history: Received 23 March 2021 Revised 15 September 2021 Accepted 16 September 2021
{"title":"A global-scale overview of precipitation-deficit flash droughts","authors":"Natalia Limones","doi":"10.3319/tao.2021.09.16.01","DOIUrl":"https://doi.org/10.3319/tao.2021.09.16.01","url":null,"abstract":"Flash droughts are defined as fast and intense dryings of the land system. In these episodes, declines in precipitation deficits are often accompanied by rapid intensifications of evaporative demand, leading to sharp soil moisture decreases and noticeable agricultural and environmental impacts. This research presents a straightforward framework for global historical characterization of precipitation-deficit-related flash droughts, examining the extent to which this type of hazard can be described using only pentad rainfall data. The Drought Exceedance Probability Index was applied to global gridded high-resolution rainfall data for 1979 2020. Sharp upsurges in the pentad index series were detected and counted to analyze the occurrence of precipitation-deficit flash droughts. The precipitation characteristics associated to flash drought incidence were explored to learn if some rainfall regimes or times of the year are more prone to the phenomenon, which could help societies become more prepared for the risk. It was observed that climates with marked inter-annual and intra-annual rainfall variability record more flash droughts, especially when that variability is significant during the local wet seasons. This is the case of regions with erratic rainfall generation mechanisms such as Mediterranean climates or monsoon climates. The episodes mainly occur during what is expected to be the humid time of the year, when they can produce greater impact. The methodology used was able to detect the most intense events described in previous studies that used variables associated to soil moisture dryness, confirming the role of acute precipitation deficits in triggering them. Article history: Received 23 March 2021 Revised 15 September 2021 Accepted 16 September 2021","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69524335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2021-01-01DOI: 10.3319/tao.2021.07.26.02
Yecheng Feng, Liguang Wu
Tropical cyclones (TCs) tend to oscillate around a mean path and the trochoidal oscillation has been documented based on radar, satellite and aircraft observational data and in numerical simulations. Currently, no consensus has been reached on the mechanisms responsible for the trochoidal oscillation in TC motion although a few theories have been proposed since 1950. In this study, the small-amplitude track oscillations of Super Typhoons Rammasun (2014) and Lekima (2019) are examined based on the 6-minute radar refelctivity and the detected oscillation in Rammasun is verified through numerical simulation. The trochoidal oscillation in the tracks of Super Typhoons Rammasun and Lekima can be retrieved with the 6-minute radar data. The detected track oscillation always exhibits cyclonic rotations around a mean track, with the amplitude of a few kilometers and the period of a few hours. The numerical simulation of Typhoon Rammasun indicates that the small-amplitude track oscillation can be simulated in terms of the period and amplitude. Based on two different center-detecting methods, it is shown that the simulated track oscillation represents the wobble of the whole inner-core circulation. Since the small-scale oscillations are closely associated with the dynamics of the TC inner-core circulation, this study suggests that the trochoidal oscillation in TC tracks may provide important information for understanding the intensity and structure changes of TCs.
{"title":"Small-amplitude trochoidal oscillations in Typhoons Rammasun (2014) and Lekima (2019)","authors":"Yecheng Feng, Liguang Wu","doi":"10.3319/tao.2021.07.26.02","DOIUrl":"https://doi.org/10.3319/tao.2021.07.26.02","url":null,"abstract":"Tropical cyclones (TCs) tend to oscillate around a mean path and the trochoidal oscillation has been documented based on radar, satellite and aircraft observational data and in numerical simulations. Currently, no consensus has been reached on the mechanisms responsible for the trochoidal oscillation in TC motion although a few theories have been proposed since 1950. In this study, the small-amplitude track oscillations of Super Typhoons Rammasun (2014) and Lekima (2019) are examined based on the 6-minute radar refelctivity and the detected oscillation in Rammasun is verified through numerical simulation. The trochoidal oscillation in the tracks of Super Typhoons Rammasun and Lekima can be retrieved with the 6-minute radar data. The detected track oscillation always exhibits cyclonic rotations around a mean track, with the amplitude of a few kilometers and the period of a few hours. The numerical simulation of Typhoon Rammasun indicates that the small-amplitude track oscillation can be simulated in terms of the period and amplitude. Based on two different center-detecting methods, it is shown that the simulated track oscillation represents the wobble of the whole inner-core circulation. Since the small-scale oscillations are closely associated with the dynamics of the TC inner-core circulation, this study suggests that the trochoidal oscillation in TC tracks may provide important information for understanding the intensity and structure changes of TCs.","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69524443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2021-01-01DOI: 10.3319/tao.2021.12.18.02
Jun Li, Yuandi Zhao, Dan Yang, J. Tanoli
The variations in extreme precipitation and their relation to large-scale climate circulation were investigated over a typical transitional climate zone named the Qinling-Dabashan Mountains from 1961 to 2018. In this study, the spatial and temporal variations in eleven extreme precipitation indices are determined using the Sen’s method, Mann test and heuristic segmentation method. The relations between extreme precipitation and the Asia summer monsoon are analyzed by cross wavelet transform methods. The major findings of this research are as follows: (1) the spatial distribution of extreme precipitation changes over time in the Qinling-Dabashan Mountains: higher precipitation intensity occur in the middle and southeastern regions, while other regions exhibit adverse variation patterns. (2) Temporally, the regional trends of only the annual total wet day precipitation are dominant in the Qinling-Dabashan Mountains and its subregions. However, the regional trends of extreme precipitation are not statistically significant. In addition, the extreme precipitation in the Qinling-Dabashan Mountains and its subregions was sensitive to environmental changes from 1961 to 2018, including intensive human activity, the Asian summer monsoon and steep terrain. Sensitivity to environmental change im-plies flash floods and other natural disasters from 1961 to 2018. (3) The East Asian Summer Monsoon has a stronger influence than the South Asian Summer Monsoon on extreme precipitation. The results of this research will aid decision-makers in their response to recent climate change scenarios in the Qinling-Dabashan Mountains.
{"title":"Variations in extreme precipitation and relation to the Asia summer monsoon over the Qinling-Dabashan Mountains, China","authors":"Jun Li, Yuandi Zhao, Dan Yang, J. Tanoli","doi":"10.3319/tao.2021.12.18.02","DOIUrl":"https://doi.org/10.3319/tao.2021.12.18.02","url":null,"abstract":"The variations in extreme precipitation and their relation to large-scale climate circulation were investigated over a typical transitional climate zone named the Qinling-Dabashan Mountains from 1961 to 2018. In this study, the spatial and temporal variations in eleven extreme precipitation indices are determined using the Sen’s method, Mann test and heuristic segmentation method. The relations between extreme precipitation and the Asia summer monsoon are analyzed by cross wavelet transform methods. The major findings of this research are as follows: (1) the spatial distribution of extreme precipitation changes over time in the Qinling-Dabashan Mountains: higher precipitation intensity occur in the middle and southeastern regions, while other regions exhibit adverse variation patterns. (2) Temporally, the regional trends of only the annual total wet day precipitation are dominant in the Qinling-Dabashan Mountains and its subregions. However, the regional trends of extreme precipitation are not statistically significant. In addition, the extreme precipitation in the Qinling-Dabashan Mountains and its subregions was sensitive to environmental changes from 1961 to 2018, including intensive human activity, the Asian summer monsoon and steep terrain. Sensitivity to environmental change im-plies flash floods and other natural disasters from 1961 to 2018. (3) The East Asian Summer Monsoon has a stronger influence than the South Asian Summer Monsoon on extreme precipitation. The results of this research will aid decision-makers in their response to recent climate change scenarios in the Qinling-Dabashan Mountains.","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"55 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69525085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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