Pub Date : 2021-01-01DOI: 10.3319/tao.2021.11.17.01
S. Tsujino, H. Kuo, Hungjui Yu, Buo‐Fu Chen, K. Tsuboki
Afternoon thunderstorms (TSs) over the Taipei metropolitan area often cause meteorological disasters. Further understanding of essential factors for TS organization is important for improving prediction accuracy. This study conducts numerical simulations in two real situations with different environmental profiles: a heavy rainfall (TS) case and a no rainfall (NoTS) case. The TS simulation reasonably captures the afternoon rainfall in the Taipei basin. The thermal structure and sea breeze evolution in the simulations are verified by the observation from a field campaign. In both cases, the sea breeze develops in the afternoon. Weak environmental flow and high humidity are observed in the TS case. In contrast, a thick and dry layer with southeasterly wind above 2-km height is presented in the NoTS case. Four idealized experiments are then performed with the initial conditions based on the actual TS/ NoTS soundings and with/without the southeasterly environmental flows. Despite the different thermal profiles, the two simulations without the southeasterly flows exhibit qualitatively similar rainfall distribution and the evolution of the sea breeze to that of the real TS simulation. However, with the southeasterly environmental flows, the simulation with the NoTS sounding exhibits considerably less convection and rainfall. Therefore, not only moisture profiles but also environmental wind profiles are critical to the TS organization. Novelly, this study further shows that the environmental flow contributes to the suppression of afternoon TSs through keeping entrainment due to the continuous supply of the dry airmass. Article history: Received 13 June 2021 Revised 29 September 2021 Accepted 17 November 2021
{"title":"Effects of mid-level moisture and environmental flow on the development of afternoon thunderstorms in Taipei","authors":"S. Tsujino, H. Kuo, Hungjui Yu, Buo‐Fu Chen, K. Tsuboki","doi":"10.3319/tao.2021.11.17.01","DOIUrl":"https://doi.org/10.3319/tao.2021.11.17.01","url":null,"abstract":"Afternoon thunderstorms (TSs) over the Taipei metropolitan area often cause meteorological disasters. Further understanding of essential factors for TS organization is important for improving prediction accuracy. This study conducts numerical simulations in two real situations with different environmental profiles: a heavy rainfall (TS) case and a no rainfall (NoTS) case. The TS simulation reasonably captures the afternoon rainfall in the Taipei basin. The thermal structure and sea breeze evolution in the simulations are verified by the observation from a field campaign. In both cases, the sea breeze develops in the afternoon. Weak environmental flow and high humidity are observed in the TS case. In contrast, a thick and dry layer with southeasterly wind above 2-km height is presented in the NoTS case. Four idealized experiments are then performed with the initial conditions based on the actual TS/ NoTS soundings and with/without the southeasterly environmental flows. Despite the different thermal profiles, the two simulations without the southeasterly flows exhibit qualitatively similar rainfall distribution and the evolution of the sea breeze to that of the real TS simulation. However, with the southeasterly environmental flows, the simulation with the NoTS sounding exhibits considerably less convection and rainfall. Therefore, not only moisture profiles but also environmental wind profiles are critical to the TS organization. Novelly, this study further shows that the environmental flow contributes to the suppression of afternoon TSs through keeping entrainment due to the continuous supply of the dry airmass. Article history: Received 13 June 2021 Revised 29 September 2021 Accepted 17 November 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":"69525322","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.2021.11.29.01
P. Tan, Jien‐Yi Tu, M. Tsai
{"title":"Large-scale processes modulating the frequency of typhoons affecting Taiwan during 1900 - 1945","authors":"P. Tan, Jien‐Yi Tu, M. Tsai","doi":"10.3319/tao.2021.11.29.01","DOIUrl":"https://doi.org/10.3319/tao.2021.11.29.01","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":"69525402","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.2021.08.31.01
T. Tseng, C. Shum, Y. Hsiao, C. Kuo, W. Yeh
Global Positioning System (GPS) station displacements in this work are derived using the so-called precise point positioning (PPP) technique with low-cost singlefrequency (SF) receivers. In the SF PPP, the ionosphere delay is the largest error source if the satellite orbits and clocks are well modeled. We use two strategies to minimize the ionosphere delay for an internal comparison: (1) correction using the global ionosphere map (GIM), and (2) estimates of the ionospheric total electron content (TEC) from SF observables (SFO). The trends of the station displacements derived from these two strategies consistently present a systematic movement toward the southwest. Here the trend is referred to the slope of a linear function used to fit the displacement data. Such a systematic movement is mainly caused by the semi-annual variation of the ionospheric TEC rather than the seasonal geophysical effect and the high-order ionosphere effect, both of which only cause the station displacements ranging from a few mm to a few cm. We present a statistical analysis in terms of correlation coefficients between the semi-annual TEC variation and the station displacement. The maximum correlation coefficient is higher than 0.8 in the U component, followed by the E and N components. In addition, the impact of the semi-annual TEC variation on the station displacement is approximately 0.71, 0.45, and 0.92 m in the north (N), east (E), and height (U) for a region close to the latitude 23°N and longitude 121°E. This suggests that the semi-annual TEC variation should be considered in a time series of station displacements derived by the SF-PPP. Article history: Received 17 February 2021 Revised 12 July 2021 Accepted 31 August 2021
{"title":"Impact of semi-annual ionospheric total electron content variation on station displacements using single-frequency PPP","authors":"T. Tseng, C. Shum, Y. Hsiao, C. Kuo, W. Yeh","doi":"10.3319/tao.2021.08.31.01","DOIUrl":"https://doi.org/10.3319/tao.2021.08.31.01","url":null,"abstract":"Global Positioning System (GPS) station displacements in this work are derived using the so-called precise point positioning (PPP) technique with low-cost singlefrequency (SF) receivers. In the SF PPP, the ionosphere delay is the largest error source if the satellite orbits and clocks are well modeled. We use two strategies to minimize the ionosphere delay for an internal comparison: (1) correction using the global ionosphere map (GIM), and (2) estimates of the ionospheric total electron content (TEC) from SF observables (SFO). The trends of the station displacements derived from these two strategies consistently present a systematic movement toward the southwest. Here the trend is referred to the slope of a linear function used to fit the displacement data. Such a systematic movement is mainly caused by the semi-annual variation of the ionospheric TEC rather than the seasonal geophysical effect and the high-order ionosphere effect, both of which only cause the station displacements ranging from a few mm to a few cm. We present a statistical analysis in terms of correlation coefficients between the semi-annual TEC variation and the station displacement. The maximum correlation coefficient is higher than 0.8 in the U component, followed by the E and N components. In addition, the impact of the semi-annual TEC variation on the station displacement is approximately 0.71, 0.45, and 0.92 m in the north (N), east (E), and height (U) for a region close to the latitude 23°N and longitude 121°E. This suggests that the semi-annual TEC variation should be considered in a time series of station displacements derived by the SF-PPP. Article history: Received 17 February 2021 Revised 12 July 2021 Accepted 31 August 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":"69524146","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.2021.09.13.02
L. Ribas-Deulofeu, Yen-Chun Wang, C. Lin
The recently exposed outcrops along the Dahan River in Shulin, northern Taiwan revealed diverse and abundant marine fossils including molluscs, shark and ray teeth, sand dollars, and otoliths from a wide range of fish taxa. In addition, numerous small and fragile fossil scleractinians were found and identified here as Dendrophyl-lia sp., from the mainly azooxanthellate (90%) dendrophylliid family. Lithology of the outcrops are mainly composed of grey sandstones from the Tapu Formation (Late Miocene), overlying on a layer of basaltic tuff. The absolute age of the boundary be-tween the Tapu Formation and the underlying Nanchuang Formation is 8 Ma, which provides indications on the maximum age possible for the scleractinian fossils found in this study. Back then, the marine ecosystem in which the sampled Dendropyllia specimens grew was probably a turbid shallow coastal environment with muddy to sandy bottom, likely at the vicinity of a river estuary, as suggested by the combined presence of previously reported fish otoliths. To our knowledge, this is the first record of Dendrophyllia fossils from Taiwan.
{"title":"First record of Late Miocene Dendrophyllia de Blainville, 1830 (Scleractinia: Dendrophylliidae) in Taiwan","authors":"L. Ribas-Deulofeu, Yen-Chun Wang, C. Lin","doi":"10.3319/tao.2021.09.13.02","DOIUrl":"https://doi.org/10.3319/tao.2021.09.13.02","url":null,"abstract":"The recently exposed outcrops along the Dahan River in Shulin, northern Taiwan revealed diverse and abundant marine fossils including molluscs, shark and ray teeth, sand dollars, and otoliths from a wide range of fish taxa. In addition, numerous small and fragile fossil scleractinians were found and identified here as Dendrophyl-lia sp., from the mainly azooxanthellate (90%) dendrophylliid family. Lithology of the outcrops are mainly composed of grey sandstones from the Tapu Formation (Late Miocene), overlying on a layer of basaltic tuff. The absolute age of the boundary be-tween the Tapu Formation and the underlying Nanchuang Formation is 8 Ma, which provides indications on the maximum age possible for the scleractinian fossils found in this study. Back then, the marine ecosystem in which the sampled Dendropyllia specimens grew was probably a turbid shallow coastal environment with muddy to sandy bottom, likely at the vicinity of a river estuary, as suggested by the combined presence of previously reported fish otoliths. To our knowledge, this is the first record of Dendrophyllia fossils from Taiwan.","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":"69524281","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.2019.02.07.01
Yuequn Dong, T. Lei, Qingwen Zhang, Xiaohui Zhuang, Fangfang Liu
Salt tracer is one of the widely used shallow water velocity measurement methods. The Pulse Boundary Model method produces low velocity at short distances from the salt injection position. This study proposes a two-step approach to accu-rately estimate the flow velocity. Experiments were carried out under three flow rates of 12, 24, and 48 L min -1 and three slope gradients of 4, 8, and 12° at six measurement positions of 0.05, 0.3, 0.6, 0.9, 1.2, and 1.5 m from the solute injection positions. The new method obtains peak velocities that are 0.999 times those of the centroid velocities, indicating that either centroid or peak time can be equally used to measure flow velocity. The new method significantly improves measurement accuracy of flow velocity at short distances, as indicated by the almost equal measured velocities at all locations as those measured at longer distances. Velocities measured by the new method were significantly higher than those measured by the Pulse Boundary Model method or the centroid velocities measured by the traditional salt tracer method. In addition, the centroid and the peak velocities obtained by the new method correlates well to those by the traditional volumetric method. The velocities measured by the volumetric method were 0.79 (centroid velocity) and 0.78 (peak velocity) times of those estimated by the new and improved method. The results show that new and improved method provides an accurate and efficient approach in measuring shallow water flow velocity at short distances.
盐示踪剂是目前应用广泛的浅水测速方法之一。脉冲边界模型方法在离盐注入位置很近的地方产生低速。本研究提出了一种两步法来精确估计流速。实验在距离溶质注入位置0.05、0.3、0.6、0.9、1.2和1.5 m的6个测量位置，以12、24和48 L min -1 3种流速和4、8和12°3个坡度梯度进行。新方法得到的峰值速度是质心速度的0.999倍，表明质心时间和峰值时间都可以用来测量流速。新方法显著提高了近距离流速的测量精度，所有位置的测量速度与较长距离的测量速度几乎相等。新方法测得的速度明显高于脉冲边界模型法或传统盐示踪法测得的质心速度。此外，新方法得到的质心和峰值速度与传统的体积法得到的结果具有较好的相关性。体积法测得的速度是新方法和改进方法测得速度的0.79倍(质心速度)和0.78倍(峰值速度)。结果表明，改进后的新方法为近距离测量浅水流速提供了一种准确、有效的方法。
{"title":"Improved accuracy of short-distance measurement of water flow velocity using Pulse Boundary Model","authors":"Yuequn Dong, T. Lei, Qingwen Zhang, Xiaohui Zhuang, Fangfang Liu","doi":"10.3319/TAO.2019.02.07.01","DOIUrl":"https://doi.org/10.3319/TAO.2019.02.07.01","url":null,"abstract":"Salt tracer is one of the widely used shallow water velocity measurement methods. The Pulse Boundary Model method produces low velocity at short distances from the salt injection position. This study proposes a two-step approach to accu-rately estimate the flow velocity. Experiments were carried out under three flow rates of 12, 24, and 48 L min -1 and three slope gradients of 4, 8, and 12° at six measurement positions of 0.05, 0.3, 0.6, 0.9, 1.2, and 1.5 m from the solute injection positions. The new method obtains peak velocities that are 0.999 times those of the centroid velocities, indicating that either centroid or peak time can be equally used to measure flow velocity. The new method significantly improves measurement accuracy of flow velocity at short distances, as indicated by the almost equal measured velocities at all locations as those measured at longer distances. Velocities measured by the new method were significantly higher than those measured by the Pulse Boundary Model method or the centroid velocities measured by the traditional salt tracer method. In addition, the centroid and the peak velocities obtained by the new method correlates well to those by the traditional volumetric method. The velocities measured by the volumetric method were 0.79 (centroid velocity) and 0.78 (peak velocity) times of those estimated by the new and improved method. The results show that new and improved method provides an accurate and efficient approach in measuring shallow water flow velocity at short distances.","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"26 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69520463","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}
The Royal Thai Survey Department and Chiang Mai University developed the Thailand geoid model 2017 (TGM2017) with a 1’ × 1’ grid to support the transformation between Global Navigation satellite System (GNSS) ellipsoid heights and Kolak-1915 vertical datum orthometric heights. TGM2017 was based on Thailand gravimetric geoid model 2017 (THAI17G) and 299 GNSS ellipsoidal heights co-located with Kolak-1915 heights. All terrestrial gravity data used for geoid computation came from the new national gravity network, consisting of 87 absolute and 9929 relative gravity stations at 10 – 25 km intervals, mostly along with existing roads. From 2016 to 2017, airborne gravity surveys were conducted at a 4000m-flight altitude and 10 km along-track spacing to acquire the gravity data over mountainous and inaccessible areas, including coastal and marine areas, at an estimated accuracy of 3.0 mGal. Long-wavelength geoid structure was controlled by the GOCE-EGM2008 combined model (GECO) and the Technical University of Denmark’s global marine gravity model 2013 (DTU13). All gravity data were combined and downward, using least-squares collocation with the residual terrain model reductions from a digital terrain elevation data level 2 (DTED2). THAI17G was determined by multi-band spherical Fast Fourier Transform and converted to TGM2017 with the 38.2cm root-mean-square (rms) fit of 299 GNSS/leveling co-points and a mean offset of 37.0 cm. This value represents the separation between Kolak-1915 and a global mean sea level. The evaluation of TGM2017 at 100 GNSS/leveling checkpoints shows the rms of 4.9 cm, consequently leading to reliable orthometric heights at a 10-cm accuracy level or better.
{"title":"The determination of Thailand Geoid Model 2017 (TGM2017) from airborne and terrestrial gravimetry","authors":"Puttipol Dumrongchai, Chawis Srimanee, Nuttanon Duangdee, Jittrakorn Bairaksa","doi":"10.3319/tao.2021.08.23.01","DOIUrl":"https://doi.org/10.3319/tao.2021.08.23.01","url":null,"abstract":"The Royal Thai Survey Department and Chiang Mai University developed the Thailand geoid model 2017 (TGM2017) with a 1’ × 1’ grid to support the transformation between Global Navigation satellite System (GNSS) ellipsoid heights and Kolak-1915 vertical datum orthometric heights. TGM2017 was based on Thailand gravimetric geoid model 2017 (THAI17G) and 299 GNSS ellipsoidal heights co-located with Kolak-1915 heights. All terrestrial gravity data used for geoid computation came from the new national gravity network, consisting of 87 absolute and 9929 relative gravity stations at 10 – 25 km intervals, mostly along with existing roads. From 2016 to 2017, airborne gravity surveys were conducted at a 4000m-flight altitude and 10 km along-track spacing to acquire the gravity data over mountainous and inaccessible areas, including coastal and marine areas, at an estimated accuracy of 3.0 mGal. Long-wavelength geoid structure was controlled by the GOCE-EGM2008 combined model (GECO) and the Technical University of Denmark’s global marine gravity model 2013 (DTU13). All gravity data were combined and downward, using least-squares collocation with the residual terrain model reductions from a digital terrain elevation data level 2 (DTED2). THAI17G was determined by multi-band spherical Fast Fourier Transform and converted to TGM2017 with the 38.2cm root-mean-square (rms) fit of 299 GNSS/leveling co-points and a mean offset of 37.0 cm. This value represents the separation between Kolak-1915 and a global mean sea level. The evaluation of TGM2017 at 100 GNSS/leveling checkpoints shows the rms of 4.9 cm, consequently leading to reliable orthometric heights at a 10-cm accuracy level or better.","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":"245 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69524123","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.2021.08.23.02
Sushmita Timilsina, M. Willberg, R. Rol
Regional Geoid for Nepal using Least-Squares Collocation Sushmita Timilsina , Martin Willberg, Roland Pail 1 Ministry of Land Management, Cooperatives and Poverty Alleviation, Land Management Training Centre, Dhulikhel, Kavrepalanchok, Nepal 2 Institute of Astronomical and Physical Geodesy, Technical University of Munich, Munich, Germany This manuscript is submitted to “Terrestrial, Atmospheric and Oceanic Sciences”
基于最小二乘配置的尼泊尔区域大地面线Sushmita Timilsina, Martin Willberg, Roland Pail 1尼泊尔Kavrepalanchok Dhulikhel土地管理、合作社和扶贫部土地管理培训中心2德国慕尼黑工业大学天文和物理大地测量研究所
{"title":"Regional geoid for Nepal using Least-Squares Collocation","authors":"Sushmita Timilsina, M. Willberg, R. Rol","doi":"10.3319/tao.2021.08.23.02","DOIUrl":"https://doi.org/10.3319/tao.2021.08.23.02","url":null,"abstract":"Regional Geoid for Nepal using Least-Squares Collocation Sushmita Timilsina , Martin Willberg, Roland Pail 1 Ministry of Land Management, Cooperatives and Poverty Alleviation, Land Management Training Centre, Dhulikhel, Kavrepalanchok, Nepal 2 Institute of Astronomical and Physical Geodesy, Technical University of Munich, Munich, Germany This manuscript is submitted to “Terrestrial, Atmospheric and Oceanic Sciences”","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":"69524134","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.2021.08.23.03
M. Ii, Tzu‐Ting Lo, Hsiao-Chung Tsai, E. Cayanan
{"title":"Assessing the potential predictability of tropical cyclone activity in the Philippines on weekly timescales","authors":"M. Ii, Tzu‐Ting Lo, Hsiao-Chung Tsai, E. Cayanan","doi":"10.3319/tao.2021.08.23.03","DOIUrl":"https://doi.org/10.3319/tao.2021.08.23.03","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":"69524138","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.2021.06.04.02
R. Wu, Xi Cao
The present study investigates the relationship of the year-to-year variations in the tropical cyclone (TC) genesis number over the western North Pacific (WNP) to the intensity of 10-20-day and 30-60-day intraseasonal oscillations (ISOs) during 1979 - 2018. It is found that the relationship between the TC genesis number and ISO intensity differs largely among the four quadrants of the WNP. The TC number in the southeast quadrant of the WNP has a close relation to the ISO intensity, but the relation is mostly weak for the TC number in the other three quadrants of the WNP. More (less) TC number in the southeast quadrant of the WNP corresponds to a stronger (weaker) ISOs. This indicates that stronger ISOs or longer active phases of the ISOs provide a favorable condition for formation of more TCs. This modulation of the ISO intensity on the TC genesis number suggests an indirect way for influence of seasonal mean background on the year-to-year variations in the WNP TC number through the ISO intensity. Further analysis suggests that this indirect way is likely a more important manner for the influence of seasonal mean background on the year-to-year variations in the genesis TC number over the WNP.
{"title":"Relation of the western North Pacific tropical cyclone genesis number to intraseasonal oscillation intensity","authors":"R. Wu, Xi Cao","doi":"10.3319/tao.2021.06.04.02","DOIUrl":"https://doi.org/10.3319/tao.2021.06.04.02","url":null,"abstract":"The present study investigates the relationship of the year-to-year variations in the tropical cyclone (TC) genesis number over the western North Pacific (WNP) to the intensity of 10-20-day and 30-60-day intraseasonal oscillations (ISOs) during 1979 - 2018. It is found that the relationship between the TC genesis number and ISO intensity differs largely among the four quadrants of the WNP. The TC number in the southeast quadrant of the WNP has a close relation to the ISO intensity, but the relation is mostly weak for the TC number in the other three quadrants of the WNP. More (less) TC number in the southeast quadrant of the WNP corresponds to a stronger (weaker) ISOs. This indicates that stronger ISOs or longer active phases of the ISOs provide a favorable condition for formation of more TCs. This modulation of the ISO intensity on the TC genesis number suggests an indirect way for influence of seasonal mean background on the year-to-year variations in the WNP TC number through the ISO intensity. Further analysis suggests that this indirect way is likely a more important manner for the influence of seasonal mean background on the year-to-year variations in the genesis TC number over the WNP.","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":"69524247","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}
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