{"title":"Comparison of surface-wind fields between Typhoon 0418 (Songda) and Typhoon 9119 (Mireille) in Western Japan","authors":"F. Fujibe, N. Kitabatake, K. Bessho, S. Hoshino","doi":"10.2467/MRIPAPERS.57.1","DOIUrl":"https://doi.org/10.2467/MRIPAPERS.57.1","url":null,"abstract":"台風0418 (2004年9月7～8日) と台風9119 (1991年9月27～28日) は互いによく似た経路で西日本を通り，ともに大きな強風被害をもたらした。これら2つの台風による風速分布の特徴を気象庁のデータを使って調べた。どちらの台風も風は中心の右側（南東側）で最も強かったが，台風9119は中心の左後方（西側）にも強風域を伴っていた。この強風域は強雨と低温を伴っており，中心後方の降雨帯に乾燥空気が侵入することによる蒸発冷却によって形成されたと考えられる。これに対して台風0418は中心後方の降雨が弱く，風速分布は軸対称な渦と移動速度との重なったものにほぼ近かったことが示された。","PeriodicalId":39821,"journal":{"name":"Papers in Meteorology and Geophysics","volume":"62 1","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69024744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Piezomagnetic Field Associated with the Mogi Model Considering Topographic Effects","authors":"Akira Yamazaki, T. Sakai","doi":"10.2467/MRIPAPERS.57.21","DOIUrl":"https://doi.org/10.2467/MRIPAPERS.57.21","url":null,"abstract":"マグマ溜りの膨張や収縮による地殻応力変化に伴って地表にどのような磁場が生じるかという問題は火山電磁気学の重要なテーマである。最も基本的な火山の地殻変動モデルである茂木モデルについては、ピエゾ磁気効果の解析解が与えられている。しかし火山では通常火山地形が存在するので、地形がピエゾ磁気効果に及ぼす影響を調べておく必要がある。この問題については三次元の数値計算が容易でないなどの理由からこれまでほとんど研究されてこなかった。筆者らは円錐形の火山地形をモデルに選定し、この地形がピエゾ磁気効果にどのような影響を及ぼすかについて調べた。計算にあたり、地殻応力の解析は有限要素法で行い、線形ピエゾ磁気効果よりピエゾ磁化を求めた。さらに、求めたピエゾ磁化を地殻全体で積分し、地表におけるピエゾ磁気効果を求めた。その結果、火山表面ではピエゾ磁気効果に占める地形効果の割合は場所によって50％にも達し、決して無視出来ない大きさであることがわかった。また火山の縁辺部においては応力集中により局所的なピエゾ磁気効果の異常が発生することがわかった。","PeriodicalId":39821,"journal":{"name":"Papers in Meteorology and Geophysics","volume":"57 1","pages":"21-36"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69024808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Modification of Sea-Salt Particles in the Remote Marine Atmosphere in the North Pacific","authors":"H. Naoe, K. Okada","doi":"10.2467/MRIPAPERS.57.47","DOIUrl":"https://doi.org/10.2467/MRIPAPERS.57.47","url":null,"abstract":"遠洋上にある南鳥島(24.3°N, 154.0°E)で1993年2月から3月にかけて海洋性エアロゾル粒子を9試料採集した。電子顕微鏡に付属のエネルギー分散型X線分析器を用いて、半径範囲0.4-2.0 μmの個々のエアロゾル粒子について各試料あたり約100個の粒子の元素組成を分析した。その結果、89%から98%は海塩粒子で、硫黄が多く含まれた粒子や鉱物粒子はともに3%の個数割合であった。海塩粒子のうち5%はCl/Naの重量比が1以下であった。これは塩素が不足し粒子が変質したことを示している。変質した海塩粒子が25%も占めた試料があり、このときの流跡線はアジア大陸に近接した海洋大気から輸送されていた。人間活動で汚染された空気塊が長距離輸送されたとき、非均質反応によって海塩粒子が変質したと考えられる。","PeriodicalId":39821,"journal":{"name":"Papers in Meteorology and Geophysics","volume":"57 1","pages":"47-54"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69024902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A boundary layer leak slot is devised to improve flow quality in an open return wind tunnel and is tested in the large meteorological wind tunnel of the Meteorological Research Institute. The feature of the slot is that the forcible exhaust, as adopted in many automobile wind tunnels, is not used. The most effective width for improvement is determined to be 40 cm, by an experiment in which the slot width defined as the streamwise opening length is varied from 0 cm to 100 cm. Installing the boundary layer leak slot upstream of the test section remarkably improved the wind velocity uniformity in the cross-direction to the centerline of the wind tunnel in the upper reaches of the test section. The improvement is not clear in the lower reaches, however. The deterioration of uniformity downstream was caused by irregular floor-surface roughness resulting from long-time use. It can be concluded that the boundary layer leak slot is an effective low-cost method of improving flow quality in an open return wind tunnel.
{"title":"Effect of a Boundary Layer Leak Slot on Improving the Test Section Flow Quality in an Open Return Meteorological Wind Tunnel","authors":"Nobuyuki Kinoshita","doi":"10.2467/mripapers.56.1","DOIUrl":"https://doi.org/10.2467/mripapers.56.1","url":null,"abstract":"A boundary layer leak slot is devised to improve flow quality in an open return wind tunnel and is tested in the large meteorological wind tunnel of the Meteorological Research Institute. The feature of the slot is that the forcible exhaust, as adopted in many automobile wind tunnels, is not used. The most effective width for improvement is determined to be 40 cm, by an experiment in which the slot width defined as the streamwise opening length is varied from 0 cm to 100 cm. Installing the boundary layer leak slot upstream of the test section remarkably improved the wind velocity uniformity in the cross-direction to the centerline of the wind tunnel in the upper reaches of the test section. The improvement is not clear in the lower reaches, however. The deterioration of uniformity downstream was caused by irregular floor-surface roughness resulting from long-time use. It can be concluded that the boundary layer leak slot is an effective low-cost method of improving flow quality in an open return wind tunnel.","PeriodicalId":39821,"journal":{"name":"Papers in Meteorology and Geophysics","volume":"56 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69025074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Tokieda, Kazutaka Enyo, H. Matsueda, M. Ishii, M. Hirota, T. Midorikawa, 隆之 時枝, 和敬 延与, 秀和 松枝, 雅男 石井, 道夫 廣田, 貴 緑川
In 2002, a new system for measuring dissolved chlorofluorocarbons (CFC-11, CFC-12, and CFC-113: CFCs) in seawater was developed by the Climate and Marine Department, Japan Meteorological Agency (JMA). During the Ryofu Maru RF03-04 cruise in the western North Pacific in April and May 2003, CFCs concentrations measured by this system were compared with those measured by the Meteorological Research Institute's (MRI's) system that had been used for CFCs measurements in this region since 2000, using a common calibration scale and the same sampling protocol. The precisions of analysis by the MRI system, as determined from analysis of replicate samples, were 0.037 pmol/kg seawater (1.4%) for CFC-12, 0.049 pmol/kg (1.0%) for CFC-11 and 0.012 pmol/kg (2.3%) for CFC-113. The precisions of analysis by the JMA system were 0.008 pmol/kg seawater (0.4%) for CFC-12, 0.011 pmol/kg (0.2%) for CFC-11 and 0.012 pmol/kg (3.0%) for CFC-113. The no discrepancy in the concentrations of CFCs measured by the MRI and JMA systems was found at the 95% of significance level for these CFCs. These results suggest that if only the calibration scale were inter-compared, we could obtain comparable CFCs data in seawater.
{"title":"A comparison of dissolved chlorofluorocarbons in seawater measured by MRI and JMA CFCs Systems.","authors":"T. Tokieda, Kazutaka Enyo, H. Matsueda, M. Ishii, M. Hirota, T. Midorikawa, 隆之 時枝, 和敬 延与, 秀和 松枝, 雅男 石井, 道夫 廣田, 貴 緑川","doi":"10.2467/MRIPAPERS.55.1","DOIUrl":"https://doi.org/10.2467/MRIPAPERS.55.1","url":null,"abstract":"In 2002, a new system for measuring dissolved chlorofluorocarbons (CFC-11, CFC-12, and CFC-113: CFCs) in seawater was developed by the Climate and Marine Department, Japan Meteorological Agency (JMA). During the Ryofu Maru RF03-04 cruise in the western North Pacific in April and May 2003, CFCs concentrations measured by this system were compared with those measured by the Meteorological Research Institute's (MRI's) system that had been used for CFCs measurements in this region since 2000, using a common calibration scale and the same sampling protocol. The precisions of analysis by the MRI system, as determined from analysis of replicate samples, were 0.037 pmol/kg seawater (1.4%) for CFC-12, 0.049 pmol/kg (1.0%) for CFC-11 and 0.012 pmol/kg (2.3%) for CFC-113. The precisions of analysis by the JMA system were 0.008 pmol/kg seawater (0.4%) for CFC-12, 0.011 pmol/kg (0.2%) for CFC-11 and 0.012 pmol/kg (3.0%) for CFC-113. The no discrepancy in the concentrations of CFCs measured by the MRI and JMA systems was found at the 95% of significance level for these CFCs. These results suggest that if only the calibration scale were inter-compared, we could obtain comparable CFCs data in seawater.","PeriodicalId":39821,"journal":{"name":"Papers in Meteorology and Geophysics","volume":"55 1","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2005-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69024836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A thermal model containing time-variable parameters is constructed from an assumed velocity field and density disturbance. The fluid field is similar to Hill's spherical vortex, and the density disturbance is represented by a low-order Hermitian function series. The time variation of the model parameters is estimated by an optimal approximation method for the inviscid and non-diffusive Boussinesq equations. Initially, there is no motion but there is a low-density disturbance in the environment of neutral stratification. The time variation of the model parameters is studied with the aid of numerical integration. The time evolution of this model within a short period seems to be qualitatively comparable with some computer simulation results.
{"title":"A Low-Order Thermal Model with a Flow Pattern Similar to Hill's Spherical Vortex","authors":"Shigeo Takeda, 重夫 武田","doi":"10.2467/MRIPAPERS.55.45","DOIUrl":"https://doi.org/10.2467/MRIPAPERS.55.45","url":null,"abstract":"A thermal model containing time-variable parameters is constructed from an assumed velocity field and density disturbance. The fluid field is similar to Hill's spherical vortex, and the density disturbance is represented by a low-order Hermitian function series. The time variation of the model parameters is estimated by an optimal approximation method for the inviscid and non-diffusive Boussinesq equations. Initially, there is no motion but there is a low-density disturbance in the environment of neutral stratification. The time variation of the model parameters is studied with the aid of numerical integration. The time evolution of this model within a short period seems to be qualitatively comparable with some computer simulation results.","PeriodicalId":39821,"journal":{"name":"Papers in Meteorology and Geophysics","volume":"55 1","pages":"45-54"},"PeriodicalIF":0.0,"publicationDate":"2005-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69024937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three types of meso- β scale bands in a precipitation system over southern Kyushu on 7 July 1996 were analyzed using output from numerical models and observational data from both the Japan Meteorological Agency (JMA) and the Torrential Rain Experiment (TREX). Four meso- β scale regions comprised the precipitation region of the system. Region Ⅰ was characterized by a unidirectional wind environment in which several short convective bands were organized. Convective cells in these short bands displayed characteristics of back-building cells. A hook-shaped band developed over western part of region Ⅰ where intense outflow from another precipitation region intruded. Another meso- β scale band was simulated in precipitation region Ⅲ . In this region, mid-level flow advected convective cells downwind as high equivalent potential temperature air entered the band from its flank, maintaining convection along the whole band length. Comparisons of airflow structures and band shapes suggest that the mid-level wind direction plays a lead role in determining the type of meso- β scale band. In addition, cold air outflow from other meso- β scale precipitation regions can influence band shape.
{"title":"Analytical and numerical studies on meso-beta scale precipitation bands observed over southern Kyushu on 7 July 1996","authors":"H. Seko, Hajime Nakamura, 弘 瀬古, 一明 中村","doi":"10.2467/MRIPAPERS.55.55","DOIUrl":"https://doi.org/10.2467/MRIPAPERS.55.55","url":null,"abstract":"Three types of meso- β scale bands in a precipitation system over southern Kyushu on 7 July 1996 were analyzed using output from numerical models and observational data from both the Japan Meteorological Agency (JMA) and the Torrential Rain Experiment (TREX). Four meso- β scale regions comprised the precipitation region of the system. Region Ⅰ was characterized by a unidirectional wind environment in which several short convective bands were organized. Convective cells in these short bands displayed characteristics of back-building cells. A hook-shaped band developed over western part of region Ⅰ where intense outflow from another precipitation region intruded. Another meso- β scale band was simulated in precipitation region Ⅲ . In this region, mid-level flow advected convective cells downwind as high equivalent potential temperature air entered the band from its flank, maintaining convection along the whole band length. Comparisons of airflow structures and band shapes suggest that the mid-level wind direction plays a lead role in determining the type of meso- β scale band. In addition, cold air outflow from other meso- β scale precipitation regions can influence band shape.","PeriodicalId":39821,"journal":{"name":"Papers in Meteorology and Geophysics","volume":"55 1","pages":"55-74"},"PeriodicalIF":0.0,"publicationDate":"2005-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69024992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Previous studies suggested that solar activity may influence the El Nino/ Southern Oscillation (ENSO) cycle, such as in the modulation of the amplitude of the Tropospheric Biennial Oscillation (TBO). This study shows that the difference of the TBO due to the solar cycle is, in fact, derived from a difference in the association of the Indian Ocean sea-surface temperatures (SSTs) with the Pacific Ocean SSTs. High SSTs appear in the Indian Ocean following a warming in the Pacific Ocean during low solar activity (LS) from summer to winter. However, such a relationship is absent during high solar activity (HS). This difference in SSTs is related to the distribution of convective activity over the equator. Convective activity is more localized over the Pacific sector during HS, but more zonal and extending over the Indian Ocean during LS. Differences are also found in the vertical velocity in the troposphere. Up-welling over a warm SST region is connected to the stratosphere during LS, but limited within the troposphere during HS.A possible mechanism suggested from this study is that the solar influence in the equatorial troposphere does not arise from a change in the ocean temperature, but originates from the equatorial stratosphere through changes in the meridional circulation. This circulation modulates the vertical extent of convective activity as well as the horizontal distribution along the equator.
{"title":"Possible solar modulation of the ENSO cycle","authors":"K. Kodera, 邦彦 小寺","doi":"10.2467/MRIPAPERS.55.21","DOIUrl":"https://doi.org/10.2467/MRIPAPERS.55.21","url":null,"abstract":"Previous studies suggested that solar activity may influence the El Nino/ Southern Oscillation (ENSO) cycle, such as in the modulation of the amplitude of the Tropospheric Biennial Oscillation (TBO). This study shows that the difference of the TBO due to the solar cycle is, in fact, derived from a difference in the association of the Indian Ocean sea-surface temperatures (SSTs) with the Pacific Ocean SSTs. High SSTs appear in the Indian Ocean following a warming in the Pacific Ocean during low solar activity (LS) from summer to winter. However, such a relationship is absent during high solar activity (HS). This difference in SSTs is related to the distribution of convective activity over the equator. Convective activity is more localized over the Pacific sector during HS, but more zonal and extending over the Indian Ocean during LS. Differences are also found in the vertical velocity in the troposphere. Up-welling over a warm SST region is connected to the stratosphere during LS, but limited within the troposphere during HS.A possible mechanism suggested from this study is that the solar influence in the equatorial troposphere does not arise from a change in the ocean temperature, but originates from the equatorial stratosphere through changes in the meridional circulation. This circulation modulates the vertical extent of convective activity as well as the horizontal distribution along the equator.","PeriodicalId":39821,"journal":{"name":"Papers in Meteorology and Geophysics","volume":"55 1","pages":"21-32"},"PeriodicalIF":0.0,"publicationDate":"2005-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2467/MRIPAPERS.55.21","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69024889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Long-term changes in diurnal variation patterns of precipitation frequency were analyzed using visual data (ww) for 42 years (1961 to 2002) in Japan. The precipitation frequency relative to the daily mean was found to have increased in the nighttime and decreased in the daytime at a rate of the order of 0.01 per decade. This change was observed for all seasons and regions. A supplementary analysis based on hourly automated data on the AMeDAS network (1979 to 2002) confirmed the relative decreasing trend of daytime precipitation frequency, apart from some differences by regions and precipitation intensity. Changes in diurnal variation patterns were also found for vapor pressure and temperature, with a relative increase in nighttime values, although little change was detected for the diurnal variation patterns of relative humidity and cloud amount.
{"title":"Long-term trends in the diurnal cycles of precipitation frequency in Japan","authors":"F. Fujibe, Nobuo Yamazaki, Mitsugi Katsuyama","doi":"10.2467/MRIPAPERS.55.13","DOIUrl":"https://doi.org/10.2467/MRIPAPERS.55.13","url":null,"abstract":"Long-term changes in diurnal variation patterns of precipitation frequency were analyzed using visual data (ww) for 42 years (1961 to 2002) in Japan. The precipitation frequency relative to the daily mean was found to have increased in the nighttime and decreased in the daytime at a rate of the order of 0.01 per decade. This change was observed for all seasons and regions. A supplementary analysis based on hourly automated data on the AMeDAS network (1979 to 2002) confirmed the relative decreasing trend of daytime precipitation frequency, apart from some differences by regions and precipitation intensity. Changes in diurnal variation patterns were also found for vapor pressure and temperature, with a relative increase in nighttime values, although little change was detected for the diurnal variation patterns of relative humidity and cloud amount.","PeriodicalId":39821,"journal":{"name":"Papers in Meteorology and Geophysics","volume":"55 1","pages":"13-19"},"PeriodicalIF":0.0,"publicationDate":"2005-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69024883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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