{"created":"2021-03-01T06:18:35.055915+00:00","id":1989,"links":{},"metadata":{"_buckets":{"deposit":"06a61413-6dc7-4624-a386-50358a69a4a6"},"_deposit":{"id":"1989","owners":[],"pid":{"revision_id":0,"type":"depid","value":"1989"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00001989","sets":["75:121:264","9:233:234"]},"item_7_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2008-03-31","bibliographicIssueDateType":"Issued"},"bibliographic_titles":[{}]}]},"item_7_date_granted_25":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2008-02-28"}]},"item_7_degree_name_20":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"修士(理学)"}]},"item_7_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"本研究では、東—東南アジアからオーストラリア、西部太平洋のミクロネシア域での降水粒子生成システムに関するビン法雲モデルを用いた数値実験を行った。この中で複数の地域を対象とした多数の実験を行うために、計算効率向上を目的としてビン法スキームに統計的手法の導入を行った。<改行>ビン法雲モデルでは、凝結成長過程と衝併合過程で非常に多くの計算時間が求められるため、両者の計算効率を向上させることでモデル全体の計算時間を大幅に減少させることが期待される。衝突併合過程に関しては、モンテカルロ法を基にした統計的手法を適用し、計算コストを従来の10%程度までに削減することができた。このモデルは乱数を使うという性質上、乱数の初期値に計算結果が依存して異なる。しかしながら、この乱数の初期値による計算結果への影響はモデルの力学場の初期値等に起因する影響に比べると遥かに小さく、雲解像モデルとして利用するにあたっては問題にならない結論を得た。凝結成長過程に関しては、移流方程式に陰解法を適用することにより計算効率の向上を図った。その結果、凝結成長過程の計算コストを従来の35%程度まで削減できた。ただし、計算のタイムステップ(dt)を大きくした場合に計算精度が著しく低下するという問題が残った。<改行>Takahashi and Keenan(2004)によれば、東—東南アジアからオーストラリア、ミクロネシア域ではビデオゾンデの観測から降水粒子形成プロセスに関して、Warm frozen-drop rain Process とGraupel growth Process と呼称する２つのプロセスによって降水粒子が形成される。そしてどちらのプロセスを介して生成された降水粒子が支配的であるかが地域によって異なることが報告されている(Takahashi, 2006)。モデルの実験結果から、降水粒子生成に関してGraupel growthProcess が支配的になるために重要な要因の１つは下層の湿度が低く、乾燥していることであり、またWarm frozen-drop rain Process が支配的になるために重要な要因の１つは雲凝結核(CCN)として大粒子エアロゾル（~1[μm]）が存在していることであると示唆された。","subitem_description_type":"Abstract"},{"subitem_description":"We have performed numerical experiments using the bin cloud microphysics to investigate the precipitation mechanism over the regions from east and southeast Asia to Australia and Micronesia. New algorithms were implemented into the bin cloud microphysics to improve the computational effeiciency of the model.<改行> The computations of condensation and collision-coagulation growths are the “hot spots” of the bin cloud microphysics, that is, where a great deal of CPU time is taken. Thus the improvement of efficiency to compute these processes can significantly reduce the whole computational time. A new stochastic algorithm was implemented into the computation of collision-coagulation growth, so that the decrease in CPU time was about 90 %. Note that the simulated result depends on the initial selection of random numbers in the new scheme. We verified that the error range of the result using the new scheme is within less than that caused by initial condition of dynamics. An implicit method was newly implemeted to solve the advection equation in the computatin of condensation growth. As a result, about 65 % of the CPU time has been cut though the precision of computation become significantly wrong when using a large time-step interval.<改行> Takahashi and Keenan (2004) suggested two growth modes, graupel growth and warm rain-frozen drop modes, in the precipitation mechanism over the regions from east and southeast Asia to Australia, and Micronesia. The dominant growth modes are differenet in these regions (Takahashi, 2006). Our simulated results showed that low humidity in the lower layer is important for the development of the graupel growth mode. On the other hand, giant aerosols whose radii are larger than 1 μm have an effect to develop the warm rain-frozen drop mode.","subitem_description_type":"Abstract"}]},"item_7_select_21":{"attribute_name":"学位","attribute_value_mlt":[{"subitem_select_item":"master"}]},"item_7_subject_13":{"attribute_name":"日本十進分類法","attribute_value_mlt":[{"subitem_subject":"451","subitem_subject_scheme":"NDC"}]},"item_7_text_24":{"attribute_name":"研究科・専攻","attribute_value_mlt":[{"subitem_text_value":"理学系研究科地球惑星科学専攻"}]},"item_7_text_27":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_text_value":"第11229号"}]},"item_7_text_4":{"attribute_name":"著者所属","attribute_value_mlt":[{"subitem_text_value":"東京大学大学院理学系研究科 地球惑星科学専攻"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"佐藤, 陽祐"}],"nameIdentifiers":[{"nameIdentifier":"5899","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2017-05-31"}],"displaytype":"detail","filename":"Y_sato_Mthesis_Lastversion_1.pdf","filesize":[{"value":"8.7 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"Y_sato_Mthesis_Lastversion_1.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/1989/files/Y_sato_Mthesis_Lastversion_1.pdf"},"version_id":"0d577261-71dc-41d6-af11-c5e74f41e81c"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2017-05-31"}],"displaytype":"detail","filename":"Y_sato_Mthesis_Lastversion_2.pdf","filesize":[{"value":"3.0 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"Y_sato_Mthesis_Lastversion_2.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/1989/files/Y_sato_Mthesis_Lastversion_2.pdf"},"version_id":"44749f70-0fbc-4fcb-8695-edd68aae5fa6"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"雲粒子成長モデリングにおける統計的手法の導入に関する研究","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"雲粒子成長モデリングにおける統計的手法の導入に関する研究"}]},"item_type_id":"7","owner":"1","path":["234","264"],"pubdate":{"attribute_name":"公開日","attribute_value":"2011-08-08"},"publish_date":"2011-08-08","publish_status":"0","recid":"1989","relation_version_is_last":true,"title":["雲粒子成長モデリングにおける統計的手法の導入に関する研究"],"weko_creator_id":"1","weko_shared_id":null},"updated":"2022-12-19T03:43:29.120324+00:00"}