日本地球惑星科学連合2019年大会

講演情報

[J] ポスター発表

セッション記号 S (固体地球科学) » S-EM 固体地球電磁気学

[S-EM18] 地磁気・古地磁気・岩石磁気

2019年5月26日(日) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:清水 久芳(東京大学地震研究所)、佐藤 雅彦(東京大学地球惑星科学専攻学専攻)

[SEM18-P03] Candidate models of IGRF13-SV from Japanese team

*清水 久芳1南 拓人1中野 慎也2高橋 太3松島 政貴4藤 浩明5 (1.東京大学地震研究所、2.統計数理研究所、3.九州大学理学部地球惑星科学科、4.東京工業大学理学院地球惑星科学系、5.京都大学大学院理学研究科附属地磁気世界資料解析センター)

キーワード:国際標準地球磁場、地球ダイナモモデリング、データ同化

International Geomagnetic Reference Field (IGRF) and its secular variation models are open to public every five years. Next IGRF models, the Gauss coefficients to represent the spatial distribution of the field at epoch 2020.0 and its secular variation (first time derivatives) in the period from 2020.0 to 2025.0, will be determined and published around December, 2019, by Working Group of IAGA V-MOD. The IGRF and its secular variation models are determined based on candidate models submitted by research groups for Working Group V-MOD. We plan to submit a candidate secular variation model to contribute for determining IGRF13-SV.
Prediction of the main geomagnetic field is necessary to obtain a candidate model for IGRF and its secular variation. Although purely statistical prediction, which had been a usual procedure in the past, can be a possible method, we employ physics-based modeling for the prediction. Since the parameters used for geodynamo calculations are not "realistic" values for the Earth's core, it is not appropriate to take geodynamo solutions as they are for the predictions. Nevertheless, it is possible to select parameter set and appropriate normalizing time-scales to obtain modeled magnetic field that is similar to the geomagnetic field. In this presentation, we are going to show candidate models of secular variation obtained by geodynamo data assimilation with discussions on the time-scales, the method of assimilation, and data-set employed for the modeling.