国際化推進共同研究概要
No. 1
19EA-1
タ イ ト ル：Dynamical mechanisms of stratospheric control on the tropical troposphere and ocean研究代表者：UEYAMA, Rei

所内世話人：

江口 菜穂

研究概要：
ここ 30 年間で北半球夏季に南東太平洋の水温の低下がみられ、それは赤道をまたぐ
南西風の強化、すなわち対流圏内の南北循環場(Hadley 循環；HD 循環)が北側へシフトしたことに起因することがわかった。さらに HD 循環の強化が、近年の温室効果気体の増加による成層圏の寒冷化によって変調をきたした成層圏の南北循環場(BrewerDobson 循環)と関係することが示唆された。今回、衛星観測から導出された雲頂高度データを用いて、熱帯対流圏界面遷移層 (TTL; Tropical Tropopause Layer) に陥入する
背の高い積雲対流の雲頂高度が、ここ 10 年間で、特にアフリカ大陸からアジア域の夏季にかけて北進していることを観測的に明らかにした。極端に深い積雲対流の増加は、
二酸化炭素濃度の増加による地表面の温暖化と、熱帯成層圏の冷却による熱帯対流
圏界面の静的安定性の低下の相乗効果によって強制されると推測される。

Dynamical Mechanisms of Stratospheric Control on the
Tropical Troposphere and Ocean
Rei Ueyama (NASA Ames Research Center)
I. Abstract
Cooling of the equatorial southeastern Pacific Ocean occurred since the
mid-to-late 1990s in association with enhanced cross-equatorial southerlies,
which were associated with a strengthening of the deep ascending branch of theboreal summer Hadley circulation over land extending into the stratosphere.
The center of anomalous convective activity moved southward to the equatorial
Indian Ocean–Maritime Continent region from boreal summer to winterfollowing the seasonal march, which strengthened the surface easterlies over theequatorial central Pacific. Accordingly, ocean surface cooling expanded over theequatorial central Pacific. Analyses of satellite-derived convective cloud top
occurrences (Pfister et al., 2020) suggest that the fundamental cause of therecent decadal change in the tropical troposphere and the ocean is a poleward
shift of convective activity that resulted from a strengthening of extreme deep
convection penetrating into the tropical tropopause layer (Fig. 1), particularly
over the African and Asian continents and adjacent oceans. We conjecture thatthe increase in extreme deep convection is forced by a combination of land
surface warming due to increased CO2 and a reduction of static stability in thetropical tropopause layer due to tropical stratospheric cooling.
II. Introduction
Changes in the tropical circulation from the mid to late 1990s included (i)a slowdown, or hiatus, of global warming associated with a decrease in thetropical eastern Pacific sea surface temperature (SST), (ii) the advancement of
the onset of the Asian summer monsoon, and (iii) an increase in precipitation inwestern Africa over the Sahel and in southern Africa during the austral summer.
In addition to these large-scale circulation changes, mesoscale phenomena suchas an increase in Mesoscale Convective Systems over the Sahel were also
reported. Each of these elements should be investigated independently in great
detail, as well as their relationships to each other and their roles in global climatechange. Without the latter, we will be unable to see the ‘big picture’. The goal ofthis study was to provide a framework for assembling these diverse pieces of theclimate-change puzzle by investigating the connection between the atmosphere,
including the stratosphere, and ocean in the tropics.
Global observational studies using various satellite datasets have given us
substantial insight on the statistical distribution of the altitudes of deep
convection, including radar from TRMM and GPM, convective overshoot using IR
satellite data, microwave from AMSU-B, IR brightness temperatures, space-borne
cloud radar from CloudSat, and space-based lidar from CALIOP. Here we makeuse of global constellation of geostationary weather satellites to estimate theheights of convective cloud tops globally every three hours.
III. Method/Data
We analyzed a variety of datasets including JRA55 reanalysis, outgoing
longwave radiation derived from High Resolution Infrared Radiation Sounder,Global Precipitation Climatology Project precipitation, COBE-1 gridded SST, andtropical overshooting clouds derived from brightness temperature differences
measured by three high-frequency channels of the Advanced Microwave Sensing
Unit module B or the Microwave Humidity Sensor.
Preliminary analyses of satellite-derived convective cloud top altitudes(Pfister et al, 2020) were also used to corroborate the tropical convective
overshooting cloud data. Our approach for calculating the convective cloud top
altitudes is based on the assumption that rainfall, screened with a proper
threshold, can define the area where convection is occurring. These rainfall data,
coupled with the infrared satellite information, can then define both the regions
where the mass-transporting convective cores occur, and their altitude.
IV. Results
The eastern equatorial Pacific Ocean in the southern hemisphere cooled
since the mid 1990s in association with a strengthening of cross-equatorialsoutherlies near the surface. We showed that this was likely induced by anorthward shift and strengthening of convective activity around theclimatological deep ascending branch of the Hadley circulation during boreal
summer over the African–Asian sector. Additionally, we found that variations inconvective activity and SST are related to vertical velocity near the tropopause(Fig. 1).

Figure 1: A schematic of the recent changes in the tropics: Lower stratosphericcooling from increased tropical upwelling (a) supports a deepening of extreme
convection over the heated continental regions (b). Extreme deep convection
over land enhances cross-equatorial near-surface winds over the ocean (c) whichfurther fuels convection through moisture transport and lowers the sea surface
temperature from summer to autumn (d).
It is difficult to demonstrate a causal relationship among variables having
large trends. Nevertheless, time lags introduced in selected variables fromsummer to autumn suggest that the aforementioned processes are related.
Current global models have difficulty simulating the effect of extreme deep
convection on the TTL. Suitably designed numerical experiments using global
models with improved convective parameterizations will be needed to add
further support to these ideas.

V. Discussion/Summary
We hypothesize that recent tropical circulation changes originate
primarily from a strengthening of deep convective activity over the continents
and their vicinity in the summer hemisphere, particularly over the African‒Asian
sector. Stratospheric variation has generally been treated as a problem separate
from recent surface climate change, but the results of this study demonstratethat stratospheric changes should be examined together with troposphericchanges. Further investigation is needed to determine whether the stratosphereis merely passively responding to the tropospheric warming or playing an activerole in the tropospheric circulation change.
To better understand the details of the stratosphere‒troposphere
coupling process, we will investigate the coupling process as depicted inconvective overshooting and cloud top data (Pfister et al., 2020) in a future
study. Specifically, the 0.25° longitude/latitude resolution, 3-hourly cloud top
data will be useful for illustrating the time evolution of deep convective activity
over a given region in response to stratospheric forcing. As illustrated in Figure
2, enhanced upwelling and subsequent cooling of the tropical lower stratosphere
support deep convective activity over land (via a reduction in static stability inthe tropical tropopause layer), most notably over tropical Africa. This isconsistent with previous findings that show that dynamically-induced tropicalstratospheric cooling can trigger deep convective activity in the troposphere(e.g., Eguchi et al., 2015; Kodera et al., 2015; Eguchi et al., 2016).
Evolution over the African sector (20W - 50E)[ω]–0.00170hPa

ascent

0
50hPa

[T]’

+3

70hPa

0K

tropical (20S-20N)
lower stratosphericforcing

100hPa–3

cloud tops
>17km

tropospheric responsein the NH tropics(12.5 - 20N)
100hPa

[ω]’

+0.03

200hPa300hPa0 Pa s-1

500hPa1000hPa–0.03(29 July 2007)

Figure 2: Evolution of (from top to bottom) pressure vertical velocity at 70
17
SPARCjws2017_Ueyama
hPa, tropical mean temperature anomaly
in the TTL, occurrenceof - October 8, 2017
convective cloud tops above 17km, and pressure vertical velocity
anomalies in the troposphere over the tropical African sector.

VI. References• Eguchi, N., Kodera, K., and Nasuno, T.: A global non-hydrostatic model studyof a downward coupling through the tropical tropopause layer during astratospheric sudden warming, Atmos. Chem. Phys., 15, 297-304, 2015.
• Eguchi, N., Kodera, K., Funatsu, B. M., Takashima, H., and Ueyama, R.: Rapid
convective transport of tropospheric air into the tropical lower stratosphere
during the 2010 sudden stratospheric warming, SOLA, 12A, 13-17, 2016.
• Kodera, K., Funatsu, B. M., Claud, C., and Eguchi, N.: The role of convective
overshooting clouds in tropical stratosphere-troposphere dynamical
coupling, Atmos. Chem. Phys., 15, 6767-6774, 2015.
• Pfister, L., Ueyama, R., Jensen, E., and Schoeberl, M.: A method for obtaining
high frequency, global, IR-based convective cloud tops for studies of thetropical tropopause layer, in preparation, 2020.
VII. List of Publications and Selected Presentations• Kodera, K., N. Eguchi, R. Ueyama, Y. Kuroda, C. Kobayashi, B. M. Funatsu,
and C. Claud (2019), Implications of tropical lower stratospheric coolingin recent trends in tropical circulation and deep convective activity,
Atmos. Chem. Phys. Discuss., 19, doi:10.5194/acp-19-2655-2019.
• Kodera, K., N. Eguchi, R. Ueyama, B. M. Funatsu, and C. Claud (2019),
Influence of tropical lower stratospheric cooling on extreme deep
convective activity and tropical cyclones, AOGS 16th Annual Meeting, 28
Jul – 2 Aug, Singapore. (oral)• Ueyama, R., and E. Jensen (2019), Impacts of deep convection on clouds
and water vapor in the UTLS, American Geophysical Union Fall Meeting
2019, 9-13 Dec, San Francisco, USA. (oral, invited)• Kodera, K., N. Eguchi, R. Ueyama, L. Pfister, B. M. Funatsu, and C. Claud(2019), Role of extreme deep convection over land on recent tropicalchange, American Geophysical Union Fall Meeting 2019, 9-13 Dec, San
Francisco, USA. (oral)• Eguchi, N., and K, Kodera (2019), Influence of stratospheric dynamics on
deep convection and equatorial waves, American Geophysical Union Fall
Meeting 2019, 9-13 Dec, San Francisco, USA. (poster)• Ueyama, R., E. Jensen, M. Krämer, L. Pfister, and M. Schoeberl (2020),
Impact of convectively-detrained ice crystals on the humidity of thetropical tropopause layer during boreal winter, 100th American
Meteorological Society Annual Meeting and Middle Atmosphere One-Day
Symposium, Boston, USA. (poster)
VIII. Research meeting and discussion
Participants: Rei Ueyama, Nawo Eguchi, Kunihiko Kodera
Date: 11 December 2019
Location: AGU Fall Meeting 2019
Discussion topics:• Possible stratospheric forcing of deep convection and precipitation
over the Sahel region in July 2010
• Asian Summer Monsoon Chemical and Climate Impact Project(ACCLIP): science goals, flight scenarios, forecast products including

SPRINTARS aerosol product, and usage of the airborne measurementsfor our research
IX. Additional information
Rei Ueyama was on maternity leave during this award period from September
through December 2019. The results reported here are based on work that was
primarily completed before and after the leave period.
X. Members
Rei Ueyama
Nawo Eguchi
Kunihiko Kodera

NASA Ames Research Center
RIAM, Kyushu University
Meteorological Research InstituteNo. 2

国際化推進共同研究概要

19EA-2
タイトル：

Model inter-comparison study of long-range chemicaltransport model to have a better understanding of PM2.5
issue over East Asia

研究代表者：

Zifa WANG

所内世話人：

鵜野 伊津志実施期間：

新型肺炎による渡航制限で予定していた来日は中止された

概要：
共同利用経費での来日は出来なかったが、2014 年から 2019 年にかけての中国—韓国—日本の PM2.5 の濃度変化についての観測データの解析とモデル結果の整理を行い越境汚染の硫酸塩から硝酸塩へのパラダイム・シフトに関して成果を取りまとめて、英文学術雑誌に投稿した。この研究の事前の会合を 2019 年６月
２８日中国大連で半日間の中国と日本の大気汚染に関する研究会として開催した。また 2020 年１月１４日から２４日まで中国大気物理研の Li Jie 教授が中国側の経費で来日し応用力学研で共同研究を行った。

No. 2
19EA-2
タイトル：

Model inter-comparison study of long-range chemicaltransport model to have a better understanding of PM2.5
issue over East Asia

研究代表者：

Zifa WANG （中国科学院大気物理研究所）

共同研究の目的
本共同研究では、中国華北平原から北京にかけて観測される高濃度の PM2.5
汚染とその韓国・日本域への越境影響について、野外観測結果の解析と複数の化学輸送モデル(NAQPMS, CMAQ, GEOS-CHEM など)を用いた相互比較実験を進めている。
中国と福岡での最新のエアロゾルの観測装置、ライダーなどを駆使したデー
タの蓄積を独自に行い、同時に、中国・韓国・台湾・日本・アメリカ合衆国の研究者が進めているアジア域の化学輸送モデル相互比較実験(MICS-Asia)への参画を通じて、PM2.5 大気汚染のモデルの問題点とその改良を進め、化学輸送モ
デルの精緻化を目指す。
共同研究の成果
最近の PM2.5 濃度の減少は、中国国内でも明らかで北京では 2013 年から 2019年にかけて年平均濃度は 102 µg/m3 から 43 µg/m3 と 58％も減少している。また、福岡でも 2014 年の 18.4 µg/m3 から 2019 年で 13.8 µg/m3 と減少している。中国
では SO2 の減少率が最大で、NOx 減少率はその 1/3 程度、NH3 排出量の経年変動はこれらに対して少ない。このため従来は(NH4)2SO4 の形成に使われた NH3 が余剰になり、NH4NO3 の生成量が増加すると考えられる。従って、越境輸送される PM2.5の組成の変化が懸念され、風下域に沈着する S/N 成分の比が変化し、海洋・陸上生態系への影響も危惧される。以上の観点から、観測データの解析とモデル
結果の整理を行い越境汚染の硫酸塩から硝酸塩へのパラダイム・シフトに関して成果を取りまとめて、英文学術雑誌に投稿した。

No. 3

国際化推進共同研究概要
19EA-3
タイトル：

Turbulent mixing in the Kuroshio Current off Taiwan

研究代表者：

JAN, Sen

所内世話人：

遠藤 貴洋

概要：国際化推進共同研究 19EA-3「Turbulent mixing in the Kuroshio Current off Taiwan」は、昨年度に引き続き、共同研究・研究集会ともに計画通りに実施された。今年度の共同研究の成果をもとに、国際誌への投稿論文 2 編を執筆中で、国際学会では 3 件の発表が行われた。また研究集会には、海外から 8 名、日本から 14 名と昨年度を上回る参加者があり、黒潮が海山を乗り越えることで生じる強い乱流混合の時空間変動の解明を進めていく上で、有意義な国際研究集会となった。Discussion session にて、次年度もこの共同研究を続けていくことで合意がなされ、その具体的な計画を議論した。

Report on 2019 RIAM International Joint Research Project

Turbulent mixing in the Kuroshio current off Taiwan
JAN, Sen (Institute of Oceanography, National Taiwan University)

Objective
Turbulent mixing in the ocean controls transport of heat,
freshwater, dissolved gasses, and pollutants. Turbulent
mixing is also of crucial importance for ocean biology, fromdetermining the flow field for the smallest plankton to setting
large-scale

gradientsofnutrient

availability.

Recentobservations suggest that the interaction of large-scale, lowfrequency geostrophic currents with steep topography
produces a rich sub-mesoscale and mesoscale vorticity field,
which initiates a cascade of energy down to small scales andturbulence. The Kuroshio off Taiwan is the very region wheresuch processes are highly expected, especially over the I-Lan
Ridge between Taiwan and Yonaguni Island, Japan (Figure 1). Figure 1. Bird’s-eye view of bathymetry around
This joint research project aims to quantify the turbulent

the I-Lan Ridge. The Kuroshio current flows

dissipation and associated nutrient transport in the Kuroshio

over the ridge to enter the East China Sea.

current over the I-Lan Ridge.

Research Plan
(1) Carry out the tow-yo microstructure measurements along transects across and downstream of the I-Lan Ridge(2) Organize an international research workshop in the end of the fiscal year, where the observed results will beshared and discussed
The members involved in this collaborative research and their roles are:•

JAN, Sen (NTU, Professor): Representative person•

YANG, Yiing Jang (NTU, Associate Professor): Analysis of the mooring data•

CHANG, Ming-Huei (NTU, Associate Professor): Analysis of the VMP-500 data•

CHEN, Jia-Lin (National Cheng Kung University, Assistant Professor): Numerical modelling using
OpenFOAM•

LIU, Chih-Lun (NTU, Research Assistant): Numerical modelling using MITgcm•

GUO, Xinyu (Ehime University, Professor): Numerical modelling using POM•

NAGAI, Takeyoshi (Tokyo University of Marine Science and Technology, Assistant Professor): Analysis of
the tow-yo microstructure profiler data•

MATSUNO, Takeshi (RIAM, Emeritus Professor): Analysis of the TurboMAP data•

SENJYU, Tomoharu (RIAM, Associate Professor): Analysis of the mooring data•

ENDOH, Takahiro (RIAM, Associate Professor): In charge of the collaborative research•

TSUTSUMI, Eisuke (The University of Tokyo, Project Assistant Professor): Numerical modelling using
MITgcmSummary of collaborative research(1) Field experiment
The field experiment was carried out over the I-Lan Ridge off Taiwan using R/V Legend on July 1-5, 2019. In
addition to Dr. Matsuno of RIAM, Dr. Nagai of Tokyo University of Marine Science and Technology and his
students joined the cruise to handle the tow-yo microstructure profiler. We carried out the microstructure
measurements along four transects across the I-Lan Ridge. The ship moved northward twice along each transect tocover both the high and low tide periods.
Based on this field experiment, we are currently writing two articles on flow instability and turbulent mixing
around sill in the I-Lan Ridge as well as its influence on nutrient transport of the Kuroshio current. The international
conference presentations related to this project are:1.

CHEN, Jia-Lin, et al., Dynamics and variability of topography-induced shear instabilities in western boundary
currents, Ocean Sciences Meeting 2020, San Diego, USA, February 16-21, 2020.

2.

MATSUNO, Takeshi, et al., Intensified vertical mixing around various sea mounts along the Kuroshio and its
contribution to the ecosystem, Ocean Sciences Meeting 2020, San Diego, USA, February 16-21, 2020.

3.

ENDOH, Takahiro, et al., Trapped core formed within second-mode nonlinear internal waves over the shelf
break of the East China Sea, Ocean Sciences Meeting 2020, San Diego, USA, February 16-21, 2020.

(2) International research workshop
In order to share and discuss the observed results, “Workshop on turbulent mixing in the Kuroshio current over
the topography” was held at RIAM on February 1, 2020. Eight overseas researchers and students as well as 14
Japanese researchers attended this workshop.
The research budget provided for this international joint research project has been used to support the travel
expenses of the following three speakers:•

YANG, Yiing Jang (NTU, Associate Professor)•

CHANG, Ming-Huei (NTU, Associate Professor)•

CHEN, Jia-Lin (National Cheng Kung University, Assistant Professor),and the following two attendees:•

ZHU, Siteng (Toyama University, Doctoral Student)•

JIE, Gao (Ehime University, Master’s Student).

Figure 2. Dr. Yiing Jang Yang of NTU presenting the

Figure 3. Dr. Takeyoshi Nagai of Tokyo University

results of the mooring observations over and aroundof Marine Science and Technology presenting thethe I-Lan ridge.

results of the tow-yo microstructure measurements.

In the discussion session of this workshop, we agreed to continue our collaborative research in the next fiscal
year, and then discuss the possibility to submit a paper introducing this joint program to the journal such as
Oceanography or Frontiers in Marine Science.
The program of the workshop is shown below.

Workshop on turbulent mixing in the Kuroshio current over the topography
Place: Conference room at 2nd floor, RIAM, Kyushu University
Date: February 1, 2020
Purpose:1) Share and discuss the analyzed results of the observations and numerical simulations of turbulent mixing
processes in the Kuroshio current2) Define the outline of several manuscripts
3) Discuss the future direction of our research cruise
Time Table:
10:30

Takahiro Endoh (RIAM, Kyushu University): Opening remarks

10:35

Sen Jan (IO, National Taiwan University): Seasonality of mixing in the Kuroshio east of Taiwan

11:05

Ming-Huei Chang (IONTU): Recent observations of small-scale processes above I-Lan Ridge

11:35

Eisuke Tsutsumi (AORI, The University of Tokyo): Strong turbulent mixing induced by Kuroshio-

topography interaction and its tidal modulation at the I-Lan Ridge: observation and numerical simulation
12:05-13:30

Lunch time

13:30

Yiing Jang Yang (IONTU): Results of mooring observations on the I-Lan Ridge

14:00

Jia-Lin Chen (National Cheng Kung University): Instability waves forced by unsteady shear flow instratified ocean
14:30

Takeyoshi Nagai (Tokyo University of Marine Science and Technology): Three-dimensional mappingof turbulent dissipation rates in the Kuroshio near I-Lan Ridge and in Tokara Strait
15:00-15:15
15:15

Coffee break

Jie Gao (CMES, Ehime University): Motion and commotion due to a seamount in the Kuroshio and theireffects on nutrient transport
15:45

Xinyu Guo (CMES, Ehime University): Temporal variations of nutrient concentration east of Taiwan

16:15

Discussion (Chairman: Xinyu Guo)

16:45

Takahiro Endoh: Closing remarks

国際化推進共同研究概要
No. 4
19EA-4
タ イ ト ル： Cloud-radiation and Climate feedbacks / Satellite multi-sensor cloud and aerosol observations
研究代表者：

WANG, Zhien

所内世話人：

佐藤 可織

研究概要：国際化推進共同研究 19EA-4 では，2019 年 11 月 25 日-11 月 27 日の期間に九州大学筑紫キャンパ
スにおいて第 8 回 EarthCARE 国際サイエンスワークショップを宇宙航空研究開発機構(JAXA)，欧州宇宙機関(ESA)，情報通信研究機構(NICT)，大気物理統合解析センター(CIRAP)，九州大学，応用力学研究所と共催した。国際ワークショプでは 5 件の基調講演の他，一般口頭発表とポスターセッショ
ンが行われ, EarthCARE, Aeolus, CloudSat, CALIPSO, MODIS, CERES, GPM, GCOM, Himawari など
衛星コミュ二ティ, DYAMOND など高解像度モデリング・コミュ二ティ, GCM 気候変動研究コミュ二ティ,
数値予報モデル・データ同化コミュ二ティなど，国内外から約 100 名の専門家が参加し，活発な議論が行われた。

Cloud-radiation and Climate feedbacks / Satellite multi-sensor cloud and aerosol observations
Zhien Wang (University of Colorado, Boulder)

Objective
Aerosol and cloud play a critical role in regulating earth energy balance; however, they are still poorly understoodand represented in weather and climate models. To advance our climate models to reliably predict future climatechanges, improved understanding of aerosol, cloud, and their interactions from observations are needed. Satellite
multi-sensor observations are essential to characterize aerosol and cloud globally and to better understand related
processes. Measurements from current CloudSat and CALIPSO satellites together with other A-train satellites andfuture EarthCARE satellite offer new opportunities to advance our understanding of cloud and aerosol. Bothlaboratories have developed multiple multi-sensor algorithms to utilize these new data. The international researchworkshop on using CloudSat and CALISPO satellite data will prepare us to more efficiently use EarthCARE datafor cutting-edge atmospheric research.

Summary of the International Research Workshop
8th International EarthCARE Science Workshop
The Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) is a joint European/Japanese (ESA/JAXA/NICT)
mission. 94GHz-Doppler cloud profiling radar, high spectral resolution lidar operated at 355nm, multi spectral
imager and broad band radiometer will be employed. The combination of these instruments will provide threedimensional distribution of clouds with vertical motion, aerosols, and precipitation and their radiative characteristics.
The eighth international EarthCARE workshop was held in Fukuoka from 25–27 November 2019, following theseventh international EarthCARE Science Workshop held in Bonn in June 2018. The workshop was a great success,and provided an excellent opportunity to address grand challenges in Earth science related to clouds, aerosols,
radiation, cloud feedback, precipitation, climate change predictions, numerical weather predictions, and extreme
events. Around 100 experts from science communities of EarthCARE, Aeolus, CloudSat, CALIPSO, MODIS,CERES, GPM, GCOM, Himawari, high resolution global modeling (such as the DYAMOND Initiative), GCM,
NWP, Assimilations, climate change predictions and modeling extreme weather events participated the workshop.
Presentations were given in the following sessions:(1) Keynote lectures 1-5(2) Observations and process studies 1-6(3) Modeling and Assimilation 1-5(4) Radiation(5) Current status of EarthCARE 1-2
Outcome of the workshop
The workshop gave rise to fruitful discussions on:
・Requirements for future water-cycle observations
・Assimilation of EarthCARE data for improving weather forecast

・Energy balance: observational and climate modeling study
・Latest results from high-resolution model inter-comparison studies on cloud and precipitation
・Current status and problems in climate modeling of aerosols and clouds - Development of accurate prognostic
cloud physics schemes using EarthCARE data
・Challenges focusing on precipitation and mixed phase cloud retrievals/ Multi-sensor synergy for studying aerosol
impacts on mixed-phase cloud properties, temperature dependency of mixed-phase cloud properties, and formodel evaluations.
・Future precipitation changes/ Process studies on the formation of warm rain and heavy precipitation.
・Development of new observation systems for: cloud and aerosols studies, satellite calibration.
・ACCP, the NASA’s satellite initiative for aerosols, clouds convection and precipitation.
Workshop Chairs:
Hajime Okamoto (Kyushu University, Japan)

Anthony Illingworth (University of Reading, UK)

Riko Oki (JAXA, Japan)

Tobias Wehr (ESA/ESTEC, The Netherlands)

Workshop Science Committee:
Zhien Wang (University of Colorado Boulder, US)

Deborah Vane (JPL, US))

Dave Winker (NASA Langley, US)

Seiji Kato (NASA Langley, US)

Masaki Satoh (University of Tokyo, Japan)

Kentaroh Suzuki (University of Tokyo, Japan)

Tomoaki Nishizawa (NIES, Japan)

Takashi Nakajima (Tokai University, Japan)

Kaori Sato (Kyushu University, Japan)

Takuji Kubota (JAXA, Japan)

Chikako Takahashi (JAXA, Japan)

Yuji Ohno (NICT, Japan)

Teruyuki Nakajima (JAXA, Japan)

Nobuhiro Takahashi (Nagoya University, Japan)

Ulla Wandinger (TROPOS, Germany)

Luca Baldini (CNR ISAC, Italy)

Alessandro Battaglia (University of Leicester, UK)

Helene Chepfer (LMD/IPSL, France)

Nicolas Clerbaux (RMIB, Belgium)

Jason Cole (Environment Canada)

Julien Delanoë (LATMOS, France)

David Donovan (KNMI, The Netherlands)

Jürgen Fischer (Free University of Berlin, Germany)

Silke Gross (DLR, Germany)

Robin Hogan (ECMWF, UK)

Rob Koopman (ESA/ESTEC, The Netherlands)

Pavlos Kollias (Stony Brook University, US)

Riko Oki (JAXA),

Tobias Wehr (ESA/ESTEC, The Netherlands)

Anthony Illingworth (University of Reading, UK)

Hajime Okamoto (Kyushu University)
International support:
JAXA, ESA, NICT, The Center for Integrated Research on Atmospheric Physics (CIRAP), Kyushu University, andResearch Institute for Applied Mechanics (RIAM).

Workshop Agenda：
8th International EarthCARE science workshop
25 November 2019 (Monday)
TIME

TITLE

Speaker

12:00

Registration

13:00

WelcomeChair: Hajime Okamoto

13:05

Welcome by RIAM

Director Kazuaki Hanada

13:15

Opening Remarks from ESA

Alain Lefebvre

13:25

Opening Remarks from JAXA

Teruyuki Nakajima
Keynote 1

Chair: Hajime Okamoto

13:35

Scientific Background of Grand Plan for Space-based Water Cycle
Observations at JAXA 

Toshiki Iwasaki

Current status of EarthCARE 1

Chair: Hajime Okamoto

14:05

Satellite, Project overview and Programmatics

Alain Lefebvre

14:25

CPR status

Eiichi Tomita
Modeling and Assimilation 1

Chair: Hajime Okamoto

14:35

EUREC4A campaign set-up, radar-lidar and in-situ measurements intrade-cumulus clouds

Sandrine Bony (Julien Delanoë)14:50

Toward better representation of aerosols and clouds in climate models:Current status and problems to be addressedToshihiko Takemura

15:05

PosterKeynote 2

16:05

Aeolus Status

Chair: Anthony Illingworth
Tommaso Parrinello

Modeling and Assimilation 2

Chair: Anthony Illingworth

16:35

Potential of EarthCARE for improving weather forecasts via direct
assimilation of radar reflectivity and lidar backscatter

Marta Janiskova (Mark Fielding)

16:50

Differing impacts of absorbing and scattering aerosols on global energy
budget: A climate modeling study

Kentaroh Suzuki

Observations and Process studies 1

Chair: Anthony Illingworth

Validation of Aeolus aerosol and cloud products with ground-based lidar
observations at different locations in the northern and southernhemispheres
A Mechanism for the Maintenance of Sharp Tropical Margins

Ulla Wandinger

17:05

17:20

17:50

5-year results of the Global Precipitation Measurement (GPM) mission inJapan
PSC climatology based on CALIOP measurements from 2006-2019

18:00

Discussion of first day

18:30

End of first day

17:35

Hirohiko Masunaga
Takuji Kubota
Michael Pitts (Hajime Okamoto)
Anthony Illingworth,Hajime Okamoto

26 November 2019 (Tuesday)
Current status of EarthCARE 2
9:00

Data Products developed in Europe and Canada

9:10

Data Products developed in Japan
Keynote 3

9:20

9:50
10:05
10:20
10:35
10:50

11:20
11:35

11:50
12:05
12:20
12:35

Energy balance, radiative heating rate in the atmosphere, andentropy production
Observations and process studies 2
A new rainfall rate algorithm for EarthCARE with independently validated
accuracy
Algorithms to retrieve optical and microphysical properties of aerosol,
cloud, and precipitation from ATLID, MSI, and CPR measurements
ATLID L2a Extinction Backscatter and Depolarization Profile Algorithms

Aerosol-cloud target classification using combined airborne lidar andradar measurements
Calibration and Validation of EarthCARE’s Cloud Profiling Radar Data
Products
Relationship of Dust Load and Cloud Phase Partitioning over High
Latitudes Using CALIPSO Products
LUNCH and Group Photo

Mixed-phase cloud macrophysical and microphysical properties
from A-train Satellites
Observations and process studies 4

A radar-only combined radar-radiometer precipitation algorithm

14:50

15:35

Chair: Robin Hogan
Seiji Kato
Chairs: Robin Hogan
Anthony Illingworth
Tomoaki Nishizawa
Dave Donovan

Chairs: Kentaroh Suzuki

NICAM results of the project DYAMOND for global storm-resolving
model intercomparison
A New Perspective for Future Precipitation Change from Intense
Extratropical Cyclones
Observations and process studies 3

15:20

14:35

Riko Oki

Modeling and Assimilations 3

15:05

14:20

Michael Eisinger

Yuichi Ohno

The contributions of passive, integrated and physical constraints tosynergistic retrievals of cloud and precipitation from EarthCARE
Development Status of Ground-based W-band Cloud Radars for
Calibration and Validation of EarthCARE/CPR
A-CARE: Improving EarthCARE aerosol classification by combining lidar
and airborne in-situ aerosol measurements
Continuous measurement of particle backscatter and extinction profiles
with a 355-nm high-spectral-resolution lidar
Feature Mask determination using UV lidar data

14:05

Robin Hogan

Doppler calibration of EarthCARE Cloud Profiling Radar using JMA Wind
Profiler Network (WINDAS)
PosterKeynote 4
13:35

Chairs:Masaki SatohChihiro Kodama (Tatsuya Seiki)
Chairs: Kentaroh Suzuki
Eleni Marinou
Ousmane O. Sy
Kazuaki Kawamoto

Chairs: Ulla Wandinger
Zhien Wang
Chairs: Ulla Wandinger
Shannon Mason (Robin Hogan)
Hiroaki Horie
Moritz Haarig
Yoshitaka Jin
Gerd-Jan van Zadelhoff
Kaya Kanemaru

PosterObservations and process studies 5

Chairs: Tomoaki Nishizawa

16:00
16:15
16:30
16:45

Heaviest rainfall and tallest storms: Their weak linkage and related
large-scale environments
Bridging CALIPSO and Earth-CARE for Cloud Science: the difference of
wavelength issue studied from IPRAL ground-based lidar
Insight into growth and decay processes of liquid cloud inferred from a
combined analysis of CloudSat and geostationary satellites
EarthCARE’s Multi-Spectral Imager aerosol stand-alone product

17:00

Methodology of early phase validation for EarthCARE MSI cloud
products, lessons learned from GCOM-C SGLI

17:15

The EarthCARE BBR BM-RAD product17:30

Methodology and results on estimating radiative fluxes for the
EarthCARE BBR instrument

Radiation

Discussion of the Second day

17:45

End of second day

19:00

Workshop Dinner

Atsushi Hamada
Marjolaine Chiriaco
Akira Yamauchi
Nicole Docter (Jurgen Fischer)Takashi Y. Nakajima
Chairs: Tomoaki Nishizawa
Nicolas Clerbaux
Carlos Domenech(Nicolas Clerbaux)
Robin Hogan,
Kentaroh Suzuki,
Ulla Wandinger,
Tomoaki Nishizawa

27 November (Wednesday)
Keynote 5

Chairs: Masaki SatohACCP: the emerging NASA vision for the futureDavid Winker

Modeling and Assimilations 5

Chairs: Masaki SatohCloud observation in the Tokyo metropolitan area using scanning Ka-bandradarsModeling of snow precipitation interaction with a 3D lidar scanner

Tadayasu Ohigashi

Takuro Michibata

10:15

Reconciling a compensating error between precipitation process
constraint and energy budget requirement
Global aerosol simulations with a cloud-system resolving model

10:30

Poster

9:00

9:30
9:45
10:00

Gilles Roy

Daisuke Goto

Observations and process studies 6

Chairs: Dave Donovan

11:00

In situ observation of cloud droplet size distribution from Tokyo Skytree

Ryohei Misumi

11:15

Spatial and seasonal variability of clouds over the South-West Indian
Ocean based on the DARDAR products
Characteristics of ice clouds over mountain regions detected by
CALIPSO and CloudSat satellite observations
Narrowing down assumptions of ice crystal shape in radar-lidar retrievals
using solar radiance measurements
On the use of a multi-wavelength high spectral resolution airborne lidar
to study the sensitivity of extinction and lidar ratio retrievals to lidar
measurement techniques

Hélène Vérèmes

11:30
11:45
12:00

12:15

Discussion of 3rd day

12:25

End of Workshop

12:30

Lab Tour (Optional)

Tatsuya Seiki
Florian Ewald
Quitterie Cazenave

Masaki Sato, Dave Donovan

Poster Exhibition
Poster Number

Poster Title

AuthorP1

EarthCARE Flight Segment Status

Michael Eisinger

P2

EarthCARE Ground Processor Development Status

Michael Eisinger

P3

Status of the optical instruments payload on ESA’s EarthCARE mission (1)Kotska Wallace

P4

Status of the optical instruments payload on ESA’s EarthCARE mission (2)Kotska Wallace

P5

Status of the optical instruments payload on ESA’s EarthCARE mission (3)Kotska Wallace

P6

JAXA A-train Products Towards Synergistic Study for EarthCARE

Yuichiro Hagihara

P7

Evaluation of Simulated EarthCARE Doppler Velocity with NICAM

Yuichiro Hagihara

P8

Observation of Atmospheric Dynamics from Spaceborne radars:
Added value of Doppler capability and sequence of “Z-only” observations

Ousmane O. Sy

P9
P10
P11

Creation of EarthCARE simulated data sets for algorithm development and testing.
JAXA EarthCARE algorithm development using the Joint-Simulator(Joint Simulator for Satellite Sensors)

Dave P. Donovan
Chikako Takahashi

The benefit of airborne measurements for EarthCARE preparation
Cloud and aerosol optical properties observed by the airborne and ground-based
lidarsExperimental validation of D parameter model for droplet sizing using off-axis lidar
measurements

Silke Gross

P14

ESA-EVE polarization lidar: A novel mobile reference system for Cal/Val activities

Peristera Paschou

P15

Validation of the EarthCARE Mission

Rob Koopman

P16

Recent development and application of Joint Simulator for Satellite Sensors

Tempei Hashino

P17

The EarthCARE Multi Spectral Imager cloud products

P18

Development and Validation of the 4-sensor algorithm for radiative fluxes

P12
P13

P19
P20

Evaluation of cloud vertical structures and their radiative effect in MIROC using
CloudSat/CALIPSO satellite observations
Monte Carlo simulator (McRALI) for three dimensional cloudy atmosphere remotesensing with high spectral resolution lidar and Doppler radar

Eiji Oikawa
Gilles Roy

Anja Hünerbein(Vasileios Tzallas)
Akira Yamauchi
Kosuke Yamamoto
Alain Alkasem

P21

Ground-based remote sensing of heterogeneous clouds using sky-view camera andthree-dimensionalradiative transfer modelRei Kudo

P22

RadSnowExp: Multi-Sensor, Multi-Platform Study of Arctic and Mid-Latitude Storms

Mengistu Wolde

P23

Precipitation characteristics in coastal area of Alaska revealed from GPM DPR andCloudSat CPR

Shunsuke Aoki

P24

Cloud structure and microphysics associated with polar lows over the Nordic Seas
based on the DARDAR satellite products

Constantino Listowski(Julien Delanoë)P25

Supercooled liquid water, ice and mixed-phase in Antarctic clouds, using the
DARDAR satellite products

Constantino Listowski(Julien Delanoë)P26

An Impact of microphysics schemes on the evaluation method using CALIPSO

Woosub Roh

P27

Identification of Particle Growth Processes in Marine Low Clouds Using Spatial
Variances of Imager-Derived Cloud Parameters

Takashi M. Nagao

P28

CADDIWA : An airborne campaign to investigate aerosol-radiation-cloud interactionsin the tropics with a multi-(space)mission perspective

Cyrille Flamant(Julien Delanoë)

P29
P30

Common Retrieval of Atmospheric Aerosol Properties for geostationary and polarorbital Satellite Imaging Sensors
How EarthCARE AC-TC products will be useful for studying regional cloud andaerosol coverage

Mayumi Yoshida
Irbah Abadnour

P31

Remote Sensing of aerosol optical properties in the coastal areas

Kazuma Aoki

P32

Profiling of aerosols and clouds in Reunion Island (21°S, 55.5°E)

Hélène Vérèmes

P33

Cirrus clouds detected by GOSAT TANSO-FTS

P34

Estimation and assimilation of cloud water content over land and its verification using
satellite-based passive and active microwave observations

Nawo Eguchi

1

Rie SETO

国際化推進共同研究概要
No. 5
19EA-5
タ イ ト ル：Japan-Korea

Oceanography

SeminaronRegional

Oceanography

andAtmospheric Sciences
研究代表者：

NOH, Yign

所内世話人：

広瀬 直毅

研究概要：
本共同研究の代表者である Noh 教授（延世大学校）と所内世話人である広瀬教授（九大応力研）がコン
ビーナーとなり、2020 年 1 月 20 日～21 日に宮崎県宮崎市内の会議施設にて、47 名が参加し、日韓海洋研究セミナー “The 16th Japan-Korea Joint Seminar on Ocean Science” を開催した。

Report2020 年 1 月 20 日～21 日に宮崎県宮崎市のホテル・フェニックスシーガイアリゾート コテージ・ヒムカ
にて、日韓海洋研究セミナー “The 16th Japan-Korea Joint Seminar on Ocean Science” を開催した。
47 名が参加し、全 36 件の講演を、年齢の若い順に発表してもらった。プログラムは、添付の通りである。
全講演を通じて活発に質疑応答が交わされた。トップバッターの申教授（公州大学校）・金研究員（KIOST）
は、定年退職のため招待者として講演を行った。学生の拙い発表の後に、博士研究員や教員がお手本を見せる意図で年齢順にしたが、コンビーナーの狙いとは逆に、学生の発表自体は、発表練習も積んで英語も流暢という印象を受けた。若者ほど質疑応答には戸惑う傾向にあり、学生（および若手研究者）の英語コ
ミュニケーションの経験機会を提供する当セミナーの存在意義は相変わらずである。
日本と韓国の海洋学者と若い学生が集い、東アジア縁辺海の研究成果をワークショップで発表すること
で研究内容の意見交換及び国際交流を増進させることができた。特に若い大学院生を育てる良い機会で、大学院の学生が英語で発表及び質疑応答をすることで国際的な感覚を身に付けることも出来た。
2 日目後半には、研究発表を元に、今後の共同研究に関する討議、特にアイデア交換を行った。
CREAMS プロジェクトに代表されるように、応用力学研究所は長年、東アジア縁辺海の海洋研究をリードしている。そこで東アジア海洋の研究を活発に行っており、地理的にも日韓の接点となる九州大学応用力学研究所が、いわば「日韓海洋学会」の中核を担ってきた。今後は、日本海洋学会と韓国海洋学会の共催として当セミナー継続する可能性を探る。特に対馬海峡の観測データや東アジア縁辺海データ同化モデルの解析値を活用することによって、日韓の領域的な海洋学の発展が望まれ、さらには環境問題や大気海
洋相互作用まで波及効果があった。
尹教授と承教授の協力で始まった日韓セミナーも既に 16 回目を迎えたが、相変わらず活気にあふれている。特に今回は韓国側からの参加者が多く、世代交代が進んでいる印象を受けた。日本側もまだ少数だ
が若く元気な大学院生がすこしずつ増えている。

The 16th Japan-Korea Joint Seminar on Ocean Sciences

Conveners: Yign NOH (Yonsei University)
Naoki HIROSE (Research Institute for Applied Mechanics, Kyushu University)
Hong-Ryeol SHIN (Kongju University)
Venue:
Phoenix Seagaia Resort Cottage HIMUKA (Miyazaki Prefecture in Japan)
Date:
January 20-21, 2020
[Monday, January 20th]
08:45

Opening Address (Naoki HIROSE)----------- Morning session ---------08:50-09:20 Hong-Ryeol SHIN (Kongju University)(invited) Physical Characteristics and Classification of the Ulleung Warm Eddy
09:20-09:30

Sung-Hyun CHO, Jae-Hong MOON (Jeju University)

Decadal variability of the Kuroshio intensity in the East China Sea and its
connection with the climate variability
09:30-09:40

Taro MOTOSHIMA, Tianran LIU, Naoki HIROSE (Kyushu University)

Global ocean modeling for thermal energy estimation
09:40-09:50

Daichi TAKATORI, Tomoharu SENJYU (Kyushu University)

Analysis of the current data recorded with a moored buoy in Tokara Strait
09:50-10:00 Takuya HIROOKA and Takahiro ENDOH (Kyushu University)

Estimates of vertical eddy diffusivity in the bottom boundary layer frommicrostructure measurements
10:00-10:10

Hyun-Jun JANG, Jae-Hong MOON (Jeju University)

Long term variation of volume transport in the Korea Straits and variation of heat
contents in the East Sea
10:10-10:20

Miho YOSHITAKE, Atsuhiko ISOBE (Kyushu University)

Numerical experiment on vertical motion of microplastics with both physical andbiological processes
10:20-10:30

Hiromi MATSUURA, Katsuto UEHARA, Shinichiro KIDA (Kyushu
University)

Decreasing trend of M2 tidal amplitude observed along northwestern Kyushu

10:30～10:45

Break

10:45-11:00

Ingwon KIM, Hong-Ryeol SHIN (Kongju University), Cheol-Ho KIM(KIOST)

Warm and Cold eddies in the southwestern East Sea (Japan Sea)
11:00-11:15

Subin KIM, Jae-Hong MOON (Jeju University)

Influence of sea surface cooling due to the Yellow Sea Bottom Cold Water onweather conditions around Korean Peninsula
11:15-11:30

Keidai MASAKI, Ning ZHAO, Naoki HIROSE (Kyushu University)

Effect of sea surface temperature on torrential rain that occurred in Tsushima on
September 1, 2015
11:30-11:45

Yuxiang QIAO, Hirohiko NAKAMURA, Ayako NISHINA and Shin-ichiro
KAKO (Kagoshima University)

Interannual-decadal velocity variations over the Kuroshio Extension and Kuroshio
system11:45-12:00

Young Min PARK (GeoSystem)

Development of a red-tide forecasting system

12:00～14:00 Lunch----------- Afternoon session ---------14:00-14:30

Cheol-Ho KIM (KIOST)

(invited) Projection of future sea level change in the East Asian Regional Seas
14:30-14:50

Akie SAKAI, Tomoharu SENJYU (Kyushu University)

Near-inertial Internal Waves in the Japan/East Sea
14:50-15:10

Sang-Chul CHA, Jae-Hong MOON (Jeju University)

Temporal evolution of global mean sea level rise
15:10-15:30

Joseph BASCONCILLO, Il-Ju MOON (Jeju University)

Increased typhoons affecting Korea and Japan in a changing climate
15:30-15:50

Yeonju CHOI, Yign NOH (Yonsei University)

The comparison of the convective boundary layer in the atmosphere and the ocean
at different latitudes
15:50-16:10

Ji-Seok HONG, Jae-Hong MOON (Jeju University)

A weakly coupled data assimilation for short-term prediction of severe weather
16:10-16:30

Byeong-Jun LIM, You-Soon CHANG (Kongju University)

Analysis of extreme sea level change around the East China Seas including Korea
16:30～16:50 Break
16:50-17:10 Il-Ju MOON, Youjung OH (Jeju University)(invited) Effects of recurvature and eye size on typhoon-induced ocean waves
17:10-17:30

Haejin KIM, Naoki HIROSE, Katsumi TAKAYAMA (Kyushu University)

Biological effects on the long-term decrease in dissolved oxygen concentration in
the East/Japan Sea
17:30-17:50

Daehyuk KIM, Hong-Ryeol SHIN (Kongju University), Cheol-Ho KIM(KIOST), Naoki HIROSE (Kyushu University)

Characteristics of the East Sea (Japan Sea) circulation depending on surface heat
flux and its effect on Branching of the Tsushima Warm Current
17:50-18:10

You-Hyun BAEK, Il-Ju MOON (Jeju University)

Accuracy of satellite-observed and numerical model-calculated SST around the
Korean peninsular

18:10-18:30

Jae-Ho LEE, You-Soon CHANG, Shaoqing ZHANG (Kongju University)

Observation System Simulation Experiment for the JMA serial observation lines in
the Northwestern Pacific
18:30-18:50

Tianran LIU, Naoki HIROSE (Kyushu University)

OTEC power potential estimation at the Aguni Basin using a high-resolution oceanmodel
19:00～ Dinner[Tuesday, January 21st ]----------- Morning session ---------08:45-09:05
Jae-Hong MOON, Joonho LEE (Jeju University)(invited) Developing the data assimilative operational forecasting model in thenorth western pacific
09:05-09:25

Ashley BRERETON, Yign NOH (Yonsei University)

A mechanism for thin phytoplankton layer generation
09:25-09:45

Dong-Hoon KIM, Chaewook LIM, Seung-Buhm WOO (Inha University)

The Deep Learning Prediction of Nino-3.4 SST Anomalies
09:45-10:05

Yohei ONUKI (Kyushu University)

Quasi-local method of wave decomposition in a slowly varying medium
10:05-10:25

Hidekazu TSUJI and Naoki HIROSE (Kyushu University)

Numerical Study of Generation and Propagation of Large Internal Waves in the
East China Sea
10:25～10:45 Break

10:45-11:05 Ichiro YASUDA (University of Tokyo)(invited) Ocean vertical mixing observation and impact
11:05-11:25

Yign NOH (Yonsei University)(invited) The route to a spring phytoplankton bloom simulated by a Lagrangianplankton model
11:25-11:45

Takeshi Matsuno (Kyushu University), Eisuke Tsutsumi (University ofTokyo), Tomoharu Senjyu, Takahiro Endoh (Kyushu University), Daisuke
Hasegawa (Tohoku National Fisheries Research Institute), Yiing Jang
Yang, Sen Jan (National Taiwan University), Hirohiko Nakamura(Kagoshima University), Xinyu Guo (Ehime University), Ichiro Yasuda(University of Tokyo)(invited) Vertical mixing intensified around sea mounts in the Kuroshio
11:45-12:05 Young Ho SEUNG (GeoSystem)(invited) A review of the Tsushima Current Dynamics
12:05-12:25 Tetsuo Yanagi (Kyushu University)(invited) Value of Relation in the Japanese Satoumi

12:25～ General Discussion (Naoki HIROSE)

14:30～17:00 Splitter Meeting国際化推進共同研究概要
No. 6
19EA-6
タ イ ト ル：Circulation and Water mass modification in the abyssal Japan/East Sea

研究代表者：

SHIN, Hong-Ryeol

所内世話人：

千手 智晴

研究概要：
深海における海水の鉛直混合は、海洋の熱塩循環を維持するために必須の現象である。海水混合のエ
ネルギー源としては潮汐と海上風が大きな割合を占めるが、日本海のような半閉鎖的な縁海では潮汐が非常に弱いため、風によって励起される内部波、特に近慣性周期の内部重力波（近慣性内部波）が重要と考えられる。日本海南東部の大和海盆の深層で、2014 年 5 月に行った流速計の係留観測の結果を解析したところ、散発的な近慣性内部波イベントが観測された。イベント期間中の流速変動には、鉛直的にコヒーレントな構造を保ちつつ、深度と共に振幅が増大するという特徴がみられた。このような特徴は、風起源の下向きに伝播する近慣性内部波と、海底で反射された上向きの近慣性内部波が重なり合うことで説明できる。また、一般に深層水の成層は弱いため、流速の底層強化にともなう鉛直シアーは容易に不安定な状況を生じ得ることが明らかとなり、近慣性内部波イベントにともなう深海での鉛直混合の促進が示唆された。
この仮説を検証し、精密化するために、2019 年 10 月に大和海盆西部の深海に再び流速計を係留した。これらの流速計は、2020 年 5 月に回収する予定である。

Circulation and water mass modification in the abyssal Japan/East Sea
Hong-Ryeol Shin (Kongju National University)
Tomoharu Senjyu (RIAM, Kyushu University)
Introduction
Vertical mixing in the deep sea is essential for maintaining the oceanic thermohaline
circulation. The main sources of energy for abyssal mixing are considered to be tides and wind (Munkand Wunsch 1998). However, the wind contribution is likely to be more in the Japan/East Sea wheretidal flows are negligible except in the Tsushima Basin in the southwest. To investigate the behaviorof near-inertial internal waves (NIWs) generated by wind in the deep sea, we have been carried out
deep flow and hydrographic observations in the southern part of Japan/East Sea. We here report theflow intensification by the superposition of NIWs in the abyssal Yamato Basin in the southeasternJapan/East Sea.
Observations
An acoustic Doppler current profiler (ADCP) and two single-point acoustic current meters
were moored at Sta. YB in the eastern Yamato Basin during the periods May 12–23 and October 16–
27, 2014 (Fig. 1). In addition, two current meters were deployed at 950 and 1975 m of Sta. YB-S
(south of Sta. YB), which were 2.6 km apart, during the period from October 14, 2013 to October 16,
2014. Therefore, we discuss the current records during May 2014. The temporal interval for themeasurements at Sta. YB was set to 1 min for all equipment, although the measurement interval forthe current meters at Sta. YB-S was set to 30 min. The spatial interval for the ADCP at Sta. YB was
set to 4-m bins. The deployment and recovery of the current meters were conducted by T/V Nagasaki
Maru of Nagasaki University.
Results and Discussion
An active NIW event occurred below 2475 m in the Yamato Basin during May 12–16, 2014
(Fig. 2). This was followed by the upward propagation of a wave packet from 2475 to 950 m at speeds
ranging 0.75–1.39 cm s−1. The near-inertial flows (1.07f) during the event exhibited a verticallycoherent phase, although their amplitude increased with depth by a factor of 1.5 from 2475 to 2635
m. The observed flow characteristics can be explained by the superposition of downward-propagating
NIWs that can be excited by a strong wind event and upward-propagating NIWs that bounced off theseabed. As the stratification in the abyssal Japan/East Sea is very weak, a slight vertical shear by theflow intensification can induce an unstable condition. This suggests the promotion of vertical mixing
in the deep sea during significant NIW events.
To confirm the above idea, we redeployed an ADCP and current meters in the bottom layerof the western Yamato Basin in October 2019. These current meters will be recovered in May 2020.

Fig. 1 Location of Sta. YB (left) and schematic of the moorings at Stas. YB and YB-S (right)

Fig. 2 Time series of inertial component of flows at Stas. YB and YB-S in May 2014. The red andblue lines indicate the zonal and meridional components. Blue arrows indicate conceptual view of theflow intensification due to the superposition of downward- and upward-propagating NIWs.

国際化推進共同研究概要
No. 7
19NU-1
タ イ ト ル：High-field side transient CHI plasma start-up on QUEST研究代表者：NELSON, Brian, A

所内世話人：

花田 和明

研究概要：

同軸ヘリシティ入射(CHI)は経済的な核融合炉を実現させる球状トカマク(ST)装置のためのプラズマ立ち上げ手法として HIT-II や NSTX などで研究されている。QUEST の CHI
実験では軽元素不純物の低減が期待される全面金属壁構造において、SF-FNSF(米国で設計されたデモ炉)に適した新配位電極の開発が行われている。HIT-II や NSTX では
容器内側壁と外側壁を連結する入射磁束の磁力線に沿って電流を駆動させる。
QUEST では下部ダイバータ板上に絶縁されたトロイダルリング状の電極が設置され、ダイバータ下の PF コイルにより形成される入射磁束はリング状電極(陰極)と外側容器
壁(陽極)を連結し、CHI プラズマは電極間にガスを入射して電圧を印加させることで生成される。2019 年度の実験ではリング状電極と中心柱間を連結させることで、HIT-II や
NSTX の結果とよく似た CHI プラズマ発展が得られた。
プラズマの平衡制御のために使用される QUEST の PF コイルはリング状電極から離れており、接続されている電源の制御速度は速くない。また現状の QUEST のトロイダル
磁場は HIT-II や NSTX の磁場よりも低い。これらの要因は適切な CHI プラズマ発展に不利となる。2019 年度の実験では QUEST の CHI システム改善のための、QUEST における HIT-II、NSTX 配位プラズマ特性の再現性が評価された。これまでのリング状電極と外側容器壁を連結した配位では、非常に高い入射電流に対してトロイダル電流の増倍率は１程度と低く、適切なプラズマ発展(狭い footprint を維持した発展)を得ることが出来なかった。リング状電極と中心柱間を連結させることで、1)入射電流値が大きく減
少して電流増倍率が増加、2)プラズマの持続時間がそれまでの数倍に改善、3)プラズ
マが狭い footprint を維持したまま真空容器内部へ大きく発展するなどの結果が得られた。これらは HIT-II、NSTX 配位プラズマ特性をよく再現している。ただし明確な閉じ込
め配位の形成は観測されなかった。
本実験結果により QUEST における HIT-II、NSTX 配位プラズマ特性の再現性が確認された。この結果に基づき、CHI 入射磁束形成のためのコイル増設が計画されている。試作コイルによる評価を実施後、常設コイルの設計、導入を行う。これによる成果は ST 装置における CHI と ECH の組み合わせ手法の研究及び核融合炉の設計に貢献する。

High-field side transient CHI plasma start-up on QUEST 

2 January 2020
R. Raman1, K. Kuroda2, K. Hanada2, H. Canbin2, M. Ono3, B.A. Nelson1, E. Hatem2, T. Onchi2, M. Hasegawa2, M.
Nagata4, O. Mitarai5, T.R. Jarboe1
1 University of Washington, Seattle, WA, USA
2 Kyushu University, Kyushu, Japan
3 Princeton Plasma Physics Laboratory, Princeton, NJ, USA
4 University of Hyogo, Himeji, Japan
5 Institute for Advanced Fusion and Plasma Education, Japan

Introduction
Methods for starting a plasma discharge in a spherical tokamak (ST) without reliance of the center
solenoid are essential for the validity of the ST concept. These methods could also simplify and reducethe cost of tokamak-based systems and make them more economical by eliminating components thatare not needed during steady-state operation. Coaxial Helicity Injection (CHI) for an ST, first developedon HIT-II at the Univ. of Washington and then further developed on NSTX, is the method for which
scaling to larger devices such as reactors is well understood. On QUEST, this method would be further
developed using the unique all metal capability of QUEST, which is predicted to reduce low-z
impurities. In addition, CHI on QUEST will develop a new configuration that is much more suited to
an ST-FNSF.
Basic concept for CHI operation on QUESTOn HIT-II, and on NSTX, CHI is implemented by driving current along externally produced field linesthat connect the inner and outer vacuum vessel components in the presence of externally generated
toroidal and poloidal magnetic fields. This is qualitatively shown in Fig. 1 (a). On QUEST, as briefly
described in Fig. 1 (b), a toroidal ring electrode is mounted on top of the existing lower divertor plate,
and the electrode separated from the divertor plate using a toroidal alumina insulator. Magnetic flux
generated by the lower divertor coils connects this electrode plate (the cathode) to the outer vessel (theanode). Gas is injected in the gap between these electrodes and a 20-30mF capacitor bank, charged up
to 2kV is discharged across these electrodes to generate the CHI plasma. In the recent experiments
conducted during 2019, the electrode was biased with respect to the center stack on QUEST as shownin Figure 1(c). This is more like the configurations used on HIT-II and NSTX.
Progress with CHI on QUEST
An area in which the implementation of CHI on QUEST is different from that on NSTX is that the
Poloidal Field (PF) coils that are needed for equilibrium control are much farther away from the CHI
electrodes and the power supplies that operate these coils have slower current slew rates than the ones

 We acknowledge helpful discussions with Prof. Zushi, Mr. Noda (V-Tech Limited) and Mr.

Rogers (Univ. of Washington) and with other members of the QUEST Team.

on NSTX. In addition, the toroidal field capability of QUEST is much lower than that on NSTX. Boththese factors have made it more difficult to properly shape the injector flux into a narrow flux foot printcondition that is necessary for forcing reconnection to occur in the injector region. To improve the CHI
design for QUEST, during 2019 we conducted a test of CHI in a HIT-II/NSTX configuration to firstassess if some of the performance features for the HIT-II/NSTX configurations could be reproduced on
QUEST. If this is indeed the case, then this would provide the needed information to address the otherconcern related to the improved positioning of the CHI injector coil with respect to the electrode.

Figure 1: (a) Layout of the transient CHI startup systems in NSTX. The blue circle is the poloidal injector flux
produced by the lower divertor coils. This connects the two lower divertor plates, which are insulated. Gas is injectedin the region below the divertor gap. On NSTX typically a 5 to 15mF capacitor bank charged up to 1.7kV is used to
produce the injector current. (b) Typical vacuum field line configuration for CHI discharge initiation on QUEST. (c)Configuration of the new injector configuration used in the 2019 experiments.

Fig 2: Comparison of transient CHI discharges in the (a) old (bias to outer vessel) configurationand in the (b) new recently conducted experiments in 2019 in which the electrode is biased withrespect to the center stack as on HIT-II and NSTX.

Figure 2 shows a comparison of two discharges in which the injector region is different. When theinjector flux is formed between the bias electrode and outer vessel wall (the old configuration) [1],the injector current flowing from electrode is very high but the toroidal current is comparable to theinjector current showing that the current multiplication ratio is about 1. The flux evolves but its
footprint becomes wide. When the injector flux is formed between the bias electrode and inner vessel
wall, the injector current is substantially reduced, and the plasma evolves with a narrow footprintconfiguration to fill the entire height of the vessel (figure 1). In addition, the plasma current pulse
duration increases by several times that in the other configuration and the outer leg of the current
channel is much clearly defined. The latter result has many similarities to the discharges generated
by the conventional electrode on HIT-II and NSTX. References [2,3].
The main results from the new configurations are:• Injector current drops to very low value, and the current multiplication ratio (toroidal current /injector current) becomes very high, as on NSTX.
• The discharge pulse duration also dramatically improves• The fast camera images show good resemblance to NSTX CHI plasmas; however, although theinjector current becomes very small, closed flux formation cannot be clearly ascertained at thistime.
These new experiments, however, are quite promising in that they have been able to reproduce manyof the important features seen on HIT-II and NSTX. An important difficulty that remains is that becauseof the large distance between the divertor coils and electrodes, only a small portion of the coil flux
connects the electrodes, and our ability to shape this flux is also very limited. These new results now
provide a basis for improving the CHI injector coil location on QUEST. To further test this configuration
with an optimally positioned injector coil, a new (temporary) PF coil will be used during the 2020
experiments. The design work for this coil has now been completed, and a new low-cost capacitor bankbased power supply is also now mostly built. The coil will be installed during January 2020. After asuccessful test during 2020, a new (permanent) CHI coil could be installed on QUEST to support
detailed CHI + ECH studies in support of ST and tokamak reactor designs. We also note that, througha collaboration with the University of Washington and PPPL, we are also conducting a conceptual
design study of the transient CHI configuration for the 3T ST-40 device in the United Kingdom.
References[1] Kuroda K et al 2018 Plasma Phys. Contr. Fusion 60 115001.
[2] Raman R et al 2004 Phys. Plasmas 11 2565.
[3] Raman R et al 2011 Phys. Plasmas 18 092504__________________________________________
 We acknowledge helpful discussions with Prof. Zushi, Mr. Noda (V-Tech Limited) and Mr. Rogers (Univ. of

Washington) and with other members of the QUEST Team.

国際化推進共同研究概要
No. 8
19NU-2タ イ ト ル：

Plasma start-up and sustainment in spherical tokamak configuration by RF研究代表者：SHEVCHENKO, Vladimir

所内世話人：

出射 浩

研究概要：
Scevchenko さん分
令和２年１月３０−３１日の 2 日間で国際 WS を開催した。欧州から 1 名、米国から 3 名、国内の学外者が 7名、別途、共同研究で訪れていた中国の研究者、応研関係者の参加があった。QUEST 実験の最近の進展に加え、国内外実験の進展、新たなシミュレーション解析などが議論された。特に今年度は、新規のST40 実験での発表があり、他の発表も加え、関連する QUEST での非誘導プラズマ電流立ち上げに関し、共同研究が広く議論された。欧州方から１件、米国から２件、中国から１件、国内で９件の研究成果発表があり、活発な議論があった。

RF-only ST plasma confinement, sustainment,
and interactions with wall materials
Vladimir Shevchenko

A program of the Workshop which was held on 30-31 January 2020 and was as following:
8th Workshop Agenda, RIAM 2020
30 January AM
10:00 ‐10:10
Vladimir Shevchenko / Kazuaki Hanada
WS purpose and agenda

10:00 - 10:40
Vladimir Shevchenko
ST40: Recent results and ECRH & HTS plans for future

10:40 - 11:20
Kazuaki Hanada
Recent results for steady state operation and plasma current start-up on QUEST（TBD）

11:20 - 12:00
Modification of plasma-facing surface in QUEST due to PWI and development ofadvanced W wall panel for ultra-long pulse operation
Naoaki Yoshida

31 January PM
12:00 - 13:00
Lunch Time

13:00 - 13:40
Recent results from TST-2
Yuichi Takase

13:40 - 14:10
Peng Yi
Thomson scattering system in TST-2

14:10 - 14:40
James Rice
Detection of Fast Electrons in SOL Plasma Using a Langmuir Probe Diagnostic

14:40 - 14:55
Yongtae Ko
Measurement of LH waves in TST-2

14:55 - 15:15
Coffee Break

15:15 - 15:55
Hitoshi Tanaka
Overview of Recent EBW Experiment in LATE

15:55 - 16:35
Kengo Kuroda
CHI Experiments in QUEST

16:40 - Group Photo & QUEST Machine Tour
31 January AM
9:30 - 10:10

X. Gao
Non-inductive current drive experiments on EAST tokamak

10:10 - 10:50
Masayuki Ono
Update on ECH /ECCD modeling

10:50 - 11:30

Nicola Bertelli
3D full wave simulations in NSTX-U plasmas with the recent developed Petra-M code

11:30 - 12:10
Sadayoshi Murakami
MHD equilibrium reproduction by visible light computed tomography in QUEST

12:10 – 14:00
Lunch

31 January PM (Drafting of proposals for experiments, diagnosis, and analysis)
14:00 ‐ All Suggested focus and output for this joint drafting session_____________________________________________________________________________The presentation summaries are as following:Vladimir Shevchenko
ST40: Recent results and ECRH & HTS plans for future
In September 2019 there was a short experimental campaign on ST40 after relocation of themachine into the new building. This campaign was conducted to re-confirm operational
status of ST40 after re-commissioning. After that several new diagnostics have been
installed and commissioned. Solenoid and additional vertical field power supplies were
installed and tested. Diagnostic Neutral Beam (DNB) injector has been delivered and partly
tested.
In Autumn 2019 installation of the second part of TF power supply was completed and 1 MW
25 keV Heating Neutral Beam (HNB) injector has been tested and installed. These
installations were followed by commissioning on ST40 in December 2019 and January 2020.
Both beams demonstrated good performance in hydrogen gas. An improved plasma
performance has been demonstrated in this second 2019 campaign taking advantage of theplasma sustainment using solenoid and upgraded plasma diagnostics. Some plasma heating
and fuelling were observed with HNB injection into plasmas. To date plasma currents
achieved in ST40 are above 0.5 MA with the current flattop up to 100 ms. Toroidal fields inexcess of 2 T at the major radius of 0.4 m have been delivered on a regular basis.
Kiloelectron volt range electron and ion temperatures have been regularly achieved during
this campaign. All diagnostics were commissioned and prepared for full scale experiments.
Currently, installation of liquid nitrogen cooling for TF and Bv coils is progress. Next
experimental campaign is planned after completion of the cooling system.
Further upgrades of ST40 include installation of the 2nd HNB 1 MW 50 keV in Summer
followed by commissioning and plasma experiments in Autumn 2020. A dual (140/105 GHz)
frequency 1 MW gyrotron is scheduled for delivery and commissioning in Q1 2021.
Another significant activity at Tokamak Energy (TE) is a high temperature superconductor(HTS) magnet development. We believe that HTS technology gives an opportunity to build acompact tokamak-reactor which would allow achievement of plasma parameters close toignition. A special magnet winding and testing facilities have been built at TE. HTS tapes
from several suppliers were tested and compared against requirements for the tokamakreactor. Using the best tape, a test magnet was developed demonstrating a world record
field of 24 T. It was shown that HTS based magnets are resilient to a thermal quench andcan withstand internal damages without causing catastrophic degradation. The next step is a
development of a full scale HTS toroidal magnetic system DEMO-4 with the target magnetic
field of 10 T at a major radius of 0.25 m. This milestone is to be achieved by the end of 2020.

Kazuaki Hanada
Recent results for steady state operation and plasma current start-up on QUEST• The QUEST project is focusing on plasma start-up with RFCD and steady state operation.

• The 28GHz RF injection system has the capability to regulate both the wave polarization
and N//. The system has also the capability to focus RF beam down to 5 cm in radius.
• More than 100kA could be obtained in N//=0.78 X-mode with a little OH provided from thepoloidal field increment. According to the RF absorption, the RF is likely to absorb toenergetic electrons. Which is useful to drive plasma current.
• Low N//=0.1, X-mode injection could successfully heat up bulk plasma up to 0.5 keV of Te.
Single pass absorption of achieved plasma parameters is expected to be approximately
40%, therefore the effective bulk heating could be obtained with a sophisticated neutral
control to avoid production of energetic electron.
• High field launch of RF has been tried to effectively excite EBW in the plasma. A new
tentative waveguide and antenna was installed for the experiment. The designed value ofmode conversion to EBW is 93%. The rest RF is absorbed at the fundamental ECR.
• Higher density and better absorption of RF in HFS launch than those in the LFS launch
could be obtained. PDI signal was measured with a movable probe and larger PDI in the
HFS launch was measured. This supports to higher mode conversion to EBW.
• To get evidence of EBWCD, TF and PF direction modification has been executed. The
plasma reproducibility is insufficient to compare the value of plasma current. The flux loop
signals denote the inversion of plasma current direction in the mid-plane, bur need to more
confirmation.
• Plasma Breakdown has been investigated with 2nd harmonic ECW. The threshold power
was much higher than fundamental ECW predicted by numerical calculation. The connection
length dependence was different from fundamental ECW.
• The hot wall plays essential roles in reducing the amount of wall-stored H and facilitating H
recycling. Only top hot wall has the capability to water cool down since 2018SS campaign.
• The clear reduction of Ha after water cooling of the top hot wall. This indicates the recycling
could be control by wall temperature.
• The cooling down from 473K of only top hot wall with water can extend the plasma duration• During long duration discharges, neutral compression could be achieved behind the bottom
divertor plate. The reason is still unclear, because there are many candidates to make thisto-bottom asymmetry. It is a future work.

Naoaki Yoshida
Modification of plasma-facing surface in QUEST due to PWI and development ofadvanced W wall panel for ultra-long pulse operation
Impurity deposition on the plasma facing surface in QUEST at preset is aggregation of
nanocrystals of carbide and metallic oxide and little amount of amorphous carbon. TDS
results indicate that its contribution to the retention and thermal desorption of H underplasma discharge is little. In contrast, large amount of H can be retained in hot wall liner
APS-W and its thermal desorption continues up to around 1000K. It can be considered that
active desorption of H from the APS-W liner causes the termination of long pulse plasma
discharges.
For ultra-long pule discharges at higher temperatures (≤773K) we have already started
development of advanced W liners, in which retention of H at high temperatures is low
enough.

Yuichi Takase

Recent results from TST-2
The capacitively-coupled combline (CCC) antennas for exciting the traveling LHW for Ip
start-up and ramp-up were developed. Outboard launch, top-launch, and “bottom-launch”(top-launch with reversed Bt) were compared. The driven current was higher for top-launchthan outboard-launch as expected, but the highest driven current was achieved by “bottomlaunch”, contrary to initial expectation. Thomson scattering measurements show peaked ne
profile and hollow Te profile with the highest temperature in the inboard edge region, andequilibrium reconstruction using an extended MHD model shows a hollow j profile. Hard Xray spectra show higher flux and effective temperature for top-launch compared to outboardlaunch, especially in the inboard edge region, consistent with Te and j profiles. A large orbit
loss fraction was inferred from the RF power modulation experiment. A combined ray-tracing
and Fokker-Planck analysis indicate n|| upshift and strong damping around r/a ~ 0.5 for toplaunch. For “bottom-launch”, n|| downshifts first, but upshifts after reflection. Once electrons
are accelerated to high energies, these electrons can absorb the downshifted n|| LHW andvery high energy electrons can be generated. The result of this analysis can explain theexperimental results.
An EC-assisted inductive Ip start-up scenarios being developed for JT-60SA on TST-2. The
trapped-particle configuration (TPC) with a weak Bv with positive decay index enlarged theoperating window for reliable start-up compared to the usual field-null configuration (FNC).
Application of EC power extended both the low pressure limit for breakdown and the highpressure limit for burn-through. The TPC was particularly beneficial at low pre-fill pressureand high EC power.
AC Ohmic coil operation is a reliable pre-ionization method. A small inboard coil can beused for pre-ionization. The breakdown voltage is nearly the same as the regular Ohmic coil.
Positive and negative triangularities can be obtained using the small inboard coil. Recent
results from TST-2

Peng Yi
Thomson scattering system in TST-2
It is useful to find the optimum operational conditions for fusion reactors if the electron
temperature and density profile measured by the Thomson scattering measurements, aswell as their scaling could be obtained.
In the study, the relation of the electron temperature (Te) and pressure (P) to the electron
density (ne), RF power (Pw), toroidal magnetic field (Bt), and plasma current (Ip), for the
scenario of D+CW+Top (deuterium, clockwise toroidal field, and top antenna), is obtained byseparate fitting for the parameters in the presumed formula. In addition, the comparisons ofdifferent scenarios, such as hydrogen (H) and D, top and out antenna, CW and counterclockwise (CCW), have been conducted to investigate the effects of them on the electron
temperature. Compared with the D+CW+Top scenario, the results show the H fuel gas gives
rise to higher electron temperature, CCW toroidal field would produce lower electron
temperature, and the out antenna results in rough same electron temperature within error
bars. On the basis of temperature relaxation time calculation for the TST-2 and theestimation of confinement time, as well as the heating power for bulk electrons and theequivalent heating power calculated by stored energy in the plasmas and confinement time,
it is feasible to explain qualitatively the measured results of electron temperature bycollisional heating.
In order to observe the temperature anisotropy in the plasmas, the double-optical-passconfiguration for Thomson scattering system in TST-2 is also investigated. The effects ofdisplacement of the focal points on the fiber’s collection efficiency are estimated, as well as
the deviation of the returned beam from the center of laser source, caused by the tilt angle ofthe distant mirror, is analyzed since the returned beam will pose the laser source injeopardy. Also, the theoretical calculations of the displacement of returned beam are verified
by corresponding measured results, and that indicates the possibility of blocking the returned
beam by putting an aperture in front of the lens or the laser source. The optimization of the
double-optical-pass configuration will be implemented in the next step.

James Rice
Detection of Fast Electrons in SOL Plasma Using a Langmuir Probe Diagnostic
Electron Energy Distribution Function (EEDF) analysis has been used to confirm thepresence of fast electron populations in SOL plasma in TST-2. A full profile of TST-2’s SOL
plasma is desired for ray-tracing and plasma simulations. To this end, a new Langmuir probe
has been installed as a prototype for a full profile of SOL parameters. This prototype has
been used to refine the measurement methods used.
Recent results from power modulation experiments show strong alteration to Te and Vflduring RF power. The positive increase to Vfl indicates RF sheath rectification is not thedominant alteration. It is thought that the non-thermal electron energy distribution in TST-2
causes an overestimation of Te. To confirm this, EEDF analysis has been used to confirm
the presence of fast electrons in SOL plasma. Preliminary results show low-temperature bulk
electrons and a higher energy component at lower density. Further research is required tobetter classify this fast electron component and identify its effect on measured plasma
parameters.

Yongtae Ko
Measurement of LH waves in TST-2
14-ch RF magnetic probe has been developed to detect LH waves (200 MHz). Parametricdecay instability corresponding to ion cyclotron quasi-mode were observed in TST-2 LH
driven plasma experiments. The interest is what the differences among launching mode,
outboard-launch, top (CW) launch and top (CCW) launch. In the experimental results, large
peak of PDI associated with ICQM was observed on sideband of the pump-wave frequency
in hydrogen plasma with outboard and top (CW) launch case, while disappeared indeuterium plasma with top (CW and CCW) launch case. The fraction of side band power(100 – 199.9 MHz) was dominant (over 100%) in inboard region with the outboard launch
and also dominant (over 200 %) in bottom-outboard region with top (CW) launch. However,with top (CCW) case, fraction was suppressed under 80 %, but direct relationship between
current drive efficiency and PDI suppression is not realized.

Hitoshi Tanaka
Overview of Recent EBW Experiment in LATE
Microwave at 2.45 GHz is used to start-up and form ST plasmas. In order to excite the EBW
via O-X-B mode conversion, three polarizations of microwave such as O-mode-like lefthanded elliptically polarized ones and X-mode-like ones are used and compared. Results ofeffect on bulk electron heating are qualitatively related to the mode conversion rate
calculated by the linear theory with the cold resonance absorption model in a slab model.
HIBP measurement have been carried out during the intermittent plasma ejection events
which usually appear when the density exceeds several times of the plasma cut off density
and the central safety factor becomes about 8. Fast space potential variations are observed
during the event, which indicate the local escape of electrons and its recovery.
An electron beam is injected from a cold cathode installed at the bottom port into a ST
plasma which is produced non-inductively by EBW. Investigation of synergistic effects ofelectron beam injection and EBW current drive has begun.

Kengo Kuroda
CHI Experiments in QUESTCHI current start-up by using simple electrode has been tested in QUEST. Initial result, inwhich the injector flux forms between electrode and outer wall shows that the reliable gas
breakdown is achieved under appropriate conditions and plasma evolves with increasing
toroidal current which is dependent on the PF configuration, but keeping a “narrow
footprint” is difficult and current multiplication I_tor/I_inj is low, ~1.
In the discharges, in which the injector flux forms between electrode and inner wall highcurrent multiplication, 5~10 and long duration 10~30ms are achieved and plasma evolves tofill vessel with keeping “narrow footprint”.
We plan to improve and further test the second configuration by installing a new (temporary)
injector flux coil that is much closer to CHI electrodes.
After verifying good closed flux surface formation a more permanent CHI coil design will beconsidered to support CHI + ECH studies.

X. GaoNon-inductive current drive experiments on EAST tokamak
Overview of experimental progress on EAST is presented. Steady-state fully non-inductive
scenarios (such as long pulse H mode, high beta-p plasma, and high beta-N plasma et al.) isdemonstrated with extension of fusion performance. Regular and low loop voltage start-ups
without resistors have been achieved on EAST tokamak in 2019.

Masayuki Ono
Update on ECH /ECCD modelling
The QUEST ECH solenoid-free start-up experiment utilizing the 28 GHz gyrotron at 2nd
harmonic frequency has demonstrated remarkable efficiency and achieved record start-up
current values [1]. The experiment provides rich opportunities to understand and optimize
ECH-based tokamak/ST current start-up and ramp-up concept. Another potentially
noteworthy aspect of the QUEST 28 GHz experiment is its very high frequency to toroidal
magnetic field ratio, which is 28 GHz/0.25T or 112GHz/1T. The higher frequency enables
higher density limit and for reactors with several Tesla toroidal field, this start-up scenario
can largely avoid the usual density limit often encountered by ECCD. Conversely this higher
harmonic scenario would enable utilization of ECH at lower magnetic field as in the case ofmany ST experiments. This scenario maybe also attractive for the ECH assisted start up forthe initial phase of ITER where the toroidal magnetic field maybe relatively low ~ 2 T. To
better understand the QUEST experimental results, we initiated a modelling effort at PPPL.
Improved modelling should also help develop better predictive capability for future ST andtokamak-based reactors. An ST/tokamak start-up modelling is a highly coupled non-linear
problem as the magnetic field topology evolves dramatically from an open vacuum field
configuration to a closed configuration. The plasma temperature evolves from a very cold
collisional regime to a very hot collision-less regime. For this task, we developed a gridbased start-up code where plasma parameters, generated plasma currents, and resulting
poloidal magnetic fields are evolved from the vacuum fields. The grad-B drift driven current
together with the processional currents can then create a closed flux surface configurationand then the bootstrap current in a closed configuration can further enhance the plasma
current. The ECH heating efficiency increases with plasma current since the confinement isincreased and resulting electron temperature rise would further increase the ECH absorption
and plasma currents. Once the plasma temperature becomes sufficiently high ~ 1 keV, asingle-pass absorption can rise sufficiently to transition to the ECCD phase. An important
point to note is that two-component distribution (hot minority and colder bulk) is highly
advantageous for hot electrons to be generated for efficient ECCD as observed in the
QUEST start-up experiment. An update of the modelling is given including somebenchmarking of RT-4 with Genray at higher temperature range of ~30 keV and also
including the effects of particle loss to better simulate the experimental situation.

Nicola Bertelli
3D full wave simulations in NSTX-U plasmas with the recent developed Petra-M code
In this work we present the recently developed tool Petra-M and its current applications.
Petra-M code [1] is a state-of-the-art generic electromagnetic simulation tool for modeling RF
wave propagation based on MFEM [http://mfem.org], open source scalable C++ finite
element method library. Commonly, RF simulation has been often limited to a relatively small
volume in front of the antenna, and it involves physics simplification from the actual
experimental situation such as stratifying antenna strap structure, flat antenna model and/or
treating the antenna front volume as vacuum. This paper, instead, shows the full 3D NSTX-U

device geometry including realistic antenna geometry in order to capture the 3D effects andthe antenna-plasma interaction in the SOL plasma and, at the same time, the core wave
propagation. A scan of the antenna phasing shows a strong interaction between FWs andthe SOL plasma for lower antenna phasing, which is consistent with previous NSTX HHFW
observations. Furthermore, the effect of the 3D wave field on the fast ion population from
NBI beams in NSTX-U is quantified by using the 3D field obtained from the Petra-M
simulations in the SPIRAL full-orbit following particle code [2]. Then we show the 3D fullwave simulations of a new HHFW 4-straps antenna recently installed by Tri-Alpha Energy on
LAPD with an initial comparison with the experimental data. Finally, initial Petra-M
simulations on the JET ITER-like antenna, ICRH/LH in WEST machine, and helicon in
KSTAR are discussed.
[1] S. Shiraiwa et al., EPJ Web of Conferences 157, 03048 (2017). [2] G. J. Kramer et al.,Plasma Phys. Control. Fusion 55, 025013 (2013).

Sadayoshi Murakami
MHD equilibrium reproduction by visible light computed tomography in QUESTWe propose a method for reconstructing image of a poloidal plasma cross section fromvisible light information in the tangential direction of tokamak. We realize a robust
reconstruction method using Laplacian eigenfunction expansion & L1 regularization. The
MHD equilibrium is calculated from reconstructed image applying TASK/EQ code. Rotating
toroidally the obtained outer flux surface, we obtain a similar image with the measured
visible light.

国際化推進共同研究概要
No. 9
19NU-3タ イ ト ル：EC and EBW simulations in QUEST plasmas

研究代表者：BERTELLI, Nicola

所内世話人：

出射 浩

研究概要：
QUEST では、28 GHz 電子サイクロトロン波による非誘導電流立ち上げを行っている。50 keV 程度の高速電子を効率良く生成し、世界最高値を誇る、高プラズマ電流立ち上げに成功している。核融合炉での炉心プラズマ電子温度より、高温度・高エネルギーとなる 50 keV の電子による波動吸収の評価で、如何に相対論的ドップラー効果を取り扱うかが課題となる。「非相対論的電子分布関数の速度微分項の速度空間積分」で評価される誘電率の非エルミート項に、質量が重くなる相対論効果を取り入れた評価と、「相対論的電子分布関数の速度微分項の速度空間積分」を用いた評価が異なる。相対論的電子分布関数を扱った
２つのコード間でベンチマーク評価し、良好な一致を得た。非相対論的電子分布関数を用いて質量が重くなる相対論効果を取り入れた評価との差を議論した。

EC and EBW simulation in QUESTBERTELLI, NICOLA
Non-inductive electron cyclotron (EC) plasma current ramp-up is an attractive start-up
method for tokamaks. The non-inductive plasma ramp- up either with or without a small
central solenoid (CS) provides distinct advantages in reactor engineering design and incost considerations when compared with conventional tokamak operations. In a sphericaltokamak (ST), the CS flux is small because the center stack area is limited. EBWHCD(electron Bernstein wave heating and current drive) has been discussed as an attractive
candidate for fully non-inductive plasma current ramp-up in the STs. The EBWHCD in
the O-X-B mode conversion scenario have been explored for steady-state ST operation
in QUEST as well as EC heating and current drive (ECHCD).
A 28-GHz ECHCD system with a quasi-optical mirror launcher was developed toprovide second harmonic（2 fce）X-mode EC
non-inductive plasma ramp-up in QUEST. In
oblique injection with a parallel refractive
index N// = 0.75 at the 2 fce resonance position,high non-inductive plasma-current of ~ 80 kA
was efficiently ramp-up with the 28 GHz wave
(Fig,1). Hard rays (HXs) were measured atforward tangential viewings for currentcarrying energetic electrons in the mid-plane.
The HX count with averaged energy of ∼ 60
keV increased following the ramp-up in
current. It is very likely that the energetic
electrons play a key role in generating theFig.1: Time evolution of plasma parametersplasma current. To consider plasma ramp-up
in 28 GHz non-inductive ramped-up plasma.
mechanism, the single pass absorption was
evaluated with a ray-tracing code. The 3 % of the bulk density was assumed as energetic
electron component. Figure 2 shows ray absorption rate along the propagation evaluatedwith the TASK/WR code [1] in various density cases. The 20-30 % of the incident power
would be absorbed as a single pass absorption at higher harmonic resonance ( 3 fce and 4fce ) due to the energetic electrons as well as the 2nd harmonics. As the benchmark, thesingle pass absorptions with various energetic-temperature electrons were assessed using
a couple of ray-tracing codes. A couple of ray tracing codes to were used to evaluated the//N// : 0.75

Absorption

2 x 1018
3 x 1018
4 x 1018
5 x 1018

3rd

4th

2nd

2 x 1018
3 x 1018
4 x 1018
5 x 1018

Fig2 : Ray absorption rate along the ray propagation with TASK/WR code.

single pass absorption. Bulk electron temperature and density are 2 x 1018 m-3 and 30 eVat the center, respectively. Figure 3 shows the evaluated single pass absorption rate as afunction of the energetic electron temperature by TASK/WR, RT-4 [2] and GENRAY [3]codes. The 1 % and 3 %energetic electron components were assumed. Evaluatedsingle pass absorption rates match well among three codes up to 30 keV, however, therate evaluated by RT-4 code become larger than the others with increasing energetic
electron temperature beyond 30 keV. The rates by TASK/WR and GENRAY codes
coincide together with, even in the highly energetic electron-temperature range. The RT4 takes the relativistic mass effect into account on electron cyclotron frequency, electron
plasma frequency, and so on after taking integral of the distribution-function derivative
at velocity in the velocity space within the non-relativistic limit. The other codes take theintegral of the derivative with no non-relativistic approximations. The difference among
the rates with the three codes is considering on the physics point of view.

Fig.3: Evaluated single pass absorption rate with1 % and 3 % energetic electron components as afunction of the energetic electron temperature by TASK/WR[1], RT-4 [2] and GENRAY [3] codes.

[1] A. Fukuyama, Fusion Eng. and Design, 146 (2011) 1149.
[2] M. Ono, N., et al., Proc. of the 23rd Topical Conference on Radio Frequency Power in Plasmas (2020).

[3] A. P. Smirnov and R. W. Harvey, Bull. Am. Phys. Soc. 40, (1995) 1837.

No. 10（様式11 ・ 拠点）

19NU-4
日本語要約
1月29日 ー2月5日に九州大学応用力学研究所に来所 し、QUESTで開催された第8回国際ワ ー クショップに参加し、 EASTに関する最新の実験デ ー タについて「Non-inductive current drive experiments on EAST tokamak」と題したの報告·議論を行った。 高温プラズマの長時間維持はQUESTとEAST（中国科学院プラズマ物理研究所に設置された中国最大のトカマク装置）の共通の主要課題 であり、 高性能化
したプラズマの長時間運転ではEASTは世界でトップ クラスである。QUESTでの粒子バランス研究とEASTの高性能運転の状況を議論し、新たな研究の可能性について議論を行った。本研究課題に関連して中国側から1名の学生が2年間派遣されており、 中国科学技術大学で学位を取得した。 今後も情報交換を進めるとともに、協力できる研究分野での研究協力や学生交流を続けていくこととした。 関連研究では以下の2報が出版されており、 中国側で1報の投稿が行われる予定である。
K. Hanada et al 2019 Nuc/. Fusion 59 076007
K. Hanada et al 2019 Nucl. Materials and Energy 19 pp544-549

No. 11（様式11 ·拠点）

19NU-5
日本語要約
1月29日 ー2月5日に九州大学応用力学研究所に来所し、 QUESTで開催された第8回国際ワ ー クショップに参加し、 議論を行った。 また、 QUESTに設置されている軟X線カメラの性能や視野等について調査し、今後の研究の発展の可能性を検討した。 議論を行った。 QUESTのRF加熱実験で得られている高/3 p配位での平衡の限界について軟X線計測で議論することができないか議論を行い、今後の検討課題とした。

No. 12（様式11 ・ 拠点）

19NU-6
日本語要約
1月 29 日ー2 月 5 日に九州大学応用力学研究所に来所し、QUESTで開催された第8回国際ワ ー クショップに参加し、 議論を行った。 高温プラズマの長時間維持は
QUESTとEAST（中国科学院プラズマ物理研究所に設置された中国最大のトカマク装置）の共通の主要課題である。 九州大学で開発された冷却水計測に基づく熱バ
ランス計測に必要な機器は、すでに中国側の外部資金によりEASTに設置され、結果についての論文が出版されている。国家公水平の枠組みで2年間1名の研究生が九州大学に滞在し、 パ ワ ー バランスの計測法や解析法について指導を受け、 その内容で中国科学技術大学にて学位を取得した。 また、 本研究課題にて実施されたEASTに関する実験研究で4報の論文がsubmitされ査読中である。また、QUEST側の論文1報が受理されている。今後はQUESTで見出されている粒子バランスとパ ワ ー バランスの関係について研究を進めていくこととしている。
K. Hanada et al 2019 Nucl. Fusion 59 076007

No. 13（様式11 ・ 拠点）

19NU-7
日本語要約
1月29日ー2月5日に九州大学応用力学研究所に来所し、QUESTで開催された第8回国際ワ ー クショップに参加し、 QUEST やEAST に関する平衡計算やそれに基づいたRF伝搬、 吸収に関する解析についての議論を行った。 本研究で導入された平衡計算コ ー ドEFITは世界標準の計算コ ー ドで、 この計算結果に基づいてRFの伝搬や吸収を議論するためのGENRAY（米国PPPLとの共同研究）を導入してQUESTの実験結果を議論している。 近年、 QUESTの平衡計算において計算結果が得られない間題が発生しており、 QUEST側が対応していたが、 今回はQUEST
で運用されているEFITをダウンロ ー ドして中国側に持ち帰り、 間題点をチェックすることとした。 QUEST実験を解析するための重要な計算コ ー ドなので、 至急の対応が必要である。 本研究に関連してQUESTから3報の論文が出版されている。
K. Hanada et al 2019 Nuc/. Fusion 59 076007
K. Hanada et al 2019 Nucl. Materials and Energy 19 pp544-549
H. ldei et al 2019 Nucl. Fusion 59 126045

国際化推進共同研究概要
No. 14
19NU-8タ イ ト ル：

Towards high mode purity in ECRH transmission and launchers fo ITER研究代表者：CARSTEN, Lechite, Hanno

所内世話人：

出射 浩

研究概要：
ITER に向けた準光学高速伝送路スイッチの開発の高電力試験を行うべく、昨年度、新たなスイッチング機
構を欧州側で準備した。日本側は、機構組み込みのための装置改造をした。今年度、新たなスイッチング機構による高電力試験を QST 那珂核融合研究所にて行った。200 kW レベルの電力で、スイッチング素子
内のアーキングを回避するために、用いる偏波面制御が必要であった。偏波面制御は、TRIAM-1M 装置で用いられていた偏波器を用いた。偏波器性能は、九州大学で低電力試験にて評価した。高電力試験では、ア−キングを低減し、発振周波数のドリフトに応じたスイッチング性能を評価した。

Report of collaboration between RIAM and IGVP in FY2019:
High-power tests of the MQIV diplexer for ITER with automatictuning at QST
Mr. Dr. Carsten Lechte
The MQIV diplexer developed at IGVP is a fast switch, power combiner, and mode filter for 170
GHz using a Fabry-Perot resonator in a compact box design that is vacuum capable and can bedirectly interfaced with the 63.5 mm ITER ECRH waveguides which are available at QST. Our
technical partners at TNO in the Netherlands have designed and built a fast mechanical tuning
control unit for the device that is also vacuum-compatible. It uses feedback to fix the output power
to either the resonant or the non-resonant output port, compensating for changes in the gyrotron
frequency and mechanical expansion of the resonator. The activities of this year have concentrated
on proving high-power compatibility and the calibration of the power monitoring sensors at the
input and the two outputs of the diplexer.

DN

DR
IN

Fig 1: Diplexer integration into the gyrotron test stand at QST. DN and DR are the dummy loads at
the non-resonant and the resonant channel, respectively, and IN is the input waveguide.
The tests were started with 10 ms pulses of 100-150 kW at 170 GHz. Occasional arcing wasobserved but the pulses were completed. The pulse length was then increased to 100 ms in the first
week, and 300 ms in the second. The power in the input and the two outputs was monitored via
diagnostic gratings on the matching mirrors, which divert a beam of -40 dB of incident power into
horn antennas in the diplexer wall. After a vacuum seal and further attenuation, the signal ismeasured with diodes. This power measurement is not calibrated. It is also very susceptible to strayradiation, i.e. 1 % of stray radiation in the box can drown out the 0.01 % signal. This has only been
evident during arcing events.

Fig 2: Demonstration of control. The upper graph shows resonant (blue) and non-resonant (red)output power. The lower graph shows arcing events.
The high power switching capability was demonstrated, see figure 2. The tuning mirror’s position
was controlled so that maximum power would come out of the resonant port. The control was not
perfect, because of noise on the power monitor signals, and the continuous arcing activity, which
was polluting the power signal. Nevertheless, a clear majority of the power is sent to the resonant
output. Furthermore, the control system was able to tune the diplexer according to the changing
frequency of the input, albeit the frequency chirp of the gyrotron was moderate in this scenario.

Fig. 3: View of arcs on coupling grating via the observation window.
The following problems were identified during testing: Arcing was happening continuously on the
coupling gratings and probably also on the resonator mirrors. In full power operation, such eventswould necessitate the termination of the pulse, which would make the device unusable. In addition,
the stray radiation caused by the arcs was degrading the control test results.
No higher power tests were possible because of the arcing and also because of the time contraints
caused by attempts to control the arcing.
For the next test period, a number of mitigation techniques are planned: electropolishing of the
problematic mirror surfaces to reduce the arcing, which may be caused by material defects in thesurfaces, and the addition of stray radiation absorbers in the box. These will be made from metal
plates with a resonant ceramic absorption coating for 170 GHz waves.

国際化推進共同研究概要
No. 15
19RE-1
タ イ ト ル： Development of III-Nitride optical devices: a materials perspective

研究代表者： GRZEGORY, IZABELLA, ALICJA

所内世話人： 寒川 義裕
研究概要：
アモノサーマル法およびハライド気相成長法＋アモノサーマル法のハイブリッド手法による窒化ガリウム（GaN）のバルク成長に関する現状を報告した。特に、アモノサーマル法における最近の GaN 成長速度、応力制御技術、純度について概観した。また、
高品質バルク GaN 基板上に成長した長寿命レーザーダイオードとそのトンネル接合を含むデバイス構造の優位性について議論した。プラズマ・アシスト分子線エピタキシーを用いることにより水素フリーでの成長が可能となるため、Mg アクセプターの活性化
熱処理が不要になるなどデバイス構造のチューニングにおいて優位性があることが示された。

FY2019 RIAM International Joint Research[19RE-1] Development of III-Nitride optical devices: a materials perspective
Izabella Grzegory
Institute of High Pressure Physics Polish Academy of Sciences
Ul. Sokołowska 29/37, 01-142 Warsaw, Poland
The current status of bulk GaN crystallization by Ammono and hybrid HVPE/Ammono methods
was reported. Extremely long living LDs and their vertical stacks including tunnel junctions grownby PA MBE was discussed.
GaN substrates with low dislocation density and flat crystallographic planes are highly desirable
in III-N technology of both electronic and optoelectronic devices. In latter case dislocations are
detrimental as non-radiative recombination centers but also as growth centers disturbing flat
crystallization front especially in thick epitaxial structures necessary for vertical integration of LEDs
and LDs.
In this joint research the current status of bulk GaN crystallization by basic ammonothermal(Ammono) and hybrid HVPE/Ammono methods was reported and discussed. In particular, recent
progress in the growth rate, stress engineering and purity in the ammonothermal process was
highlighted.
Very high quality substrates fabricated from the bulk GaN crystals were used for epitaxial growthof quantum structures of LDs and their vertical stacks containing tunnel junctions, by PA MBE. It
was shown that extremely long lifetimes of the devices can be achieved due to the use of the neardislocation free GaN substrates.
The PA MBE is particularly useful for growing vertically integrated structures including tunnel pn junctions since the method is hydrogen free and activation of Mg-acceptors is not necessary.
Therefore, perfect 2-fold and 3-fold stacks of full LD structures could be grown straightforward.
Corresponding devices will be characterized and their current and potential advantages was discussed.

国際化推進共同研究概要

No.16
19RE-2タ イ ト ル：Cold Crucible Czochralski (3C)研究代表者：ZAIDAT, Kader

所内世話人：柿本 浩一

研 究 期 間：2019 年 6 月 10 日 ～ 6 月 15 日

概シリコン半導体の新規結晶成長法の実現に向けた提案に関して議論を行要：った。特に局所磁場の発生方法に関して定量的な議論を、数値計算結果
を交えて議論した。その結果、従来不可能であった局所磁場の発生が可能であることを見つけた。

Project: Cold Crucible Czochralski
Acronym: 3CZ
Scientific partners: SiMaP France/ RIAM Japan

1) Summary of the visit in 2015 at Kyushu University by Dr K. Zaidat

The goal of the visit was to present the scientific context (bibliography) at the Pr Kakimoto‘sgroup in order to discuss on the possibility to decrease the contamination (oxygen and carbon)
during the Czochralski (Cz) process.
The visit was very fruitful for the two groups, in fact the Dr Zaidat has presented his idea on
the possibility to use cold crucible in order to avoid oxygen during the Cz process. After somepresentations on the different relative work on the topic it appears:
That the cold crucible will be a good compromise to avoid the contamination but thedifficulty will be to adapt the thermal insulation around the ingot in order to avoid the thermal
stress induced by the crucible.
The fluid flow induced inside a cold crucible will be the key parameter to achieve alarge ingot with this technic.
According to the Pr Kakimoto, the dislocation density should be decrease (comparing
the classical technic) only if the level of carbide and oxygen will be decrease at the same levelof the Floating zone.
In conclusion, it was really a pleasure for the two groups to discuss on this critical point
especially on the carbide and oxygen contamination. The two groups hope to continue tocollaborate on this topic in the future.

2) Summary of the visit in 2016 at Nagoya during the International Conference ofCrystal Growth and Epitaxy-2016
After a first visit in 2015 (see resume before), it was identified to find a solution on thecontrol of the fluid flow inside a cold crucible. The two teams have discussed during the
ICCGE conference organised by the Pr Kakimoto in order to propose a solution of thistechnical point.
The SIMAP team will try to add a static magnetic field in order to damped the liquid anddecrease the velocity induced by the cold crucible. A first 2D model must be develop in orderto understand the interaction between a static magnetic field and the electromagnetic field
induced by the cold crucible.

3) Summary of the visit in 2019 at Kyushu University by Kader Zaidat
This visit was the third visit on the same topic.
Pr K. Zaidat has presented the last results on the effect of the magnetic field induced by a
Halbach configuration. A long discussion on the adaptation of this kind of structure wasdiscussed for floating zone process.
Pr K. Zaidat has proposed and developed a new model for Halbach configuration study inorder to include it in a global model of the Kakimoto's group.

国際化推進共同研究概要

No.17
19RE-3タ イ ト ル：Development of a Reliable Method for Dynamic Responses Prediction of Floating Wind
Turbines研究代表者：HU, Zhiqiang

所内世話人：

胡 長洪

研究概要：
本国際化推進共同研究について今年度は 2 年目で，共同研究を予定通り実施した。特に、浮体式
洋上風力発電システム用のセミサブ型浮体の動特性解析に関する機械学習の応用可能性について検討を行った。R2 年１月に応研で開催された国際研究集会「International RIAM Symposium on Novel
Computational and Experimental Methods for Complicated Fluid-Structure Interactions」に出席し、「AMachine Learning based Software-In-the-Loop method to Predict and Monitor the global dynamic responsesof floating wind turbine system」のタイトルで共同利用成果の発表を行い、参加者との研究交流を行った。

Report for 2019 RIAM International Joint Research Project[19RE-3]
Development of a Reliable Method for Dynamic Responses
Prediction of Floating Wind Turbines
Zhiqiang Hu
Marine, Offshore and Subsea Technology, School of Engineering, Newcastle University, UK

During year of 2019, fruitful collaborative works have been conducted between RIAM Kyushu
University and Newcastle University. The outcomes are listed as below.
1) Attendance of RIAM International Symposium on Novel Computational and Experimental
Methods for Complicated Fluid-Structure Interactions, at RIAM Kyushu University in Jan
2020.
2) Collaborations on the proposal and development of a novel method to use machine-learningtechnology with theoretical and experimental ways to predict dynamic responses of floating
wind turbine. Zhiqiang Hu at Newcastle University has submitted a proposal to EPSRC
UK for a funding application, and Professor Changhong Hu has kindly joined theapplication team. It is expected that EPSRC will make the decision in early 2020.
3) Based on the research in year 2019/20, a collaborative conference paper entitled ‘SoftwareIn-the-Loop Method to Predict the Global Dynamic Responses of Full-scale Floating Wind
Turbines by Using Artificial Neural Network’ has been published on the 11th International
Workshop on Ship and Marine Hydrodynamics, at Hamburg Germany, September 22-25,
2019. The paper was presented by Mr. Peng Chen, a PhD student of Zhiqiang Hu at
Newcastle University.
1. RIAM international symposium
An international symposium ‘Novel Computational and Experimental Methods forComplicated Fluid-Structure Interactions’ was successfully held at RIAM Kyushu University
on 20-21st Jan 2020. Professor Zhiqiang Hu attended this symposium and made an academicpresentation with topic on ‘A Machine Learning based Software-In-the-Loop method to Predictand Monitor the global dynamic responses of floating wind turbine system’. This presentation
introduced the latest research outcome of Zhiqiang Hu’s research team at Newcastle University
during year 2019. This research aims to propose a new method, which utilizes Software-in-theLoop method with machine learning (Artificial Neural Network) approach for FOWT’sdynamic responses prediction. With the attendance of this symposium, Zhiqiang Hu has madefruitful discussions with other scholars, and most of all, a fruitful discussion and future planwith professor Changhong Hu to continue and extend the collaborations in the field of artificial
intelligence.
2. Collaborative research on AI technology for floating wind turbine
In the year of 2019, a collaborative research aiming to apply AI technology in the FOWT

research was developed, based on the cooperation between Professor Changhong Hu at RIAM,
Kyushu University and Professor Zhiqiang Hu at Newcastle University. This research willpropose a novel method to solve the challenge of satisfying Fr. And Re. at the same time for
FOWT. At the moment, this challenge is the obstacle to predict dynamic response of FOWT
during the design stage, and wind industry has emphasized this as one of the critical challenges
that must be overcome within the next few years. The collaborative research has led to an
application to EPSRC UK, and Professor Changhong Hu has provided strong support for the
proposal.
In addition, thanks for the support and collaboration in 2019, a collaborative conference paper
submitted to the 11th International Workshop on Ship and Marine Hydrodynamics (IWSH2019),
Hamburg, Germany. The paper is titled ‘Software-In-the-Loop method to predict the global
dynamic responses of prototype FOWTs by using Artificial Neural Network algorithm’. This
paper has been presented on the ISWH2019.
In year 2020, the research on AI technology with FOWT will be conducted to a further step.
This research includes three phases in terms of Numerical modeling, Experimental combination
and Real time monitoring. In the first phase, a method combing machine learning (ANN)approach with an in-house programme DARwind is proposed. In the second phase, theprogramme is optimized through correlation analysis based on real-measurement data and basinmodel data. In last phase, A methodology will be established, including perfecting the scale
relationship between the data of basin model test and that of full-scale measurement, thenumerical simulation application in design and real-time monitoring, and the risk control inwind farm management. Professor Changhong Hu will continue do his contribution on the CFD
calculation validation.

国際化推進共同研究概要

No.18
19RE-4
タ イ ト ル：Novel computational and experimental approaches to the analysis of complicatedfluid-structure interactions

研究代表者：

WAN, Decheng

所内世話人：

胡 長洪

研究概要：
２年間予定されている国際化推進共同研究「Novel computational and experimental approaches to theanalysis of complicated fluid-structure interactions」の初年度で，共同研究・研究集会とも予定通り実施した。特に大規模風力発電所における風車間後流干渉を考慮した高精度 LES シミュレーションについて共同研究を実施し、関連の研究成果は５編の国際学会論文を投稿し採択された。R2 年 1 月 20
日～21 日に国際研究集会「International RIAM Symposium on Novel Computational and Experimental
Methods for Complicated Fluid-Structure Interactions」が開催され、外国から 11 名、日本から約３０名の参加者があり、海洋再生可能エネルギー開発に重要な研究課題である流体・構造連成解析に関して有意義な国際研究集会となった。

Report for 2019 RIAM International Joint Research Project[19RE-4]

Novel computational and experimental approaches to the analysis ofcomplicated fluid-structure interactions
Decheng Wan
School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, China

1. Purpose
Marine renewable energy devices are usually installed in a sea area where severe environmental conditions
have to be considered. On the other hand, cost control is strictly required for those devices in order to passeconomic evaluations. Therefore for successful design of those devices, accurate numerical methods as wellas efficient experimental methods are required to evaluate the hydro- and aerodynamic performance of thesedevices. This joint research project focuses on one of the most important fundamental fluid mechanics
problems in marine renewable energy development, the fluid-structure interaction problem. Researchers,
especially younger researchers, including but not limited to SJTU and RIAM, are invited to exchange theirknowhow on development of computational and experimental tools for the purpose.

2. Research Plan
This joint research project is planned for two years. FY2019 is the first year of the project. The major
research topic is the development of novel CFD and experimental methods for analysis of complicated fluidstructure interaction problems in ocean engineering and marine renewable energy developments. CFD codes
which are developed in SJTU and RIAM will be compared to the experiments. In the end of 2019, as the main
event of this international joint research project, International RIAM Symposium on Novel Computational andExperimental Methods for Complicated Fluid-Structure Interactions will been carried out. Researchers
involved in this joint research project will present and discuss their research progresses.
The members involved in this collaborative research are shown in the following table.
Researcher’s Name

Name of University
or Institute

Present Status or Grade(graduate students)

Decheng Wan

SJTU

Professor

Representative person (CFD )Jianhua Wang

SJTU

Assistant Professor

Co-researcher (CFD)

Cheng Liu

SJTU

Associate Professor

Co-researcher (CFD)

Weiwen Zhao

SJTU

PhD student

Co-researcher (CFD)

Guanyu Zhang

SJTU

PhD student

Co-researcher (CFD)

Zheng Li

SJTU

PhD student

Co-researcher (CFD)

Cong Liu

SJTU

PhD student

Co-researcher (CFD)

Mohamed M. Kamra

RIAM

Research Fellow

Co-researcher (CFD)

Makoto Sueyoshi

RIAM

Assistant professor

Co-researcher (experiment)

Changhong Hu

RIAM

Professor

RIAM AttendantResearcher role

3. Summary of Collaboration Research
In 2019, large-eddy simulations of complex wake flows around large wind farm in real wind environments
have been carried. In order to improve the economic performance of wind power generation, the wind turbine
is developing towards the direction of floating type and large scale. In the present work, the complex wakeflows around large wind farm in real wind environments are investigated. A large eddy simulation and an
actuator disk model are applied to simulate the wake field and aerodynamic loads of wind turbines in large
wind turbine. The influence of inflow wind speed, surface roughness length and atmosphere boundary layeron the turbine aerodynamics and wake characteristics are discussed in detail. Moreover, the yaw-control
optimization for large wind farm based on the particle swarm algorithm is evaluated by LES simulation.
International conference papers related to this joint research project in 2019 are listed as follows.
1) Hao Guo, Jianhua Wang, Decheng Wan, Changhong Hu, Benchmark Computations on Motion
Responses and Bow Waves of the Ship in Regular Waves, Proceedings of the Twenty-ninth (2019)
International Ocean and Polar Engineering Conference, Honolulu, Hawaii, USA, June 16-21, 2019, pp.
2871-2878
2) Xinwang Liu, Decheng Wan, Gang Chen, Changhong Hu, Wigley Hull Form Optimization with orwithout Bulbous Bow, Proceedings of the Twenty-ninth (2019) International Ocean and Polar
Engineering Conference, Honolulu, Hawaii, USA, June 16-21, 2019, pp. 4486-4493
3) Xu Ning, Yang Huang, Decheng Wan, Changhong Hu, Numerical Study of Wake Interaction and its
Effect on Wind Turbine Aerodynamics Based on Actuator Line Model, Proceedings of the Twenty-ninth(2019) International Ocean and Polar Engineering Conference, Honolulu, Hawaii, USA, June 16-21,
2019, pp. 483-490
4) Xu Ning, Decheng Wan, LES Study of Wake Meandering in Different Atmospheric Stabilities and Its
Effects on Wind Turbine Aerodynamics, Sustainability, 2019, 11(24), 6939,
https://doi.org/10.3390/su11246939
5) Ping Cheng, Yang Huang, Decheng Wan, A numerical model for fully coupled aero-hydrodynamic
analysis of floating offshore wind turbine, Ocean Engineering, 2019, 173: 183–196

As a main event of this international joint research project, ‘International Symposium on Novel
Computational and Experimental Methods for Complicated Fluid-Structure Interactions’ was held on January
20-21, 2020. On the symposium, overseas scholars are invited to present their recent researches on ocean
renewable energy development.
The research budget provided for this international joint research has been used to support part of thetravel expenses of the following 5 scholars to attend the symposium.
1.

Decheng Wan, Professor, Shanghai Jiao Tong University, China

2.

Weiwen Zhao, Assistant Professor, Shanghai Jiao Tong University, China

3.

Yuan Zhuang, PhD Student, Shanghai Jiao Tong University, China

4.

Ye Li, Professor, Shanghai Jiao Tong University, China

5.

Zhiqiang Hu, Professor, Newcastle University, UK

The program of the symposium is as follows.

PROGRAM
Date: January 20-21, 2020
Place: Meeting Room at 2nd Floor, RIAM, Kyushu University
20 January (Monday)
13:00 - 13:10

Opening Address by Changhong Hu
Chair: Changhong Hu

Session 1
13:10 - 13:50

13:50 - 14:20

Takayuki Aoki (Tokyo Institute of Technology)
Invited Lecture
Weakly Compressible Flow Computations for Incompressible Two-phase flows andFluid-Structure Interactions
Mohamed Kamra (Kyushu University)
Development of Unstructured Mesh CFD Code for Fluid-Structure Interactions

14:20 - 14:50

14:50 - 15:20

Weiwen Zhao, Decheng Wan (Shanghai Jiao Tong University, China)
Numerical Investigations of Vortex-Induced Vibration of Flexible Riser under Motionsof Floating Platform
Seiya Watanabe (RIAM, Kyushu University)
Large-scale FSI Simulations for Free-surface Flow Using Lattice Boltzmann Methodwith Adaptive Mesh Refinement

15:20 - 15:50

Coffee break
Chair: Decheng Wan

Session 2
15:50 - 16:30

Young-Ho Lee (Korea Maritime & Ocean University, Korea)
Invited Lecture
KMOU Offshore Energy Research Activities and KOREA Strategy on Floating Offshore
Wind Development

16:30 - 17:00

Yuan Zhuang, Decheng Wan (Shanghai Jiao Tong University, China）
Combined Solver HOS and naoe-FOAM-SJTU for Wave-Structure Interactions

17:00 - 17:30

17:30 - 18:00

Takao Fukumoto (Hiroshima University)
Estimation of Hydrodynamic Forces by Integrating Unsteady-Pressure Distribution
Measured with FBG Pressure Sensors
Kurniawan Waskito, Masashi Kashiwagi, Hidetsugu Iwashita, Munehiko Hinatsu(Osaka University)
Prediction of Nonlinear Wave Loads Using Measured Pressure Distribution on Ship Hull

18:00 - 18:30

Isshiki Hiroshi (Institute of Numerical Analysis)
Node Generation in Numerical Calculation by Stochastic Sampling – Application to
Interpolation of a Function and Solution of Burgers Equation Using Collocation Method

18:00 - 20:00

Dinner Party

21 January (Tuesday)

Chair: Tomoaki Utsunomiya

Session 3
9:20 - 10:00

Ye Li (Shanghai Jiao Tong University, China)
Invited Lecture
Numerical and Experimental Investigation of Offshore Renewable Energy System

10:00 - 10:30

10:30 - 11:00

11:00 - 11:30

11:30 - 12:00

12:00 - 13:20

Lin Yang, Q.W. Ma and Kangping Liao (Harbin Engineering University, China)
Coupled Aero-Elastic Analysis of a Wind Turbine System using CFD and Finite Element
MethodZhiqiang Hu (Newcastle University, UK)
A Machine Learning based Software-In-the-Loop method to Predict and Monitor the global
dynamic responses of floating wind turbine system
Decheng Wan (Shanghai Jiao Tong University, China)
Large-Eddy Simulations of Complex Wake Flows around Large Wind Farm in Real Wind
Environments
Tarek Dief, Mostafa Rushdi, Amr Halawa, Shigeo Yoshida (RIAM, Kyushu University)
Hardware-in-the-Loop (HIL) and Experimental Results for the 7 kW Pumping Kite Power
SystemLunch break
Chair: Yingyi Liu

Session 4
13:00 - 13:30

Christopher Vogel (Oxford University, UK)
Invited Lecture
Multi-Scale Fluid Dynamics in Offshore Renewable Energy

13:30 - 14:00

Dezhi Ning (Dalian University of Technology, China)
Hydrodynamic Performance of a Dual-Chamber OWC Wave Energy Converter

14:00 - 14:30

Guojian Chen (Bureau Veritas Marine China Co., ltd)
Windmill R&D progressing in BV

14:30 - 15:00

Ying Gou (Dalian University of Technology, China）
Vertical Motion Response of a Submerged Body Induced by Internal Solitary Waves

15:00 - 15:30

Guanghua He (Harbin Institute of Technology, China)
Study on a Wave Energy Converter with eight round Floats

15:30 - 15:40

Closing Address by Decheng Wan

国際化推進共同研究概要
No. 1919RE-5
タ イ ト ル：

Downwind Turbine Technologies, Model Development and Verification

研究代表者：CHOKANI, Ndaona
所内世話人：吉田 茂雄
研究概要：
タワーの風下側にロータを配置するダウンウィンドロータは，今日の商業風車においてはほとんど見られない．しかし，ロータが若干下方に傾斜していること，タワーとのクリアランスが大きくなること，ヨー方向の空力安定性が優れていることから，複雑地形向け，将来の浮体式洋上風車ならびに超大型風車に適した技術として注目されている．しかし，これまでの風車はほとんどがタワーの風上側にロータを持つアップウィ
ンド風車であり，ダウンウィンド風車の解析法や設計基準は十分ダウンウィンド風車に対応していないものがある．そのような状況に鑑み，本プロジェクトでは，解析モデルの開発を行う．
本研究では，ダウンウィンド風車のモデル開発・評価に関するワークショップを 2 回開催した．実施した．
主な成果は以下のとおりである．
・空力弾性解析用の 2MW ベースラインモデルを開発した・ロータ～タワーの干渉に関する各種モデルを開発した．
・暴風待機時のパッシブヨーの特性に関する解析条件を検討した．
・大型化に対するダウンウィンドロータの優位性を検討した．

Downwind Turbine Technologies, Model Development and Verification
Applicant: Ndaona Chokani, Senior Scientist, ETH Zurich
RIAM Attendant: Shigeo Yoshida, Professor

1. OUTLINE OF THE WORKSHOP
1.1 CENER, Pamplona, Spain(1) Date: 2019/05/13(mon)-14(tue)(2) Place: CENER (Pamplona, Spain)(3) Participants:(CENER) Antonio Ugarte OLARREAGA, Xabier
MUNDUATE, Ivan MALLAFRE(X1 Wind) Alex RAVENTOS, Rocio TORRES(IWES) Elia DANIELE(BWC) Sandy BUTTERFIELD(NREL) Rick DAMIANI(Hitachi) Yasuo OSONE, Kunihiko TOMIYASU,
Soichiro KIYOKI, Nobuo NAMURA(WEIT) Masataka OWADA(KU RIAM) Shigeo YOSHIDA

2. REPORTS
WP1-1) Baseline Model, UTokyo
Aeroelastic models of a 2MW baseline downwind
turbine model were defined. Power coefficient to tip
speed ratio is shown in Fig 1. The tower was designed
to avoid resonace in the opration conditions as shownin Fig 2.
The Bladed and FAST models were delivered to themembers to proceed the verification study in eachresearch subject.

1.2 Hitachi, Hitachinaka, Japan(1) Date: 2019/10/23(tue)-24(wed)(2) Place: Hitachi (Hitachinaka, Japan)(3) Participants:(NREL) Nick JOHNSON(IWES) Elia DANIELE(UTokyo) Atsushi YAMAGUCHI(Hitachi) Yasuo OSONE, Kunihiko TOMIYASU,
Soichiro KIYOKI, Nobuo NAMURA, Yusuke
OTAKE, Takumi TADANO(WEIT) Masataka OWADA(KU RIAM) Shigeo YOSHIDA

1

0.8

Frequency (Hz)

1.3 Outlines of the Task
WP1) Model Development& Verification
WP1-1) 2MW Baseline Turbine Model
WP1-2) Tower Shadow
WP1-3) Nacelle-Rotor Interaction
WP1-4) Stability & Control
WP1-5) Complex Terrain
WP2) Design and LCOE Assessment
WP2-1) Blade Optimization for Downwind
Turbines
WP2-2) Scalability Benefits for Downwind
Turbines
WP3 Recommended Practice
WP3-1) Standards Evaluation for Downwind
Turbines
WP3-2) RP for Downwind Turbines

Fig 1 Power coefficient to tip speed ratio

1P
3P
tower 1st mode

0.6

0.4

0.2

0
0

5

10

15

20

25

wind speed (m/s)

Fig 2 Excitation frequencies and tower 1-st modebending frequency

WP1-2) Tower Shadow, KU
Some research results on tower shadow modeling of
downwind turbines in Blade-Element and Momentum(BEM) method, which was not considered in theformer methods were reported.
(1) Tower Variable Load [1]The variable load model of downwind turbine tower,
which was not considered in the previous model, isformulated as below, using lifting-line theory.
CdT = DT 
2 

2U 0 

−U 0

du
dv
dw 
+ r
−w

dxT
dxT
dxT 

It was verified by the CFD of rotor-tower-nacelleconfigurations at rated and cut-out operating
conditions. It shows fairly nice agreement with the
CFD in particular out-board section and at low thrust
conditions as shown in Fig 3. However, there still besome more room for improvement in inboard sections.

Fig 4 Rotor thrust to tower drag: (T) 13m/s, (B) 25 m/s(3) Dynamic Blade Load [3]The dynamic blade load model was reported. Thismodel was developed based on the former study ofMunduate [4]. Two points were modified from thereference; 1) application of Moriarty’s tower wakemodel [5] and 2) wake entrance condition. エラー!
スイッチの指定が正しくありません。 shows theanalysis and experiment results on a 1 m diametermodel. Where, UG indicates University Glasgow’s
former model and KU does present model. The present
model was successfully shown the increase in load
before the wake entrance was modeled better than theprevious work.

Fig 3 Variable loads of the downwind turbine tower at
100% rotor radius: (T) 13 m/s, (B) 25 m/s(2) Tower Average Load [2]And the average tower load model was also
introduced based on the momentum theory, which
consists with velocity and pressure gradient terms.
CdTV = CdTV + CdTP() 2  dd= −CdT 0 1 − T 2 +

T

T

T

The model was validated by the wind tunnel test. It
shows good agreement with the wind tunnel test data
as shown in Fig 4.

Fig 5 Blade section (75% rotor radius) lift coefficient
to rotor azimuth, UG model
The scale effects of the model were investigated. Fig
6 is the simulation results for the similar models. The
top, middle and bottom subplots are analysis resultswith x1 model (1 m rotor diameter), x3 (3 m), and x10(10m), respectively. Here the tip speeds are set to be
identical. As shown in these figures, the variation of
the lift coefficients are decreasing as the scale getting
larger.

エラー! 参照元が見つかりません。 is theanlysis results for the 2 MW baseline model. The
top and bottom subplots are at 13 m/s and 25 m/s
respectively. The tower shadow effects are still large
as compared with the previous figure as the tower
diameter is large and the clearance between the rotor
and the tower is smaller in the realistic turbine.

Fig 6 Blade section lift coefficient to rotor azimuth:scale (T) x1, (M) x3, (B) x10, KU model

Fig 8 Flow around the tower and the blade (75% rotor
radius): azimuth at (T) 60 deg, (M) 180 deg, (B) 300
deg, at 13 m/s(4) Influence of Karman Vortex [6]CFD results for a 0.7 m test model are shown in Fig
8. The top, middle and bottom subplots are those at 60
deg, 180 deg, and 300 deg of rotor azimuth angles, at
75% rotor radius. The blade passes through the vortex
at 60 deg and 300 deg, whereas, between vortex at 180
deg of rotor azimuth angles.

Thrust Coefficient [-] (VR/NR)

Fig 7 Blade section lift (75% rotor radius) coefficient
to rotor azimuth of 2MW DT: (T) 13 ms/, (B) 25 m/s

0.75

0.20

0.70

0.15

0.65

0.10

0.60

0.05

0.55

0.00

Thrust Coefficient [-] (VO/NR)

Rotor thrust and torque on 75% radius are shown in
Fig 9 and Fig 10. The load fluctuations appear as oneof the blades approaches to the tower. Furthermore, theamplitudes are strongly correspondent with theinteraction with the vortex behind the tower; thefluctuation tends to be large when the blade passes
through the vertex.

VR/NR

VO/NR
0.50

-0.05
0

60

120

180

240

300

360

Azimuth Angle [deg]Fig 9 Rotor thrust coefficient (75% rotor radius) torotor azimuth: (VR) 13 m/s, (VO) 25 m/s

0.15

0.05
VR/NR

0.04

0.13

0.03

0.12

0.02

0.11

0.01

0.10

Torque Coefficient [-] (VO/NR)

Torque Coefficient [-] (VR/NR)

VO/NR
0.14

0.00
0

60

120

180

240

300

360

Azimuth Angle [deg]Fig 10 Rotor torque coefficient (75% rotor radius) torotor azimuth: (VR) 13 m/s, (VO) 25 m/s
1.5
VR/NR
VO/NR

Lift Coefficient [-]

1.0
0.5

affect the frequency of the lift.
Tower drag coefficient is shown in エラー! 参照
元 が 見 つ か り ま せ ん 。 . it consists of two
components; interaction by blade and Karman vortices.
The former is still dominant in 13 m/s, as the thrust islarge, but, the component almost disappears in 25 m/s
when thrust is almost zero.
WP1-2) Tower Shadow, IWES
Fluid-structure interaction analysis for DTs withtubular and truss towers (square cross section) werereported. The truss tower, which was expressed byrectangular columns, showed larger wind speed
dissipation behind the tower as shown in Fig 1. It also
shows larger load fluctuation the one of the blades passthrough the wake of the tower. It also shows, theexcitation in the twist of blade adversely affects theload fluctuation as shown in エラー! 参照元が見つかりません。. This results is different from the next
section. The cross section of the truss tower affects theresult drastically.

0.0
-0.5
-1.0

-1.5
0

60

120

180

240

300

360

Azimuth Angle [deg]Fig 11 Tower lift coefficient (75% rotor radius) torotor azimuth: (VR) 13 m/s, (VO) 25 m/s

Fig 1 Wakes behind the tubular and truss towers

1.0
0.9

Drag Coefficient [-]

0.8
0.7

0.6
0.5
0.4
0.3
0.2
VR/NR

0.1

VO/NR

0.0
0

60

120

180

240

300

360

Azimuth Angle [deg]Fig 12 Tower drag coefficient (75% rotor radius) torotor azimuth: (VR) 13 m/s, (VO) 25 m/s
Tower lift coefficient at 75% rotor radius is shownin Fig 11. It shows the Karman vortex is dominant for
the lift unlike the rotor loads. The wind speed aroundthe tower decreases in 13 m/s (rated wind speed) as
rotor thrust is larger than at 25 m/s. These differences

Fig 13 Thrust fluctuation by the towers
WP1-2) Tower Shadow, X1 Wind
The concept of X1 Wind was introduced. CFD was
conducted for the monopole and the truss structure(cylindrical cross section). The wake of the truss
shows much smaller wake as compared with thetubular tower in both of downwind and upwind rotor(Fig 14, Fig 15). It indicates the truss tower can beBlade Flapwise Bending Moment
Normalized by the Load of Active Yaw Control[-]effective to reduce the impact loads on blades.
1

0.8

0.6

0.4

0.2

0

Each Seed & Each Blade
Typical value-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5
Long-period Change Rate of Wind Direction [deg/s]

Fig 17 Blade root flapwise bending to wind directionchange rate

Fig 14 CFD behind a tubular and a truss towers

WP1-5) Complex Terrain, CENER
Outlines of the NEWA-ALEX17 project was
introduced by CENER. The test site is shown in Fig
18.
Transect with RHIs: WS3: 15 Degree and WS5: 20 Degree max. range 4500 m

Height asl [m]

2500

1500
1000
500
- 2000

Fig 15 Wind speed distribution behind the towers

10minutes Averaged Yaw Misalignment[deg]

0

1000

2000

3000

4000

5000

4.736 ×106

4.734 ×106

Height asl [m]

VM1
WS1

1200

WS3

4.732 ×106

1000

WS4

WS2

800

4.730 ×106

VM2
WS5
600

4.728 ×10

10

WS5

WS3

- 1000Distance from WS3 [m]Northing [m]WP1-4) Stability, Hitachi [7][8]The extreme loads of a 5.2 MW DT in parked
condition in Typhpoon #21 in 2017 were simulated.
Yaw angles by the measurement and the analysis areshown in Fig 16. Blade root flapwise bending moment
are shown in Fig 17. The results are consistent with themeasurement.

2000

6
400

4.726 ×1065612 000

614 000

616 000

618 000

620 000

622 000

Easting [m]0

Fig 18 Test site for ALEX17-5

WP2-1) Blade Optimization, NREL
Baseline
10MW
rotor
was
WISDEM/RotorSE.

-10
-15
-20
-25

Measurement(13-15hour)
Measurement(13.5-14.5hour)
Simulation(13.5-14.5hour)
35404510minutes Averaged Wind Speed[m/s]Fig 16 Yaw misalignment to wind speed

50

createdin

WP2-2) Blade Optimization, Hitachi
Fatigue calculation and tower shadow model wereintroduced in this research. Natural frequencies inflap-wise and edgewise are the output of the
optimization. Design variables are not optimized forpre-bent blades as present cost is not considered. Less
than 5m is recommended due to the manufacturing andtransportation. The tower shadow model is too

pessimistic. Therefore, the advantage of downwind
turbines is underestimation.
WP2-1) Blade Optimization, CENER

The CENER airfoil family was introduced. It was
designed for high Reynolds number at high lift
coefficient as shown in Fig 19. And it is also
designed for insensitivity roughness. It is effective
to maintain efficiency, reduce rotor speed at thesame AEP level, chord reduction for a slender blade(Fig 20).

Fig 19 Lift to drag coefficients of DU-W-210 and
CENER S836 airfoils

Fig 20 Optimal blade chord length distribution using
DU and CENER airfoils
WP2-2 Scalability Benefits, NREL
The scalability benefits of downwind rotor will bedemonstrated. The approaches are as below.
- 2MW DWT LCOE Input data
- CAPEX: ORCA, regional cost analyzer- O&M Cost: ECN’s Offshore O&M Tool

3. REFERNCES[1] Yoshida, S., Combined Blade-Element Momentum- Lifting Line Model for Variable Loads on
Downwind Turbine Towers, energies, 2018.
[2] Yoshida, S., et al., Rotor Thrust Effects on Mean
Load of Downwind Turbine Towers, #40 Wind
Energy Utilization Symposium, 2018.
[3] Yoshida, S., et al., Unsteady Tower Shadow Modelfor Downwind Turbines, #41 Wind Energy
Utilization Symposium, 2019.
[4] Munduate, X., Coton, F.N., Galbraith, R.A.M., An
Investigation of the Aerodynamic Responses of aWind Turbine Blade to Tower Shadow, J. Solar
Energy Engineering, 126, 1034-1040, 2004.
[5] Moriarty, P.J. and Hansen, A.C., AeroDyn Theory
Manual, NREL/EL-500-36881, National Renewable
Energy Laboratory, 2005.
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国際化推進共同研究概要
No. 20
19RE-6
タ イ ト ル：

Coupled aerodynamic and floating platform dynamics

研究代表者：

VOGEL, Christopher, Reiner

所内世話人：

劉 盈溢

研究概要：

近海の風力資源が豊富と考えられ、洋上浮体式風車が最適な選択肢。レイノルズ数とフルード数が同じ速度でスケーリングしないため、時間領域の数値法がこの連成問題に非常に適当と考えます。 いくつかの適切な修正を加えた翼素運動量理論は、風車の空気力
学に最も効果的です。 ただし、ピッチ運動をする浮体式風車では、個々のブレードに対し、
ピッチ制御が必要と思われ、非定常流れを考慮する必要があります。 Vogel と Liu の専門知識を組み合わせて、風車とプラットフォーム間の結合に関するさらなる研究、それらの相互効果および代替の風車制御を検討する予定です。
Floating wind turbines are attractive considering the wind resources in the ocean far
offshore. Due to that the Reynolds number and the Froude number do not scale at thesame rate, a time-domain numerical method may be much suitable for the coupledproblem. The Blade Element Momentum Theory with some appropriate modifications are
effective for the wind turbine aerodynamics. However, unsteady inflow needs to beconsidered for a pitching floating wind turbine for which an individual blade pitch
controller may be therefore necessary. Combining the expertise of Vogel and Liu, further
work on coupling between wind turbine and platform, their mutual effects and alternative
turbine controllers is going to be considered in the future.

Introduction
Cost of installation and the drive to deployment in deeper waters are two of the key factors that areleading to the development of floating offshore wind turbines. A similar process has been occurring in tidal
stream energy, where deploying turbines from a floating platform offers improved access for maintenanceas the technology develops. The coupled platform motion and turbine dynamics in both cases make this achallenging problem to address, as turbine loads are affected by platform motion and vice versa (van derVeen et al. 2012). It is necessary to resort to analytical or numerical techniques to investigate these
problems, as the key non-dimensional parameters for coupled turbine-platform motion, the Reynolds
number and the Froude number, do not scale at the same rate. However, analytical and numerical models
also have limitations which must be appreciated for the coupled problem.
Although solving floating body problems can be conveniently considered in a frequency domain analysis,
only the simplest turbine representations may be investigated through this approach. Real turbines
operate in a complex way in response to the prevailing wind, and the additional effect of platform motion
on turbine performance is non-linear. Hence, time domain methods are more suitable for investigating
coupled turbine-platform dynamics, although appropriate parametrisation of added mass and damping
effects is still required.
Methodology
Blade element momentum theory has been widely applied to wind turbine problems as an approach that
couples the leading order two-dimensional aerofoil aerodynamics with the overall changes in momentum inthe fluid due to the thrust of the turbine. Correction factors are applied in the blade root and tip regions
in order to account for departures from the simplified theory. Modifications to the theory are alsoavailable to account for the blocked flow environment encountered by tidal stream turbines (Vogel et al.
2018).
The effects of unsteady inflow on blade loading, and consequences for the design and operation of anaxial flow turbine are described below.
Results
Below rated flow speed, wind and tidal stream turbines are typically designed to operate at a condition
that maximises efficiency corresponding to the largest lift-to-drag ratio (achieved at angle of attack α*).
Above rated flow speed turbine performance is adjusted to limit power as required. As shown in Fig 1, achange in the inflow conditions (here the rotational speed of the turbine is held constant) results in achange in the magnitude and direction of the incident flow vector at the aerofoil section. As the turbine’stip-speed-ratio is generally between 6-10, the impact of the changes in the magnitude of the flow vector
is less significant than that of the changes in the angle of attack. Although only a few degrees, this may
significantly affect turbine performance as the turbine may approach, or even go into stall, when theapparent flow speed increases.
The turbines typically respond to changes in incident flow by altering rotational speed or blade pitch angle
in order to return to the optimal operating condition (Wu et al. 2018). Changes to rotational speed may beachieved faster than changes in blade pitch angle, whereas the response time of blade pitch adjustments
is slower. However, the change in flow experienced by each blade is unlikely to be the same for a pitching
floating wind or tidal turbine due to the different positions of the blades, so collective-control (turbine
speed or collective pitch control) applied to the whole rotor will not restore the performance of theturbine. Instead, individual blade pitch is likely to be a better solution. Furthermore, individual blade pitch
control offers the potential to adjust blade operation as the turbine rotates through a vertical shear
profile.

Fig 1: Aerofoil section (left) indicating blade forces and inflow velocity change due to a change in incident
flow (shown in blue) and the required blade pitch adjustment (green) to return to optimal operation.
Further work is required to couple turbine performance to platform dynamics in order to explore thefeedback that the change in wind turbine operation has on platform motion and loads, and also toinvestigate whether alternative forms of turbine control compared to fixed-foundation turbines may be
helpful for mitigating the unsteady effects on floating wind turbines. This will draw on the experience ofVogel’s work in aerodynamics of wind turbines, including the development of wind turbine wakes andsubsequent impact on downstream turbines (Vogel & Willden 2020) and Liu’s experience in floating body
dynamics and floating wind turbines.
References
van der Veen, GJ, Couchman, IJ, Bowyer, RO (2012) Control of floating wind turbines. American Control
Conference 2012 pp.3148-3153.
Vogel, CR, Willden, RHJ, Houlsby, GT (2018) Blade element theory for a tidal turbine. Ocean Engineering

169 pp.215-226.
Vogel, CR, Willden, RHJ (2020) Investigation of wind turbine wake superposition models using ReynoldsAveraged Navier-Stokes simulations. Wind Energy 23(3) pp.593-607.
Wu, Z, Gao, W, Gao, T, Yan, G, Zhang, H, Yan, S, Wang, X (2018) State-of-the-art review on frequency
response of wind power plants in power systems. Journal of Modern Power Systems and Clean Energy 6
pp.1-16.