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アプリケーションラボ（APL）

セミナーのお知らせ

APL ゲストセミナー

日時：
2016年12月8日（木） 15:00-16:00
場所：
横浜研究所 交流棟二階 小会議室１＋２
発表者：
Dr. Erik van Sebille (Grantham Institute & Department of Physics, Imperial College London)
タイトル：
Our plastic oceans: sources, pathways, and risks of marine litter
概要：
Plastic is one of the best materials ever invented, but it doesn't belong in the ocean. Large pieces of it can entangle turtles, birds, sharks, and other marine animals. Tiny bits of plastic, the result of the degrading actions of waves and Sun, can linger around for decades; once they get into the food chain, they too can adversely affect marine life. Many of us - scientists and concerned citizens alike - think that humankind should try to clean up oceanic plastic. But before we can best start the process, we need to understand how plastic moves through the ocean and how and where it poses most risk.
In this presentation, I will discuss how ocean currents move plastic around the globe, and how the floating plastic eventually accumulates in the infamous garbage patches in the middle of our oceans. I will show where plastic poses most risk to marine life such as seabirds and turtles. All of this feeds directly into the discussion on solutions and mitigation strategies to marine litter, whether they be engineering, policy or societal.

第27回 APL Open Forum

日時：
2016年11月25日（金） 15:45〜17:30
場所：
横浜研究所 交流棟2F 小会議室1+2
発表者1：
Tsutomu Hihara
タイトル：
Development of high-level satellite sea surface temperature product using data assimilation
概要：
For dynamic interpolation of Himawari-8 SST and GCOM-W SST data, we have developed an Ensemble Kalman Filter system based on a 3km-resolution ocean circulation model south of Japan. Analysis SST is produced in 2-day and 1-day interval by assimilating satellite sea surface height anomaly, in-situ temperature and salinity, in addition to composite of Himawari-8 and GCOM-W SST. The analysis represents the fine-scale frontal wave activity along the Kuroshio front together with the Kuroshio path positions as observed. We find that, though the composite of the high-frequency Himawari-8 SST snapshots is effective to exclude the invisible portions due to the cloud effects, dynamic interpolation of SST with the data-assimilative ocean model is reasonably working to reproduce the Kuroshio frontal wave evolution contaminated by the remaining cloud noise in the original SST observation. Our system reasonably extracts the dynamically-consistent information in time and space from Himawari-8 SST.
発表者2：
Miho Ishizu
タイトル：
My previous studies and future work
概要：
The focus of my research has been mainly to understand the distribution of physical and biogeochemical properties in the ocean and to learn what is major controlling process in term of physical oceanography. To achieve this I have used a combination of observations and experiments with numerical models. My first study was to clarify the formation mechanism of the upwelling phenomena, called the cold-water belt formed off the Soya Warm Current (SWC), on the northeast coast of Hokkaido, Japan. The second was to clarify the distribution of biogeochemical parameter in the local region as well as the global ocean. The third was to get the ocean circulation on Otsuchi Bay along the Sanriku Coast, Japan. Now I have been concerned with the project of Marine Crisis Watch (MCW), addressing ocean warming and acidification. In this APL forum, I will give a talk about my past studies and the content of my part of the MCW project.

APL ゲストセミナー

日時：
2016年10月12日（水）13:30～14:30
場所：
横浜研究所 交流棟二階 小会議室１＋２
発表者：
仁科　慧 (Kei Nishina)、東京大学大気海洋研究所
タイトル：
鉛直二次元非静水圧モデルを用いた三陸沖の shelf-break における内部潮汐の発生過程に関する研究
概要：
　三陸のリアス式海岸に存在する中小の湾では、夏季を中心とした成層期に二重潮（二枚潮、逆潮）と呼ばれる、上下逆向きで振幅が10～20cm/sの傾圧循環が間欠的に発生することが古くから知られている。二重潮は湾外水の貫入を伴うため、三陸リアス湾の恵み豊かな海洋環境の維持に重要な役割を果たしていると考えられる。しかしながら、そのメカニズムは、内部潮汐が主な原因とされているものの、詳しい機構はわかっていない。
　筆者らは鉛直二次元非静水圧モデルを用いて理想化実験を行い、三陸沖の shelf-break 付近における内部潮汐の発生過程を調べた。この海域に注目したのは、大槌湾を中心とした三陸における近年の集中的な観測から、二重潮によって湾内に貫入してくる水塊が当該海域に由来すると考えられたためである。
　理想化実験の結果、三陸沖の夏季における典型的な成層構造を用いると、大陸斜面の傾きと内部波の特性曲線の傾きが近く（subcritical）、斜面上で発生した内部波が収束されるため、陸棚上で発生する内部波の振幅が大きくなることがわかった。また、斜面の傾きを変えた実験を行ったところ、斜面と特性曲線の傾きが非常に近く（near-critical）なると、陸棚上の内部波のエネルギーが減少することも示唆された。これは、near-critical の場合には、順圧潮汐が下げ潮の際に斜面上の等密度面が押し下げられて成層が強まるとsuper-criticalになって、一時的に内部波が陸棚上に入射できなくなるためと考えられる。

第26回 APL Open Forum

日時：
2016年9月30日（金） 15:45～17:30
場所：
横浜研究所 交流棟2F 小会議室1+2
発表者1：
Ryo Furue
タイトル：
On the Leeuwin Current System and its linkage to zonal flows in the South Indian Ocean
概要：
The Leeuwin Current System (LCS) along the coast of Western Australia consists of the southward-flowing Leeuwin Current (LC), the northward-flowing Leeuwin Undercurrent (LUC), and neighboring flows in the South Indian Ocean (SIO). Using geostrophic currents obtained from a highly-resolved (1/8°) hydrographic climatology (CSIRO Atlas of Regional Seas, CARS), we describe the spatial structure and annual variability of the LC, LUC, and SIO zonal currents, estimate their transports, and identify linkages among them.
In CARS, the LC is supplied partly by water from the tropics but mostly by shallow (z > −200m) eastward flows in the SIO, and it loses water by downwelling across the bottom of this layer. The downwelling is so strong that, despite the large SIO inflow, the horizontal transport of the LC does not much increase to the south. This LC transport is significantly smaller than previously reported.
The LUC is supplied by water from south of Australia, by eastward inflow from the SIO south of 28°S, and by the downwelling from the LC, and in response strengthens northward, reaching a maximum near 28°S. North of 28°S it loses water by outflow into subsurface westward flow and despite an additional downwelling from the LC, it decreases to the north. The seasonality of the LUC is described for the first time.
発表者2：
Akira Kuwano-Yoshida; co-authors: Hideharu Sasaki, Yoshikazu Sasai
タイトル：
Impact of explosive cyclones on the deep ocean in the North Pacific using an eddy-resolving OGCM
概要：
The oceanic response to explosive cyclones over the North Pacific in winter is investigated using eddy-resolving 34-yr hindcast simulation data of a quasi-global ocean. The North Pacific is the deepest ocean under the atmospheric storm track, and its response appears as a horizontal divergence of the surface layer above depths of 60 m and upward flow that reaches depths of 2000 m. A case study of a typical explosive cyclone using hourly outputs from January 2011 shows that the explosive cyclone induces horizontal divergence within the surface-mixed layer and upward flow that reaches depths of 6000 m. The flow causes oceanic internal waves and temperature cooling because of the vertical advection in the deep ocean. The interannual variability of explosive cyclone activity in January affects the amplitude of the vertical motion and the daily-scale temperature variations in the deep ocean.

第25回 APL Open Forum

日時：
2016年8月5日（金） 15:45～17:30
場所：
横浜研究所 情報技術棟　4階　会議室
発表者1：
Ingo Richter
タイトル：
The influence of mean state biases on seasonal prediction skill - results from AMIP-style experiments
概要：
The link between mean state biases and skill in reproducing surface wind and precipitation anomalies in the tropics is examined using atmosphere-only experiments in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and customized sensitivity tests with the SINTEX-F general circulation model (GCM). Multi-model atmosphere-only experiments with prescribed SST warming suggest that, on the whole, the anomaly correlation coefficient (ACC) of surface wind and precipitation is rather insensitive to warming on the order of 4 K. When SST biases from a free-running control simulation are prescribed in SINTEX-F, ACC only deteriorates moderately in the equatorial Pacific and Atlantic. The spatial patterns of ACC reveal areas of both decrease and increase over the tropical Pacific and Atlantic. Generally, ACC tends to increase where mean precipitation increases and vice versa, regardless of whether the precipitation changes improve or deteriorate the bias. The results suggest that, in the context of atmosphere-only simulations, improving SST and precipitation biases does not necessarily improve the skill in reproducing anomalies of surface wind and precipitation.
発表者2：
Pascal Oettli
タイトル：
Palm Oil Production in Malaysia and Newly Found Climate Phenomena
概要：
Oil palm is one of the most important oil crops in the world and is extracted from fresh fruit bunch (FFB). Indonesia and Malaysia account for 81% of the total global production of palm oil, while Malaysia itself accounts for 39% of world palm oil production and 44% of world exports. In 2011, oil palm was accounting for USD 16.8 billion of Malaysia’s Gross National Income with a production of 88 million Mg of FFB yield, from 4 million ha. This represents an average of 18.7 Mg ha−1. Because of the relationship between oil palm and FFB, any decrease in the latter will dramatically affect the former. Thus, the negative impact of El Niño on yearly FFB yield is well known and described. After an El Niño occurred, rainfall tend to decrease and maximum temperature to increase, aggravating the water stress. However, the influence of other climate modes (IOD, El Niño Modoki, Ningaloo Niño) on yearly FFB yield has to be clarified. This may lead to a statistical forecast of the annual FFB yield.

APL ゲストセミナー

日時：
2016年6月30日（木） 14:00～16:00
場所：
横浜研究所 情報技術棟　5階　大会議室
発表者：
Prof. John L. Wilkin (Rutgers University)
タイトル：
Data Assimilative Modeling in Coastal and Shelf Waters of the U.S. Mid-Atlantic Bight and Gulf of Maine
概要：
Coastal ocean models that downscale basin and global scale models are widely used to study regional circulation at enhanced resolution and locally important ecosystem and biogeochemical processes. When operated as now-cast/forecast systems, these models offer predictions that assist decision-making for maritime applications.
Rutgers University operates such a system for shelf waters of the Mid-Atlantic Bight (MAB) and Gulf of Maine (GoM) where the MARACOOS and NERACOOS associations of U.S. IOOS operate coastal ocean observing systems that deliver a dense observation set using CODAR HF-radar, autonomous underwater glider vehicles (AUGV), telemetering moorings, and drifting buoys. Other U.S. national and global observing systems deliver further sustained observations from moorings, ships, profiling floats, and a constellation of satellites.
Our MAB/GoM re-analysis and forecast system uses the Regional Ocean Modeling System (ROMS; myroms.org) with 4-dimensional Variational (4DVAR) data assimilation to adjust initial conditions, boundary conditions, and surface forcing in each analysis cycle. Data routinely assimilated include CODAR velocities, altimeter satellite sea surface height (with coastal corrections), satellite temperature (microwave and infrared), in situ CTD data from AUGV and ships (NMFS Ecosystem Monitoring voyages), and all in situ data reported to the WMO GTS network.
A separate climatological data assimilative analysis of long-term mean hydrographic and velocity observations specifies the regional Mean Dynamic Topography that augments altimeter sea level anomaly data, and is also used to adjust boundary condition biases that would otherwise be introduced in downscaling from global models.
System performance is described with respect to the impact of satellite, CODAR and in situ observations on analysis skill. Preliminary results from a 2-way nested modeling system that adds enhanced resolution over the NSF OOI Pioneer Array in the central MAB are also shown.
Since the Ocean Observations Panel for Climate (OOPC) meeting in Sendai last year we have moved forward in planning for a possible international collaborative effort focusing on 'Boundary Currents and Shelf Sea Interactions'. I may take just a few minutes at the start of my talk to describe what that effort might entail. We certainly hope that Japanese investigators might be interested in being involved in this program as it evolves in the context of western Pacific boundary currents.

第24回 APL Open Forum

日時：
2016年6月24日（金） 15:45～17:30
場所：
横浜研究所 交流棟2階　小会議室
発表者1：
Tak Ikeda
タイトル：
Spatio-seasonal Patterns of Malaria in Limpopo, South Africa using Self-Organizing Maps
発表者2：
Venkata Ratnam
タイトル：
On heat and cold waves over India

APL ゲストセミナー

日時：
2016年6月21日（火） 11:00～12:00
場所：
横浜研究所 交流棟2階　小会議室
発表者：
Dr. Krishna Kumar (Qatar Meteorological Department, Doha, Qatar)
タイトル：
Expected Future Changes in the Climate and Severe Weather Events in the State of Qatar and adjacent region
概要：
The region of Middle East and Arabian Gulf where the State of Qatar is located extends from the eastern fringes of Mediterranean to the western parts of South Asia. The State of Qatar is dominated by subtropical dry, hot desert climate with low rainfall, very high temperatures in summer and a big difference between maximum and minimum temperatures, especially in the inland areas. The coastal areas are influenced by the Arabian Gulf, and have lower maximum, but higher minimum temperatures and a higher moisture percentage in the air.
By virtue of its geographical location, the State of Qatar and the adjacent region experiences very high temperatures exceeding 45°C on many days with severe heat stress conditions extending several days in summer. The global warming therefore, can have profound impact on the mean climate as well as extreme weather events over the region that may affect both natural and human systems significantly in different countries in the region. Therefore, it is important to assess the future changes in climate along with its extremes for planning mitigation and adaptation measures. Simulations from a large suite of CMIP5 models corresponding to RCP4.5 and RCP8.5 have been utilized for this purpose. The changes in seasonal mean and weather extremes are assessed for three future time slices of 2016-2035, 2046-2065 and 2080- 2099 with respect to the baseline period of 1986-2005. Temperature and precipitation extremes were assessed using several indices including those that capture heat stress. The observed changes in weather extremes were also analysed using a long record (1962-2014) of meteorological data at Doha, Qatar. Model simulations indicate a significant change in frequency and intensity of both temperature and precipitation extremes that may have serious implications on human health, water resources and the onshore/offshore infrastructure in this region. Data from Meteorological Research Institute (MRI) 20km simulation for the present (1979-2003) and one future time slice (2075-2099) corresponding to RCP8.5 have also been utilized to assess the impact of climate change on regional climate extremes as well. The scenarios generated with the MRI model simulation were compared with the coarse resolution CMIP5 model scenarios to identify region specific features that might be better resolved in the former simulation. At city level, the MRI simulations captured the observed trends much better and hence seemed more suitable for future assessments compared to coarse resolution CMIP5 simulations.

APL ゲストセミナー

日時：
2016年6月17日（金） 14:00〜
場所：
横浜研究所 交流棟2階　小会議室
発表者：
Prof. Lakshmi Kantha (University of Colorado at Boulder, USA)
タイトル：
Turbulent Mixing in the Oceans and the Atmosphere
概要：
In the global ocean, measurements of the dissipation rate of turbulence kinetic energy are now quite routine. The same cannot be said about the atmosphere. Such measurements have been difficult to make in the atmosphere, because an instrument similar to an oceanic microstructure profiler is not available. However, measurements have recently been made in the atmosphere using very high-resolution balloon-borne sensors. It is now possible to use these data to obtain a unified picture of turbulence in the oceans and the atmosphere. However, without knowledge of the scales involved, it is hard to assess the reliability of the observational data. By appealing to closure models of turbulence and imposing appropriate limits on turbulence scales, it is possible to remove questionable data and obtain a more accurate picture of mixing. In this talk, we will describe our approach and the results that lead to a Grand Diagram of Turbulence in the oceans and the atmosphere.

第23回 APL Open Forum

日時：
2016年5月27日（金） 15:45～17:30
場所：
横浜研究所 交流棟2階　小会議室
発表者1：
Satyaban Ratna
タイトル：
On the Improvement of SINTEX-F2 Seasonal Prediction over Southeast Asia Using Dynamical Downscaling Approach
概要：
In this study, an attempt is made to improve the seasonal prediction over Southeast Asia by downscaling SINTEX-F2 CGCM retrospective seasonal forecasts with the use of the Weather Research and Forecasting (WRF) model. Downscaling experiments were performed at 27 km resolution over Southeast Asia for the boreal summer season for the 14 year period (2000 – 2014). The WRF model is integrated from 1 May to 31 August for each of the year using the boundary conditions from one month lead retrospective seasonal forecasts of SINTEX-F2. The mean climatology and interannual variability of the downscaled prediction rainfall are analyzed over sub-regions of Southeast Asia by comparing with the various observed rainfall data. The results indicate that dynamical downscaling approach is seen to improve the spatial and temporal distribution of rainfall compared to the SINTEX-F2 predicted rainfall. The downscaling prediction has better skill over the Indonesia region compared with the mainland Southeast Asia. The downscaled prediction rainfall is also analyzed for the extreme seasons (drought and floods) over four sub-regions of Southeast Asia and it is seen that WRF model could improve the rainfall anomaly compared to the SINTEX-F2 data.
発表者2：
Nobumasa Komori
タイトル：
Influence of the Gulf Stream on the hemispheric-scale coupled atmosphere-ocean-sea ice system
概要：
In this study, we artificially changed the path of the Gulf Stream in a global coupled GCM by slightly modifying the bottom topography around the Florida Peninsula and investigated the response of the hemispheric-scale coupled atmosphere-ocean-sea ice system. When the narrow channel east of the Florida Peninsula is deep enough in the model, the Gulf Stream takes a realistic path around the peninsula (otherwise the Antilles Current is enhanced unrealistically), but it overshoots northward in comparison to the case with the shallower channel. As a result, positive sea surface temperature (SST) anomalies are found around the Gulf Stream "Extension" (after it separates from the east coast of the North America) and in the Barents Sea. This is consistent with the observed fact that northward shift of the Gulf Stream Extension induces positive SST anomaly in the Barents Sea. On the other hand, SST around Japan increases as opposed to the previous studies that warm anomaly in the Barents Sea brings cold anomaly over Eastern Eurasia. In our model, decrease of sea ice in the Arctic Ocean caused by the modification of bottom topography creates negative sea-level pressure anomaly that elongates along the entire Arctic rim, which may induce northward shift of the atmospheric circulation in the lower Troposphere and the subtropical gyre in the North Pacific, and hence, positive SST anomaly around the Kuroshio Extension.

第22回 APL Open Forum

日時：
2016年4月22日（金） 15:45～17:30
場所：
横浜研究所 交流棟2階　小会議室
発表者1：
Toru Miyama
タイトル：
Dynamics of the Isoguchi Jet: eddy – topography interaction
概要：
Dynamics of a Quasi-stationary jet (QSJ) between the subtropical and the subarctic gyres in the North Pacific (Isoguchi jet) is discussed using an idealized two-layer model. The experiments using the model suggests a sea mount, which is merely 500 m high, exerts a jet along its eastern flank. The characteristics of baroclinic Rossby waves are affected significantly by a barotropic flow over the sea mount. A surface baroclinic jet is formed where a characteristic curve originating in the subtropical gyre and that originating in the subpolar gyre meet because the pycnocline depth varies discontinuously there. Eddy-topography interaction (aka Neptune Effect) produces anticyclonic barotropic circulation around the sea mound. Some sensitivity experiments will be presented to show the dynamics mentioned above.
発表者2：
Sergey Varlamov
タイトル：
Status of JCOPE high resolution tide resolving ocean re-analysis for seas around Japan and some aspects of very fine resolution downscaled ocean simulations
概要：
14 years long simulation (2002-2015) for the seas around Japan was performed with 1/36 degree tide resolving JCOPE-T ocean model. Hourly model output results are available for analysis and can be used as initial and boundary conditions for the downscaled ocean modeling. Examples of model set-up and simulation with very fine resolution of 400-200m for number of regions was performed. Discussed would be some details of internal waves presentation and energetics depending on model resolution and analysis area locations.