Lab members in December 2013

We have more rapid changes in my lab than the quarterly updates. Africa Perianez (fourth from left) of German Weather Service (DWD) is visiting from Thursday, December 5 to Friday 13, 2013. We started collaborations on theoretical developments of localization methods and other topics in ensemble data assimilation. Also, Ms. Yukie Komori (second from right) is our new assistant. This picture includes everyone in the lab except for some Visiting Researchers, Drs. Juan Ruiz, Shu-Chih Yang, and Masahiro Sawada.

A multi-scale localization method was developed

We developed a new approach to error-covariance localization that considers multi-scale structure of the forecast error covariance in ensemble data assimilation methods. We found that this new approach is practical and very effective in improving accuracy of ensemble data assimilation.

With higher-resolution models, we tend to have more sampling noise in the shorter range due to limited ensemble size. This limits the use of observation data only in a limited range even though the data should impact a larger area. The figure above illustrates how the proposed multi-scale localization works. The patterns indicate what impact the observation data at the star point have. We mix the shorter-range impact (top left) with the longer-range impact (bottom left) to obtain a hybrid of both (right). This way, we preserve more structure in the shorter range, while we still include impact on an extended area using the smoothed error covariance (or smoothed ensemble perturbations). For more details, please refer to our recent publications:

• Miyoshi, T. and K. Kondo, 2013: A multi-scale localization approach to an ensemble Kalman filter. SOLA, 9, 170-173. doi:10.2151/sola.2013-038
• Kondo, K., T. Miyoshi and H. L. Tanaka, 2013: Parameter sensitivities of the dual-localization approach in the local ensemble transform Kalman filter SOLA, 9, 174-177. doi:10.2151/sola.2013-039

Lab members for 2013 fourth quarter

Team photo as of November 7, 2013 at the welcome party in Kachoen. We are expanding. Seven members are in the picture, and there are four more visiting members not in the picture. New members include Dr. Hazuki Arakida (front left), Mr. Marimo Ohhigashi (back, second from left), and Ms. Rie Deguchi (front right).

RIKEN-Kyoto University Joint Workshop on Data Assimilation

On August 9, 2013, we had the first RIKEN-Kyoto University Joint Workshop on Data Assimilation in RIKEN AICS, Kobe, Japan. The workshop webpage is available only in Japanese, since we intended to exchange ideas among Japanese scientists in both sides.

Data assimilation requires interdisciplinary developments based on statistics and applied mathematics, and it is essential to make a productive collaboration between mathematicians and scientists in application fields. Fortunately, I got to know Professor Sakajo a few years ago in Sapporo, and since then we have been exchanging ideas. Recently I moved from Maryland to Kobe, and Professor Sakajo also moved from Sapporo to Kyoto. We now have this geographical advantage, and try to make our collaborations more active and productive. This is the first workshop to have mathematicians from Professor Sakajo's group and scientists in my group get together, exchange ideas and have active discussions.

We are planning the second workshop in Kyoto in March 18-20, with a prestigious invited speaker Professor Brian Hunt from the University of Maryland.

Two new members

We have two new members starting on August 1, 2013. Professor Shu-Chih Yang (right) is a professor in Taiwanese National Central University and is visiting my lab until mid September as a Visiting Scientist. Dr. Koji Terasaki (left) joined my lab as a Postdoctoral Researcher.

Lab members for 2013 second quarter

Team photo as of May 29, 2013. Prof. Shinichiro Shima (left) from the University of Hyogo and Dr. Masahiro Sawada (second from right) from the University of Tokyo just started in May as visiting scientists. Also, Ms. Naomi Tamura (right), an assistant to the DA team is in the picture, and another assistant Ms. Yuri Iida was very kind and took this nice picture. Dr. Shigenori Otsuka (second from left), myself (third from left), and Keiichi Kondo (third from right) are also in the picture.

Thank you, wonderful visitors!

On Monday, February 25, the day before the Data Assimilation Workshop, four visitors visited my lab. Professor Eugenia Kalnay (third from left) is my former adviser and came a long way from the East Coast of the US. Professor Shu-Chih Yang (third from right) is my former classmate and one of my best friends, coming from Taiwan. Dr. Ji-Sun Kang (second from right) was a colleague until last December in Maryland but moved to Korea recently. Guo-Yuan Lien (left) is a student in Maryland. We enjoyed seeing each other and had fruitful scientific discussions. All four visitors attended the Data Assimilation Workshop, and Eugenia and Guo-Yuan attended the AICS symposium on Thursday and Friday, and spent the whole week. I am very grateful to the four wonderful visitors and hope they enjoyed their stay in Kobe.