Data Assimilation Seminar Series

Next Seminar

Date & Time May 7, 2019 (2019-06 (58th)), 15:30-16:30
Place & Contact Room: C107
RIKEN Center for Computational Science (R-CCS)
7-1-26 Minatojima-minami-machi, Chuo-ku, Kobe, 650-0047, Japan
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To enter the R-CCS building, please contact the following address in advance.
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Language English

Professor Ming-Cheng Shiue (National Chiao Tung University)


Mathematical analysis of data assimilation algorithms based on synchronization of truth and models

Abstract In this talk, we first recall continuous and discrete data assimilation algorithms that were proposed for designing finite-dimensional feedback controls for two-dimensional Navier-Stokes equations. Then, two new nudging methods, hybrid nonlinear and delay-coordinate nudging are considered and studied.

In the first part, hybrid nonlinear continuous data assimilation algorithms for Lorenz systems will be studied and presented. In the literature, Pecora and Carrol (1990) considered a linear synchronization for a three-variable Lorenz model and numerically found that observing the z variable did not lead to synchronization while observing x or y did. Later, for the same type of synchronization, it was found that synchronizing with y observations is more efficient than with x in Yang et al. (2006). These phenomena will be proven mathematically and explained. Furthermore, three-type hybrid nonlinear nudging techniques are considered to speed up the convergence of rate for the linear nudging one. It is shown that the approximate solutions converge to the unknown reference solutions over time provided that the first or second variable of Lorenz systems is only synchronized. Numerical simulations are performed to demonstrate these results. This is joint work with Yi Juna Du.

In the second part, two new continuous and discrete data assimilation algorithms for two-dimensional Navier-Stokes equations are presented and studied. The explicit use of present and past observations at each time step provides a way that new methods might outperform the old one, which was successfully tested for Lorenz 96 model. In this talk, we will give preliminary results that provide sufficient conditions on the finite-dimensional spatial resolution of the collected data and observational measurements to make sure that the approximate solutions obtained from the new algorithms converge to the unknown reference solutions over time.


Number Date Speaker Title (crick the title to see abstract & PDF)



Apr 25,


Dr. Atsushi Okazaki
Impact of geostationary satellite borne precipitation radar on numerical weather prediction: An observing system simulation experiment with an ensemble Kalman filter for a typhoon case



Feb 1,


Dr. Tie Dai
Development and application of aerosol data assimilation in NICAM



Jan 28,


Ms. Jemima Tabeart
(U of Reading)

Using reconditioning to study the impact of correlated observation errors in the Met Office 1D-Var system



Jan 28,


Dr. Alison Fowler
(U of Reading)

Data compression in the presence of observation error correlations



Jan 18,


Prof. Eugenia Kalnay
(U of Maryland)

Can large-scale solar and wind farms create a significant climate change? A model experiment in the Sahara



Dec 19,


Dr. Tetsuo Nakazawa

Is the Trend in Tropical Cyclone Formation Frequency due to Global Warming?



Nov 13,


Prof. Roland Potthast
(DWD/U of Reading)

New Observations and Algorithmic Developments for Convective Scale Ensemble Data Assimilation



Oct 25,


Dr. Jing-Shan Hong
(CWB, Taiwan)

Re-Center algorithm on the Continuous Cycling Radar Data Assimilation: Multi-scale Blending Scheme



Jul 27,


Prof. Pierre Tandeo

(IMT Atlantique)

Data-driven methods in geophysics
2018-07 (48th)

Jul 27,


Dr. Hironori Arai

(U Tokyo)

Establishing an integrated MRV system of Greenhouse gas emission from wetlands with Japanese earth-observation/modelling technologies and a data assimilation technique
2018-06 (47th) Jun 28, 2018 Prof. John C. Wells
(Ritsumeikan U)
Towards nowcasting in Lake Biwa: field tests of acoustic tomography, and discussion of some theorems relating the flow at a water surface to that below
2018-05 (46th) Apr 17, 2018 Dr. Kohei Takatama
Regional atmospheric data assimilation coupled with an ocean mixed layer model: a case of typhoon Soudelor (2015)
2018-04 (45th) Feb 16, 2018 Prof. Pierre Tandeo
(IMT Atlantique)
The analog data assimilation: method, applications and implementation
2018-03 (44th) Feb 9, 2018 Prof. Roland Potthast
(DWD/U of Reading)
Data Assimilation From Minutes to Days
2018-02 (43rd) Jan 29, 2018 Dr. Shinsuke Satoh
Three-dimensional precipitation data measured by phased array weather radar every 30 seconds
2018-01 (42nd) Jan 18, 2018 Prof. David J. Stensrud
(Penn State U)
2017-16 (41st) Dec 11, 2017 Dr. Tsuyoshi Thomas Sekiyama
(Meteorological Research Institute, Japan Meteorological Agency)
Data assimilation of atmospheric chemistry: past, present, and future
2017-15 (40th) Nov 17, 2017 Prof. Yusuke Uchiyama
(Kobe U)
Challenges and issues in forward regional ocean modeling: Eddies, terrestrial influences, and surface gravity waves
2017-14 (39th) Oct 12, 2017 Mr. Krishnamoorthy Chandramouli
(IIT Madras)
Dr. Koji Terasaki
Impact of assimilating humidity sounder radiances with the NICAM-LETKF system
2017-13 (38th) Sep 26, 2017 Mr. Cheng Da
(U of Maryland)
Dr. Guo-Yuan Lien
Assimilation of the GSMaP Precipitation Data with the SCALE-LETKF System
2017-12 (37th) Aug 16, 2017 Ms. Paula Maldonado
(CONICET-U of Buenos Aires)
Radar Data Assimilation in a Case of Deep Convection in Argentina
2017-11 (36th) Aug 16, 2017 Mr. Sam Hatfield
(Oxford U)
How low can you go? Reducing the precision of data assimilation to improve forecast skill
2017-10 (35th) Aug 4, 2017 Dr. Chih-Chien Tsai
(TTFRI, Taiwan)
Preliminary Experimental Results of Polarimetric Radar Data Assimilation in the Case of Typhoon Soudelor (2015)
2017-09 (34th) Jun 26, 2017 Dr. Toshio Iguchi
Radar Measurement of Precipitation from Space: TRMM/PR and GPM/DPR rain retrieval algorithms data
2017-08 (33rd) May 18, 2017 Dr. Guo-Yuan Lien
30-second-cycle convection-resolving data assimilation of dense phased array weather radar data
2017-07 (32nd) Mar 7, 2017 Dr. Alison Fowler
(U of Reading)
On the interaction of observation and a-priori error correlations in data assimilation
2017-06 (31st) Mar 7, 2017 Dr. Joanne A. Waller
(U of Reading)
Diagnosing observation error statistics for numerical weather prediction
2017-05 (30th) Mar 7, 2017 Prof. Nancy K. Nichols
(U of Reading)
New applications and challenges in data assimilation
2017-04 (29th) Mar 6, 2017 Prof. Steven J. Greybush
(Penn State U)
Ensembles, Data Assimilation, and Predictability for Winter Storms
2017-03 (28th) Mar 6, 2017 Prof. Eugenia Kalnay
(U of Maryland)
Modeling Sustainability: Coupling Earth and Human System Models
2017-02 (27th) Feb 7, 2017 Prof. Hiromichi Nagao
(U of Tokyo)
Promises and Challenges in Assimilation of Infrared and Microwave All-sky Satellite Radiances for Convection-Permitting Analysis and Prediction
2017-01 (26th) Jan 13, 2017 Prof. Fuqing Zhang
(Penn State U)
Data assimilation for massive autonomous systems based on a second-order adjoint method
2016-09 (25th) Dec 22, 2016 Dr. Takahiro Nishimichi
(Kavli IPMU, U of Tokyo)
Dark Emulator: cosmic large-scale structures and parameter estimate
2016-08 (24th) Dec 21, 2016 Dr. Takumi Honda
Assimilating All-Sky Himawari-8 Satellite Infrared Radiances: Preliminary Case Studies
2016-07 (23rd) Nov 24, 2016 Mr. Yasumitsu Maejima
Impacts of dense and frequent surface observations on a sudden severe rainstorm forecast: A case of an isolated convective system
2016-06 (22nd) June 13, 2016 Mr. Yasutaka Ikuta
Assimilation of GPM/DPR at JMA
2016-05 (21st) Apr 14, 2016 Dr. Yohei Sawada
Advancing land data assimilation science to monitor terrestrial water and vegetation dynamics
2016-04 (20th) Mar 16, 2016 Dr. Juan Ruiz
(U Buenos Aires (CIMA)/RIKEN AICS)
Implementation and evaluation of a regional data assimilation system based on WRF-LETKF
2016-03 (19th) Mar 7, 2016 Prof. Roland Potthast
(DWD/U of Reading)
On Ensemble and Particle Filters for Large-Scale Data Assimilation
2016-02 (18th) Mar 2, 2016 Ms. Chang Yaping
Dr. Shunji Kotsuki
Ensemble data assimilation of MODIS surface temperature into land surface model
2016-01 (17th) Feb 17, 2016 Mr. Sho Yokota
Comparison between LETKF and EnVAR with observation localization
2015-10 (16th) Dec 25, 2015 Dr. Shunji Kotsuki
Ensemble Data Assimilation of GSMaP precipitation into the nonhydrostatic global atmospheric model NICAM
2015-09 (15th) Dec 15, 2015 Dr. Kozo Okamoto
Assimilation of cloud-affected infrared radiances
2015-08 (14th) Oct 21, 2015 Prof. Kosuke Ito
(U of the Ryukyus)
Advanced data assimilation techniques for predicting tropical cyclone intensities
2015-07 (13th) Sep 16, 2015 Mr. Shumpei Terauchi
(U of Tsukuba)
Dr. Guo-Yuan Lien
Verification of the near-real-time weather forecasts and study on 2015 typhoon Nangka with the SCALE-LETKF system
2015-06 (12th) Sep 2, 2015 Dr. Daisuke Hotta
Diagnostic methods for ensemble data assimilation
2015-05 (11th) Jun 25, 2015 Dr. Koji Terasaki
Applying the Local Transform Ensemble Kalman Filter to the non-hydrostatic atmospheric model NICAM
2015-04 (10th) Jun 5, 2015 Prof. S. Lakshmivarahan
(U of Oklahoma)
Nonlinear dynamics and Predicitability
2015-03 (9th) Apr 17, 2015 Prof. Takeshi Enomoto
Assimilation and forecast experiments using bright band heights
2015-02 (8th) Mar 24, 2015 Dr. Shigenori Otsuka
Towards 100-m resolution prediction of local convective storms: predictability and nowcasting
2015-01 (7th) Jan 20, 2015 Dr. Nobumasa Komori
Development of an ensemble-based data assimilation system with a coupled atmosphere-ocean GCM
2014-06 (6th) Dec 26, 2014 Dr. Keiichi Kondo
The 10,240-member ensemble Kalman filtering with an intermediate AGCM without localization
2014-05 (5th) Nov 26, 2014 Prof. Shin-ichiro Shima
(U of Hyogo/RIKEN AICS)
Data assimilation experiments of the dynamic global vegetation model SEIB-DGVM with simulated GPP observations
2014-04 (4th) Nov 26, 2014 Prof. Takeshi Ise
(Kyoto U)
Simulating terrestrial ecosystems: current progress and future perspectives
2014-03 (3rd) Oct 31, 2014 Prof. Masayuki Yokozawa
(Shizuoka U)
Evaluating the productivities of major crops at the global scale using process-based crop model
2014-02 (2nd) Sep 10, 2014 Dr. Guo-Yuan Lien
Ensemble Assimilation of Global Large-scale Precipitation
2014-01 (1st) July 23, 2014 Dr. Juan Ruiz
(U of Buenos Aires (CIMA)/RIKEN AICS)
Efficient parameter estimation for numerical weather prediction models using data assimilation

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