A5015005479- Meteorological Phenomena and Simulations
- Climate variability and models
- Geophysics and Gravity Measurements
- Tropical and Extratropical Cyclones Research
- Oceanographic and Atmospheric Processes
- Atmospheric and Environmental Gas Dynamics
- Ocean Waves and Remote Sensing
- Soil Moisture and Remote Sensing
- Precipitation Measurement and Analysis
- Fault Detection and Control Systems
- Wind and Air Flow Studies
- Image and Signal Denoising Methods
- Ionosphere and magnetosphere dynamics
- Target Tracking and Data Fusion in Sensor Networks
- GNSS positioning and interference
- Xenotransplantation and immune response
- Electromagnetic Scattering and Analysis
- Adaptive optics and wavefront sensing
- Ergonomics and Musculoskeletal Disorders
- Fluid Dynamics and Turbulent Flows
- Seismic Imaging and Inversion Techniques
- Forecasting Techniques and Applications
- Calibration and Measurement Techniques
- Flood Risk Assessment and Management
- Matrix Theory and Algorithms
Japan Meteorological Agency
2011-2025
Meteorological Research Institute
2018-2025
European Centre for Medium-Range Weather Forecasts
2020-2025
University of Maryland, College Park
2016-2018
RIKEN Center for Computational Science
2017
Abstract The relative importance between the sensible heat supply from ocean and latent heating is assessed for maintenance of near-surface mean baroclinicity in major storm-track regions, by analyzing steady linear responses a planetary wave model to individual components zonally asymmetric thermal forcing taken global reanalysis dataset. experiments carried out separately North Atlantic, Pacific, south Indian Oceans indicate that distinct local maxima observed along storm tracks can be...
Abstract In numerical weather prediction (NWP), a large number of observations are used to create initial conditions for forecasting through process known as data assimilation. An assessment the value these NWP can guide us in design future observation networks, help identify problems with assimilation system, and allow assess changes system. However, be challenging convection‐permitting NWP. This is because verification forecasts not easy, forecast model strongly nonlinear, limited‐area...
Abstract In 2011, the National Oceanic and Atmospheric Administration (NOAA) began a cooperative initiative with academic community to help address vexing issue that has long been known as disconnection between operational research realms for weather forecasting data assimilation. The is gap, more exotically referred “valley of death,” efforts within broader NOAA’s activities, which are heavily driven by constraints. With stated goals leveraging benefit mission offering path operations...
Abstract Despite dramatic improvements over the last decades, operational NWP forecasts still occasionally suffer from abrupt drops in their forecast skill. Such skill “dropouts” may occur even a perfect system because of stochastic nature but can also result flaws system. Recent studies have shown that dropouts due not to model’s deficiencies misspecified initial conditions, suggesting they could be mitigated by improving quality control (QC) so observation-minus-background (O-B)...
Abstract. Global Navigation Satellite System (GNSS) polarimetric radio occultation (PRO) observations sense the presence of hydrometeor particles along ray path by measuring difference excess phases in horizontally and vertically polarised carrier waves. As a first step towards using these data assimilation model diagnostics, forward operator for GNSS-PRO observable ΦDP (polarimetric differential phase shift) has been implemented extending existing two-dimensional bending-angle observations....
Klöwer et al., (2024). SpeedyWeather.jl: Reinventing atmospheric general circulation models towards interactivity and extensibility. Journal of Open Source Software, 9(98), 6323, https://doi.org/10.21105/joss.06323
The ability of ensemble Kalman filter (EnKF) algorithms to extract information from observations is analyzed with the aid concept degrees freedom for signal (DFS). A simple mathematical argument shows that DFS EnKF bounded above by size, which entails assimilating much more than size automatically leads underestimation. Since a trace posterior error covariance mapped onto normalized observation space, underestimated implies overconfidence (underdispersion) in analysis spread, which, cycled...
Abstract We propose a unifying theory for covariance inflation (CI) in the Ensemble Kalman Filter (EnKF) that encompasses all existing CI methods and can explain many open problems CI. Each method is identified with an function alters analysis perturbations through their singular values. Inflation functions are usually considered as of values background or perturbations. However, we have shown it more fruitful if viewed reduction factors after assimilation. These indeed comprise spectra...
Abstract. To successfully assimilate data from a new observing system, it is necessary to develop appropriate selection strategies, assimilating only the generally useful data. This development work usually done by trial and error using system experiments (OSEs), which are very time resource consuming. study proposes new, efficient methodology accelerate ensemble forecast sensitivity observations (EFSO). First, non-cycled assimilation of observation conducted compute EFSO diagnostics for...
Data assimilation (DA) methods require an estimate of observation error covariance [Formula: see text] as external parameter that typically is tuned in a subjective manner. To facilitate objective and systematic tuning within the context ensemble Kalman filtering, this paper introduces method for estimating how forecast errors would be changed by increasing or decreasing each element text], without need adjoint model DA system, combining adjoint-based text]-sensitivity diagnostics presented...
Abstract In operational numerical weather prediction (NWP), forecast verification against analysis from the same experiment is part of standard evaluation practice. This “own‐analysis” beneficial in providing complete and uniform spatial coverage but known to suffer overestimated skill scores when applied short‐range forecasts due inevitable positive correlation between errors. To alleviate this problem, a new approach termed “twin‐analysis” proposed. approach, are verified “twin analyses”...
Abstract. Global Navigation Satellite System (GNSS) Polarimetric Radio-Occultation (PRO) observations sense the presence of hydrometeor particles along ray path by measuring difference excess phases in horizontally and vertically polarised carrier waves. As a first step towards using these data assimilation model diagnostics, forward operator for GNSS-PRO observable ΦDP (polarimetric differential phase shift) has been implemented extending existing two-dimensional radio-occultation bending...
Abstract Part 1 of this study shows the existence a unifying theory that encompasses all exiting covariance inflation (CI) methods under framework functions operating on eigenvalues ensemble transform matrix. Given vast space potential functions, natural question is how to choose optimal one. This part 2 adaptive can be implemented in context estimate on‐the‐fly from observations. Estimation prior (PIF) equivalent estimation background error covariances G observation space. However,...
The medium‐range ensemble prediction system (EPS) at the Japan Meteorological Agency (JMA), like other operational EPSs, suffers from overconfident probabilistic forecasts in lower troposphere and over oceans particular. To alleviate this issue, a new scheme to perturb sea surface temperature (SST) is proposed tested. method statistically generates SST perturbations that account for time‐varying errors of prescribed control member. Despite its simplicity purely statistical nature, able...
Abstract. To successfully assimilate data from a new observing system, it is necessary to develop appropriate selection strategies, assimilating only the generally useful data. This development work usually done by trial-and-error using system experiments, which are very time- and resource-consuming. study proposes new, efficient methodology accelerate Ensemble Forecast Sensitivity Observations (EFSO). First, non-cycled assimilation of observation conducted compute EFSO diagnostics for each...
A new grid system on a sphere is proposed that allows for straight-forward implementation of both spherical-harmonics-based spectral methods and gridpoint-based multigrid methods. The latitudinal gridpoints in the are equidistant transforms direction performed using Clenshaw-Curtis quadrature. with this quadrature shown to be exact within machine precision provided truncation such there at least 2N + 1 total wavenumber N. implemented tested shallow-water equations model hydrostatic dry...
In the ensemble transform Kalman filter (ETKF), an matrix (ETM) is a that maps background perturbations to analysis perturbations. All valid ETMs are shown be square roots of error covariance in space preserve mean. ETKF chooses positive symmetric root Ts as its ETM, which justified by fact closest identity I sense Frobenius norm. Besides this minimum norm property, observed have diagonally predominant property (DPP), i.e., diagonal terms at least order magnitude larger than off-diagonal terms.
The widely-adopted discretisation of the horizontal pressure gradient term formulated by Simmons and Burridge (1981) for atmospheric models on $\sigma$-$p$ hybrid vertical coordinate is found to incur spectral blocking rotational wind components at high levels when used in a semi-Lagrangian model run linear grid. A remedy this issue proposed tested using semi-implicit hydrostatic primitive equations model. method removes aliasing errors wavenumbers ensuring that rotation-free property...
Abstract The Lorenz N-cycle is an economical time integration scheme that requires only one function evaluation per step and a minimal memory footprint, but yet possesses high order of accuracy. Despite these advantages, it has remained less commonly used in meteorological applications, partly because its lack semi-implicit formulation. In this paper, novel modification to the proposed. advantage proposed new preserves use original explicit scheme. Unlike traditional Robert–Asselin (RA)...