A5090237440- Meteorological Phenomena and Simulations
- Ancient Mediterranean Archaeology and History
- Climate variability and models
- Atmospheric and Environmental Gas Dynamics
- Archaeology and Historical Studies
- Classical Antiquity Studies
- Historical and Architectural Studies
- Wind and Air Flow Studies
- Archaeological and Historical Studies
- Geophysics and Gravity Measurements
- Historical and Religious Studies of Rome
- Scottish History and National Identity
- Oceanographic and Atmospheric Processes
- American Constitutional Law and Politics
- Medieval Architecture and Archaeology
- Reservoir Engineering and Simulation Methods
- Soil Geostatistics and Mapping
- Byzantine Studies and History
- Archaeological Research and Protection
- Air Quality Monitoring and Forecasting
- Underwater Acoustics Research
- Ancient Egypt and Archaeology
- GNSS positioning and interference
- Ocean Waves and Remote Sensing
- Atmospheric chemistry and aerosols
Purdue University West Lafayette
1993-2024
Bursa Uludağ Üni̇versi̇tesi̇
2018
NOAA National Centers for Environmental Prediction
2002-2016
National Oceanic and Atmospheric Administration
1982-2015
NOAA Environmental Modeling Center
1997-2013
NOAA Earth System Research Laboratory
2009
University of Maryland, College Park
2006
Science Applications International Corporation (United States)
2006
NOAA Climate Prediction Center
2006
University Corporation for Atmospheric Research
2006
In 1997, during the late stages of production NCEP–NCAR Global Reanalysis (GR), exploration a regional reanalysis project was suggested by GR project's Advisory Committee, “particularly if RDAS [Regional Data Assimilation System] is significantly better than global at capturing hydrological cycle, diurnal cycle and other important features weather climate variability.” Following 6-yr development effort, NCEP's North American Regional (NARR) completed in 2004, data are now available to...
At the National Meteorological Center (NMC), a new analysis system is being extensively tested for possible use in operational global data assimilation system. This called spectral statistical- interpolation (SSI) because coefficients used NMC model are analyzed directly using same basic equations as statistical (optimal) interpolation. Results from several months of parallel testing with have been very encouraging. Favorable features include smoother increments, greatly reduced changes...
In this study, a global three-dimensional variational analysis system is formulated in model grid space. This formulation allows greater flexibility (e.g., inhomogeneity and anisotropy) for background error statistics. A simpler formulation, inhomogeneous only the latitude direction, was chosen these initial tests. The statistics are defined as functions of latitudinal estimated with National Meteorological Center (NMC) method. horizontal scales variables obtained through variances their...
Abstract At the National Centers for Environmental Prediction (NCEP), a new three-dimensional variational data assimilation (3DVAR) analysis system was implemented into operational Global Data Assimilation System (GDAS) on 1 May 2007. The system, Gridpoint Statistical Interpolation (GSI), replaced Spectral (SSI) 3DVAR which had been since 1991. GSI developed at Modeling Center NCEP as part of an effort to create more unified, robust, and efficient scheme. key aspect is that it formulates in...
Abstract An ensemble Kalman filter–variational hybrid data assimilation system based on the gridpoint statistical interpolation (GSI) three-dimensional variational (3DVar) was developed. The performance of investigated using National Centers for Environmental Prediction (NCEP) Global Forecast System model. Experiments covered a 6-week Northern Hemisphere winter period. Both control and forecasts were run at same, reduced resolution. Operational conventional satellite observations along with...
At the National Meteorological Center (NMC), a new analysis system was implemented into operational Global Data Assimilation System on 25 June 1991. This is referred to as Spectral Statistical Interpolation (SSI) because spectral coefficients used in NMC model are analyzed directly using same basic equations statistical (optimum) interpolation. The major differences between SSI and conventional optimum interpolation (OI) previously operationally at are: –The variables closely related of...
Abstract In this second part of a two-part study recursive filter techniques applied to the synthesis covariances in variational analysis, methods by which non-Gaussian shapes and spatial inhomogeneities anisotropies for may be introduced well-controlled way are examined. These permit an analysis scheme possess covariance structures with adaptive variations amplitude, scale, profile shape, degrees local anisotropy, all as functions geographical location altitude. First, it is shown how wider...
The construction and application of efficient numerical recursive filters for the task convolving a spatial distribution "forcing" terms with quasi-Gaussian self-adjoint smoothing kernel in two or three dimensions are described. In context variational analysis, this operation may be interpreted as convolution covariance function background error given forcing terms, which constitutes one most computationally intensive components iterative solution analysis problem. Among technical aspects...
Abstract In 2006, the National Centers for Environmental Prediction (NCEP) implemented Real-Time Mesoscale Analysis (RTMA) in collaboration with Earth System Research Laboratory and Environmental, Satellite, Data Information Service (NESDIS). this work, a description of RTMA applied to 5-km resolution conterminous U.S. grid Digital Forecast Database is given. Its two-dimensional variational data assimilation (2DVAR) component used analyze near-surface observations described detail, brief...
A critical analysis was made of cucurbit descriptions in Dioscorides' De Materia Medica, Columella's Re Rustica and Pliny's Historia Naturalis, works on medicine, agriculture natural science the 1st century ce, as well Mishna Tosefta, compilations rabbinic law derived from same time period together with images dating antiquity including paintings, mosaics sculpture. The goal to identify taxonomically Mediterranean cucurbits at Roman Empire. By ancient times, long-fruited forms Cucumis melo...
A Kalman filter algorithm is implemented for a linearized shallow-water model over the continental United States. It used to assimilate simulated data from existing radiosonde network, demonstration network of 31 Doppler wind profilers in central States, and hypothetical radiometers located at five profiler sites. We provide some theoretical justification Phillips' hypothesis, we use with modification, formulate error covariance matrix required by filter. Our results show that assimilating...
Abstract The gridpoint statistical interpolation (GSI) analysis system is a unified global/regional three-dimensional variational data assimilation (3DVAR) code that has been under development for several years at the National Centers Environmental Prediction (NCEP)/Environmental Modeling Center. It recently implemented into operations NCEP in both global and North American systems (GDAS NDAS, respectively). An important aspect of this improving balance produced by GSI. improved between...
Recent changes in the operational National Centers for Environmental Prediction (formerly Meteorological Center) global analysis–forecast system are described. The most significant analysis change was direct use of satellite-measured radiances as input to system. Other involved inclusion near-surface winds from ERS-1 satellite and addition a constraint on divergence increment. In forecast model, parameterization deep convection boundary layer scheme were modified. During two months tests...
Abstract At the National Centers for Environmental Prediction, global ensemble forecasts from Kalman filter scheme in Global Forecast System are applied a regional three-dimensional (3D) and four dimensional (4D) ensemble–variational (EnVar) data assimilation system. The application is one-way variational method using hybrid static error covariances. To enhance impact, three new features have been added to existing EnVar system Gridpoint Statistical Interpolation (GSI). First, constant...
Four-dimensional variational (4DVAR) data assimilation experiments for the East Coast winter storm of 25 January 2000 (i.e., "blizzard 2000") were performed. This has received wide attention in United States, because it was one major failures operational forecast system. All models U.S. National Weather Service (NWS) failed to produce heavy precipitation over Carolina–New Jersey corridor, especially during early stage development. The considered analysis cycle this study is that 0000 1200...
Abstract This paper describes a new velocity–azimuth display (VAD)-based dealiasing method developed for automated radar radial velocity data quality control to satisfy the high-quality standard and efficiency required by operational assimilation. The is built on an alias-robust (AR-VAD) analysis. It upgrades simplifies previous three-step in three major aspects. First, AR-VAD used with sufficiently stringent threshold conditions place of original modified VAD preliminary reference check...
This paper describes significant changes to the U.S. National Centers for Environmental Prediction (NCEP, formerly NMC, Meteorological Center) global data assimilation system that were made operational in January, 1995. The emphasis is on 3D-variational analysis, which has been running operationally since June, 1991. include additions of new types, modifications background error, and addition a weak constraint divergence tendency. A uniform improvement fit 6 hour forecast guess all...
A case study is utilized to determine the sensitivity of Eta Data Assimilation System (EDAS) all operational observational data types used within it. The work described in this paper should be interest Model users trying identify impact each type and could benefit other modelers use EDAS analyses forecasts as initial conditions for models. chosen one characterized by strong Atlantic Pacific maritime cyclogenesis, shortly after began using three-dimensional variational analysis. control run...
Abstract Anisotropic recursive filters are implemented within a three-dimensional variational data assimilation (3DVAR) framework to efficiently model the effect of flow-dependent background error covariance. The covariance is based on an estimated field and idea Riishøjgaard. In anisotropic case, pattern can be stretched or flattened in directions oblique alignment grid coordinates constructed by applying, at each point, six along corresponding, general, special configuration lines grid....
The errors in the first-guess (forecast field) of an analysis system vary from day to day, but, as all current operational data assimilation systems, forecast error covariances are assumed be constant time NCEP three-dimensional variational (known a spectral statistical interpolation or SSI). This study focuses on impact modifying statistics by including effects “errors day” system. An estimate uncertainty, defined bred growing vectors global ensemble forecast, is applied SSI used spatially...
As part of the International Symposium on Assimilation Observations in Meteorology and Oceanography, a panel discussion was held O1997, Meteorological Society Japan evening 15 March 1995. The purpose this to focus what next major areas research data assimilation should be. panelists had five minutes each for short presentations followed by an open discussion. Appendix summarizes opinions panelists, few additional well-known practitioners assimilation, requiring development future. Several...
The National Centers for Environmental Prediction fine-resolution four-dimensional variational (4DVAR) data assimilation system is used to study the Great Plains tornado outbreak of 3 May 1999. It was found that 4DVAR method able capture very well important precursors tornadic activity, such as upper- and low-level jet streaks, wind shear, humidity field, surface CAPE, so on. also demonstrated that, in this particular synoptic case, characterized by fast-changing mesoscale systems, model...