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Yuanfu Xie authored and/or contributed to the following articles/publications.
In recent years, the Earth System Research Laboratory (ESRL) of the National Oceanic and Atmospheric Administration (NOAA) has developed a space and time mesoscale analysis system (STMAS), which is currently a sequential three-dimensional variational data assimilation (3DVAR) system and is developing into a sequential 4DVAR in the near future. I...
Severe Weather Forecasts using the Space and Time Mesoscale Analysis System (STMAS)
Severe weather events cause tremendous property damage and life loss every year worldwide. To improve severe weather forecasts, data assimilation techniques are very critical in forecasting hurricane and storms. The Space and Time Mesoscale Analysis System (STMAS) developed at NOAA/Earth System Research Laboratory/Global Systems Division is a mu...
A recursive filter or parameterized curve fitting technique is usually used in a three-dimensional variational data assimilation (3DVAR) scheme to approximate the background error covariance, which can only represent the errors of an ocean field over a predetermined scale. Without an accurate flow-dependent error covariance that is al...
Diagnosis of three-dimensional water vapor using a GPS network
In recent years techniques have been developed to obtain integrated water vapor along slant paths between ground-based Global Positioning System (GPS) receivers and the GPS satellites. Results are presented of an observing system simulation (OSS) to determine whether three-dimensional water vapor fields could be recovered from a high-resoluti...
Spatial computational modes in the centered finite-differencing schemes
The computational modes associated with a centered finite-differencing scheme in space are studied. The existence and impact of these computational modes in a numerical solution are demonstrated with the use of theoretical analyses and numerical experiments. The results show that the computational modes due to a spatial discretization can have ...
On the use of slant observations from GPS to diagnose three-dimensional water vapor using 3DVAR
Practical update criteria for reduced hessian SQP: Global analysis
In this paper, a new update criterion is proposed to improve the Nocedal-Overton update criterion for reduced Hessian successive quadratic programming (SQP). Global and R-linear convergence is proved for the new criterion and the Nocedal-Overton criterion using nonorthogonal basis matrices, which allow efficient implementations of the reduced H...
The En4DVar method is designed to combine the flow-dependent statistical covariance information of EnKF into the traditional 4DVar method. However, the En4DVar method is still hampered by its strong dependence on the adjoint model of the underlying forecast model and by its complexity, maintenance requirements, and the high cost of computer impl...
Institution National Oceanic and Atmospheric Administration - NOAA
High-altitude, long-endurance Unmanned Aircraft Systems (HALE UAS) are capable of extended flights for atmospheric sampling. A case study was conducted to evaluate the potential impact of dropwindsonde observations from HALE UAS on tropical cyclone track prediction; tropical cyclone intensity was not addressed. This study employs a global observ...
Institutions Earth System Research Laboratory - ESRL National Center for Atmospheric Research - NCAR
Ensemble transform sensitivity method for adaptive observations
The Ensemble Transform (ET) method has been shown to be useful in providing guidance for adaptive observation deployment. It predicts forecast error variance reduction for each possible deployment using its corresponding transformation matrix in an ensemble subspace. In this paper, a new ET-based sensitivity (ETS) method, which calculates the gr...
Institution National Oceanic and Atmospheric Administration - NOAA
Future cost-competitive electricity systems and their impact on US CO2 emissions
Carbon dioxide emissions from electricity generation are a major cause of anthropogenic climate change. The deployment of wind and solar power reduces these emissions, but is subject to the variability of the weather. In the present study, we calculate the cost-optimized configuration of variable electrical power generators using weather data wi...
Institutions Earth System Research Laboratory - ESRL National Oceanic and Atmospheric Administration - NOAA
The planning and design of an electric power system, including high-voltage direct-current transmission, is a complex optimization problem. The optimization must integrate and model the engineering requirements and limitations of the generation, while simultaneously balancing the system electric load at all times. The problem is made more diffic...
Institutions Earth System Research Laboratory - ESRL National Oceanic and Atmospheric Administration - NOAA
Rapid Mesoscale Environmental Changes Accompanying Genesis of an Unusual Tornado
This study documents a very rapid increase in convective instability, vertical wind shear, and mesoscale forcing leading to the formation of a highly unusual tornado as detected by a ground-based microwave radiometer and wind profiler, and in 1-km resolution mesoanalyses. Mesoscale forcing for the rapid development of severe convection began wit...
Institutions National Center for Atmospheric Research - NCAR National Oceanic and Atmospheric Administration - NOAA
The accurate and timely depiction of the state of the atmosphere on multiple scales is critical to enhance forecaster situational awareness and to initialize very short-range numerical forecasts in support of nowcasting activities. The Local Analysis and Prediction System (LAPS) of the Earth System Research Laboratory (ESRL)/Global Systems Divis...
Institution National Oceanic and Atmospheric Administration - NOAA
This study examines the sensitivity of simulated precipitation to planetary boundary layer (PBL) schemes over the Tibetan Plateau (TP) and the Yangtze River Valley (YRV). The summer precipitation from 15 June to 30 July 2010 is simulated with the Weather Research and Forecasting (WRF) model over these areas. Three PBL parameterization schemes, M...
Institution National Oceanic and Atmospheric Administration - NOAA
Community Data Assimilation Research and Development
The quality of Numerical Weather Predictions (NWP) critically depends on the choice of initial conditions. In the US alone, a number of major Data Assimilation (DA) systems have been developed to provide estimates of the state of the atmosphere to initialize NWP forecasts. While these schemes contain state-of-the-art algorithms (i.e., the scient...
Institution National Oceanic and Atmospheric Administration - NOAA