scholarly journals A North American Hourly Assimilation and Model Forecast Cycle: The Rapid Refresh

2016 ◽  
Vol 144 (4) ◽  
pp. 1669-1694 ◽  
Author(s):  
Stanley G. Benjamin ◽  
Stephen S. Weygandt ◽  
John M. Brown ◽  
Ming Hu ◽  
Curtis R. Alexander ◽  
...  
Keyword(s):  
Situational Awareness ◽  
Regional Analysis ◽  
Three Dimensional ◽  
Wrf Model ◽  
Forecast Model ◽  
The United States ◽  
Model Forecast ◽  
Forecast System ◽  
Analysis System ◽  
Environmental Prediction

Abstract The Rapid Refresh (RAP), an hourly updated assimilation and model forecast system, replaced the Rapid Update Cycle (RUC) as an operational regional analysis and forecast system among the suite of models at the NOAA/National Centers for Environmental Prediction (NCEP) in 2012. The need for an effective hourly updated assimilation and modeling system for the United States for situational awareness and related decision-making has continued to increase for various applications including aviation (and transportation in general), severe weather, and energy. The RAP is distinct from the previous RUC in three primary aspects: a larger geographical domain (covering North America), use of the community-based Advanced Research version of the Weather Research and Forecasting (WRF) Model (ARW) replacing the RUC forecast model, and use of the Gridpoint Statistical Interpolation analysis system (GSI) instead of the RUC three-dimensional variational data assimilation (3DVar). As part of the RAP development, modifications have been made to the community ARW model (especially in model physics) and GSI assimilation systems, some based on previous model and assimilation design innovations developed initially with the RUC. Upper-air comparison is included for forecast verification against both rawinsondes and aircraft reports, the latter allowing hourly verification. In general, the RAP produces superior forecasts to those from the RUC, and its skill has continued to increase from 2012 up to RAP version 3 as of 2015. In addition, the RAP can improve on persistence forecasts for the 1–3-h forecast range for surface, upper-air, and ceiling forecasts.

Development of a Real-Time Regional Ocean Forecast System with Application to a Domain off the U.S. East Coast

2004 ◽  
Vol 38 (1) ◽  
pp. 61-79 ◽  
Author(s):  
Laurence C. Breaker ◽  
Desiraju B. Rao ◽  
John G.W. Kelley ◽  
Ilya Rivin
Keyword(s):  
Real Time ◽  
East Coast ◽  
Weather Prediction ◽  
Forecast Model ◽  
The United States ◽  
Ocean Model ◽  
Sea Surface ◽  
Forecast System ◽  
Environmental Prediction ◽  
The U.S

This paper discusses the needs to establish a capability to provide real-time regional ocean forecasts and the feasibility of producing them on an operational basis. Specifically, the development of a Regional Ocean Forecast System using the Princeton Ocean Model (POM) as a prototype and its application to the East Coast of the U.S. are presented. The ocean forecasts are produced using surface forcing from the Eta model, the operational mesoscale weather prediction model at the National Centers for Environmental Prediction (NCEP). At present, the ocean forecast model, called the East Coast-Regional Ocean Forecast System (EC-ROFS) includes assimilation of sea surface temperatures from in situ and satellite data and sea surface height anomalies from satellite altimeters. Examples of forecast products, their evaluation, problems that arose during the development of the system, and solutions to some of those problems are also discussed. Even though work is still in progress to improve the performance of EC-ROFS, it became clear that the forecast products which are generated can be used by marine forecasters if allowances for known model deficiencies are taken into account. The EC-ROFS became fully operational at NCEP in March 2002, and is the first forecast system of its type to become operational in the civil sector of the United States.

scholarly journals Increasing vertical resolution in US models to improve track forecasts of Hurricane Joaquin with HWRF as an example

2016 ◽  
Vol 113 (42) ◽  
pp. 11765-11769 ◽  
Author(s):  
Banglin Zhang ◽  
Richard S. Lindzen ◽  
Vijay Tallapragada ◽  
Fuzhong Weng ◽  
Qingfu Liu ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
Forecast Model ◽  
Vertical Resolution ◽  
Global Forecast System ◽  
Forecast System ◽  
Atlantic Basin ◽  
Hurricane Track ◽  
Environmental Prediction ◽  
The Impact ◽  
Positive Impacts

The atmosphere−ocean coupled Hurricane Weather Research and Forecast model (HWRF) developed at the National Centers for Environmental Prediction (NCEP) is used as an example to illustrate the impact of model vertical resolution on track forecasts of tropical cyclones. A number of HWRF forecasting experiments were carried out at different vertical resolutions for Hurricane Joaquin, which occurred from September 27 to October 8, 2015, in the Atlantic Basin. The results show that the track prediction for Hurricane Joaquin is much more accurate with higher vertical resolution. The positive impacts of higher vertical resolution on hurricane track forecasts suggest that National Oceanic and Atmospheric Administration/NCEP should upgrade both HWRF and the Global Forecast System to have more vertical levels.

scholarly journals A Dynamical Initialization Scheme for Real-Time Forecasts of Tropical Cyclones Using the WRF Model*

2013 ◽  
Vol 141 (3) ◽  
pp. 964-986 ◽  
Author(s):  
Dong-Hyun Cha ◽  
Yuqing Wang
Keyword(s):  
Real Time ◽  
Large Scale ◽  
Initial Conditions ◽  
Wrf Model ◽  
Forecast Model ◽  
Initial Position ◽  
Northwest Pacific ◽  
Forecast System ◽  
Positive Effects ◽  
Forecast Models

Abstract To improve the initial conditions of tropical cyclone (TC) forecast models, a dynamical initialization (DI) scheme using cycle runs is developed and implemented into a real-time forecast system for northwest Pacific TCs based on the Weather Research and Forecasting (WRF) Model. In this scheme, cycle runs with a 6-h window before the initial forecast time are repeatedly conducted to spin up the axisymmetric component of the TC vortex until the model TC intensity is comparable to the observed. This is followed by a 72-h forecast using the Global Forecast System (GFS) prediction as lateral boundary conditions. In the DI scheme, the spectral nudging technique is employed during each cycle run to reduce bias in the large-scale environmental field, and the relocation method is applied after the last cycle run to reduce the initial position error. To demonstrate the effectiveness of the proposed DI scheme, 69 forecast experiments with and without the DI are conducted for 13 TCs over the northwest Pacific in 2010 and 2011. The DI shows positive effects on both track and intensity forecasts of TCs, although its overall skill depends strongly on the performance of the GFS forecasts. Compared to the forecasts without the DI, on average, forecasts with the DI reduce the position and intensity errors by 10% and 30%, respectively. The results demonstrate that the proposed DI scheme improves the initial TC vortex structure and intensity and provides warm physics spinup, producing initial states consistent with the forecast model, thus achieving improved track and intensity forecasts.

Predictability of ECMWF Cubic Octahedral Nature Run (ECO1280) using Finite-Volume Cubed-Sphere Global Forecast System (FV3GFS) Compared to Real-World Predictability

2020 ◽  
Author(s):  
Sean Casey ◽  
Lidia Cucurull ◽  
Andres Vidal
Keyword(s):  
Finite Volume ◽  
Real World ◽  
Forecast Model ◽  
Global Forecast System ◽  
Forecast System ◽  
Weather Forecasts ◽  
Global Nature ◽  
System Assessment ◽  
Cubed Sphere ◽  
Environmental Prediction

<p>Under the Quantitative Observing System Assessment Program, the National Oceanic and Atmospheric Administration's (NOAA's) Atlantic Oceanographic and Meteorological Laboratory (AOML) is preparing to utilize the 9-km-resolution European Centre for Medium-Range Weather Forecasts (ECWMF) Cubic Octahedral grid global Nature Run (ECO1280) for observation simulation and conducting Observing System Simulation Experiments (OSSEs).   As part of the OSSE calibration, and before experiments can be run, it needs to be shown that the forecast model used in the OSSEs does not do a better job in predicting the Nature Run meteorology than it does in predicting the real world. Otherwise, the conclusions from the OSSEs in such a configuration may misstate the potential impact of a given instrument. In this presentation, the predictability of the new global OSSE system being developed at NOAA will be discussed. The NOAA/National Centers for Environmental Prediction (NCEP) Finite-Volume Cubed-Sphere Global Forecast System (FV3GFS) is used to test predictability over the first two months of ECO1280 (October-November 2015), comparing forecasts using simulated observations with added errors to real-world observations.  Only conventional observations will be utilized in both cases.  </p>

scholarly journals The Development of a Terrain-Resolving Scheme for the Forward Model and Its Adjoint in the Four-Dimensional Variational Doppler Radar Analysis System (VDRAS)

2017 ◽  
Vol 145 (1) ◽  
pp. 289-306 ◽  
Author(s):  
Sheng-Lun Tai ◽  
Yu-Chieng Liou ◽  
Juanzhen Sun ◽  
Shao-Fan Chang
Keyword(s):  
Doppler Radar ◽  
Three Dimensional ◽  
Wrf Model ◽  
Radar Data ◽  
Forward Model ◽  
Immersed Boundary ◽  
Topographic Effects ◽  
Moist Convection ◽  
Analysis System ◽  
New System

Abstract The four-dimensional Variational Doppler Radar Analysis System (VDRAS) developed at the National Center for Atmospheric Research (NCAR) is significantly improved by implementing a terrain-resolving scheme to its forward model and adjoint based on the ghost cell immersed boundary method (GCIBM), which allows the topographic effects to be considered without the necessity to rebuild the model on a terrain-following coordinate system. The new system, called IBM_VDRAS, is able to perform forward forecast and backward adjoint model integration over nonflat lower boundaries, ranging from mountains with smooth slopes to buildings with sharp surfaces. To evaluate the performance of the forward model over complex terrain, idealized numerical experiments of a two-dimensional linear mountain wave and three-dimensional leeside vortices are first conducted, followed by a comparison with a simulation by the Weather Research and Forecasting (WRF) Model. An observing system simulation experiment is also conducted with the assimilation of simulated radar data to examine the ability of IBM_VDRAS in analyzing orographically forced moist convection. It is shown that the IBM_VDRAS can retrieve terrain-influenced three-dimensional meteorological fields including winds, thermodynamic, and microphysical parameters with reasonable accuracy. The new system, with the advanced radar data assimilation capability and the GCIBM terrain scheme, has the potential to be used for studying the evolution of convective weather systems under the influence of terrain.

scholarly journals The NCEP Climate Forecast System Version 2

2014 ◽  
Vol 27 (6) ◽  
pp. 2185-2208 ◽  
Author(s):  
Suranjana Saha ◽  
Shrinivas Moorthi ◽  
Xingren Wu ◽  
Jiande Wang ◽  
Sudhir Nadiga ◽  
...  
Keyword(s):  
Energy Use ◽  
Initial Conditions ◽  
Forecast Model ◽  
Seasonal Prediction ◽  
The United States ◽  
Climate Forecast ◽  
Seasonal Forecasts ◽  
Forecast System ◽  
Climate Forecast System ◽  
Ncep Climate Forecast System

Abstract The second version of the NCEP Climate Forecast System (CFSv2) was made operational at NCEP in March 2011. This version has upgrades to nearly all aspects of the data assimilation and forecast model components of the system. A coupled reanalysis was made over a 32-yr period (1979–2010), which provided the initial conditions to carry out a comprehensive reforecast over 29 years (1982–2010). This was done to obtain consistent and stable calibrations, as well as skill estimates for the operational subseasonal and seasonal predictions at NCEP with CFSv2. The operational implementation of the full system ensures a continuity of the climate record and provides a valuable up-to-date dataset to study many aspects of predictability on the seasonal and subseasonal scales. Evaluation of the reforecasts show that the CFSv2 increases the length of skillful MJO forecasts from 6 to 17 days (dramatically improving subseasonal forecasts), nearly doubles the skill of seasonal forecasts of 2-m temperatures over the United States, and significantly improves global SST forecasts over its predecessor. The CFSv2 not only provides greatly improved guidance at these time scales but also creates many more products for subseasonal and seasonal forecasting with an extensive set of retrospective forecasts for users to calibrate their forecast products. These retrospective and real-time operational forecasts will be used by a wide community of users in their decision making processes in areas such as water management for rivers and agriculture, transportation, energy use by utilities, wind and other sustainable energy, and seasonal prediction of the hurricane season.

scholarly journals Impacts of Biomass Burning Emission Inventories and Atmospheric Reanalyses on Simulated PM10 over Indochina

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 160
Author(s):  
Kyohei Takami ◽  
Hikari Shimadera ◽  
Katsushige Uranishi ◽  
Akira Kondo
Keyword(s):  
Air Quality ◽  
Biomass Burning ◽  
Model Simulation ◽  
Global Analysis ◽  
Wrf Model ◽  
The United States ◽  
Emission Inventories ◽  
Fire Emissions ◽  
Percentage Difference ◽  
Environmental Prediction

Biomass burning (BB) is a major source of atmospheric particles over Indochina during the dry season. Moreover, Indochina has convoluted meteorological scales, and regional meteorological conditions dominate the transport patterns of pollutants. This study focused on the impacts of BB emission inventories and atmospheric reanalyses on simulated PM10 over Indochina in 2014 using the Community Multiscale Air Quality (CMAQ) model. Meteorological fields to input to CMAQ were produced by using the Weather Research and Forecasting (WRF) model simulation with the United States National Centers for Environmental Prediction Final (NCEP FNL) Operational Global Analysis or European Centre for Medium Range Weather Forecasts Interim Reanalysis (ERA-interim). The Fire INventory from NCAR (FINN) v1.5 or the Global Fire Emissions Database including small fires (GFED v4.1s) was selected for BB emissions for the air quality simulation. The simulation case with NCEP FNL and FINN v1.5 (FNL + FINN) performed best throughout 2014, including the season when BB activities were intensified. The normalized percentage difference for maximum daily mean PM10 concentrations at Chiang Mai for FNL + FINN and the two simulation cases applying GFED v4.1s for BB emissions (−53% to −27%) was much larger than that between the FNL + FINN and ERA + FINN cases (10%). BB emission inventories more strongly impacted PM10 simulation than atmospheric reanalyses in highly polluted areas by BB over Indochina in 2014.

scholarly journals Improving Incremental Balance in the GSI 3DVAR Analysis System

2009 ◽  
Vol 137 (3) ◽  
pp. 1046-1060 ◽  
Author(s):  
Daryl T. Kleist ◽  
David F. Parrish ◽  
John C. Derber ◽  
Russ Treadon ◽  
Ronald M. Errico ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Normal Mode ◽  
Three Dimensional ◽  
Substantial Improvement ◽  
Environmental Modeling ◽  
Variational Data Assimilation ◽  
North American Data ◽  
Analysis System ◽  
Environmental Prediction ◽  
Statistical Interpolation

Abstract The gridpoint statistical interpolation (GSI) analysis system is a unified global/regional three-dimensional variational data assimilation (3DVAR) analysis code that has been under development for several years at the National Centers for Environmental Prediction (NCEP)/Environmental Modeling Center. It has recently been implemented into operations at NCEP in both the global and North American data assimilation systems (GDAS and NDAS, respectively). An important aspect of this development has been improving the balance of the analysis produced by GSI. The improved balance between variables has been achieved through the inclusion of a tangent-linear normal-mode constraint (TLNMC). The TLNMC method has proven to be very robust and effective. The TLNMC as part of the global GSI system has resulted in substantial improvement in data assimilation at NCEP.

scholarly journals The Impact of Airborne Radio Occultation Observations on the Simulation of Hurricane Karl (2010)

2018 ◽  
Vol 146 (1) ◽  
pp. 329-350 ◽  
Author(s):  
X. M. Chen ◽  
S.-H. Chen ◽  
J. S. Haase ◽  
B. J. Murphy ◽  
K.-N. Wang ◽  
...  
Keyword(s):  
Radio Occultation ◽  
Three Dimensional ◽  
Wrf Model ◽  
Tangent Point ◽  
Sea Level Pressure ◽  
Analysis System ◽  
The Tropics ◽  
Ray Path ◽  
The Impact ◽  
First Time

Abstract This study evaluates, for the first time, the impact of airborne global positioning system radio occultation (ARO) observations on a hurricane forecast. A case study was conducted of Hurricane Karl during the Pre-Depression Investigation of Cloud-Systems in the Tropics (PREDICT) field campaign in 2010. The assimilation of ARO data was developed for the three-dimensional variational (3DVAR) analysis system of the Weather Research and Forecasting (WRF) Model version 3.2. The impact of ARO data on Karl forecasts was evaluated through data assimilation (DA) experiments of local refractivity and nonlocal excess phase (EPH), in which the latter accounts for the integrated horizontal sampling along the signal ray path. The tangent point positions (closest point of an RO ray path to Earth’s surface) drift horizontally, and the drifting distance of ARO data is about 2 to 3 times that of spaceborne RO, which was taken into account in these simulations. Results indicate that in the absence of other satellite observations, the assimilation of ARO EPH resulted in a larger impact on the analysis than local refractivity did. In particular, the assimilation of ARO observations at the actual tangent point locations resulted in more accurate forecasts of the rapid intensification of the storm. Among all experiments, the best forecast was obtained by assimilating ARO data with the most accurate geometric representation, that is, the use of nonlocal EPH operators with tangent point drift, which reduced the error in the storm’s predicted minimum sea level pressure (SLP) by 43% beyond that of the control experiment.

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