<p><b>weiwang</b> 2008-04-25 18:42:07 -0600 (Fri, 25 Apr 2008)</p><p>intro update from Jordan<br>
</p><hr noshade><pre><font color="gray">Modified: trunk/wrf/technote/intro.tex
===================================================================
--- trunk/wrf/technote/intro.tex 2008-04-25 20:45:48 UTC (rev 60)
+++ trunk/wrf/technote/intro.tex 2008-04-26 00:42:07 UTC (rev 61)
@@ -1,56 +1,57 @@
\chapter{Introduction}
\label{introduction_chap}
-
-The development of the Weather Research and Forecasting (WRF)
-modeling system is a multi-agency effort intended to provide
-a next-generation mesoscale forecast model and data assimilation
-system that will advance both the understanding and prediction
+The Weather Research and Forecasting (WRF) modeling system is
+a capability for the numerical generation of atmospheric simulations.
+These may be produced both prospectively, as in real-time forecasts,
+or retrospectively, as in case studies.
+The development of the WRF system has been a multi-agency effort
+to create a next-generation mesoscale forecast model
+and data assimilation system to advance the understanding and prediction
of mesoscale weather and accelerate the transfer of research
-advances into operations. The model is being developed as a
-collaborative effort among the NCAR Mesoscale and Microscale Meteorology
-(MMM) Division, the National Oceanic and Atmospheric Administration's
+advances into operations. WRF was developed as a collaborative effort
+among the National Center for Atmospheric Research's (NCAR)
+Mesoscale and Microscale Meteorology (MMM) Division, the
+National Oceanic and Atmospheric Administration's
(NOAA) National Centers for Environmental Prediction (NCEP) and
Forecast System Laboratory (FSL), the Department of Defense's Air Force Weather
Agency (AFWA) and Naval Research Laboratory (NRL), the Center
for Analysis and Prediction of Storms (CAPS) at the University
of Oklahoma, and the Federal Aviation Administration (FAA),
-along with the participation of a number of university scientists.
+with the participation of university scientists.
-The WRF model is designed to be a flexible, state-of-the-art,
-portable code that is efficient in a massively parallel computing
-environment. A modular single-source code is maintained that can be
-configured for both research and operations. It offers numerous physics
-options, thus tapping into the experience of the broad modeling
-community. Advanced data assimilation systems are being developed and
-tested in tandem with the model.
-WRF is maintained and supported as a community model to
-facilitate wide use, particularly for research and teaching, in the university
-community. It is suitable for use in a broad spectrum of applications
-across scales ranging from meters to thousands of kilometers. Such
-applications include research and operational numerical weather prediction (NWP),
-data assimilation and
-parameterized-physics research, downscaling climate simulations,
-driving air quality models, atmosphere-ocean coupling, and idealized
-simulations (e.g boundary-layer eddies, convection, baroclinic waves).
-With WRF as a common tool in the university and operational centers,
-closer ties will be promoted between these communities, and research
-advances will have a direct path to
-operations. These hallmarks make the WRF modeling system unique in the
-history of NWP in the United States.
+WRF reflects flexible, state-of-the-art, portable code that is
+efficient in computing environments ranging from massively-parallel
+supercomputers to laptop systems.
+Its modular single-source code can be configured for both
+research and operational applications. Its spectrum of physics
+and dynamics options reflects the experience and input of the
+broad scientfic community. Its variational data assimilation system (WRF-Var)
+allows it to ingest a host of observation types in pursuit of optimal
+initial conditions. WRF is maintained and supported as a community model to
+facilitate wide use internationally, for research, operations, and teaching.
+It is suitable for use in a broad span of applications across
+scales ranging from large-eddy to global scales. Such applications
+include real-time numerical weather prediction (NWP), data assimilation
+development and studies, parameterized-physics research, regional
+climate simulations, air quality modeling, atmosphere-ocean coupling, and
+idealized simulations. Goals of having WRF as a common tool in the
+university/research and operational communities are to promote
+closer ties between the groups and to shorten the path of research
+advances to operations. These aims have made the WRF endeavor
+noteworthy in the evolution of NWP. At the time of this writing,
+the WRF registered user community numbers over 6000, and WRF is in
+operational and research use around the world.
The principal components of the WRF system are depicted in Figure 1.1.
The WRF Software Framework (WSF) provides the infrastructure
-that accommodates multiple dynamics solvers, physics packages that
-plug into the solvers through a standard physics interface, programs
-for initialization, and the WRF variational data assimilation (WRF-Var) system.
-As of this writing there are two dynamics solvers in
-the WSF: the Advanced Research WRF (ARW) solver (originally referred to
+that accommodates dynamics solvers, physics packages that
+interface with the solvers, programs for initialization, and the
+WRF-Var system. There are two dynamics solvers in the WSF: the
+Advanced Research WRF (ARW) solver (originally referred to
as the Eulerian mass or $``$em" solver) developed primarily at NCAR, and
-the NMM (Nonhydrostatic Mesoscale Model) solver developed at NCEP,
-which will be documented and supported to the community
-by the Developmental Testbed Center (DTC).
-While there are multiple solvers, and while not all physics are available to
-both solvers, the WSF is common to all components.
+the NMM (Nonhydrostatic Mesoscale Model) solver developed at NCEP.
+Community support for the former is provided by the MMM Division of NCAR
+and that for the latter is provided by the Developmental Testbed Center (DTC).
%
% Figure 1.1
@@ -63,38 +64,41 @@
\section {Advanced Research WRF}
-The ARW system consists of the ARW dynamics solver together with other
-components of the WRF system needed to produce a simulation. Thus, it
-also encompasses physics schemes, initialization routines, and a data
-assimilation package. The ARW shares the WSF, the framework common
-to all WRF modeling system components, including the NMM solver.
-Similarly, the physics packages are available to both the ARW and NMM solvers. In
-this vein, it should be understood that the association of a component
-of the WRF system with the ARW does not preclude it from being a
-component of any other WRF configuration. The following section
-highlights the major features of the ARW system, Version 2, and reflects
-elements of WRF Version 2, which was first released in May 2004.
+The ARW is the ARW dynamics solver together with other
+components of the WRF system compatible with that solver and
+used in producing a simulation. Thus, it is a subset of
+the WRF modeling system that in addition to the ARW solver
+encompasses physics schemes, numerics/dynamics options,
+initialization routines, and a data assimilation package (WRF-Var).
+The ARW solver shares the WSF with the NMM solver and all other
+WRF components within the framework. Physics packages are
+largely shared by both the ARW and NMM solvers, although specific
+compatibility varies with the schemes considered.
+The association of a component of the WRF system with
+the ARW subset does not preclude it from being a
+component of any WRF configuration involving the NMM solver.
+The following section highlights the major features of the
+ARW, Version 3, and reflects elements of WRF Version 3,
+which was first released in March 2008.
-This technical note will focus on the scientific and algorithmic approaches
-in the ARW. Discussed are the ARW solver, available physics options,
+This technical note focuses on the scientific and algorithmic approaches
+in the ARW. Discussed are the solver, physics options,
initialization capabilities, boundary conditions, and grid-nesting techniques.
-The WSF provides the software infrastructure for all WRF configurations
-and is documented separately \citep{michalak99,michalak04}. The WRF-Var program,
-a component of the broader WRF system, has been
+The WSF provides the software infrastructure for all WRF configurations.
+WRF-Var, a component of the broader WRF system, was
adapted from MM5 3DVAR \citep{barker04} and is encompassed within the ARW.
-As a separate document detailing the broader WRF-Var system will be
-forthcoming, this technical note will focus on a summary of the changes and updates
-implemented to adapt this data assimilation capability from the MM5 to WRF.
-For those seeking information on running the ARW modeling system,
-details on its use are contained in the {\wrf} User's Guide \citep{wang04}.
+This technical note summarizes the changes implemented to adapt
+this data assimilation capability from the MM5 to WRF.
+For those seeking information on running the ARW system,
+the {\wrf} User's Guide (update citation \citep{wang04})
+has the details on its operation.
-\section {Major Features of the ARW System}
+\section {Major Features of the ARW System, Version 3}
\vskip 12pt
{</font>
<font color="gray">oindent\bf ARW Solver}
\vskip 12pt
-
\begin{description}
\setlength{\itemsep}{-5pt}
\item{$\bullet$} {\em Equations:}
@@ -119,6 +123,7 @@
\item{$\bullet$} {\em Time Integration:}
Time-split integration using a 3rd order Runge-Kutta scheme with
smaller time step for acoustic and gravity-wave modes.
+Variable time step capability.
%
\item{$\bullet$} {\em Spatial Discretization:}
2nd to 6th order advection options in horizontal and vertical.
@@ -126,13 +131,17 @@
\item{$\bullet$} {\em Turbulent Mixing and Model Filters:} Sub-grid scale
turbulence formulation in both coordinate and physical space.
Divergence damping, external-mode filtering, vertically implicit
-acoustic step off-centering. Explicit filter option also available.
+acoustic step off-centering. Explicit filter option.
+Digital filter initialization (DFI) capability.
%
\item{$\bullet$} {\em Initial Conditions:}
Three dimensional for real-data, and one-, two- and
three-dimensional using idealized data.
A number of test cases are provided.
%
+\item{$\bullet$} {\em Nudging:}
+Grid (analysis) and observation nudging capabilities available.
+%
\item{$\bullet$} {\em Lateral Boundary Conditions:}
Periodic, open, symmetric, and specified options available.
%
@@ -152,7 +161,10 @@
Curvature terms included.
%
\item{$\bullet$} {\em Nesting:}
-One-way, two-way, and moving nests.
+One-way interactive, two-way interactive, and moving nests.
+%
+\item{$\bullet$} {\em Global Grid:}
+Global simulation capability.
\end{description}
\vskip 12pt
@@ -161,7 +173,7 @@
\begin{description}
\setlength{\itemsep}{-5pt}
-\item{$\bullet$} {\em Microphysics:} Bulk schemes ranging from simplified
+\item{$\bullet$} {\em Microphysics:} Schemes ranging from simplified
physics suitable for mesoscale modeling to sophisticated mixed-phase
physics suitable for cloud-resolving modeling.
%
@@ -180,6 +192,47 @@
Cloud effects and surface fluxes are included.
\end{description}
+\vskip 12pt
+{</font>
<font color="blue">oindent\bf WRF-Chem}
+\vskip 12pt
+
+\begin{description}
+\setlength{\itemsep}{-5pt}
+\item{$\bullet$} Online (or ``inline'') model, in which the model is consistent,
+with all transport done by the meteorology model.
+%
+\item{$\bullet$} Dry deposition, coupled with the soil/vegetation scheme.
+%
+\item{$\bullet$} Aqueous phase chemistry coupled to some of the microphysics and aerosol schemes.
+%
+\item{$\bullet$} Three choices for biogenic emissions:
+No biogenic emissions; Online calculation of biogenic emissions; Online modification
+of user specified biogenic emissions (e.g., EPA Biogenic Emissions Inventory System (BEIS)).
+%
+\item{$\bullet$} Two choices for anthropogenic emissions:
+No anthropogenic emissions and user-specified anthropogenic emissions.
+%
+\item{$\bullet$} Two choices for gas-phase chemical reaction calculations:
+RADM2 chemical mechanism and CBM-Z mechanism.
+%
+\item{$\bullet$} Several choices for gas-phase chemical reaction calculations
+through the use of the Kinetic Pre-Processor (KPP).
+%
+\item{$\bullet$} Three choices for photolysis schemes:
+Madronich scheme coupled with hydrometeors, aerosols, and convective parameterizations;
+Fast-J Photolysis scheme coupled with hydrometeors, aerosols, and convective parameterizations;
+FTUV scheme scheme coupled with hydrometeors, aerosols, and convective parameterizations.
+%
+\item{$\bullet$} Choices for aerosol schemes:
+The Modal Aerosol Dynamics Model for Europe (MADE/SORGAM);
+Model for Simulating Aerosol Interactions and Chemistry (MOSAIC); and
+The GOCART aerosol model (experimental).
+%
+\item{$\bullet$} A tracer transport option in which the chemical mechanism,
+deposition, etc., has been turned off.
+\end{description}
+
+
</font>
<font color="black">ewpage
\vskip 12pt
{</font>
<font color="gray">oindent\bf WRF-Var System}
@@ -187,6 +240,8 @@
\begin{description}
\setlength{\itemsep}{-5pt}
+\item{$\bullet$} WRF-Var merged into WRF software framework.
+%
\item{$\bullet$} Incremental formulation of the model-space cost function.
%
\item{$\bullet$} Quasi-Newton or conjugate gradient minimization algorithms.
@@ -199,7 +254,8 @@
eigenvectors of vertical error. Horizontal/vertical errors are
non-separable (horizontal scales vary with vertical eigenvector).
%
-\item{$\bullet$} Background cost function ($J_b$) preconditioning via a control variable transform ${\rm U}$ defined as ${\bf B}={\rm U} {\rm U}^T$.
+\item{$\bullet$} Background cost function ($J_b$) preconditioning
+via a control variable transform ${\rm U}$ defined as ${\bf B}={\rm U} {\rm U}^T$.
%
\item{$\bullet$} Flexible choice of background error model and control variables.
%
@@ -207,7 +263,8 @@
NMC-method of averaged forecast differences or suitably averaged
ensemble perturbations.
%
-\item{$\bullet$} Unified 3D-Var (4D-Var under development), global and regional, multi-model capability.
+\item{$\bullet$} Unified 3D-Var (4D-Var under development), global
+and regional, multi-model capability.
%
\end{description}
</font>
</pre>