<p><b>gill</b> 2008-06-09 14:09:45 -0600 (Mon, 09 Jun 2008)</p><p>mods from Wei<br>
<br>
M initialization.tex<br>
M lbc.tex<br>
M nest.tex<br>
</p><hr noshade><pre><font color="gray">Modified: trunk/wrf/technote/initialization.tex
===================================================================
--- trunk/wrf/technote/initialization.tex 2008-06-06 21:45:09 UTC (rev 84)
+++ trunk/wrf/technote/initialization.tex 2008-06-09 20:09:45 UTC (rev 85)
@@ -7,7 +7,8 @@
real-data cases. Both 2D and 3D tests cases for idealized
simulations are provided.
Several sample cases for real-data simulations are provided, which
-rely on pre-processing from an external package that converts
+rely on pre-processing from an external package (usually the
+WRF Preprocessor System, referred to as WPS) that converts
the large-scale GriB data into a format suitable for ingest by the ARW's
real-data processor.
@@ -28,14 +29,14 @@
The ARW comes with a number of test cases using idealized
environments, including large eddy simulations (em\_les),
-sea breezes ( em\_seabreeze), mountain waves (em\_hill2d\_x), squall lines
+sea breezes (em\_seabreeze2d\_x), mountain waves (em\_hill2d\_x), squall lines
(em\_squall2d\_x, em\_squall2d\_y), supercell thunderstorms
(em\_quarter\_ss), gravity currents (em\_grav2d\_x), baroclinic
-waves (em\_b\_wave), and global systems (em\_heldsuarez).
+waves (em\_b\_wave), and global domains (em\_heldsuarez).
A brief description of these test cases can be
found in the README\_test\_cases file provided in the ARW release.
The test cases include examples of atmospheric
-flows at fine scales (e.g., the gravity current example has a grid-spacing of
+flows at fine scales (e.g., the LES example has a grid-spacing of
100 meters and a time step of 1 second) and examples of flow at large
scales (e.g., the Held Suarez global test case uses a grid-spacing around 600 km and
a time step of 1800 s), in addition to the traditional mesoscale and
@@ -44,9 +45,9 @@
starting point for constructing idealized flow simulations by modifying
initializations that closely resemble a desired initialization.
-All of these tests use as input a 1D sounding specified as a function of
+Most of these tests use as input a 1D sounding specified as a function of
geometric height $z$ (except for the baroclinic wave case that uses a 2D
-sounding specified in $[y,z]$), and, with the exception of the baroclinic
+profile specified in $[y,z]$), and, with the exception of the baroclinic
wave test case, the sounding files are in text format that can be
directly edited by the user. The 1D specification of the sounding in
these test files requires the surface values of pressure, potential
@@ -58,7 +59,7 @@
Two sets of thermodynamic fields are needed for the model--- the
reference state and the perturbation state (see Chapter
-\ref{equation_chap} for further discussion of the equations). The
+\ref{equation_chap} for discussion of the equations). The
reference state used in the idealized initializations is computed using
the input sounding from which the moisture is discarded (because the
reference state is dry). The perturbation state is computed using the full
@@ -184,7 +185,8 @@
\end{figure}
The input to the ARW real-data processor from
-WPS contains 3-dimensional fields of temperature (K), relative humidity
+WPS contains 3-dimensional fields (including
+the surface) of temperature (K), relative humidity
(%), geopotential height (m), pressure (Pa),
and the horizontal components of momentum (m/s, already rotated to the model
projection).
@@ -197,7 +199,7 @@
surface pressure and sea-level pressure (Pa), layers of soil temperature (K) and soil moisture (kg/kg,
either total moisture, or
binned into total and liquid content),
-snow depth (m), skin temperature (K), and sea ice.
+snow depth (m), skin temperature (K), sea surface temperature (K), and a sea ice flag.
\subsection{Reference State}
\label{initialization_real_base_section}
@@ -414,10 +416,12 @@
If the land/water
mask for a location is flagged as a water point, then the vegetation and soil categories must also
recognize the location as the special water flag for each of their respective categorical indices.
+Similarly, if the land/water mask is flagged as a land point, the vegetation and soil
+categories must be assigned to one of the available land indices.
The values for the soil temperature and soil moisture come from WPS on the
native levels originally defined for those variables
-in the large-scale model. WPS does no vertical interpolation for the
+by an external model. WPS does no vertical interpolation for the
soil data. While it is typical to try to match the ARW soil scheme with
the incoming data, that is not a requirement. Pre-processor {\it real} will vertically interpolate
(linear in depth below the ground) from the incoming levels to the requested soil layers to be
@@ -484,7 +488,6 @@
\begin{equation}
y_n = \sum_{k=0}^{N} h_k x_{n-k} + \sum_{k=1}^{N} b_k y_{n-k}.
-</font>
<font color="black">otag
\end{equation}
</font>
<font color="gray">oindent
@@ -525,7 +528,6 @@
\begin{equation}
{\bf X}_{ini} = \sum_{n=0}^{2N} h_n \left[ {\bf X}_{ana} \right]_n^D,
-</font>
<font color="black">otag
\end{equation}
</font>
<font color="gray">oindent
@@ -544,8 +546,7 @@
model initial state, ${\bf X}_{ana}$, the DDFI scheme is expressed as
\begin{equation}
-{\bf X}_{ini} = \sum_{n=0}^{2N} h_n \left[ \left[ {\bf X}_{ana} \right]_{-N}^A \right]_n^D,
-</font>
<font color="blue">otag
+{\bf X}_{ini} = \sum_{n=0}^{2N} h_n \left[ \left[ {\bf X}_{ana} \right]_{-n}^A \right]_n^D,
\end{equation}
</font>
<font color="gray">oindent
@@ -563,7 +564,6 @@
\begin{equation}
{\bf X}_{ini} = \sum_{n=0}^{2N} h_n \left[ \sum_{n'=0}^{2N} h_{n'} \left[ {\bf X}_{ana} \right]_{-n}^A \right]_n^D.
-</font>
<font color="gray">otag
\end{equation}
\subsection{Backward Integration}
Modified: trunk/wrf/technote/lbc.tex
===================================================================
--- trunk/wrf/technote/lbc.tex 2008-06-06 21:45:09 UTC (rev 84)
+++ trunk/wrf/technote/lbc.tex 2008-06-09 20:09:45 UTC (rev 85)
@@ -5,22 +5,12 @@
that are suitable for idealized flows, and a specified lateral boundary
condition for real-data simulations is available. These choices are
handled via a run-time option in the Fortran namelist file.
-The coarsest
-grid of any single simulation is eligible for any of the lateral
-boundary selections. For example, real-data cases could use combinations
-of periodic, symmetric, or open lateral boundary conditions instead of the
-more traditional time-dependent conditions provided by an external
-boundary file. However, use of the specified time-dependent lateral boundary
-conditions for one of the idealized simulations
-is not possible because an external boundary file is not generated.
-The ARW supports rectangular horizontal grid
-refinement with integer ratios of the
-parent and child grid distances and time steps.
-
For nesting, all fine domains use the
nest time-dependent lateral boundary condition where the outer row and column of the
fine grid is specified from the parent domain, described in
Section \ref{nest-lbc}.
+The remaining lateral boundary options are exclusively
+for use by the most coarse/parent domain.
\section{Periodic Lateral Boundary Conditions}
@@ -152,12 +142,14 @@
a Mercator projection is needed to make this possible.
The coarse grid specified lateral boundary is comprised of both a specified and
-a relaxation zone as shown in Fig. \ref{figure:spec}).
+a relaxation zone (as shown in Fig. \ref{figure:spec}).
For the coarse grid, the specified zone is determined entirely by
temporal interpolation from an external
-forecast or analysis (supplied by the SI). The width of the specified zone is run-time
+forecast or analysis (supplied by WPS). The width of the specified zone is run-time
configurable, but is typically set to 1 (i.e., the last
-row and column along the outer edge of the coarse grid).
+row and column along the outer edge of the most coarse grid
+is entirely specified by temporal interpolation using data
+from an external model).
The second region of the lateral boundary for the coarse grid is the relaxation zone.
The relaxation zone is where the model is nudged or relaxed
towards the large-scale forecast (e.g., rows and columns 2 through 5 in
@@ -175,7 +167,7 @@
\end{equation}
</font>
<font color="gray">oindent where $n$ is the number of grid points in from the outer row or column along the boundary
($SpecZone + 1 \leq n \leq SpecZone + RelaxZone - 1$; see Fig. \ref{figure:spec})
-and $\psi_{LS}$ is the large-scale value obtained by spatial and temporal interpolation from the analyses. $\Delta^2$
+and $\psi_{LS}$ is the large-scale value obtained by spatial and temporal interpolation from the external analysis or model forecast by WPS . $\Delta^2$
is a 5-point horizontal smoother applied along $\eta$-surfaces.
The weighting function
coefficients $F_1$ and $F_2$ in \eqref{lbc_relax} are given by
Modified: trunk/wrf/technote/nest.tex
===================================================================
--- trunk/wrf/technote/nest.tex 2008-06-06 21:45:09 UTC (rev 84)
+++ trunk/wrf/technote/nest.tex 2008-06-09 20:09:45 UTC (rev 85)
@@ -24,7 +24,7 @@
describe the various nesting options available in the ARW and the numerical
coupling between the grids.
-\section {Overview}
+\section {Overview of Nesting Options}
%
% 1-way vs 2-way
@@ -80,16 +80,20 @@
2-way nesting, several options for initializing the fine grid
are provided.
\begin{itemize}\setlength{\parskip}{-4pt}
-\item All of the fine grid variables can be interpolated from the coarse grid (useful
-when a fine grid starts later in the coarse grid forecast).
+\item All of the fine grid variables (both meteorological and
+terrestrial) can be interpolated from the coarse grid (useful
+when a fine grid starts later in the coarse-grid forecast).
\item All of the fine grid variables can be input from an external file
which has high-resolution information for both the meteorological
-and the terrestrial fields (a standard set-up when the fine-grid topography
-is expected to impact the forecast).
+and the terrestrial fields (a standard set-up when the fine-grid
+terrestrial fields are expected to impact the forecast).
\item The fine grid can have some of the variables initialized with a
high-resolution external data set, while other variables are
-interpolated from the coarse grid (permits an improved 3D-Var initialization of the
-coarse grid's metoerological fields to be consistent with the fine grid).
+interpolated from the coarse grid (for example this would permit
+the improved analysis from the 3D-Var initialization of the
+coarse grid's meteorological fields to remain consistent with the fine grid).
+This option allows the fine grid to start later in the coarse-grid's
+forecast, but with the advantage of higher-resolution static fields.
\item For a moving nest, an external orography file may be used to update
the fine grid terrain elevation.
\end{itemize}
@@ -126,7 +130,7 @@
\ref{figure:nest_domains}b).
Any valid fine grid may either be a static domain or it may be a moving nest
(with either prescribed incremental shifts or with automatic moves
-via the 500 mb height vortex following algorithm).
+via a vortex following algorithm, such as the 500 mb height).
The ARW does not permit overlapping
grids, where a coarse grid point is contained within more than a
single child grid (i.e., both of which are at the same nest level with respect
@@ -146,8 +150,38 @@
domain 1 could be 90 km, for
domain 2 could be 45 km, and for domain 3 could be 30 km.
-\section{Nesting and Staggering}
+\section{Moving Nests}
+The moving nest capabilities in ARW are simply extensions to the
+suite of nesting options. All descriptions covering the
+specifics for the fine-grid
+domains (initialization, feedback, configurations, staggering,
+lateral boundaries, etc.) apply also to moving nests. In
+general, all nests
+in an ARW forecast are eligible to be moving nests. The ARW
+provides two methods to have nests move during the model
+integration: specified and automatic.
+
+For a specified move, the timing of a nest move and the extent
+of the lateral move is defined entirely by the user. For the
+automatically moving nest, the fine grid is initialized to cover
+a well defined vortex, and the nest moves to maintain this vortex
+in the center of the fine grid. For both types of moving nests,
+multiple levels of domains may move. However, most of the
+instances where a moving nest is utilized are during tropical
+cyclone tracking via the vortex following technique.
+
+After a nested domain has moved a parent grid-cell distance,
+the majority of the data in the domain is still valid. The
+data that is not along the outer row or column of the nested
+domain is shifted to the new location in that domain.
+Once a domain moves, the data in the outer
+row or column falls into two categories: discarded data on the
+trailing edge, and horizontally interpolated data on the
+leading edge in the direction of the nest move.
+
+\section{Staggering and Feedback}
+
The ARW uses an Arakawa-C grid staggering. As shown in Fig.
\ref{figure:cg_fg}, the $u$ and $v$ components
of horizontal velocity are normal to the respective faces of the
</font>
</pre>