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P1 - overview Flashcards

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1
Q

WRF:

A

Weather Research and Forecasting Model

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2
Q

WRF: Weather Research and Forecasting Model
–  Used for

A

both research and operational forecasting

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3
Q

WRF: Weather Research and Forecasting Model
–  Used for both research and operational forecasting
•  It is a supported “community model”, i.e.

A

a free and shared resource with distributed development and centralized support

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4
Q

It is a supported “community model”, i.e. a free and shared resource with distributed development and centralized support
•  Its development is led by

A

NCAR, NOAA/ ESRL and NOAA/NCEP/EMC with partnerships at AFWA, FAA, DOE/PNNL and collaborations with universities and other government agencies in the US and overseas

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5
Q

WRF has two dynamical cores:

A

The Advanced Research WRF (ARW) and

Nonhydrostatic MesoscaleModel (NMM)

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6
Q

WRF has two dynamical cores: The Advanced Research WRF (ARW) and Nonhydrostatic MesoscaleModel (NMM)
–  Dynamical core includes mostly

A
  • advection,
  • pressure gradients,
  • Coriolis,
  • buoyancy,
  • filters,
  • diffusion, and
  • timestepping
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7
Q

The Advanced Research WRF (ARW) and Nonhydrostatic MesoscaleModel (NMM)

both are

A

Eulerianmass dynamical cores with terrain-following vertical coordinates

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8
Q

ARW support and development are centered at

A

NCAR/MMM

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9
Q

NMM development is centered at

A

NCEP/EMC and support is provided by NCAR/DTC (operationally now only used for HWRF)

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10
Q

The Advanced Research WRF (ARW) and Nonhydrostatic MesoscaleModel (NMM)

Both are downloadable in

A

the same WRF tar file

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11
Q

The Advanced Research WRF (ARW) and Nonhydrostatic MesoscaleModel (NMM)

what are the things shared between the dynamical cores

A
  • Physics,
  • the software framework, and
  • parts of data pre- and post-processing
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12
Q

ARW and NMM can be used for

A
  • Atmospheric physics/parameterization research
  • Case-study research
  • Real-time NWP and forecast system research
  • Data assimilation research
  • Teaching dynamics and NWP
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13
Q

ARW only can be used for

A
  • Regional climate and seasonal time-scale research
  • Coupled-chemistry applications
  • Global simulations
  • Idealized simulations at many scales (e.g. convection, baroclinic waves, large eddy simulations)
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14
Q

WRF Modeling System Flow chart

A
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15
Q

Modeling System Components

A

WRF Pre-processing System

WRF Model (ARW and NMM dynamical cores)

Graphics and verification tools including MET

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16
Q

explain:

WRF Pre-processing System

A
  • Real-data interpolation for NWP runs (WPS)
  • Program for adding more observations to analysis (obsgrid)
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17
Q

explain:

WRF Model (ARW and NMM dynamical cores)

A
  • Initialization programs for real and (for ARW) idealized data (real.exe/ideal.exe)
  • –  Numerical integration program (wrf.exe)
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18
Q

WPS and WRF Program Flow

A
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19
Q

Real-Data Applications of WRF

A
  • Numerical weather prediction
  • Meteorological case studies
  • Regional climate
  • Applications: air quality, wind energy, hydrology, etc
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20
Q

Real-Data Applications need

A

time-independent information for chosen domain(simulation grid area)

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21
Q

Real-Data Applications

GEOGRID program

A
  • Map projection information
  • Topographic information
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22
Q

Real-Data Applications

GEOGRID program

Map projection information

A
  • 2d gridded latitude,
  • longitude,
  • Coriolis parameter,
  • map-scale factors, etc
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23
Q

Real-Data Applications

GEOGRID program

Topographic information

Study These Flashcards
A

2d gridded elevation,

vegetation and soil categories, etc.

24
Q

Real-Data Applications need the following

Study These Flashcards
A
  • Need time-dependent information
  • Initial conditions (initial analysis time)
  • Boundary conditions (later times)
    • except if running WRF globally
  • UNGRIB and METGRIDprograms
25
Real-Data Applications UNGRIBand METGRIDprograms
* 3d fields of horizontal wind, temperature, geopotential height, relative humidity * 2d fields of surface or sea-level pressure, surface temperature, relative humidity, horizontal winds *   Time-sensitive land-surface fields: snow-cover, soil temperature, soil moisture
26
Real-Data Applications Regional domains need
specified lateral boundary conditions at later times (e.g. every 6 hours) through forecast period * 3d fields of horizontal wind, temperature, geopotential height, water vapor * 2d field of surface pressure
27
Long simulations (\> 1 week) also need
lower boundary condition at later times * 2d fields of sea-surface temperature, sea-ice, vegetation fraction
28
Lateral Boundary Conditions (linear in time) –  The wrfbdyfile contains
later gridded information at model points in a zone (e.g.) 5 points wide around the domain
29
Lateral Boundary Conditions (linear in time) –  The wrfbdyfile contains later gridded information at model points in a zone (e.g.) 5 points wide around the domain –  The boundary fields are
linearly time-interpolated from boundary times to the current model time
30
Lateral Boundary Conditions (linear in time) –  The wrfbdyfile contains later gridded information at model points in a zone (e.g.) 5 points wide around the domain –  The boundary fields are linearly time-interpolated from boundary times to the current model time –  This specifies
the outer values, and is used to nudge the next 4 interior points
31
Lower Boundary Condition (step-wise) –  New SSTs are
read in and overwritten at each analysis time from wrflowinpfile
32
Pre-processing for regional domains therefore needs
multiple times for lateral boundary conditions during whole forecast period (UNGRIB and METGRID should be run for all needed analysis times)
33
Pre-processing for regional domains therefore needs multiple times for lateral boundary conditions during whole forecast period (UNGRIB and METGRID should be run for all needed analysis times) –  Note: Global models only need
initial analysis
34
Pre-processing for regional domains therefore needs multiple times for lateral boundary conditions during whole forecast period (UNGRIB and METGRID should be run for all needed analysis times) –  Note: Global models only need initial analysis – Real-time regional NWP often uses .................... for ....................
global forecast for boundary conditions
35
Long simulations also need lower boundary information on
SST and sea ice to update them over periods of weeks, months, years
36
Nesting
Running multiple domains with increasing resolution in nested areas
37
Nesting Running multiple domains with increasing resolution in nested areas •  Parent has
specifiedboundary conditions from wrfbdy fie
38
Nested boundary conditions come from
parent
39
Nesting (Two-Way)
Lateral boundary condition is provided by parent domain at every parent step
40
Nesting (Two-Way) Lateral boundary condition is provided by parent domain at every parent step •  Method is same as for
outer domain (specified and relaxation zones)
41
Nesting (Two-Way) •  Lateral boundary condition is provided by parent domain at every parent step •  Method is same as for outer domain (specified and relaxation zones) •  Additional fields include
vertical motion and microphysics species
42
Nesting (Two-Way) •  Lateral boundary condition is provided by parent domain at every parent step •  Method is same as for outer domain (specified and relaxation zones) •  Additional fields include vertical motion and microphysics species •  Feedback:
Interior of nest overwrites overlapped parent area
43
Nesting (Two-Way) •  Sequence
Parent domain runs a time-step to t+dt –  Nest boundaries from beginning and end of timestep interpolated –  Nest runs typically three steps (dt/3) using timeinterpolated parent info at nest boundaries –  After nest reaches t+dt, feedback overwrites parent in overlapped region –  Repeat
44
One-Way Nesting
As two-way nesting but no feedback Can also be done with NDOWNprogram to take a previous WRF run output and provide nest boundary conditions at parent output frequency
45
One-Way Nesting •  As two-way nesting but no feedback •  Can also be done with NDOWNprogram to take a previous WRF run output and provide nest boundary conditions at parent output frequency – Uses
parent WRF run instead of analysis for initial and lateral boundary conditions
46
WPS Functions
# Define simulation domain area (and nests) •  Produce terrain, landuse, soil type etc. on the simulation domain (“static”fields) •  De-grib GRIB files for meteorological data (u, v, T, q, surface pressure, soil data, snow data, sea-surface temperature, etc.) •  Interpolate meteorological data to WRF model grid (horizontally) •  Optionally add more observations to analysis (separate obsgrid program)
47
WPS Data •  Geogrid:
We provide elevation, landuse, soil type data (static fields) – Or user can input own static data in same easy-to-write format
48
WPS Data Metgrid:
Supports input of timedependent data (dynamic fields) – UNGRIB can provide these from GriB files – Or user can input own data in same “intermediate format”(simple binary files)
49
WPS and WRF Program Flow
50
DATA FLOW
51
WRF real and ideal functions •  REAL
–  Creates initial and boundary condition files for real-data cases –  Does vertical interpolation to model levels (when using WPS) –  Does vertical dynamic (hydrostatic) balance –  Does soil vertical interpolations and land-use mask checks
52
IDEAL (ARW only)
–  Programs for setting up idealized case –  Simple physics and usually single sounding –  Initial conditions and dynamic balance
53
WRF Model functions
–  Dynamical core (ARW or NMM) is compiletime selectable –  Uses initial conditions from REAL or IDEAL (ARW) –  Real-data cases use boundary conditions from REAL –  Runs the model simulation with run-time selected namelist switches (such as physics choices, timestep, length of simulation, etc.) –  Outputs history and restart files
54
ARW Dynamics Key features:
* Fully compressible, non-hydrostatic (with hydrostatic option) * •  Mass-based terrain following coordinate * Arakawa C-grid staggering
55
ARW Model Key features:
3rd-order Runge-Kutta time integration scheme •  High-order advection scheme •  Scalar-conserving (positive definite option) •  Complete Coriolis, curvature and mapping terms •  Two-way and one-way nesting
56
Graphics and Verification Tools ARW and NMM
–  RIP4 (Read, Interpolate and Plot) –  Unified Post-Processor (UPP) •  Conversion to GriB (for GrADS and GEMPAK) –  MET (Model Evaluation Toolkit)
57
Graphics and Verification Tools ARW
–  NCAR Graphics Command Language (NCL) –  ARWpost •  Conversion program for GrADS –  VAPOR (3D visualization tool) –  IDV (3D visualization tool)

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