# Presentation: 111973

## Introduction to MM5 modeling system: main programs (parts 1 & 2) 

- José L. Hernández, PhD
- Computer Science and Mathematics Division
- P.O. Box 2008, MS 6016
- Oak Ridge, TN, 37830
- USA

## Introduction: MM5 Modeling System 

- The PSU/NCAR mesoscale model is a limited-area, nonhydrostatic1 or hydrostatic2 (Version 2 only), terrain-following sigma-coordinate model designed to simulate or predict mesoscale and regional-scale atmospheric circulation.
- It has been developed at Penn State and NCAR as a community mesoscale model and is continuously being improved by contributions from users at several universities and government laboratories.
- It is supported by several pre- and post-processing programs, which are referred to collectively as the MM5 modeling system.
- It is freely provided and supported by the Mesoscale Prediction Group in the Mesoscale and Microscale Meteorology Division, NCAR.
- 		_[http://www.mmm.ucar.edu/mm5/mm5-home.html](http://www.mmm.ucar.edu/mm5/mm5-home.html)_

- Continue ...

**Notes:**
 When the horizontal scale becomes smaller than the vertical scale, the nonhydrostatic dynamics can not be neglected. The nonhydrostatic part is associated with pressure changes arising from velocity fluctuations. P = Ph + q; q=(
(2) Hydrostatic Equilibrium dP = - ro.g.dz The model was hydrostatic since typical horizontal grid size in mesoscale models are comparable to vertical depth of features of interest. In such case pressure is determined by the overlying air mass.

## MM5 Modeling System    

- Since its introduction in 1978, it has undergone many changes
- (i) a multiple-nest capability
- (ii) nonhydrostatic dynamics, which allows the model to be used at a few-kilometer scale
- (iii) multitasking capability on shared- and distributed-memory machines
- (iv) a four-dimensional data-assimilation1 capability
- (v) more physics options.

**Notes:**
(1) Data assimilation is essentially an objective analysis (sequential estimation or inverse methods) that combines data with a numerical model to produce first a better estimate of fluid state and then a prediction of later behavior.

## Content

- 		Part 1
- Flow chart of the model
- 	   - Additional features
- Vertical and Horizontal grids
- Nesting
- Main Programs
- 	- Terrain
- 	- Regrid
- 	- Objective An.(little_r)
- 	- Interpf
- 	- MM5
- Physics options (ch 8.3)
- 	- Interactions

- 		Part 2
- Nestdown
- Interpb
- Land cover categories (LU, Veg, soil) and Physics
- NOAH Land Surface Model
- 	http://www.emc.ncep.noaa.gov/mmb/gcp/noahlsm/README_2.2.htm
- Reanalysis data
- 	ECMWF; 	NCEP

## 	Part 1

- Terrestrial and isobaric meteorological data are horizontally interpolated (TERRAIN and REGRID) from a regular to a variable high-resolution on several map projections.
- Since the interpolation does not provide mesoscale detail, the interpolation may be enhanced (RAWINS or little_r) with observations using objective analysis (successive-scan, multiquadric ).
- Program INTERPF performs the vertical interpolation from pressure to the sigma coordinate levels .
- MM5 is a regional model. It requires an initial and lateral boundary condition to run.
- To produce lateral BC for a model run, one needs gridded data for the entire time period of model integration.

**Notes:**
NOTES: 
1. The flow chart show the order of the programs and and flow of the data
2. All Documentation is available online at  the MM5 web page

## MM5 Additional features

- Globally re-locatable
- Map projections: Polar stereographic; Lambert conformal; Mercator.
- Variable resolution
- Terrain elevation, landuse, soil type, and other datasets are provided at fine resolution (USGS, 30sec).
- Flexible and multiple nesting can be configured to run from global scale down to cloud scale in one model.
- Terrain-following vertical coordinates.

- Choices of advanced physical parameterization.
- Four-dimensional data assimilation system via nudging.
- The MM5 runs on various computer platforms:
- Cray, SGI, IBM, Alpha, Sun,HP, and PCs running Linux.
- Parallelization: Cray (EL, J90, YMP), HP-SPP2000, SGI, SUN, Alpha, and Linux

## Vertical grid

- The model gets and analyzes its data on pressure surfaces, which are interpolated to a nondimensional vertical coordinate σ
- lower σ levels **follow the terrain** while the upper surface is flat.
- Intermediate levels progressively flatten as the pressure decreases toward the chosen top pressure. Sigma is defined as
- p is the pressure, p*t* is a specified constant top pressure, p*s* is the surface pressure.
- 	P = P**h** + P**nh**	P = P(vel.changes)

**Notes:**
NOTE
1. Vertical levels may vary from ten to forty but there is no limit in principle. 

## Horizontal grid

- The horizontal grid has an Arakawa-Lamb B-staggering of the velocity variables with respect to the scalars.
- The scalars (T, q etc.) are defined at the center of the grid square, while the eastward (u) and northward (v) velocity components are collocated at the corners.
- The center points of the grid squares are referred to as cross points, and the corner points are dot points.
- Hence horizontal velocity is defined at dot points. Preprocessors do the interpolations to assure consistency with the grid.

## Nesting

- Multiple nesting with up to nine domains running at the same time and completely interacting.
- Multiple nests are allowed on a given level of nesting (domains 2 and 3), and they are also allowed to overlap.
- Domain 4 is at the third level, meaning that its grid size and time step are nine times less than for domain 1.
- Nests may be turned on and off at any time in the simulation, and moving a domain is also possible during a simulation.

- Nesting ratio is always 3:1 for two-way Interaction.
- Two-way means that the nest's input from the coarse mesh comes via its boundaries, while the feedback to the coarser mesh occurs over the nest interior.

**Notes:**
NOTES
1. Whenever a mother nest is terminated all its descendent nests also are turned off.

## Terrain

- TERRAIN begins any complete forecast simulation in MM5 modeling system is.
- This program horizontally interpolates (or analyzes) the regular *latitude -longitude* terrain elevation and vegetation (land use) onto the chosen mesoscale domains.
-  If the Land-Surface Model (LSM) will be used, additional fields such as soil types, vegetation fraction, and annual deep soil temperature will also be generated.

- TERRAIN performs two tasks
- 1. Set up mesoscale domains: coarse and fine grids
- 2. Produce terrestrial data fields for all of the mesoscale domains, which will first be used by REGRID, and later by MM5 and NESTDOWN. Computes a few constant fields ( coriolis, lat, lon, map scale factor)

- Continue ...

## Terrain

- TERRAIN is composed of four parts:
- 1. Source data input
- 2. Interpolation from lat/long source data to mesoscale grid;
- 3. Nest interface adjustment and feed back;
- 4. Output terrain elevation, land use and other terrestrial data in MM5 format.

- Continue ...

## Terrain

- The data available as input to the program TERRAIN include terrain elevation, landuse/vegetation, land-water mask, soil types, vegetation fraction and deep soil temperature.
- Since the original data come from different sources, they have different formats and layouts. These data sets are translated to a standard format which is used by the TERRAIN program.

**Elevation:** **Terrain Height **
- Land Use

| Resolut | Source | Coverage | Size
MB |
| --- | --- | --- | --- |
| 1deg
111km | USGS | Global | .13 |
| 10 min
18.5 km | USGS | Global | 4.7 |
| 2 min
3.7 | USGS | Global | 116 |
| 30 sec
.925 km | USGS | Global | 1866 |

| Resolut | Source | Coverage | Size
MB |
| --- | --- | --- | --- |
| 1 deg | PSU/NCAR | Global | .84 |
| 30 min | PSU/NCAR | Global | 3.4 |
| 10 min | PSU/NCAR | Global | 30.3 |

## Regrid

**Purpose**
- To read gridded meteorological analyses and forecasts on pressure levels and interpolate them to the horizontal grid and map projection as defined by the preprocessor program TERRAIN.
- To handle pressure-level and surface analyses. 2D interpolation is performed on these levels.
- To takes input from TERRAIN, and creates files for RAWINS, LITTLE_R, or INTERPF.
- These outputs are used as the first guess to an objective analysis (RAWINS or LITTLE_R), or as analyses which are to be directly interpolated to the MM5 model levels for initial and boundary conditions for MM5 (INTERPF).

- Continue ...

## Regrid handle various tasks 

- 	**1) Data input (reading original meteorological analyses)**
- 	**2) Interpolation to MM5 grid.**
- Data input is handled by the programs known as "pregrid", and the interpolation to the MM5 grid by "regridder".
- The pregrid tasks are further subdivided into programs to read specific data formats, while regridder tasks are managed in a single program.
- The users can easily write their own data input programs and provide it to the MM5 Modeling System.

**Pregrid programs** can read many data sets in GRIB format, and non-GRIB data sets. They also expect to find tables which tell them what fields to access from the input files.
- The **regridder** program expects to find from pregrid: temperature, U,V wind, relative humidity, height of pressure levels, SLP, SST, and snow-cover data. Other fields may be used and passed on to the rest of the modeling system.
- You should **verify** that the files to regridder contain the necessary fields. To verify, run regridder and see error messages

## Regrid Input data

- Common analyses include:
- 	NCEP GDAS
- 	NCEP/NCAR Reanalysis
- 	NCEP EDAS
- 	ECMWF Reanalysis
- Users must to get gridded analyses or forecasts.
** **
- Real-time analyses and forecasts include:
- 	 NCEP ETA analysis and forecast
- 	 NCEP AVN analysis and forecast
-      http://www.emc.ncep.noaa.gov/data

- NCEP/NCAR Reanalysis: global analysis beginning in 1948
- 	http://www.cdc.noaa.gov/cdc/reanalysis/reanalysis.shtml
- ECMWF-ERA: 40 Years Re-Analysis, monthly daily fields
- 	http://data.ecmwf.int/data/d/era40_daily/

## Objective Analysis (little_r) 

**Purpose**
- The goal is to improve meteorological analyses (the *first guess* ) on the mesoscale grid by incorporating information from observations.
- These observations have been "direct" but today remote sensed data are available for researchers and operational modelers.
- Effective use of these indirect observations for objective analysis is not a trivial task.
- Methods commonly employed for satellite and direct observations include "3DVAR" and "4DVAR“ variational techniques.

- A recent additon is the 3DVAR package, which allows for variational assimilation of both direct observations and indirect observations.
- LITTLE_R and RAWINS include:
- Cressman-style or Multiquadric objective analysis.
- To screen the data for suspect observations (quality control).
- Procedures to input bogus data.
- Expanded Grid: to incorporate data from outside your grid to improve analyses near the boundaries.

- Continue ...

## Objective Analysis (little_r)

- Output from the objective analysis programs is used to:
- Provide fields for Initial and Boundary conditions (to INTERPF).
- Provide 3-d fields for analysis-nudging FDDA (through program INTERPF).
- Provide surface fields for surface-analysis-nudging FDDA.

**Cressman Scheme** successive scans nudge a first-guess field toward the observations.
**Ellipse Scheme**In analyses of wind and relative humidity (fields strongly deformed by the wind) at pressure levels, the circles from the standard Cressman scheme are elongated into ellipses oriented along the flow.

## INTERPF 

**Purpose**
- To handles the data transformation required to go from the analysis programs to the mesoscale model.
- This need vertical interpolation, diagnostic computation, and data reformatting.
- INTERPF takes REGRID, RAWINS, LITTLE_R, or INTERPB output data as input to generate a model initial, lateral boundary condition and a lower boundary condition.

- Continue ...

## INTERPF 

**Surface Pressure Computation implies**
- first guess , extrapolation, correction of temperature
- That is used for hydrostatic and then nonhydrostatic calculations

**Procedure**
- input LITTLE_R, RAWINS, REGRID, or INTERPB data
- pressure level Qv for Psfc
- interpolate variables from pressure coordinates to hydrostatic s
- u, v, RH: linear in pressure
- theta: linear in ln pressure
- remove integrated mean divergence
- compute base state
- compute w
- re-interpolate u, v, t, Qv
- compute perturbation pressure
- save Tsfc and SST for daily mean for lower boundary file
- output current data for boundary file
- output interpolated data for initial conditions
- output data for lower boundary file

**Notes:**
There are 3 primary binary output files from the INTERPF: 
	1 MMINPUT_DOMAINn file contains the time dependent 3D and 2D fields, such as wind, temp, moisture and pressure. 
	2 BDYOUT_DOMAINn file contains the lateral boundaries of the 3D fields 
	3 LOWBDY_DOMAINn file contains either daily means of, or time-varying surface temperature 

## MM5

**	****Purpose**
- This is the numerical weather prediction part of the modeling system.
- MM5 can be used for a broad spectrum of theoretical and real-time studies, including applications of both predictive simulation and 4D data assimilation to monsoons, hurricanes, and cyclones.
- On the smaller scales (2-200 km), MM5 can be used for studies involving mesoscale convective systems, fronts, land-sea breezes, mountain-valley circulations, and urban heat islands.

**	****	**
**Basic Equations of MM5**
- In terrain following coord (x, y, *s* ), these are the equations for the nonhydrostatic model's basic variables excluding moisture.  **Equations**
**	****	**

## MM5: Physics Options

- Cumulus parameterizations (ICUPA): allows different schemes of cumulus formation considering updraft, downdraft, entrainment, detrainment, compensating subsidence which also control heating profile, rainfall efficiency depending on the scale and grid size.
- PBL Schemes (IBLTYP): Planetary boundary layer options dealing with processes of atmospheric vertical mixing (exchange of energy and vapor), turbulence (TKE).
- Explicit Moisture Schemes (IMPHYS): allow to set microphysics processes which control nonconvective precipitation, cloud and rain water, snow, ice and hail processes among others.
- Radiation Schemes (IFRAD): set radiative processes to take place by predicting temperature profiles, short and long wave irradiances and interactions through clouds.
- Surface Schemes (ISOIL): Define the behavior of ground temperature and soil moisture considering water and energy exchange between soil and low surface layer.

## Interactions of Parameterizations 

## Boundary conditions

**Lateral boundary conditions (IBOUDY)**
**0. Fixed - **This will not allow time variation at lateral boundaries. Not recommended for real-data applications.
**2. Time-dependent/Nest - **Outer two rows and columns have specified values of all predicted fields. Recommended for nests where time-dependent values are supplied by the parent domain. Not recommended for coarse mesh where only one outer row and column would be specified.
**3. Relaxation/inflow-outflow - **Outer row and column is specified by time-dependent value, next four points are relaxed towards the boundary values with a relaxation constant that decreases linearly away from the boundary.
**Lower boundary conditions**
- The LOWBDY_DOMAINx file provides sea-surface temperature, substrate temperature, and optionally snow cover and sea-ice. The switch ISSTVAR allows multiple times in this file (created by INTERPF) to be read in as the model runs, which is the method of updating these fields in long-term simulations.
**Upper boundary condition (IFUPR)**
**0. No upper boundary condition - **Rigid lid with no vertical motion at the model top. This may be preferable for very coarse mesh simulations (50 km or more grids).
**1. Upper radiative condition -**Top vertical motion calculated to reduce reflection of energy from the model top preventing some spurious noise or energy build-up over topography. This is recommended for grid-lengths below 50 km. It works better for hydrostatic gravity wave scales, rather than inertial or nonhydrostatic scales.

## Part 2: 

- 	**NESTDOWN**** **
- This program horizontally interpolates *s-*coordinate data, from coarse to a fine grid.
- Modifying the number of vertical levels to increase vertical resolution to complement a finer horizontal grid. The **input** data is on a *s-*coordinate, either output from the mesoscale model or the initial condition file for model input. The output remains on the *s-*coordinate.
- This program **requires** that the fine grid TERRAIN data be made available as input.
- There are several advantages when it is used from coarse to higher resolution:
- 	1) the model has lateral boundary conditions that use consistent physics
- 	2) the lateral boundary conditions are available at a relatively high temporal frequency;
- 	3) the vertical structure of the atmosphere is not significantly modified through vertical interpolation. Without the inclusion of observations, though, the model is able to drift.

## INTERPB 

**Purpose**
- Handles the data transformation required to go from the mesoscale model on *s* coordinates back to pressure levels.
- This program only handles vertical interpolation and a few diagnostics.
- The output from this program is suitable for input to REGRIDDER (to re-grid a model forecast), LITTLE_R (for pressure-level re-analysis), INTERPF (for pressure to *s* interpolation for generating model input) and GRAPH (for visualization and diagnostic computation).
- In practice, much of the post-analysis performed with MM5 data is done interactively with diagnostic and visualization tools that can handle simple vertical coordinate transformations on-the-fly.
- input model input or model output data (INTERPF, NESTDOWN, MM5)

- compute total pressure on dot and cross points
- compute RH and Z on *s* levels
- compute 2D fields on both staggerings: surface pressure, sea level pressure, latitude, longitude, "computationally expedient" surface pressure
- extrapolate below ground and above top *s* surface

## Land cover categories and Physics

- Table 4.2a Description of 13-category (PSU/NCAR) land-use categories and physical parameters
- Table 4.2b Description of 17-category (SiB) vegetation categories and physical parameters
- Table 4.2c Description of 25-category (USGS) vegetation categories and physical parameters for N.H. summer (15 April - 15 October) and winter (15 October - 15 April).

## NOAH Land Surface Model

- This LSM simulates soil moisture (both liquid and frozen), soil temperature, skin temperature, snowpack depth, snowpack water equivalent (and hence snowpack density), canopy water content, and the energy flux and water flux terms of the surface energy balance and surface water balance.
**How to Set Program Switches to Run LSM**
**Terrain - **In *terrain.deck*, set namelist variable **LSMDATA = .T.,** and select values 1 or 2 for VEGTYPE.
**	****set NewLandUseOnly = FALSE **
**	****set LandSurface = TRUE a**nd either  **set VegType = USGS **or **set VegType = SiB**
- The rest of the *terrain.deck* is the same.) Note that SiB data is only available for North America, but these categories corresepond to those used in the Eta model's operational LSM. Also, note that the SiB classification lacks an `urban' category.
- These setups will make use of the terrestrial datasets to create the following additional fields on the model grid in the *TERRAIN* output:
- 1. *VEGFRCnn* (nn=1,12): vegetation fraction monthly climatology
- 2. *TEMPGRD*: annual mean ground temp adjusted to model terrain elevation
- 3. *SOILINDX*: dominant soil type (currently 30" over US, 5-minutes elsewhere)

## NOAH LSM flow chart 

- To use the Noah LSM option, the MM5 model requires several additional input fields. The Version 3 *TERRAIN* program provides an annual-mean deep soil temperature adjusted to model terrain elevation, a monthly climatological vegetation fraction, dominant soil type, and dominant vegetation type in each grid cell. All of the inputs to the *TERRAIN* program are provided by mesouser.

## Reanalysis data:		

- The ERA-40 data set corresponds to the version of ECMWF reanalysis which uses variational data assimilation system and improved forecast models to provide global distribution of in-situ and remotely sensed data since mid-1957 with time and spatial resolution data of 6 hours and 125 km respectively. Simmons and Gibson (2000) describe this updated version of the ECMWF reanalysis. The European Centre for Medium-Range Weather Forecasts (ECMWF, the Centre) is an international organisation supported by 25 European States.
- The NCEP/NCAR Reanalysis 1 project is using a state-of-the-art analysis/forecast system to perform data assimilation using past data from 1948 to the present. A large subset of this data is available from CDC in its original 4 times daily format and as daily averages. However, the data from 1948-1957 is a little different, in the regular (non-Gaussian) gridded data. That data was done at 8 times daily in the model, because the inputs available in that era were available at 3Z, 9Z, 15Z, and 21Z, whereas the 4x daily data has been available at 0Z, 6Z, 12Z, and 18Z. These latter times were forecasted and the combined result for this early era is 8x daily. The local ingestion process took only the 0Z, 6Z, 12Z, and 18Z forecasted values, and thus only those were used to make the daily time series and monthly means here.

## ECMWF-ERA40 and NCEP ReanalysisLatest versions

- They are using state of the art data assimilation system considering a mix of satellite-observation-modeling data for a period of 5 decades.
- Reanalysis data from ECMWF and NCEP represents important tools to validate GCM modeling outputs and input data for regional models.
- They have been improved and successfully compared to several global and regional observations during at least last decade.
- They are very well documented free data available at:
- 		http://data.ecmwf.int/data/d/era40_daily/
- 		http://www.cdc.noaa.gov/cdc/reanalysis/reanalysis.shtml

## Reanalysis data basic features

- 	The ECMWF 40 years re-analysis (ERA40)uses data assimilation and in-situ and remotely-sensed measurements since 1957- to Aug-2002 with 6 hours time resolution, 125 km horizontal resolution and 60 levels. There are available other resolution for this data set, like the 2.5 degree monthly means with 17 Standard pressure levels.
- 	The NCEP/NCAR Reanalysis uses state-of-the-art data assimilation system  to build 8 times daily data since 1948 to present with T62 (192x94, for flux related variables: long and shorth wave rad.) grid or 2.5x2.5 degrees (pressure and surface data). 17 sigma pressure levels.

## Regional Modeling and Reanalysis variables of interest

|  | NCEP | ERA40 |
| --- | --- | --- |
| Volum. Soil Moist. | Surf. Flux. Data:
   Soil Moist 0-10cm,  
  10cm-200cm | Surface :
  Volumetric soil water 
   (4 layers) |
| Rainfall rate | Surf. Flux. Data:
   Precipitation rate
   Convec. Precip. | Surface :
   Convective precip.
    Total precipit. |
| Air Temp. (2m) | Surf. Flux. Data:
   | Surface:
  2m Temp. and Dew Point. |
| Surface Rainfall | Surface Data:
Precipitable water |  |