WRF学习之 ch5 WRF模式（九）运行WRF：物理和动力选项，选项的总结

Physics and Dynamics Options
Physics Options
WRF offers multiple physics options that can be combined in any way. The options typically range from simple and efficient, to sophisticated and more computationally costly, and from newly developed schemes, to well-tried schemes such as those in current operational models.

The choices vary with each major WRF release, but here we will outline those available in WRF Version 3 and 4.

  1. Microphysics (mp_physics)

a. Kessler scheme: A warm-rain (i.e. no ice) scheme used commonly in idealized cloud modeling studies (mp_physics = 1).

b. Purdue Lin scheme: A sophisticated scheme that has ice, snow and graupel processes, suitable for real-data high-resolution simulations (2).

c. WRF Single-Moment 3-class scheme: A simple, efficient scheme with ice and snow processes suitable for mesoscale grid sizes (3).

d. WRF Single-Moment 5-class scheme: A slightly more sophisticated version of (c) that allows for mixed-phase processes and super-cooled water (4).

e. Eta microphysics: The operational microphysics in NCEP models. A simple efficient scheme with diagnostic mixed-phase processes. For fine resolutions (< 5km) use option (5) and for coarse resolutions use option (95).

f. WRF Single-Moment 6-class scheme: A scheme with ice, snow and graupel processes suitable for high-resolution simulations (6).

g. Goddard 4-ice microphysics scheme (7) predicts hail and graupel separately, provides effective radii for radiation. Replaced older Goddard scheme in V4.1.

h. New Thompson et al. scheme: A new scheme with ice, snow and graupel processes suitable for high-resolution simulations (8). This adds rain number concentration and updates the scheme from the one in Version 3.0. New in Version 3.1.

i. Milbrandt-Yau Double-Moment 7-class scheme (9). This scheme includes separate

categories for hail and graupel with double-moment cloud, rain, ice, snow, graupel and hail. New in Version 3.2. (Note: Do not use this scheme in V3.6 and V3.6.1.)

j. Morrison double-moment scheme (10). Double-moment ice, snow, rain and graupel for cloud-resolving simulations. New in Version 3.0.

k. CAM V5.1 2-moment 5-class scheme.

l. Stony Brook University (Y. Lin) scheme (13). This is a 5-class scheme with riming intensity predicted to account for mixed-phase processes. New in Version 3.3.

m. WRF Double-Moment 5-class scheme (14). This scheme has double-moment rain. Cloud and CCN for warm processes, but is otherwise like WSM5. New in Version 3.1.

n. WRF Double-Moment 6-class scheme (16). This scheme has double-moment rain. Cloud and CCN for warm processes, but is otherwise like WSM6. New in Version 3.1.

o. NSSL 2-moment scheme (17, 18). New since Version 3.4, this is a two-moment scheme for cloud droplets, rain drops, ice crystals, snow, graupel, and hail. It also predicts average graupel particle density, which allows graupel to span the range from frozen drops to low-density graupel. There is an additional option to predict cloud condensation nuclei (CCN, option 18) concentration (intended for idealized simulations). The scheme is intended for cloud-resolving simulations (dx <= 2km) in research applications. Since V3.5, two more one-moment schemes have been added (19 and 21). Option 19 is a single-moment version of the NSSL scheme, and option 21 is similar to Gilmore et al. (2004). Option 22 (new in V3.7) is the two moment scheme (option 17) without hail.

p. WSM7 (24). As WSM6, but adding a hail category. New in V4.1.

q. WDM7 (26). As WDM6, but adding a hail category. New in V4.1.

r. Thompson aerosol-aware (28). This scheme considers water- and ice-friendly aerosols. A climatology dataset may be used to specify initial and boundary conditions for the aerosol variables (Thompson and Eidhammer, 2014, JAS.) New in Version 3.6. A surface dust scheme is added in Version 4.0.

s. HUJI (Hebrew University of Jerusalem, Israel) spectral bin microphysics, full (32) and ‘fast’ (30) versions are available since Version 3.6.

t. Morrison double-moment scheme with CESM aerosol (40): must be used together with MSKF cumulus scheme. New in Version 4.0.

u. P3 (Morrison and Milbrandt) (50, 51, 52): Predicted Particle Property scheme. This has one ice category that represents a combination of ice, snow and graupel, and also carries prognostic arrays for rimed ice mass and rimed ice volume. Double moment rain and ice (50). P3-nc (51): As P3 but adds supersaturation dependent activation and double-moment cloud water. New in V3.9. P3-2ice (52): As in P3-nc but with two arrays for ice. New in V4.0.

v. Jensen ISHMAEL (55): Scheme that predicts particle shapes and habits in ice crystal growth. New in V4.1.

2.1 Longwave Radiation (ra_lw_physics)

a. RRTM scheme (ra_lw_physics = 1): Rapid Radiative Transfer Model. An accurate scheme using look-up tables for efficiency. Accounts for multiple bands, and microphysics species. For trace gases, the volume-mixing ratio values for
CO2=330e-6, N2O=0. and CH4=0. in pre-V3.5 code; in V3.5, CO2=379e-6, N2O=319e-9 and CH4=1774e-9. See section 2.3 for time-varying option.

b. GFDL scheme (99): Eta operational radiation scheme. An older multi-band scheme with carbon dioxide, ozone and microphysics effects.

c. CAM scheme (3): from the CAM 3 climate model used in CCSM. Allows for aerosols and trace gases. It uses yearly CO2, and constant N2O (311e-9) and CH4 (1714e-9). See section 2.3 for the time-varying option.

d. RRTMG scheme (4): A new version of RRTM added in Version 3.1. It includes the MCICA method of random cloud overlap. For major trace gases, CO2=379e-6, N2O=319e-9, CH4=1774e-9. See section 2.3 for the time-varying option. In V3.7, a fast version is introduced as option 24.

e. Goddard scheme (5). Efficient, multiple bands, ozone from simple climatology. Designed to run with Goddard microphysics particle radius information. Updated in V4.1.

f. Fu-Liou-Gu scheme (7). multiple bands, cloud and cloud fraction effects, ozone profile from climatology and tracer gases. CO2=345e-6. New in Version 3.4.

g. RRTMG-K scheme (14): A version of RRTMG scheme improved by Baek (2017), A revised radiation package of G-packed McICA and two-stream approximation: Performance evaluation in a global weather forecasting model, J. Adv. Model. Earth Syst., 9, doi:10.1002/2017MS000994). New in V4.0.

2.2 Shortwave Radiation (ra_sw_physics)

a. Dudhia scheme: Simple downward integration allowing efficiently for clouds and clear-sky absorption and scattering (ra_sw_physics = 1).

b. Goddard shortwave: Two-stream multi-band scheme with ozone from climatology and cloud effects (2).

c. GFDL shortwave: Eta operational scheme. Two-stream multi-band scheme with ozone from climatology and cloud effects (99).

d. CAM scheme: from the CAM 3 climate model used in CCSM. Allows for aerosols and trace gases (3).

e. RRTMG shortwave. A new shortwave scheme with the MCICA method of random cloud overlap (4). New in Version 3.1. In V3.7, a fast version is introduced as option 24.

f. Goddard scheme (5). Efficient, multiple bands, ozone from simple climatology. Designed to run with Goddard microphysics particle radius information. Updated in V4.1.

g. Fu-Liou-Gu scheme (7). multiple bands, cloud and cloud fraction effects, ozone profile from climatology, can allow for aerosols. New in Version 3.4.

h. Held-Suarez relaxation. A temperature relaxation scheme designed for idealized tests only (31).

i. RRTMG-K (14): A version of RRTMG scheme improved by Baek (2017). New in V4.0.

Related options:

  • Slope and shading effects. slope_rad = 1 modifies surface solar radiation flux according to terrain slope. topo_shading = 1 allows for shadowing of neighboring grid cells. Use only with high-resolution runs with grid size less than a few kilometers. Since Version 3.2, these are available for all shortwave options.

  • swrad_scat: scattering turning parameter for ra_sw_physics = 1. Default value is 1, which is equivalent to 1.e-5 m2/kg. When the value is greater than 1, it increases the scattering.

  • swint_opt: Interpolation of short-wave radiation based on the updated solar zenith angle between SW calls. Available since V3.5.1.

2.3 Input to radiation options

a. CAM Green House Gases: Provides yearly green house gases from 1765 to 2500. The option is activated by compiling WRF with the macro –DCLWRFGHG added in configure.wrf. Once compiled, CAM, RRTM and RRTMG long-wave schemes will see these gases. Five scenario files are available: from IPCC AR5: CAMtr_volume_mixing_ratio .RCP4.5, CAMtr_volume_mixing_ratio.RCP6, and CAMtr_volume_mixing_ratio.RCP8.5; from IPCC AR4: CAMtr_volume_mixing_ratio.A1B, and CAMtr_volume_mixing_ratio.A2. The default points to the RCP8.5 file. New in Version 3.5.

b. Climatological ozone and aerosol data for RRTMG: The ozone data is adapted from CAM radiation (ra_*_physics=3), and it has latitudinal (2.82 degrees), height and temporal (monthly) variation, as opposed to the default ozone used in the scheme that only varies with height. This is activated by the namelist option o3input = 2, which becomes the default option in V3.7. The aerosol data is based on Tegen et al. (1997), which has 6 types: organic carbon, black carbon, sulfate, sea salt, dust and stratospheric aerosol (volcanic ash, which is zero). The data also has spatial (5 degrees in longitude and 4 degrees in latitudes) and temporal (monthly) variations. The option is activated by the namelist option aer_opt = 1. New in Version 3.5.

c. Aerosol input for RRTMG and Goddard radiation options (aer_opt = 2). Either AOD or AOD plus Angstrom exponent, single scattering albedo, and cloud asymmetry parameter can be provided via constant values from namelist or 2D input fields via auxiliary input stream 15. Aerosol type can be set too. New in V3.6.

d. Aerosol input for RRTMG radiation scheme from climatological water- and ice-friendly aerosols (aer_opt = 3). It works with Thompson microphysics option 28. New in V3.8.

e. Effective cloud water, ice and snow radii from Thompson (since 3.5.1), WSM, WDM and NSSL microphysics schemes (new in V3.7) are used in RRTMG.

2.4 Cloud fraction option

icloud: = 1, use Xu-Randall method; = 2, use threshold method which gives either 0 or 1 cloud fraction; = 3, use a RH-based method that follows Sundqvist et al. (1989). The threshold of RH depends on grid sizes (new in V3.7, fixed in V3.8, further tuned in V3.9).

3.1 Surface Layer (sf_sfclay_physics)

a. MM5 similarity: Based on Monin-Obukhov with Carslon-Boland viscous sub-layer and standard similarity functions from look-up tables (sf_sfclay_physics = 91). In V3.7, the thermal and moisture roughness lengths (or exchange coefficients for heat and moisture) over ocean are changed to COARE 3 formula (Fairall et al. 2003)

b. Eta similarity: Used in Eta model. Based on Monin-Obukhov with Zilitinkevich thermal roughness length and standard similarity functions from look-up tables (2).

c. Pleim-Xiu surface layer. (7). New in Version 3.0.

d. QNSE surface layer. Quasi-Normal Scale Elimination PBL scheme’s surface layer option (4). New in Version 3.1.

e. MYNN surface layer. Nakanishi and Niino PBL’s surface layer scheme (5). New in Version 3.1.

f. TEMF surface layer. Total Energy – Mass Flux surface layer scheme. New in Version 3.3.

g. Revised MM5 surface layer scheme (option 11 prior to V3.6, renamed to option 1 since V3.6): Remove limits and use updated stability functions. New in Version 3.4. (Jimenez et al. MWR 2012). In V3.7, the code is sped up to give similar timing as with the old MM5 scheme. The thermal and moisture roughness lengths (or exchange coefficients for heat and moisture) over ocean are changed to COARE 3 formula (Fairall et al. 2003) in V3.7.

h. Other: iz0tlnd = 1 (works with sf_sfclay_physics = 1, 91, and 5), Chen-Zhang thermal roughness length over land, which depends on vegetation height, 0 = original thermal roughness length in each sfclay option. New in Version 3.2.

3.2 Land Surface (sf_surface_physics)

a. (1)5-layer thermal diffusion: Soil temperature only scheme, using five layers.

b. (2) Noah Land Surface Model: Unified NCEP/NCAR/AFWA scheme with soil temperature and moisture in four layers, fractional snow cover and frozen soil physics. New modifications are added in Version 3.1 to better represent processes over ice sheets and snow covered area.

  • In V3.6, a sub-tiling option is introduced, and it is activated by namelist sf_surface_mosaic = 1, and the number of tiles in a grid box is defined by namelist mosaic_cat, with a default value of 3.

    c. (3) RUC Land Surface Model: This model has a layer approach to the solution of energy and moisture budgets in that the atmospheric fluxes, as well as soil fluxes, are computed in the middle of the first atmospheric layer and the top soil layer, respectively, and these fluxes modify the heat and moisture storage in the layer spanning the ground surface. The RUC LSM currently uses 9 levels in soil with higher resolution near the interface with the atmosphere. (NOTE: if initialized from the model with low resolution near the surface, like the Noah LSM, the top levels could be too moist causing moist/cold biases in the model forecast. Solution: cycle soil moisture and let it spin-up for at least several days to fit the vertical structure of RUC LSM).

The prognostic variable for soil moisture is volumetric soil moisture content minus the residual soil moisture tied to soil particles and therefore not participating in moisture transport. The RUC LSM takes into account freezing and thawing processes in the soil. It is able to use the explicit mixed-phase precipitation provided by the cloud microphysics schemes. It has a simple treatment of sea ice which solves heat diffusion in sea ice and allows evolving snow cover on top of sea ice. In the warm season, RUC LSM corrects soil moisture in the cropland areas to compensate for irrigation in these regions.

Snow, accumulated on top of soil, can have up to two layers depending on snow depth (ref S16). When snow layer is very thin, it is combined with the top soil layer to avoid excessive radiative cooling at night. The grid cell can be partially covered with snow, when snow water equivalent is below a threshold value of 3 cm. When this condition occurs, surface parameters, such as roughness length and albedo, are computed as a weighted average of snow-covered and snow-free areas. The energy budget utilizes an iterative snow melting algorithm. Melted water can partially refreeze and remain within the snow layer, and the rest of it percolates through the snow pack, infiltrates into soil and forms surface runoff. Snow density evolves as a function of snow temperature, snow depth and compaction parameters. Snow albedo is initialized from the maximum snow albedo for the given vegetation type, but it can also be modified depending on snow temperature and snow fraction. To obtain a better representation of snow accumulated on the ground, the RUC LSM has introduced estimation of frozen precipitation density.

The most recent modifications to RUC LSM include refinements to the interception of liquid or frozen precipitation by the canopy, and also the “mosaic” approach for patchy snow with a separate treatment of energy and moisture budgets for snow-covered and snow-free portions of the grid cell, and aggregation of the separate solutions at the end of time step.

The datasets needed to initialize RUC LSM include:

  1. High-resolution dataset for soil and land-use types;

  2. Climatological albedo for snow-free areas;

  3. Spatial distribution of maximum surface albedo in the presence of snow cover;

  4. Fraction of vegetation types in the grid cell to take into account sub-grid-scale heterogeneity in computation of surface parameters;

  5. Fraction of soil types within the grid cell;

  6. Climatological greenness fraction;

  7. Climatological leaf area index;

  8. Climatological mean temperature at the bottom of soil domain;

  9. Real-time sea-ice concentration;

  10. Real-time snow cover to correct cycled in RAP and HRRR snow fields.

The recommended namelist options:

sf_surface_physics = 3

num_soil_layers = 9,

usemonalb = .true.,

rdlai2d = .true.,

mosaic_lu = 1

mosaic_soil = 1

References:

Smirnova et al (2016, Mon. Wea. Rev., S16);

RAP and HRRR that use RUC LSM as their land component: https://rapidrefresh.noaa.gov/RAP and https://rapidrefresh.noaa.gov/hrrr/HRRR.

(from Tanya Smirnova, GSD/NOAA)

d. (7) Pleim-Xiu Land Surface Model. For a more detailed description of the PX LSM, including pros/cons, best practices, and recent improvements, see http://www2.mmm.ucar.edu/wrf/users/docs/PX-ACM.pdf

Two-layer scheme with vegetation and sub-grid tiling (7). New in Version 3.0: The Pleim-Xiu land surface model (PX LSM; Pleim and Xiu 1995; Xiu and Pleim 2001) was developed and improved over the years to provide realistic ground temperature, soil moisture, and surface sensible and latent heat fluxes in mesoscale meteorological models. The PX LSM is based on the ISBA model (Noilhan and Planton 1989), and includes a 2-layer force-restore soil temperature and moisture model. the top layer is taken to be 1 cm thick, and the lower layer is 99 cm. Grid aggregate vegetation and soil parameters are derived from fractional coverage of land use categories and soil texture types. There are two indirect nudging schemes that correct biases in 2-m air temperature and moisture by dynamic adjustment of soil moisture (Pleim and Xiu, 2003) and deep soil temperature (Pleim and Gilliam, 2009).

Users should recognize that the PX LSM was primarily developed for retrospective simulation, where surface-based observations are available to inform the indirect soil nudging. While soil nudging can be disabled using the FDDA namelist.input setting "pxlsm_soil_nudge," little testing has been done in this mode, although some users have reported reasonable results. Gilliam and Pleim (2010) discuss the implementation in the WRF model and provide typical configurations for retrospective applications. If soil nudging is activated, modelers must use the Obsgrid objective re-analysis utility to produce a surface nudging file with the naming convention "wrfsfdda_d0." Obsgrid takes WPS "met_em" files and LittleR observation files and produces the "wrfsfdda_d0" file. The PX LSM uses 2-m temperature and mixing ratio re-analyses from this file for the deep soil moisture and temperature nudging. If modelers want to test PX LSM in forecast mode with soil nudging activated, forecasted 2-m temperature and mixing ratio can be used with empty observation files to produce the "wrfsfdda_d0" files, using Obsgrid, but results will be tied to the governing forecast model.

f. (4) Noah-MP (multi-physics) Land Surface Model: uses multiple options for key land-atmosphere interaction processes. Noah-MP contains a separate vegetation canopy defined by a canopy top and bottom with leaf physical and radiometric properties used in a two-stream canopy radiation transfer scheme that includes shading effects. Noah-MP contains a multi-layer snow pack with liquid water storage and melt/refreeze capability and a snow-interception model describing loading/unloading, melt/refreeze, and sublimation of the canopy-intercepted snow. Multiple options are available for surface water infiltration and runoff, and groundwater transfer and storage including water table depth to an unconfined aquifer. Horizontal and vertical vegetation density can be prescribed or predicted using prognostic photosynthesis and dynamic vegetation models that allocate carbon to vegetation (leaf, stem, wood and root) and soil carbon pools (fast and slow). New in Version 3.4. (Niu et al. 2011)

g. (8) SSiB Land Surface Model: This is the third generation of the Simplified Simple Biosphere Model (Xue et al. 1991; Sun and Xue, 2001). SSiB is developed for land/atmosphere interaction studies in the climate model. The aerodynamic resistance values in SSiB are determined in terms of vegetation properties, ground conditions and bulk Richardson number according to the modified Monin–Obukhov similarity theory. SSiB-3 includes three snow layers to realistically simulate snow processes, including destructive metamorphism, densification process due to snow load, and snow melting, which substantially enhances the model’s ability for the cold season study. To use this option, ra_lw_physics and ra_sw_physics should be set to either 1, 3, or 4. The second full model level should be set to no larger than 0.982 so that the height of that level is higher than vegetation height. New in Version 3.4.

h. Fractional sea-ice (fractional_seaice = 1). Treat sea-ice as fractional field. Require fractional sea-ice as input data. Data sources may include those from GFS or the National Snow and Ice Data Center (http://nsidc.org/data/seaice/index.html). Use XICE for Vtable entry instead of SEAICE. This option works with sf_sfclay_physics = 1, 2, 5, and 7, and sf_surface_physics = 2, 3, and 7 in the present release. New in Version 3.1.

i. (5) CLM4 (Community Land Model Version 4, Oleson et al. 2010; Lawrence et al. 2010): CLM4 was developed at the National Center for Atmospheric Research with many external collaborators and represents a state-of-the-science land surface process model. It contains sophisticated treatment of biogeophysics, hydrology, biogeochemistry, and dynamic vegetation. In CLM4, the land surface in each model grid cell is characterized into five primary sub-grid land cover types (glacier, lake, wetland, urban, and vegetated). The vegetated sub-grid consists of up to 4 plant functional types (PFTs) that differ in physiology and structure. The WRF input land cover types are translated into the CLM4 PFTs through a look-up table. The CLM4 vertical structure includes a single-layer vegetation canopy, a five-layer snowpack, and a ten-layer soil column. An earlier version of CLM has been quantitatively evaluated within WRF in Jin and Wen (2012; JGR-Atmosphere), Lu and Kueppers (2012; JGR-Atmosphere), and Subin et al. (2011; Earth Interactions) (from Jin). New in Version 3.5. Updated for 20/21 category MODIS landuse data in V3.6.

3.3 Urban Surface (sf_urban_physics – replacing old switch ucmcall)

The orban physics options work with Noah LSM since V3.1, and with NoahMP since V3.9.

a. Urban canopy model (1): 3-category UCM option with surface effects for roofs, walls, and streets. In V3.7, a green roof option is added.

b. BEP (2). Building Environment Parameterization: Multi-layer urban canopy model that allows for buildings higher than the lowest model levels. Only works with Noah LSM and Boulac and MYJ PBL options. New in Version 3.1.

c. BEM (3). Building Energy Model. Adds to BEP, building energy budget with heating and cooling systems. Works with same options as BEP. New in Version 3.2.

3.4 Lake Physics (sf_lake_physics)

a. CLM 4.5 lake model (1). The lake scheme was obtained from the Community Land Model version 4.5 (Oleson et al. 2013) with some modifications by Gu et al. (2013). It is a one-dimensional mass and energy balance scheme with 20-25 model layers, including up to 5 snow layers on the lake ice, 10 water layers, and 10 soil layers on the lake bottom. The lake scheme is used with actual lake points and lake depth derived from the WPS, and it also can be used with user defined lake points and lake depth in WRF (lake_min_elev and lakedepth_default). The lake scheme is independent of a land surface scheme and therefore can be used with any land surface scheme embedded in WRF. The lake scheme developments and evaluations were included in Subin et al. (2012) and Gu et al. (2013) (Subin et al. 2012: Improved lake model for climate simulations, J. Adv. Model. Earth Syst., 4, M02001. DOI:10.1029/2011MS000072; Gu et al. 2013: Calibration and validation of lake surface temperature simulations with the coupled WRF-Lake model. Climatic Change, 1-13, 10.1007/s10584-013-0978-y).

  1. Planetary Boundary layer (bl_pbl_physics)

a. Yonsei University scheme: Non-local-K scheme with explicit entrainment layer and parabolic K profile in unstable mixed layer (bl_pbl_physics = 1).

  • topo_wind: = 1: Topographic correction for surface winds to represent extra drag from sub-grid topography and enhanced flow at hill tops (Jimenez and Dudhia, JAMC 2012). Works with YSU PBL only. New in Version 3.4. = 2: a simpler terrain variance-related correction. New in Version 3.5.

  • ysu_topdown_pblmix: = 1: option for top-down mixing driven by radiative cooling. New in V3.7.

b. Mellor-Yamada-Janjic scheme: Eta operational scheme. One-dimensional prognostic turbulent kinetic energy scheme with local vertical mixing (2).

c. MRF scheme: Older version of (a) with implicit treatment of entrainment layer as part of non-local-K mixed layer (99).

d. ACM2 PBL: Asymmetric Convective Model with non-local upward mixing and local downward mixing (7). New in Version 3.0.

e. Quasi-Normal Scale Elimination PBL (4). A TKE-prediction option that uses a new theory for stably stratified regions (Available since 3.1). Daytime part uses eddy diffusivity mass-flux method with shallow convection (mfshconv = 1) which is added in Version 3.4.

f. Mellor-Yamada Nakanishi and Niino Level 2.5 PBL (5). Predicts sub-grid TKE terms. New in Version 3.1 with significant update in V3.8.

  • icloud_bl: = 1, option to couple subgrid-scale clouds from MYNN to radiation;
  • bl_mynn_cloudpdf: = 1, Kuwano et al (2010); = 2, Chaboureau and Bechtold (2002, JAS, with mods, default);
  • bl_mynn_cloudmix: = 1, mixing cloud water and ice (qnc and qni are mixed when scalar_pblmix = 1);
    The above three options are new in V3.8.
  • bl_mynn_edmf = 1, activate mass-flux in MYNN (ok to try since v3.9);
  • bl_mynn_mixlength = 2: 1 is from RAP/HRRR, 2 is from blending (also available from v3.9).

g. Mellor-Yamada Nakanishi and Niino Level 3 PBL (6). Predicts TKE and other second-moment terms. New in Version 3.1.

h. BouLac PBL (8): Bougeault-Lacarrère PBL. A TKE-prediction option. New in Version 3.1. Designed for use with BEP urban model.

i. UW (Bretherton and Park) scheme (9). TKE scheme from CESM climate model. New in Version 3.3.

j. Total Energy - Mass Flux (TEMF) scheme (10). Sub-grid total energy prognostic variable, plus mass-flux type shallow convection. New in Version 3.3.

k. LES PBL: A large-eddy-simulation (LES) boundary layer is available in Version 3. For this, bl_pbl_physic = 0, isfflx = 1, and sf_sfclay_physics and sf_surface_physics are selected. This uses diffusion for vertical mixing and must use diff_opt = 2, and km_opt = 2 or 3, see below. Alternative idealized ways of running the LESPBL are chosen with isfflx = 0 or 2. New in Version 3.0.

l. Grenier-Bretherton-McCaa scheme (12): This is a TKE scheme. Tested in cloud-topped PBL cases. New in Version 3.5.

m. Shin-Hong scheme (11): Include scale dependency for vertical transport in convective PBL. Vertical mixing in the stable PBL and free atmosphere follows YSU. This scheme also has diagnosed TKE and mixing length output. New in V3.7.

  1. Cumulus Parameterization (cu_physics)

a. Kain-Fritsch scheme: Deep and shallow convection sub-grid scheme using a mass flux approach with downdrafts and CAPE removal time scale (cu_physics = 1).

  • kfeta_trigger = 1 – default trigger; = 2 – moisture-advection modulated trigger function [based on Ma and Tan (2009, Atmospheric Research)]. May improve results in subtropical regions when large-scale forcing is weak.

  • cu_rad_feedback = true – allow sub-grid cloud fraction interaction with radiation. New in V3.6. (Alapaty et al. 2012, Geophysical Research Letters)

b. Betts-Miller-Janjic scheme. Operational Eta scheme. Column moist adjustment scheme relaxing towards a well-mixed profile (2).

c. Grell-Devenyi (GD) ensemble scheme: Multi-closure, multi-parameter, ensemble method with typically 144 sub-grid members (moved to option 93 in V3.5).

d. Simplified Arakawa-Schubert (SAS) (4). Simple mass-flux scheme with quasi-equilibrium closure with shallow mixing scheme (and momentum transport in NMM only). Adapted for ARW in Version 3.3.

e. Grell 3D is an improved version of the GD scheme that may also be used on high resolution (in addition to coarser resolutions) if subsidence spreading (option cugd_avedx) is turned on (5). New in Version 3.0.

f. Tiedtke scheme (U. of Hawaii version) (6). Mass-flux type scheme with CAPE-removal time scale, shallow component and momentum transport. New in Version 3.3.

g. Zhang-McFarlane scheme (7). Mass-flux CAPE-removal type deep convection from CESM climate model with momentum transport. New in Version 3.3.

h. New Simplified Arakawa-Schubert (NSAS) (96). New mass-flux scheme with deep and shallow components and momentum transport. New in Version 3.3. This was option 14 in V3.*.

i. New Simplified Arakawa-Schubert (84, HWRF version). New mass-flux scheme with deep and shallow components and momentum transport. New in Version 3.4.

j. Grell-Freitas (GF) scheme (3): An improved GD scheme that tries to smooth the transition to cloud-resolving scales, as proposed by Arakawa et al. (2004). New in Version 3.5.

k. Old Kain-Fritsch scheme: Deep convection scheme using a mass flux approach with downdrafts and CAPE removal time scale (99).

l. Multi-scale Kain-Fritsch scheme (11): using scale-dependent dynamic adjustment timescale, LCC-based entrainment. Also uses new trigger function based on Bechtold. New in V3.7. An option to use CESM aerosol is added in V4.0.

m. New Tiedtke scheme (16): this version is similar to the Tiedtke scheme used in REGCM4 and ECMWF cy40r1. New in V3.7, updated in V3.8.

n. Kain-Fritsch-Cumulus Potential scheme (10): this option modifies the KF ad-hoc trigger function with one linked to boundary layer turbulence via probability density function (PDFs) using cumulus potential scheme. The scheme also computes the cumulus cloud fraction based on the time-scale relevant for shallow cumuli. (Berg et al. 2013.) New in V3.8.

o. KIAPS SAS (14): Based on NSAS, but scale-aware. New in V4.0.

  1. Shallow convection option (shcu_physics)

a. ishallow = 1, shallow convection option on. Works together with Grell 3D scheme (cu_physics = 5) – will move to shcu_physics category in the future.

b. UW (Bretherton and Park) scheme (2). Shallow cumulus option from CESM climate model with momentum transport. New in Version 3.3.

c. GRIMS (Global/Regional Integrated Modeling System) scheme (3): it represents the shallow convection process by using eddy-diffusion and the pal algorithm, and couples directly to the YSU PBL scheme. New in Version 3.5.

d. NSAS shallow scheme (4): This is extracted from NSAS, and should be used with KSAS deep cumulus scheme. New in V4.0.

e. Deng shallow scheme (5): Only runs with MYNN and MYJ PBL schemes. New in V4.1.

  1. Other physics options

a. Options to use for tropical storm and hurricane applications:

  • sf_ocean_physics = 1 (renamed from omlcall in previous versions): Simple ocean mixed layer model (1): 1-D ocean mixed layer model following that of Pollard, Rhines and Thompson (1972). Two other namelist options are available to specify the initial mixed layer depth (although one may ingest real mixed layer depth data) (oml_hml0) and a temperature lapse rate below the mixed layer (oml_gamma). Since V3.2, this option works with all sf_surface_physics options.

  • sf_ocean_physics = 2: New in V3.5. 3D Price-Weller-Pinkel (PWP) ocean model based on Price et al. (1994). This model predicts horizontal advection, pressure gradient force, as well as mixed layer processes. Only simple initialization via namelist variables ocean_z, ocean_t, and ocean_s is available in V3.5.

  • isftcflx: Modify surface bulk drag (Donelan) and enthalpy coefficients to be more in line with recent research results of those for tropical storms and hurricanes. This option also includes dissipative heating term in heat flux. It is only available for sf_sfclay_physics = 1. There are two options for computing enthalpy coefficients: isftcflx = 1: constant Z0q (since V3.2) for heat and moisture; isftcflx = 2 Garratt formulation, slightly different forms for heat and moisture.

b. Other options for long simulations (new in Version 3.1):

  • tmn_update: update deep soil temperature (1).

  • sst_skin: calculate skin SST based on Zeng and Beljaars (2005) (1)

  • bucket_mm: bucket reset value for water equivalent precipitation accumulations (value in mm, -1 = inactive).

  • bucket_J: bucket reset value for energy accumulations (value in Joules, -1 = inactive). Only works with CAM and RRTMG radiation (ra_lw_physics = 3 and 4 and ra_sw_physics = 3 and 4) options.

  • To drive WRF model with climate data that does not have leap year, there is a compile option to do that. Edit configure.wrf and
    add -DNO_LEAP_CALENDAR to the macro ARCH_LOCAL.

c. Land model input options:

  • usemonalb: When set to .true., it uses monthly albedo fields from geogrid, instead of table values

  • rdlai2d: When set to .true., it uses monthly LAI data from geogrid (new in V3.6) and the field will also go to wrflowinp file if sst_update is 1.

d. gwd_opt: Gravity wave drag option. Recommended for all grid sizes. This scheme includes two subgrid topography effects: gravity wave drag and low-level flow blocking. The latter was added in V3.7. Since V4.0, the input wind to the scheme is rotated to the earth coordinate, and the output is adjusted back to the projection domain. This enables the scheme to be used for all map projections supported by WRF. In order to apply this option properly, appropriate input fields from geogrid must be used. See the “Selecting Static Data for the Gravity Wave Drag Scheme” section in Chapter 3 of this guide for details. New in Version 3.1, updated in V3.7 and V4.0

e. windfarm_opt: Wind turbine drag parameterization scheme. It represents sub-grid effects of specified turbines on wind and TKE fields. The physical charateristics of the wind farm is read in from a file and use of the manufacturers’ specification is recommeded. An example of the file is provided in run/wind-turbine-1.tbl. The location of the turbines are read in from a file, windturbines.txt. See README.windturbine in WRF/ directory for more detail. New in Version 3.3, and in this version it only works with 2.5 level MYNN PBL option (bl_pbl_physics=5), and updated in V3.6.

  1. Physics sensitivity options

a. no_mp_heating: When set to 1, it turns off latent heating from microphysics. When using this option, cu_physics should be set to 0.
b. icloud: When set to 0, it turns off cloud effect on optical depth in shortwave radiation options 1, 4 and longwave radiation option 1, 4. Note since V3.6, this namelist also controls which cloud fraction method to use for radiation.
c. isfflx: When set to 0, it turns off both sensible and latent heat fluxes from the surface. This option works for sf_sfclay_physics = 1, 5, 7, 11.
d. ifsnow: When set to 0, it turns off snow effect in sf_surface_physics = 1.
Diffusion and Damping Options
Diffusion in WRF is categorized under two parameters: the diffusion option and the K option. The diffusion option selects how the derivatives used in diffusion are calculated, and the K option selects how the K coefficients are calculated. Note that when a PBL option is selected, vertical diffusion is done by the PBL scheme, and not by the diffusion scheme. In Version 3, vertical diffusion is also linked to the surface fluxes.

1.1 Diffusion Option (diff_opt)

a. Simple diffusion: Gradients are simply taken along coordinate surfaces (diff_opt = 1).

b. Full diffusion: Gradients use full metric terms to more accurately compute horizontal gradients in sloped coordinates (diff_opt = 2). This option can be used with real-data cases since V3.6.1.

1.2 K Option (km_opt)

Note that when using a PBL scheme, only options (a) and (d) below make sense, because (b) and (c) are designed for 3d diffusion.

a. Constant: K is specified by namelist values for horizontal and vertical diffusion (km_opt = 1).

b. 3d TKE: A prognostic equation for turbulent kinetic energy is used, and K is based on TKE (km_opt = 2).

c. 3d Deformation: K is diagnosed from 3d deformation and stability following a Smagorinsky approach (km_opt = 3).

d. 2d Deformation: K for horizontal diffusion is diagnosed from just horizontal deformation. The vertical diffusion is assumed to be done by the PBL scheme (km_opt = 4).

1.3 6th Order Horizontal Diffusion (diff_6th_opt)

6th-order horizontal hyper diffusion (del^6) on all variables to act as a selective short-wave numerical noise filter. Can be used in conjunction with diff_opt. diff_6th_opt = 1: simple; = 2: positive definite. Option 2 is recommended (option 1 should be avoided). In V4.0, a few controls are introduced: diff_6th_slopeopt (0,1) controls whether this option will be turned off over steep terrain; diff_6th_thresh sets the threshold value for terrain slopes above which this option will be turned off.

1.4 Nonlinear Backscatter Anisotropic (NBA) (sfs_opt)

Sub-grid turbulent stress option for momentum in LES applications. New in Version 3.2. sfs_opt = 1 diagnostic sub-grid stress to be used with diff_opt = 2 and km_opt = 2 or 3. sfs_opt = TKE sub-grid stress to be used with diff_opt = 2 and km_opt = 2.

  1. Damping Options

These are independently activated choices.

a. Upper Damping: Either a layer of increased diffusion (damp_opt =1) or a Rayleigh relaxation layer (2) or an implicit gravity-wave damping layer (3, new in Version 3.0), can be added near the model top to control reflection from the upper boundary.

b. Vertical velocity damping (w_damping): For operational robustness, vertical motion can be damped to prevent the model from becoming unstable with locally large vertical velocities. This only affects strong updraft cores, so has very little impact on results otherwise.

c. Divergence Damping (sm_div): Controls horizontally-propagating sound waves.

d. External Mode Damping (em_div): Controls upper-surface (external) waves.

e. Time Off-centering (epssm): Controls vertically-propagating sound waves.

Advection Options
a. Horizontal advection orders for momentum (h_mom_adv_order) and scalar (h_sca_adv_order) can be 2ndto 6th, with 5th order being the recommended one.

b. Vertical advection orders for momentum (v_mom_adv_order) and scalar (v_sca_adv_order) can be 2ndand 6th, with 3rd order being the recommended one.

c. Monotonic transport (option 2, new in Version 3.1) and positive-definite advection option (option 1) can be applied to moisture (moist_adv_opt), scalar (scalar_adv_opt), chemistry variables (chem_adv_opt) and tke (tke_adv_opt). Option 1 replaces pd_moist = .true. etc. in previous versions.

d. WENO (weighted essentially non-oscillatory) (option 3 for 5th order WENO; option 4 for 5th order WENO with positive definite limiter): for moisture (moist_adv_opt), scalar (scalar_adv_opt), chemistry variables (chem._adv_opt) and TKE (tke_adv_opt). For momentum, momentum_adv_opt = 3.

Some notes about using monotonic and positive-definite advection options:

The positive-definite and monotonic options are available for moisture, scalars, chemical scalers and TKE in the ARW solver. Both the monotonic and positive-definite transport options conserve scalar mass locally and globally and are consistent with the ARW mass conservation equation. We recommend using the positive-definite option for moisture variables on all real-data simulations. The monotonic option may be beneficial in chemistry applications and for moisture and scalars in some instances.

When using these options there are certain aspects of the ARW integration scheme that should be considered in the simulation configuration.

(1) The integration sequence in ARW changes when the positive-definite or monotonic options are used. When the options are not activated, the timestep tendencies from the physics (excluding microphysics) are used to update the scalar mixing ratio at the same time as the transport (advection). The microphysics is computed, and moisture is updated, based on the transport+physics update. When the monotonic or positive definite options are activated, the scalar mixing ratio is first updated with the physics tendency, and the new updated values are used as the starting values for the transport scheme. The microphysics update occurs after the transport update using these latest values as its starting point. It is important to remember that for any scalars, the local and global conservation properties, positive definiteness and monotonicity depend upon each update possessing these properties.

(2) Some model filters may not be positive definite.

i. diff_6th_opt = 1 is not positive definite nor monotonic. Use diff_6th_opt = 2 if you need this diffusion option (diff_6th_opt = 2 is monotonic and positive-definite). We have encountered cases where the departures from monotonicity and positive-definiteness have been very noticeable.

ii. diff_opt = 1 and km_opt = 4 (a commonly-used real-data case mixing option) is not guaranteed to be positive-definite nor monotonic due to the variable eddy diffusivity, K. We have not observed significant departures from positive-definiteness or monotonicity when this filter is used with these transport options.

iii. The diffusion option that uses a user-specified constant eddy viscosity is positive definite and monotonic.

iv. Other filter options that use variable eddy viscosity are not positive definite or monotonic.

(3) Most of the model physics are not monotonic nor should they be - they represent sources and sinks in the system. All should be positive definite, although we have not examined and tested all options for this property.

(4) The monotonic option adds significant smoothing to the transport in regions where it is active. You may want to consider turning off the other model filters for variables using monotonic transport (filters such as the second and sixth order horizontal filters). At present it is not possible to turn off the filters for the scalars but not for the dynamics using the namelist - one must manually comment out the calls in the solver.

Other Dynamics Options
a. The model can be run hydrostatically by setting the non_hydrostatic switch to .false.

b. The Coriolis term can be applied to wind perturbation (pert_coriolis = .true.) only (idealized only).

c. For diff_opt = 2 only, vertical diffusion may act on full fields (not just on perturbation from the 1D base profile (mix_full_fields = .true.; idealized only).

d. To obtain more accurate solution with moisture, one can add

use_q_diabatic: which considers moisture tendency from microphysics in small steps. This option could make time-step more restrictive.
use_theta_m: which considers moisture effect on pressure in small steps. The current implementation may cost a bit more to run.

Lateral Boundary Condition Options
a. Periodic (periodic_x / periodic_y): for idealized cases.

b. Open (open_xs, open_xe, open_ys, open_ye): for idealized cases.

c. Symmetric (symmetric_xs, symmetric_xe, symmetric_ys, symmetric_ye): for idealized cases.

d. Specified (specified): for real-data cases. The first row and column are specified with external model values (spec_zone = 1, and it should not change). The rows and columns in relax_zone have values blended from an external model and WRF. The value of relax_zone may be changed, as long as spec_bdy_width = spec_zone + relax_zone. This can be used with periodic_x in tropical channel simulations.

spec_exp: exponential multiplier for the relaxation zone ramp, used with a specified boundary condition. 0. = linear ramp, default; 0.33 = ~3*dx exp decay factor. This may be useful for long simulations.

2021-01-12 16:55

posted @ 2024-09-04 05:55  chinagod  阅读(184)  评论(0)  编辑  收藏  举报