AMPS Configuration

Current AMPS Configuration

AMPS uses WRF ARW version 3.9.1.1, with polar modifications to the released code to better treat the polar environment. 

Vertical Coordinate:

    AMPS uses the WRF hybrid vertical coordinate, in which model levels follow the terrain near the surface, and gradually flatten to isobaric levels at higher model levels (target level ETAC = 0.2).

Vertical Grid:

    WRF uses a staggered vertical grid on an η (eta) coordinate, with half-η levels defined halfway between full-η levels.

    The AMPS configuration features 61 full-η levels and 60 half-η levels, specified as follows:

      half-η
      index
      half-η
      level
      60
      0.99840
      59
      0.99435
      58
      0.98875
      57
      0.98175
      56
      0.97335
      55
      0.96355
      54
      0.95235
      53
      0.93975
      52
      0.92575
      51
      0.91035
      50
      0.89360
      49
      0.87555
      48
      0.85620
      47
      0.83560
      46
      0.81380
      45
      0.79085
      44
      0.76685
      43
      0.74190
      42
      0.71610
      41
      0.68955
      40
      0.66235
      39
      0.63455
      38
      0.60620
      37
      0.57740
      36
      0.54825
      35
      0.51885
      34
      0.48930
      33
      0.45970
      32
      0.43015
      31
      0.40075
      30
      0.37165
      29
      0.34305
      28
      0.31515
      27
      0.28815
      26
      0.26225
      25
      0.23760
      24
      0.21430
      23
      0.19245
      22
      0.17205
      21
      0.15305
      20
      0.13550
      19
      0.11945
      18
      0.10485
      17
      0.09162
      16
      0.079695
      15
      0.06896
      14
      0.059295
      13
      0.050625
      12
      0.04289
      11
      0.036045
      10
      0.030025
      9
      0.02474
      8
      0.020105
      7
      0.016055
      6
      0.012530
      5
      0.009465
      4
      0.00681
      3
      0.004515
      2
      0.00253
      1
      0.0008
      full-η
      index
      full-η
      level
      61
      1.0000
      60
      0.9968
      59
      0.9919
      58
      0.9856
      57
      0.9779
      56
      0.9688
      55
      0.9583
      54
      0.9464
      53
      0.9331
      52
      0.9184
      51
      0.9023
      50
      0.8849
      49
      0.8662
      48
      0.8462
      47
      0.8250
      46
      0.8026
      45
      0.7791
      44
      0.7546
      43
      0.7292
      42
      0.7030
      41
      0.6761
      40
      0.6486
      39
      0.6205
      38
      0.5919
      37
      0.5629
      36
      0.5336
      35
      0.5041
      34
      0.4745
      33
      0.4449
      32
      0.4154
      31
      0.3861
      30
      0.3572
      29
      0.3289
      28
      0.3014
      27
      0.2749
      26
      0.2496
      25
      0.2256
      24
      0.2030
      23
      0.1819
      22
      0.1622
      21
      0.1439
      20
      0.1271
      19
      0.1118
      18
      0.0979
      17
      0.08534
      16
      0.07405
      15
      0.06387
      14
      0.05472
      13
      0.04653
      12
      0.03925
      11
      0.03284
      10
      0.02721
      9
      0.02227
      8
      0.01794
      7
      0.01417
      6
      0.01089
      5
      0.00804
      4
      0.00558
      3
      0.00345
      2
      0.00160
      1
      0.00000

Horizontal Grids:

    The AMPS configuration features five two-way interactive grids as follows (see Maps):

      Grid
      x
      dimension
      y
      dimension
      grid-cell
      size (km)
      end hour
      1
      413
      545
      24
      120
      2
      835
      787
      8
      120
      3
      676
      1036
      2.67
      39
      5
      769
      901
      0.89
      39
      6
      652
      571
      2.67
      39
    (Note that the grid numbering skips domain 4, which was used in older AMPS configurations. The area of the older domain 4 has been subsumed into the expanded domain 3).

Model Input:

Data Assimilation:

    WRFVAR 3D Variational data assimilation is used.

    Hybrid option running since 2016-05-25/12, currently using an ensemble of approximately 15 members in conjunction with the usual BE Stats.

Options (Physics parameterizations, mostly):

    For details on these options below, see the Chapter 5 of the WRF ARW Users' Guide.

    Long-wave Radiation:

      RRTMG Longwave radiation scheme (ra_lw_physics=4), updated every 15 minutes (radt=15).

    Short-wave Radiation:

      Goddard shortwave radiation scheme (ra_sw_physics=2), updated every 15 minutes (radt=15).

    Boundary Layer:

      Mellor-Yamada-Janjic (Eta) TKE scheme (bl_pbl_physics=2), updated every time step (bldt=0).

    Surface-layer Scheme:

      Monin-Obukhov (Janjic Eta) scheme (sf_sfclay_physics=2),

    Land-surface Option:

      Unified Noah LSM (sf_surface_physics=2),

    Microphysics:

      WSM 5-class scheme (mp_physics=4)

    Cumulus Parameterization:

      Kain-Fritsch (new Eta) parameterization (cu_physics=1) on 24- and 8-km grids, updated every time step (cudt=0)
      No cumulus parameterizations (cu_physics=0) on 2.67- and 0.89-km grids

    Sea-ice:

      A fractional sea-ice implementation is used, in which the surface-layer scheme is called twice: first for completely frozen conditions, then for completely open water conditions. The results of these two calls are then weighted by the sea-ice fraction to determine surface fluxes and other terms.

    Upper Boundary Condition:

      Model top at 10 mb.  Vertical velocity damping is applied (w_damping=1) in the top 7.5 km (zdamp = 7500.)

Namelists:

e-mail: Kevin Manning

Last modified: 2019-02-08 Fri 11:23:16 MST