Partitioning the input files

ROMS requires partitioned (or tiled) input files so that the simulation can be parallelized over multiple nodes. ROMS-Tools can create these partitioned files for you.

Writing some example files

First we make some (non-partitioned) example files, which we will then partition in the next section.

Example grid file

from roms_tools import Grid

grid = Grid(
    nx=300,
    ny=150,
    size_x=23000,
    size_y=12000,
    center_lon=-161.0,
    center_lat=14.4,
    rot=-3.0,
)

grid.ds

<xarray.Dataset> Size: 5MB
Dimensions:       (eta_rho: 152, xi_rho: 302, xi_u: 301, eta_v: 151,
                   eta_coarse: 77, xi_coarse: 152, s_rho: 100, s_w: 101)
Coordinates:
    lat_rho       (eta_rho, xi_rho) float64 367kB -46.17 -46.0 ... 40.06 39.92
    lon_rho       (eta_rho, xi_rho) float64 367kB 110.6 111.3 ... 313.9 314.5
    lat_u         (eta_rho, xi_u) float64 366kB -46.08 -45.91 ... 40.13 39.99
    lon_u         (eta_rho, xi_u) float64 366kB 110.9 111.6 ... 313.6 314.2
    lat_v         (eta_v, xi_rho) float64 365kB -45.94 -45.77 ... 39.82 39.68
    lon_v         (eta_v, xi_rho) float64 365kB 110.5 111.1 ... 313.8 314.4
    lat_coarse    (eta_coarse, xi_coarse) float64 94kB -46.48 -46.14 ... 40.08
    lon_coarse    (eta_coarse, xi_coarse) float64 94kB 110.4 111.7 ... 314.9
Dimensions without coordinates: eta_rho, xi_rho, xi_u, eta_v, eta_coarse,
                                xi_coarse, s_rho, s_w
Data variables: (12/15)
    angle         (eta_rho, xi_rho) float64 367kB 0.3739 0.3739 ... -0.3063
    f             (eta_rho, xi_rho) float64 367kB -0.0001049 ... 9.333e-05
    pm            (eta_rho, xi_rho) float64 367kB 1.838e-05 ... 1.838e-05
    pn            (eta_rho, xi_rho) float64 367kB 1.936e-05 ... 1.936e-05
    spherical     |S1 1B b'T'
    mask_rho      (eta_rho, xi_rho) int32 184kB 1 1 1 1 1 1 1 ... 0 0 0 0 0 0 0
    ...            ...
    mask_coarse   (eta_coarse, xi_coarse) int32 47kB 1 1 1 1 1 1 ... 0 0 0 0 0 0
    h             (eta_rho, xi_rho) float64 367kB 4.082e+03 4.082e+03 ... 5.0
    sigma_r       (s_rho) float32 400B -0.995 -0.985 -0.975 ... -0.015 -0.005
    Cs_r          (s_rho) float32 400B -0.992 -0.9753 ... -8.89e-05 -9.874e-06
    sigma_w       (s_w) float32 404B -1.0 -0.99 -0.98 -0.97 ... -0.02 -0.01 0.0
    Cs_w          (s_w) float32 404B -1.0 -0.9837 -0.9667 ... -3.95e-05 0.0
Attributes: (12/13)
    title:                   ROMS grid created by ROMS-Tools
    roms_tools_version:      2.6.3.dev44+g780e06f.d20250623
    size_x:                  23000
    size_y:                  12000
    center_lon:              -161.0
    center_lat:              14.4
    ...                      ...
    straddle:                False
    topography_source_name:  ETOPO5
    hmin:                    5.0
    theta_s:                 5.0
    theta_b:                 2.0
    hc:                      300.0

xarray.Dataset

• Dimensions:
  • eta_rho: 152
  • xi_rho: 302
  • xi_u: 301
  • eta_v: 151
  • eta_coarse: 77
  • xi_coarse: 152
  • s_rho: 100
  • s_w: 101
• Coordinates: (8)
  • lat_rho
    (eta_rho, xi_rho)
    float64
    -46.17 -46.0 -45.83 ... 40.06 39.92

    long_name :

    latitude of rho-points

    units :

    degrees North

    array([[-46.16910584, -45.99920641, -45.82977196, ..., -51.6280793 ,
            -51.80159217, -51.97481688],
           [-45.71561908, -45.54553519, -45.37590918, ..., -51.17598841,
            -51.34938421, -51.52248088],
           [-45.25737055, -45.08710682, -44.91729385, ..., -50.7190019 ,
            -50.89227747, -51.06524306],
           ...,
           [ 44.15929823,  44.32685053,  44.49493765, ...,  39.26302523,
             39.12173752,  38.98150629],
           [ 44.61883884,  44.786174  ,  44.95405042, ...,  39.73181352,
             39.59087008,  39.45098455],
           [ 45.07364742,  45.24076092,  45.4084221 , ...,  40.19599137,
             40.05539524,  39.91585842]], shape=(152, 302))

  • lon_rho
    (eta_rho, xi_rho)
    float64
    110.6 111.3 111.9 ... 313.9 314.5

    long_name :

    longitude of rho-points

    units :

    degrees East

    array([[110.63268987, 111.25607415, 111.87781199, ..., 284.18414316,
            284.87968911, 285.57810271],
           [110.37725037, 111.00209059, 111.62529936, ..., 284.47451978,
            285.17070202, 285.86971229],
           [110.1236204 , 110.74988351, 111.37453059, ..., 284.7618603 ,
            285.45863539, 286.15819877],
           ...,
           [ 80.0338    ,  80.65153611,  81.27075814, ..., 312.9622652 ,
            313.54496506, 314.12692566],
           [ 79.78968279,  80.40591619,  81.02364916, ..., 313.15381069,
            313.73470511, 314.31485385],
           [ 79.54396349,  80.1586634 ,  80.77487611, ..., 313.34618695,
            313.92525713, 314.50357551]], shape=(152, 302))

  • lat_u
    (eta_rho, xi_u)
    float64
    -46.08 -45.91 ... 40.13 39.99

    long_name :

    latitude of u-points

    units :

    degrees North

    array([[-46.08409918, -45.91442989, -45.74523495, ..., -51.54122316,
            -51.71487008, -51.88824223],
           [-45.63052109, -45.46066377, -45.29127377, ..., -51.0891867 ,
            -51.26272202, -51.43597162],
           [-45.17218354, -45.0021428 , -44.83256235, ..., -50.63225626,
            -50.80567675, -50.9788007 ],
           ...,
           [ 44.24300639,  44.41082838,  44.57917603, ...,  39.33406113,
             39.19225014,  39.05148902],
           [ 44.70243763,  44.87004568,  45.03818592, ...,  39.80267787,
             39.66121038,  39.52079426],
           [ 45.15713458,  45.32452417,  45.49245244, ...,  40.26668261,
             40.1255617 ,  39.98549361]], shape=(152, 301))

  • lon_u
    (eta_rho, xi_u)
    float64
    110.9 111.6 112.2 ... 313.6 314.2

    long_name :

    longitude of u-points

    units :

    degrees East

    array([[110.94458973, 111.56714697, 112.188073  , ..., 283.83743273,
            284.53156025, 285.22853489],
           [110.6898763 , 111.31389703, 111.93630134, ..., 284.12747669,
            284.82225989, 285.51985116],
           [110.43695582, 111.0624072 , 111.68625737, ..., 284.41450623,
            285.10990174, 285.80806611],
           ...,
           [ 80.34248407,  80.96095963,  81.5809352 , ..., 312.67063269,
            313.2537086 , 313.83603671],
           [ 80.09761382,  80.71459345,  81.33308692, ..., 312.86307845,
            313.44435218, 314.02487162],
           [ 79.85112614,  80.46657885,  81.08355882, ..., 313.05636451,
            313.63581709, 314.21450922]], shape=(152, 301))

  • lat_v
    (eta_v, xi_rho)
    float64
    -45.94 -45.77 -45.6 ... 39.82 39.68

    long_name :

    latitude of v-points

    units :

    degrees North

    array([[-45.9424336 , -45.77244114, -45.6029101 , ..., -51.40212354,
            -51.57557815, -51.74873907],
           [-45.48656498, -45.31639039, -45.14667011, ..., -50.94758328,
            -51.12091922, -51.29395057],
           [-45.02593352, -44.85558138, -44.68567643, ..., -50.48814801,
            -50.66136218, -50.83426097],
           ...,
           [ 43.92722473,  44.09488417,  44.26307519, ...,  39.02636265,
             38.88490355,  38.74450019],
           [ 44.38913352,  44.55657806,  44.72456064, ...,  39.49745866,
             39.35634231,  39.21628316],
           [ 44.84630899,  45.01353414,  45.18130377, ...,  39.96394219,
             39.82317162,  39.68345967]], shape=(151, 302))

  • lon_v
    (eta_v, xi_rho)
    float64
    110.5 111.1 111.8 ... 313.8 314.4

    long_name :

    longitude of v-points

    units :

    degrees East

    array([[110.50444777, 111.12856586, 111.75104497, ..., 284.33004906,
            285.0259194 , 285.72463755],
           [110.24991957, 110.87547696, 111.49941059, ..., 284.61889626,
            285.31538096, 286.01467379],
           [109.99719231, 110.6241562 , 111.24951194, ..., 284.90472843,
            285.60178464, 286.30160921],
           ...,
           [ 80.15553805,  80.77401577,  81.39397241, ..., 312.86658495,
            313.45018256, 314.03304423],
           [ 79.91222055,  80.52921086,  81.14769394, ..., 313.05771499,
            313.63951655, 314.2205756 ],
           [ 79.66730815,  80.28278046,  80.89975898, ..., 313.24967229,
            313.82965906, 314.40889706]], shape=(151, 302))

  • lat_coarse
    (eta_coarse, xi_coarse)
    float64
    -46.48 -46.14 -45.8 ... 40.36 40.08

    long_name :

    latitude of rho-points on coarsened grid

    units :

    degrees North

    array([[-46.48075282, -46.14137268, -45.8036789 , ..., -51.59326881,
            -51.94091045, -52.28762924],
           [-45.57158172, -45.23146126, -44.89297815, ..., -50.68694931,
            -51.034163  , -51.38037753],
           [-44.64573177, -44.30490294, -43.96566229, ..., -49.76351568,
            -50.11027909, -50.45596848],
           ...,
           [ 43.37658285,  43.71258369,  44.05037584, ...,  38.76538418,
             38.47971335,  38.19769852],
           [ 44.30534667,  44.64050315,  44.97749696, ...,  39.7111741 ,
             39.42686159,  39.14621623],
           [ 45.21755038,  45.55183116,  45.88799504, ...,  40.64080163,
             40.35786906,  40.07861411]], shape=(77, 152))

  • lon_coarse
    (eta_coarse, xi_coarse)
    float64
    110.4 111.7 112.9 ... 313.7 314.9

    long_name :

    longitude of rho-points on coarsened grid

    units :

    degrees East

    array([[110.44908147, 111.69356711, 112.93234024, ..., 283.00178422,
            284.38656875, 285.78135556],
           [109.93765956, 111.18795101, 112.43263361, ..., 283.57899001,
            284.96642937, 286.36359894],
           [109.43258489, 110.68845389, 111.93882259, ..., 284.14589766,
            285.53569432, 286.93494798],
           ...,
           [ 80.08684327,  81.32743472,  82.57322197, ..., 311.79703384,
            312.96927589, 314.13892384],
           [ 79.60324901,  80.8379649 ,  82.07797673, ..., 312.18381408,
            313.34893651, 314.51141709],
           [ 79.11413726,  80.34276329,  81.57678052, ..., 312.57358453,
            313.73145411, 314.88663795]], shape=(77, 152))

• Data variables: (15)
  • angle
    (eta_rho, xi_rho)
    float64
    0.3739 0.3739 ... -0.3063 -0.3063

    long_name :

    Angle between xi axis and east

    units :

    radians

    array([[ 0.37387327,  0.37387327,  0.37277666, ..., -0.38308688,
            -0.38244923, -0.38244923],
           [ 0.37069678,  0.37069678,  0.36962768, ..., -0.379126  ,
            -0.3784701 , -0.3784701 ],
           [ 0.36756704,  0.36756704,  0.36652492, ..., -0.37523148,
            -0.37455799, -0.37455799],
           ...,
           [ 0.36254747,  0.36254747,  0.36373582, ..., -0.30436629,
            -0.30204157, -0.30204157],
           [ 0.36555522,  0.36555522,  0.3667708 , ..., -0.30649268,
            -0.30414162, -0.30414162],
           [ 0.3686074 ,  0.3686074 ,  0.36985072, ..., -0.30864931,
            -0.30627153, -0.30627153]], shape=(152, 302))

  • f
    (eta_rho, xi_rho)
    float64
    -0.0001049 -0.0001046 ... 9.333e-05

    long_name :

    Coriolis parameter at rho-points

    units :

    second-1

    array([[-1.04921474e-04, -1.04622334e-04, -1.04323096e-04, ...,
            -1.14027854e-04, -1.14300751e-04, -1.14572150e-04],
           [-1.04120976e-04, -1.03819058e-04, -1.03517042e-04, ...,
            -1.13311909e-04, -1.13587340e-04, -1.13861259e-04],
           [-1.03305447e-04, -1.03000748e-04, -1.02695950e-04, ...,
            -1.12581042e-04, -1.12859010e-04, -1.13135452e-04],
           ...,
           [ 1.01324457e-04,  1.01629156e-04,  1.01933954e-04, ...,
             9.20488622e-05,  9.17708937e-05,  9.14944520e-05],
           [ 1.02158067e-04,  1.02459985e-04,  1.02762001e-04, ...,
             9.29671339e-05,  9.26917026e-05,  9.24177841e-05],
           [ 1.02976623e-04,  1.03275763e-04,  1.03575001e-04, ...,
             9.38702428e-05,  9.35973453e-05,  9.33259468e-05]],
          shape=(152, 302))

  • pm
    (eta_rho, xi_rho)
    float64
    1.838e-05 1.838e-05 ... 1.838e-05

    long_name :

    Curvilinear coordinate metric in xi-direction

    units :

    meter-1

    array([[1.83794072e-05, 1.83794072e-05, 1.83794072e-05, ...,
            1.83794072e-05, 1.83794072e-05, 1.83794072e-05],
           [1.83794072e-05, 1.83794072e-05, 1.83794072e-05, ...,
            1.83794072e-05, 1.83794072e-05, 1.83794072e-05],
           [1.82116600e-05, 1.82116600e-05, 1.82116600e-05, ...,
            1.82116600e-05, 1.82116600e-05, 1.82116600e-05],
           ...,
           [1.82116600e-05, 1.82116600e-05, 1.82116600e-05, ...,
            1.82116600e-05, 1.82116600e-05, 1.82116600e-05],
           [1.83794072e-05, 1.83794072e-05, 1.83794072e-05, ...,
            1.83794072e-05, 1.83794072e-05, 1.83794072e-05],
           [1.83794072e-05, 1.83794072e-05, 1.83794072e-05, ...,
            1.83794072e-05, 1.83794072e-05, 1.83794072e-05]], shape=(152, 302))

  • pn
    (eta_rho, xi_rho)
    float64
    1.936e-05 1.936e-05 ... 1.936e-05

    long_name :

    Curvilinear coordinate metric in eta-direction

    units :

    meter-1

    array([[1.93575769e-05, 1.93575769e-05, 1.93575769e-05, ...,
            1.93575769e-05, 1.93575769e-05, 1.93575769e-05],
           [1.91794938e-05, 1.91794938e-05, 1.91794938e-05, ...,
            1.91794938e-05, 1.91794938e-05, 1.91794938e-05],
           [1.90044348e-05, 1.90044348e-05, 1.90044348e-05, ...,
            1.90044348e-05, 1.90044348e-05, 1.90044348e-05],
           ...,
           [1.90044348e-05, 1.90044348e-05, 1.90044348e-05, ...,
            1.90044348e-05, 1.90044348e-05, 1.90044348e-05],
           [1.91794938e-05, 1.91794938e-05, 1.91794938e-05, ...,
            1.91794938e-05, 1.91794938e-05, 1.91794938e-05],
           [1.93575769e-05, 1.93575769e-05, 1.93575769e-05, ...,
            1.93575769e-05, 1.93575769e-05, 1.93575769e-05]], shape=(152, 302))

  • spherical
    ()
    |S1
    b'T'

    Long_name :

    Grid type logical switch

    option_T :

    spherical

    array(b'T', dtype='|S1')

  • mask_rho
    (eta_rho, xi_rho)
    int32
    1 1 1 1 1 1 1 1 ... 0 0 0 0 0 0 0 0

    long_name :

    Mask at rho-points

    units :

    land/water (0/1)

    array([[1, 1, 1, ..., 1, 0, 0],
           [1, 1, 1, ..., 1, 0, 0],
           [1, 1, 1, ..., 1, 0, 0],
           ...,
           [0, 0, 0, ..., 0, 0, 0],
           [0, 0, 0, ..., 0, 0, 0],
           [0, 0, 0, ..., 0, 0, 0]], shape=(152, 302), dtype=int32)

  • mask_u
    (eta_rho, xi_u)
    int32
    1 1 1 1 1 1 1 1 ... 0 0 0 0 0 0 0 0

    long_name :

    Mask at u-points

    units :

    land/water (0/1)

    array([[1, 1, 1, ..., 1, 0, 0],
           [1, 1, 1, ..., 1, 0, 0],
           [1, 1, 1, ..., 1, 0, 0],
           ...,
           [0, 0, 0, ..., 0, 0, 0],
           [0, 0, 0, ..., 0, 0, 0],
           [0, 0, 0, ..., 0, 0, 0]], shape=(152, 301), dtype=int32)

  • mask_v
    (eta_v, xi_rho)
    int32
    1 1 1 1 1 1 1 1 ... 0 0 0 0 0 0 0 0

    long_name :

    Mask at v-points

    units :

    land/water (0/1)

    array([[1, 1, 1, ..., 1, 0, 0],
           [1, 1, 1, ..., 1, 0, 0],
           [1, 1, 1, ..., 0, 0, 0],
           ...,
           [0, 0, 0, ..., 0, 0, 0],
           [0, 0, 0, ..., 0, 0, 0],
           [0, 0, 0, ..., 0, 0, 0]], shape=(151, 302), dtype=int32)

  • angle_coarse
    (eta_coarse, xi_coarse)
    float64
    0.3755 0.3749 ... -0.3085 -0.3073

    long_name :

    Angle between xi axis and east on coarsened grid

    units :

    radians

    array([[ 0.37546152,  0.37490634,  0.37260072, ..., -0.38588694,
            -0.38475305, -0.3844388 ],
           [ 0.36913191,  0.36860411,  0.36640829, ..., -0.37805474,
            -0.37684639, -0.37651405],
           [ 0.36296571,  0.36246436,  0.36037474, ..., -0.37044997,
            -0.36917165, -0.36882234],
           ...,
           [ 0.35812454,  0.35869879,  0.36091337, ..., -0.30461023,
            -0.30009445, -0.29895147],
           [ 0.36405135,  0.36465233,  0.36697356, ..., -0.30888051,
            -0.30426054, -0.3030916 ],
           [ 0.37013349,  0.37076208,  0.37319352, ..., -0.31325886,
            -0.30853205, -0.30733648]], shape=(77, 152))

  • mask_coarse
    (eta_coarse, xi_coarse)
    int32
    1 1 1 1 1 1 1 1 ... 0 0 0 0 0 0 0 0

    long_name :

    Mask at rho-points on coarsened grid

    units :

    land/water (0/1)

    array([[1, 1, 1, ..., 1, 0, 0],
           [1, 1, 1, ..., 1, 0, 0],
           [1, 1, 1, ..., 1, 0, 0],
           ...,
           [0, 0, 0, ..., 0, 0, 0],
           [0, 0, 0, ..., 0, 0, 0],
           [0, 0, 0, ..., 0, 0, 0]], shape=(77, 152), dtype=int32)

  • h
    (eta_rho, xi_rho)
    float64
    4.082e+03 4.082e+03 ... 5.0 5.0

    long_name :

    Bathymetry at rho-points

    units :

    meter

    array([[4082.14631299, 4082.14631299, 4127.74578094, ...,  193.05247614,
             136.23853119,  136.23853119],
           [4082.14631299, 4082.14631299, 4127.74578094, ...,  193.05247614,
             136.23853119,  136.23853119],
           [4087.83641216, 4087.83641216, 4128.38381609, ...,  183.78104732,
             134.15508954,  134.15508954],
           ...,
           [   5.        ,    5.        ,    5.        , ...,    5.        ,
               5.        ,    5.        ],
           [   5.        ,    5.        ,    5.        , ...,    5.        ,
               5.        ,    5.        ],
           [   5.        ,    5.        ,    5.        , ...,    5.        ,
               5.        ,    5.        ]], shape=(152, 302))

  • sigma_r
    (s_rho)
    float32
    -0.995 -0.985 ... -0.015 -0.005

    long_name :

    Fractional vertical stretching coordinate at rho-points

    units :

    nondimensional

    array([-0.995, -0.985, -0.975, -0.965, -0.955, -0.945, -0.935, -0.925,
           -0.915, -0.905, -0.895, -0.885, -0.875, -0.865, -0.855, -0.845,
           -0.835, -0.825, -0.815, -0.805, -0.795, -0.785, -0.775, -0.765,
           -0.755, -0.745, -0.735, -0.725, -0.715, -0.705, -0.695, -0.685,
           -0.675, -0.665, -0.655, -0.645, -0.635, -0.625, -0.615, -0.605,
           -0.595, -0.585, -0.575, -0.565, -0.555, -0.545, -0.535, -0.525,
           -0.515, -0.505, -0.495, -0.485, -0.475, -0.465, -0.455, -0.445,
           -0.435, -0.425, -0.415, -0.405, -0.395, -0.385, -0.375, -0.365,
           -0.355, -0.345, -0.335, -0.325, -0.315, -0.305, -0.295, -0.285,
           -0.275, -0.265, -0.255, -0.245, -0.235, -0.225, -0.215, -0.205,
           -0.195, -0.185, -0.175, -0.165, -0.155, -0.145, -0.135, -0.125,
           -0.115, -0.105, -0.095, -0.085, -0.075, -0.065, -0.055, -0.045,
           -0.035, -0.025, -0.015, -0.005], dtype=float32)

  • Cs_r
    (s_rho)
    float32
    -0.992 -0.9753 ... -9.874e-06

    long_name :

    Vertical stretching function at rho-points

    units :

    nondimensional

    array([-9.91966903e-01, -9.75310326e-01, -9.57903922e-01, -9.39797223e-01,
           -9.21044052e-01, -9.01701748e-01, -8.81830335e-01, -8.61491978e-01,
           -8.40749860e-01, -8.19667757e-01, -7.98309207e-01, -7.76737094e-01,
           -7.55012929e-01, -7.33196437e-01, -7.11345196e-01, -6.89514160e-01,
           -6.67755604e-01, -6.46118581e-01, -6.24649167e-01, -6.03389859e-01,
           -5.82379997e-01, -5.61655402e-01, -5.41248500e-01, -5.21188438e-01,
           -5.01500964e-01, -4.82208848e-01, -4.63331670e-01, -4.44886118e-01,
           -4.26886171e-01, -4.09343123e-01, -3.92265856e-01, -3.75660986e-01,
           -3.59532982e-01, -3.43884379e-01, -3.28715861e-01, -3.14026594e-01,
           -2.99814165e-01, -2.86074877e-01, -2.72803813e-01, -2.59995013e-01,
           -2.47641608e-01, -2.35735863e-01, -2.24269405e-01, -2.13233232e-01,
           -2.02617854e-01, -1.92413345e-01, -1.82609484e-01, -1.73195779e-01,
           -1.64161548e-01, -1.55495971e-01, -1.47188202e-01, -1.39227331e-01,
           -1.31602496e-01, -1.24302894e-01, -1.17317833e-01, -1.10636741e-01,
           -1.04249209e-01, -9.81450155e-02, -9.23141390e-02, -8.67467746e-02,
           -8.14333707e-02, -7.63645992e-02, -7.15314075e-02, -6.69250041e-02,
           -6.25368580e-02, -5.83587363e-02, -5.43826595e-02, -5.06009422e-02,
           -4.70061824e-02, -4.35912535e-02, -4.03493047e-02, -3.72737721e-02,
           -3.43583524e-02, -3.15970331e-02, -2.89840512e-02, -2.65139174e-02,
           -2.41813995e-02, -2.19815224e-02, -1.99095625e-02, -1.79610383e-02,
           -1.61317140e-02, -1.44175906e-02, -1.28148990e-02, -1.13201011e-02,
           -9.92987957e-03, -8.64113960e-03, -7.45099736e-03, -6.35678275e-03,
           -5.35603240e-03, -4.44648601e-03, -3.62608512e-03, -2.89296708e-03,
           -2.24546436e-03, -1.68210152e-03, -1.20159215e-03, -8.02837836e-04,
           -4.84925782e-04, -2.47127580e-04, -8.88979121e-05, -9.87376825e-06],
          dtype=float32)

  • sigma_w
    (s_w)
    float32
    -1.0 -0.99 -0.98 ... -0.01 0.0

    long_name :

    Fractional vertical stretching coordinate at w-points

    units :

    nondimensional

    array([-1.  , -0.99, -0.98, -0.97, -0.96, -0.95, -0.94, -0.93, -0.92,
           -0.91, -0.9 , -0.89, -0.88, -0.87, -0.86, -0.85, -0.84, -0.83,
           -0.82, -0.81, -0.8 , -0.79, -0.78, -0.77, -0.76, -0.75, -0.74,
           -0.73, -0.72, -0.71, -0.7 , -0.69, -0.68, -0.67, -0.66, -0.65,
           -0.64, -0.63, -0.62, -0.61, -0.6 , -0.59, -0.58, -0.57, -0.56,
           -0.55, -0.54, -0.53, -0.52, -0.51, -0.5 , -0.49, -0.48, -0.47,
           -0.46, -0.45, -0.44, -0.43, -0.42, -0.41, -0.4 , -0.39, -0.38,
           -0.37, -0.36, -0.35, -0.34, -0.33, -0.32, -0.31, -0.3 , -0.29,
           -0.28, -0.27, -0.26, -0.25, -0.24, -0.23, -0.22, -0.21, -0.2 ,
           -0.19, -0.18, -0.17, -0.16, -0.15, -0.14, -0.13, -0.12, -0.11,
           -0.1 , -0.09, -0.08, -0.07, -0.06, -0.05, -0.04, -0.03, -0.02,
           -0.01,  0.  ], dtype=float32)

  • Cs_w
    (s_w)
    float32
    -1.0 -0.9837 ... -3.95e-05 0.0

    long_name :

    Vertical stretching function at w-points

    units :

    nondimensional

    array([-1.0000000e+00, -9.8373526e-01, -9.6669787e-01, -9.4893485e-01,
           -9.3049794e-01, -9.1144282e-01, -8.9182830e-01, -8.7171561e-01,
           -8.5116738e-01, -8.3024728e-01, -8.0901909e-01, -7.8754598e-01,
           -7.6589024e-01, -7.4411261e-01, -7.2227168e-01, -7.0042384e-01,
           -6.7862266e-01, -6.5691894e-01, -6.3536018e-01, -6.1399072e-01,
           -5.9285146e-01, -5.7197994e-01, -5.5141032e-01, -5.3117341e-01,
           -5.1129663e-01, -4.9180421e-01, -4.7271729e-01, -4.5405400e-01,
           -4.3582967e-01, -4.1805691e-01, -4.0074578e-01, -3.8390404e-01,
           -3.6753717e-01, -3.5164866e-01, -3.3624011e-01, -3.2131144e-01,
           -3.0686098e-01, -2.9288566e-01, -2.7938116e-01, -2.6634204e-01,
           -2.5376186e-01, -2.4163328e-01, -2.2994828e-01, -2.1869811e-01,
           -2.0787355e-01, -1.9746487e-01, -1.8746199e-01, -1.7785452e-01,
           -1.6863190e-01, -1.5978335e-01, -1.5129805e-01, -1.4316508e-01,
           -1.3537359e-01, -1.2791272e-01, -1.2077171e-01, -1.1393995e-01,
           -1.0740692e-01, -1.0116233e-01, -9.5196031e-02, -8.9498125e-02,
           -8.4058918e-02, -7.8868978e-02, -7.3919117e-02, -6.9200397e-02,
           -6.4704172e-02, -6.0422052e-02, -5.6345928e-02, -5.2467976e-02,
           -4.8780646e-02, -4.5276675e-02, -4.1949075e-02, -3.8791135e-02,
           -3.5796430e-02, -3.2958798e-02, -3.0272348e-02, -2.7731461e-02,
           -2.5330773e-02, -2.3065183e-02, -2.0929839e-02, -1.8920140e-02,
           -1.7031731e-02, -1.5260493e-02, -1.3602542e-02, -1.2054225e-02,
           -1.0612117e-02, -9.2730094e-03, -8.0339154e-03, -6.8920576e-03,
           -5.8448706e-03, -4.8899921e-03, -4.0252637e-03, -3.2487246e-03,
           -2.5586106e-03, -1.9533504e-03, -1.4315632e-03, -9.9205703e-04,
           -6.3382636e-04, -3.5605079e-04, -1.5809362e-04, -3.9500741e-05,
            0.0000000e+00], dtype=float32)

• Indexes: (0)
• Attributes: (13)

  title :

  ROMS grid created by ROMS-Tools

  roms_tools_version :

  2.6.3.dev44+g780e06f.d20250623

  size_x :

  23000

  size_y :

  12000

  center_lon :

  -161.0

  center_lat :

  14.4

  rot :

  -3.0

  straddle :

  False

  topography_source_name :

  ETOPO5

  hmin :

  5.0

  theta_s :

  5.0

  theta_b :

  2.0

  hc :

  300.0

filepath_grid = "/pscratch/sd/n/nloose/grids/my_roms_grid.nc"

grid.save(filepath_grid)

INFO - Writing the following NetCDF files:
/pscratch/sd/n/nloose/grids/my_roms_grid.nc

[PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.nc')]

Example surface forcing file

from roms_tools import SurfaceForcing
from datetime import datetime

start_time = datetime(2011, 1, 1)
end_time = datetime(2011, 1, 2)

era5_path = "/global/cfs/projectdirs/m4746/Datasets/ERA5/GLOBAL/reanalysis-era5-single-levels_2011-01.nc"

surface_forcing = SurfaceForcing(
    grid=grid,
    start_time=start_time,
    end_time=end_time,
    source={"name": "ERA5", "path": era5_path},
    use_dask=True,
)

INFO - Data will be interpolated onto fine grid.
INFO - Applying 2D horizontal fill to the source data before regridding.
INFO - Applying 2D horizontal fill to the source data before regridding.

surface_forcing.ds

<xarray.Dataset> Size: 32MB
Dimensions:   (time: 25, eta_rho: 152, xi_rho: 302)
Coordinates:
    number    int64 8B 0
    expver    (time) <U4 400B dask.array<chunksize=(1,), meta=np.ndarray>
    abs_time  (time) datetime64[ns] 200B 2011-01-01 ... 2011-01-02
  * time      (time) float64 200B 4.018e+03 4.018e+03 ... 4.019e+03 4.019e+03
Dimensions without coordinates: eta_rho, xi_rho
Data variables:
    uwnd      (time, eta_rho, xi_rho) float32 5MB dask.array<chunksize=(1, 152, 302), meta=np.ndarray>
    vwnd      (time, eta_rho, xi_rho) float32 5MB dask.array<chunksize=(1, 152, 302), meta=np.ndarray>
    swrad     (time, eta_rho, xi_rho) float32 5MB dask.array<chunksize=(1, 152, 302), meta=np.ndarray>
    lwrad     (time, eta_rho, xi_rho) float32 5MB dask.array<chunksize=(1, 152, 302), meta=np.ndarray>
    Tair      (time, eta_rho, xi_rho) float32 5MB dask.array<chunksize=(1, 152, 302), meta=np.ndarray>
    rain      (time, eta_rho, xi_rho) float32 5MB dask.array<chunksize=(1, 152, 302), meta=np.ndarray>
    qair      (time, eta_rho, xi_rho) float32 5MB dask.array<chunksize=(1, 152, 302), meta=np.ndarray>
Attributes:
    title:                 ROMS surface forcing file created by ROMS-Tools
    roms_tools_version:    2.6.3.dev44+g780e06f.d20250623
    start_time:            2011-01-01 00:00:00
    end_time:              2011-01-02 00:00:00
    source:                ERA5
    correct_radiation:     True
    wind_dropoff:          False
    use_coarse_grid:       False
    model_reference_date:  2000-01-01 00:00:00
    type:                  physics

xarray.Dataset

• Dimensions:
  • time: 25
  • eta_rho: 152
  • xi_rho: 302
• Coordinates: (4)
  • number
    ()
    int64
    0

    array(0)

  • expver
    (time)
    <U4
    dask.array<chunksize=(1,), meta=np.ndarray>

    Array Chunk Bytes 400 B 16 B Shape (25,) (1,) Dask graph 25 chunks in 4 graph layers Data type

  • abs_time
    (time)
    datetime64[ns]
    2011-01-01 ... 2011-01-02

    long_name :

    absolute time

    array(['2011-01-01T00:00:00.000000000', '2011-01-01T01:00:00.000000000',
           '2011-01-01T02:00:00.000000000', '2011-01-01T03:00:00.000000000',
           '2011-01-01T04:00:00.000000000', '2011-01-01T05:00:00.000000000',
           '2011-01-01T06:00:00.000000000', '2011-01-01T07:00:00.000000000',
           '2011-01-01T08:00:00.000000000', '2011-01-01T09:00:00.000000000',
           '2011-01-01T10:00:00.000000000', '2011-01-01T11:00:00.000000000',
           '2011-01-01T12:00:00.000000000', '2011-01-01T13:00:00.000000000',
           '2011-01-01T14:00:00.000000000', '2011-01-01T15:00:00.000000000',
           '2011-01-01T16:00:00.000000000', '2011-01-01T17:00:00.000000000',
           '2011-01-01T18:00:00.000000000', '2011-01-01T19:00:00.000000000',
           '2011-01-01T20:00:00.000000000', '2011-01-01T21:00:00.000000000',
           '2011-01-01T22:00:00.000000000', '2011-01-01T23:00:00.000000000',
           '2011-01-02T00:00:00.000000000'], dtype='datetime64[ns]')

  • time
    (time)
    float64
    4.018e+03 4.018e+03 ... 4.019e+03

    long_name :

    relative time: days since 2000-01-01 00:00:00

    units :

    days

    array([4018.      , 4018.041667, 4018.083333, 4018.125   , 4018.166667,
           4018.208333, 4018.25    , 4018.291667, 4018.333333, 4018.375   ,
           4018.416667, 4018.458333, 4018.5     , 4018.541667, 4018.583333,
           4018.625   , 4018.666667, 4018.708333, 4018.75    , 4018.791667,
           4018.833333, 4018.875   , 4018.916667, 4018.958333, 4019.      ])

• Data variables: (7)
  • uwnd
    (time, eta_rho, xi_rho)
    float32
    dask.array<chunksize=(1, 152, 302), meta=np.ndarray>

    long_name :

    10 meter wind in x-direction

    units :

    m/s

    Array Chunk Bytes 4.38 MiB 179.31 kiB Shape (25, 152, 302) (1, 152, 302) Dask graph 25 chunks in 85 graph layers Data type float32 numpy.ndarray

  • vwnd
    (time, eta_rho, xi_rho)
    float32
    dask.array<chunksize=(1, 152, 302), meta=np.ndarray>

    long_name :

    10 meter wind in y-direction

    units :

    m/s

    Array Chunk Bytes 4.38 MiB 179.31 kiB Shape (25, 152, 302) (1, 152, 302) Dask graph 25 chunks in 85 graph layers Data type float32 numpy.ndarray

  • swrad
    (time, eta_rho, xi_rho)
    float32
    dask.array<chunksize=(1, 152, 302), meta=np.ndarray>

    long_name :

    downward short-wave (solar) radiation

    units :

    W/m^2

    Array Chunk Bytes 4.38 MiB 179.31 kiB Shape (25, 152, 302) (1, 152, 302) Dask graph 25 chunks in 106 graph layers Data type float32 numpy.ndarray

  • lwrad
    (time, eta_rho, xi_rho)
    float32
    dask.array<chunksize=(1, 152, 302), meta=np.ndarray>

    long_name :

    downward long-wave (thermal) radiation

    units :

    W/m^2

    Array Chunk Bytes 4.38 MiB 179.31 kiB Shape (25, 152, 302) (1, 152, 302) Dask graph 25 chunks in 53 graph layers Data type float32 numpy.ndarray

  • Tair
    (time, eta_rho, xi_rho)
    float32
    dask.array<chunksize=(1, 152, 302), meta=np.ndarray>

    long_name :

    air temperature at 2m

    units :

    degrees Celsius

    Array Chunk Bytes 4.38 MiB 179.31 kiB Shape (25, 152, 302) (1, 152, 302) Dask graph 25 chunks in 53 graph layers Data type float32 numpy.ndarray

  • rain
    (time, eta_rho, xi_rho)
    float32
    dask.array<chunksize=(1, 152, 302), meta=np.ndarray>

    long_name :

    total precipitation

    units :

    cm/day

    Array Chunk Bytes 4.38 MiB 179.31 kiB Shape (25, 152, 302) (1, 152, 302) Dask graph 25 chunks in 53 graph layers Data type float32 numpy.ndarray

  • qair
    (time, eta_rho, xi_rho)
    float32
    dask.array<chunksize=(1, 152, 302), meta=np.ndarray>

    long_name :

    absolute humidity at 2m

    units :

    kg/kg

    Array Chunk Bytes 4.38 MiB 179.31 kiB Shape (25, 152, 302) (1, 152, 302) Dask graph 25 chunks in 78 graph layers Data type float32 numpy.ndarray

• Indexes: (1)
  • time
    PandasIndex

    PandasIndex(Index([            4018.0, 4018.0416666666665, 4018.0833333333335,
                     4018.125, 4018.1666666666665, 4018.2083333333335,
                      4018.25, 4018.2916666666665, 4018.3333333333335,
                     4018.375, 4018.4166666666665, 4018.4583333333335,
                       4018.5, 4018.5416666666665, 4018.5833333333335,
                     4018.625, 4018.6666666666665, 4018.7083333333335,
                      4018.75, 4018.7916666666665, 4018.8333333333335,
                     4018.875, 4018.9166666666665, 4018.9583333333335,
                       4019.0],
          dtype='float64', name='time'))

• Attributes: (10)

  title :

  ROMS surface forcing file created by ROMS-Tools

  roms_tools_version :

  2.6.3.dev44+g780e06f.d20250623

  start_time :

  2011-01-01 00:00:00

  end_time :

  2011-01-02 00:00:00

  source :

  ERA5

  correct_radiation :

  True

  wind_dropoff :

  False

  use_coarse_grid :

  False

  model_reference_date :

  2000-01-01 00:00:00

  type :

  physics

filepath_forcing = "/pscratch/sd/n/nloose/forcing/my_surface_forcing.nc"

surface_forcing.save(filepath_forcing)

INFO - Writing the following NetCDF files:
/pscratch/sd/n/nloose/forcing/my_surface_forcing_201101.nc

[########################################] | 100% Completed | 304.59 s

[PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing_201101.nc')]

Partitioning existing files

We will now partition the two files written in the previous section. However, note that the partition_netcdf tool in ROMS-Tools operates independently of whether the files were originally created using ROMS-Tools.

from roms_tools import partition_netcdf

We need to tell the partition_netcdf function what domain decomposition to use via the following two parameters:

• np_eta : The number of partitions along the eta direction (corresponding to ny in the grid).

• np_xi : The number of partitions along the xi direction (corresponding to nx in the grid).

%time partition_netcdf(filepath_grid, np_eta=3, np_xi=6)

CPU times: user 310 ms, sys: 60 ms, total: 370 ms
Wall time: 420 ms

[PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.00.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.01.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.02.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.03.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.04.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.05.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.06.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.07.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.08.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.09.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.10.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.11.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.12.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.13.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.14.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.15.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.16.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.17.nc')]

%time partition_netcdf(filepath_forcing, np_eta=3, np_xi=6)

CPU times: user 53.1 s, sys: 27.4 s, total: 1min 20s
Wall time: 1min 20s

[PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.00.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.01.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.02.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.03.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.04.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.05.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.06.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.07.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.08.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.09.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.10.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.11.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.12.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.13.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.14.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.15.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.16.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.17.nc')]

Providing a list of files

The partition_netcdf function also accepts a list of input files, allowing you to partition multiple NetCDF files in a single call.

%time partition_netcdf([filepath_grid, filepath_forcing], np_eta=3, np_xi=6)

CPU times: user 54.1 s, sys: 32.5 s, total: 1min 26s
Wall time: 1min 26s

[PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.00.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.01.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.02.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.03.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.04.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.05.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.06.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.07.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.08.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.09.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.10.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.11.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.12.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.13.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.14.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.15.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.16.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.17.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.00.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.01.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.02.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.03.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.04.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.05.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.06.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.07.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.08.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.09.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.10.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.11.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.12.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.13.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.14.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.15.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.16.nc'),
 PosixPath('/pscratch/sd/n/nloose/forcing/my_surface_forcing.17.nc')]

Specifying an output directory for partitioned files

The partition_netcdf function accepts an optional output_dir parameter, which allows you to control where the partitioned files are saved.

• If output_dir is set to None (the default), partitioned files are saved in the same directory as the input file.

• If an explicit output_dir is provided, all partitioned files will be written to that location.

In the examples above, we used the default behavior. Now let’s specify a custom output_dir to save the output files elsewhere.

%time partition_netcdf(filepath_grid, np_eta=3, np_xi=6, output_dir='/pscratch/sd/n/nloose/grids/partitioned')

CPU times: user 315 ms, sys: 56.1 ms, total: 371 ms
Wall time: 423 ms

[PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.00.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.01.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.02.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.03.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.04.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.05.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.06.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.07.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.08.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.09.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.10.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.11.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.12.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.13.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.14.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.15.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.16.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/partitioned/my_roms_grid.17.nc')]

Ignoring Coarse Dimensions During Partitioning

The grid file generated by ROMS-Tools always includes the dimensions eta_coarse and xi_coarse. These dimensions, along with their associated variables, are only relevant when coarse-resolution forcing is used. This typically applies when surface forcing fields are generated on a grid coarser than the ROMS model grid, see the ROMS-Tools documentation on surface forcing. The coarse forcing configuration is activated when the ROMS bulk_frc.opt file includes the setting:

interp_frc = 1

With this option enabled, ROMS interpolates surface forcing data from the coarse grid onto the fine model grid at runtime.

If your simulation does not use coarse forcing, then the eta_coarse and xi_coarse dimensions in the grid file can be safely ignored, including during partitioning. This allows for a broader range of valid values for np_eta and np_xi, since only the fine grid dimensions must be divisible by these parameters. In contrast, if the coarse dimensions eta_coarse, xi_coarse are included, both fine and coarse grid sizes must be divisible by np_eta and np_xi.

The partition_netcdf() function provides a parameter include_coarse_dimensions to control this behavior.

Example

Our grid above was created with:

• nx = 300 (corresponding to xi_rho)

• ny = 150 (corresponding to eta_rho)

By default, ROMS-Tools also includes coarse grid dimensions:

• nx / 2 = 150 (corresponding to xi_coarse)

• ny / 2 = 75 (corresponding to eta_coarse)

Now let’s try partitioning with:

• np_xi = 12

• np_eta = 6

These values divide the fine dimensions:

• np_xi = 12 divides nx = 300

• np_eta = 6 divides ny = 150

However, they do not divide the coarse dimensions:

• 12 does not divide 150

• 6 does not divide 75

As a result, if include_coarse_dims = True (the default), partitioning will fail with an error like:

%time partition_netcdf(filepath_grid, np_eta=6, np_xi=12, include_coarse_dims=True)

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
File <timed eval>:1

File /global/cfs/cdirs/m4746/Users/nora/roms-tools/roms_tools/tiling/partition.py:347, in partition_netcdf(filepath, np_eta, np_xi, output_dir, include_coarse_dims)
    344 input_file = fp.with_suffix(".nc")
    345 ds = xr.open_dataset(input_file, decode_timedelta=False)
--> 347 file_numbers, partitioned_datasets = partition(
    348     ds, np_eta=np_eta, np_xi=np_xi, include_coarse_dims=include_coarse_dims
    349 )
    351 if output_dir:
    352     output_dir = Path(output_dir)

File /global/cfs/cdirs/m4746/Users/nora/roms-tools/roms_tools/tiling/partition.py:162, in partition(ds, np_eta, np_xi, include_coarse_dims)
    157     xi_psi_domain_size = integer_division_or_raise(
    158         ds.sizes["xi_psi"] - 3 * n_xi_ghost_cells, np_xi, "xi_psi"
    159     )
    161 if "eta_coarse" in dims_to_partition:
--> 162     eta_coarse_domain_size = integer_division_or_raise(
    163         ds.sizes["eta_coarse"] - 2 * n_eta_ghost_cells, np_eta, "eta_coarse"
    164     )
    165 if "xi_coarse" in dims_to_partition:
    166     xi_coarse_domain_size = integer_division_or_raise(
    167         ds.sizes["xi_coarse"] - 2 * n_xi_ghost_cells, np_xi, "xi_coarse"
    168     )

File /global/cfs/cdirs/m4746/Users/nora/roms-tools/roms_tools/tiling/partition.py:127, in partition.<locals>.integer_division_or_raise(a, b, dimension)
    125     return a // b
    126 else:
--> 127     raise ValueError(
    128         f"Dimension '{dimension}' of size {a} cannot be evenly divided into {b} partitions."
    129     )

ValueError: Dimension 'eta_coarse' of size 75 cannot be evenly divided into 6 partitions.

To avoid this, you can set include_coarse_dims = False to skip partitioning along the coarse dimensions:

%time partition_netcdf(filepath_grid, np_eta=6, np_xi=12, include_coarse_dims=False)

CPU times: user 1.25 s, sys: 240 ms, total: 1.49 s
Wall time: 1.71 s

[PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.00.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.01.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.02.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.03.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.04.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.05.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.06.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.07.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.08.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.09.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.10.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.11.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.12.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.13.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.14.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.15.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.16.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.17.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.18.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.19.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.20.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.21.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.22.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.23.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.24.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.25.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.26.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.27.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.28.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.29.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.30.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.31.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.32.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.33.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.34.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.35.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.36.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.37.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.38.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.39.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.40.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.41.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.42.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.43.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.44.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.45.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.46.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.47.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.48.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.49.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.50.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.51.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.52.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.53.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.54.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.55.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.56.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.57.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.58.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.59.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.60.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.61.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.62.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.63.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.64.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.65.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.66.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.67.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.68.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.69.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.70.nc'),
 PosixPath('/pscratch/sd/n/nloose/grids/my_roms_grid.71.nc')]