grb_utils.py

"""Support functions
"""

import numpy
import pygrib

ww3_f = "data/nww3.t00z.grib.grib2.grb"

# Region lat/lon bounding boxes
region_box = {
    "gold_coast": {
        "lat": [-31, -25],
        "lon": [152, 157]
    }
}

# Era5 variable names
var_names = [
    u'10 metre U wind component',
    u'10 metre V wind component',
    u'Mean direction of total swell',
    u'Mean direction of wind waves',
    u'Mean period of total swell',
    u'Mean period of wind waves',
    u'Mean wave direction',
    u'Mean wave direction of first swell partition',
    u'Mean wave direction of second swell partition',
    u'Mean wave period',
    u'Mean wave period based on first moment for swell',
    u'Mean wave period of first swell partition',
    u'Mean wave period of second swell partition',
    u'Significant height of combined wind waves and swell',
    u'Significant height of wind waves'
]

var_names_short = [
    u'10u',
    u'10v',
    u'mdts',
    u'mdww',
    u'mpts',
    u'mpww',
    u'mwd',
    u'mwd1',
    u'mwd2',
    u'mwp',
    u'mwp1',
    u'mwp2',
    u'p1ps',
    u'shww',
    u'swh'
]

# WW3 variable names
ww3_var_names = [
    u"Direction of wind waves",
    u"Mean period of wind waves",
    u"Primary wave direction",
    u"Primary wave mean period",
    u"Significant height of combined wind waves and swell",
    u"Significant height of wind waves",
    u"U component of wind",
    u"V component of wind"
]

ww3_var_names_short = [
    u"wvdir",
    u"mpww",
    u"dirpw",
    u"perpw",
    u"swh",
    u"shww",
    u"u",
    u"v"
]

# Wavewatch III lat/lon grid


def ww3_grid(in_ww3_grb=None):
    """
    Return the lat and lon grid locations
    for WW3 model.

    Uses `ww3_f` as input but this could be
    any WW3 output file
    """

    if in_ww3_grb is None:
        # Read file
        in_ww3_grb = pygrib.open(ww3_f)

    # Get gribmessage
    grb = in_ww3_grb.read(1)[0]

    lat, lon = grb.latlons()

    # Reset
    in_ww3_grb.seek(0)

    return lat, lon


def ww3_mask(lat_range, lon_range, in_ww3_grb=None):
    """

    """
    # Read file
    if in_ww3_grb is None:
        in_ww3_grb = pygrib.open(ww3_f)

    # Get gribmessage
    grb = in_ww3_grb.read(1)[0]

    # Get data
    data = grb.data(lat1=lat_range[0], lat2=lat_range[1],
                    lon1=lon_range[0], lon2=lon_range[1])

    # Reset
    in_ww3_grb.seek(0)

    # Return mask
    return data[0].mask