Climatology mean

This notebook demonstrates how to calculate a climatological mean of a long time-series of data.

from earthkit import data as ekd
from earthkit import transforms as ekt
from earthkit.transforms._tools import earthkit_remote_test_data_file

# Get some demonstration ERA5 data, this could be any url or path to an ERA5 grib or netCDF file.
remote_era5_file = earthkit_remote_test_data_file("ERA5-Reading-2m-temperature-1940-2025.nc")
era5_data = ekd.from_source("url", remote_era5_file)
era5_xr = era5_data.to_xarray()

# Total climatology, i.e. the mean over all time steps:
climatology_mean = ekt.climatology.mean(era5_xr, climatology_range=("1991", "2020"))
climatology_mean

<xarray.Dataset> Size: 20B
Dimensions:    ()
Coordinates:
    latitude   float64 8B ...
    longitude  float64 8B ...
Data variables:
    t2m        float32 4B 283.7
Attributes:
    Conventions:             CF-1.7
    GRIB_centre:             ecmf
    GRIB_centreDescription:  European Centre for Medium-Range Weather Forecasts
    GRIB_edition:            1
    GRIB_subCentre:          0
    history:                 2024-09-02T04:48 GRIB to CDM+CF via cfgrib-0.9.1...
    institution:             European Centre for Medium-Range Weather Forecasts

xarray.Dataset

• Dimensions:
• Coordinates: (2)
  • latitude
    ()
    float64
    ...

    long_name :

    latitude

    standard_name :

    latitude

    stored_direction :

    decreasing

    units :

    degrees_north

    [1 values with dtype=float64]

  • longitude
    ()
    float64
    ...

    long_name :

    longitude

    standard_name :

    longitude

    units :

    degrees_east

    [1 values with dtype=float64]

• Data variables: (1)
  • t2m
    ()
    float32
    283.7

    GRIB_NV :

    0

    GRIB_Nx :

    1440

    GRIB_Ny :

    721

    GRIB_cfName :

    unknown

    GRIB_cfVarName :

    t2m

    GRIB_dataType :

    an

    GRIB_gridDefinitionDescription :

    Latitude/Longitude Grid

    GRIB_gridType :

    regular_ll

    GRIB_iDirectionIncrementInDegrees :

    0.25

    GRIB_iScansNegatively :

    0

    GRIB_jDirectionIncrementInDegrees :

    0.25

    GRIB_jPointsAreConsecutive :

    0

    GRIB_jScansPositively :

    0

    GRIB_latitudeOfFirstGridPointInDegrees :

    90.0

    GRIB_latitudeOfLastGridPointInDegrees :

    -90.0

    GRIB_longitudeOfFirstGridPointInDegrees :

    0.0

    GRIB_longitudeOfLastGridPointInDegrees :

    359.75

    GRIB_missingValue :

    3.4028234663852886e+38

    GRIB_name :

    2 metre temperature

    GRIB_numberOfPoints :

    1038240

    GRIB_paramId :

    167

    GRIB_shortName :

    2t

    GRIB_stepType :

    instant

    GRIB_stepUnits :

    1

    GRIB_totalNumber :

    0

    GRIB_typeOfLevel :

    surface

    GRIB_units :

    K

    long_name :

    2 metre temperature

    standard_name :

    unknown

    units :

    K

    array(283.68542, dtype=float32)

• Attributes: (7)

  Conventions :

  CF-1.7

  GRIB_centre :

  ecmf

  GRIB_centreDescription :

  European Centre for Medium-Range Weather Forecasts

  GRIB_edition :

  1

  GRIB_subCentre :

  0

  history :

  2024-09-02T04:48 GRIB to CDM+CF via cfgrib-0.9.10.4/ecCodes-2.26.0 with {"source": "../../../../../admp-scratch/data/arco-job-76964210-9c34-4488-a458-d3511cc8a37a-inputs/pre-reanalysis_era5_single_levels-sfc:1-sst-20150131-000000.grib", "filter_by_keys": {}, "encode_cf": ["parameter", "time", "geography", "vertical"]}

  institution :

  European Centre for Medium-Range Weather Forecasts

# Monthly climatology, i.e. the mean for each month of the year:
climatology_monthly_mean = ekt.climatology.monthly_mean(era5_xr, climatology_range=("1991", "2020"))
climatology_monthly_mean

<xarray.Dataset> Size: 160B
Dimensions:    (month: 12)
Coordinates:
  * month      (month) int64 96B 1 2 3 4 5 6 7 8 9 10 11 12
    latitude   float64 8B 51.5
    longitude  float64 8B -1.0
Data variables:
    t2m        (month) float32 48B 278.0 278.2 280.0 282.3 ... 284.2 280.8 278.4
Attributes:
    Conventions:             CF-1.7
    GRIB_centre:             ecmf
    GRIB_centreDescription:  European Centre for Medium-Range Weather Forecasts
    GRIB_edition:            1
    GRIB_subCentre:          0
    history:                 2024-09-02T04:48 GRIB to CDM+CF via cfgrib-0.9.1...
    institution:             European Centre for Medium-Range Weather Forecasts

xarray.Dataset

• Dimensions:
  • month: 12
• Coordinates: (3)
  • month
    (month)
    int64
    1 2 3 4 5 6 7 8 9 10 11 12

    array([ 1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12])

  • latitude
    ()
    float64
    51.5

    long_name :

    latitude

    standard_name :

    latitude

    stored_direction :

    decreasing

    units :

    degrees_north

    array(51.5)

  • longitude
    ()
    float64
    -1.0

    long_name :

    longitude

    standard_name :

    longitude

    units :

    degrees_east

    array(-1.)

• Data variables: (1)
  • t2m
    (month)
    float32
    278.0 278.2 280.0 ... 280.8 278.4

    GRIB_NV :

    0

    GRIB_Nx :

    1440

    GRIB_Ny :

    721

    GRIB_cfName :

    unknown

    GRIB_cfVarName :

    t2m

    GRIB_dataType :

    an

    GRIB_gridDefinitionDescription :

    Latitude/Longitude Grid

    GRIB_gridType :

    regular_ll

    GRIB_iDirectionIncrementInDegrees :

    0.25

    GRIB_iScansNegatively :

    0

    GRIB_jDirectionIncrementInDegrees :

    0.25

    GRIB_jPointsAreConsecutive :

    0

    GRIB_jScansPositively :

    0

    GRIB_latitudeOfFirstGridPointInDegrees :

    90.0

    GRIB_latitudeOfLastGridPointInDegrees :

    -90.0

    GRIB_longitudeOfFirstGridPointInDegrees :

    0.0

    GRIB_longitudeOfLastGridPointInDegrees :

    359.75

    GRIB_missingValue :

    3.4028234663852886e+38

    GRIB_name :

    2 metre temperature

    GRIB_numberOfPoints :

    1038240

    GRIB_paramId :

    167

    GRIB_shortName :

    2t

    GRIB_stepType :

    instant

    GRIB_stepUnits :

    1

    GRIB_totalNumber :

    0

    GRIB_typeOfLevel :

    surface

    GRIB_units :

    K

    long_name :

    2 metre temperature

    standard_name :

    unknown

    units :

    K

    array([278.0421 , 278.1557 , 279.9539 , 282.28928, 285.4562 , 288.428  ,
           290.47485, 290.1296 , 287.5465 , 284.20837, 280.7618 , 278.4292 ],
          dtype=float32)

• Attributes: (7)

  Conventions :

  CF-1.7

  GRIB_centre :

  ecmf

  GRIB_centreDescription :

  European Centre for Medium-Range Weather Forecasts

  GRIB_edition :

  1

  GRIB_subCentre :

  0

  history :

  2024-09-02T04:48 GRIB to CDM+CF via cfgrib-0.9.10.4/ecCodes-2.26.0 with {"source": "../../../../../admp-scratch/data/arco-job-76964210-9c34-4488-a458-d3511cc8a37a-inputs/pre-reanalysis_era5_single_levels-sfc:1-sst-20150131-000000.grib", "filter_by_keys": {}, "encode_cf": ["parameter", "time", "geography", "vertical"]}

  institution :

  European Centre for Medium-Range Weather Forecasts

# Daily climatology, i.e. the mean for each day of the year:
climatology_daily_mean = ekt.climatology.daily_mean(era5_xr, climatology_range=("1991", "2020"))
climatology_daily_mean

<xarray.Dataset> Size: 4kB
Dimensions:    (dayofyear: 366)
Coordinates:
  * dayofyear  (dayofyear) int64 3kB 1 2 3 4 5 6 7 ... 361 362 363 364 365 366
    latitude   float64 8B 51.5
    longitude  float64 8B -1.0
Data variables:
    t2m        (dayofyear) float32 1kB 278.3 278.0 277.6 ... 277.9 277.9 276.0
Attributes:
    Conventions:             CF-1.7
    GRIB_centre:             ecmf
    GRIB_centreDescription:  European Centre for Medium-Range Weather Forecasts
    GRIB_edition:            1
    GRIB_subCentre:          0
    history:                 2024-09-02T04:48 GRIB to CDM+CF via cfgrib-0.9.1...
    institution:             European Centre for Medium-Range Weather Forecasts

xarray.Dataset

• Dimensions:
  • dayofyear: 366
• Coordinates: (3)
  • dayofyear
    (dayofyear)
    int64
    1 2 3 4 5 6 ... 362 363 364 365 366

    array([  1,   2,   3, ..., 364, 365, 366], shape=(366,))

  • latitude
    ()
    float64
    51.5

    long_name :

    latitude

    standard_name :

    latitude

    stored_direction :

    decreasing

    units :

    degrees_north

    array(51.5)

  • longitude
    ()
    float64
    -1.0

    long_name :

    longitude

    standard_name :

    longitude

    units :

    degrees_east

    array(-1.)

• Data variables: (1)
  • t2m
    (dayofyear)
    float32
    278.3 278.0 277.6 ... 277.9 276.0

    GRIB_NV :

    0

    GRIB_Nx :

    1440

    GRIB_Ny :

    721

    GRIB_cfName :

    unknown

    GRIB_cfVarName :

    t2m

    GRIB_dataType :

    an

    GRIB_gridDefinitionDescription :

    Latitude/Longitude Grid

    GRIB_gridType :

    regular_ll

    GRIB_iDirectionIncrementInDegrees :

    0.25

    GRIB_iScansNegatively :

    0

    GRIB_jDirectionIncrementInDegrees :

    0.25

    GRIB_jPointsAreConsecutive :

    0

    GRIB_jScansPositively :

    0

    GRIB_latitudeOfFirstGridPointInDegrees :

    90.0

    GRIB_latitudeOfLastGridPointInDegrees :

    -90.0

    GRIB_longitudeOfFirstGridPointInDegrees :

    0.0

    GRIB_longitudeOfLastGridPointInDegrees :

    359.75

    GRIB_missingValue :

    3.4028234663852886e+38

    GRIB_name :

    2 metre temperature

    GRIB_numberOfPoints :

    1038240

    GRIB_paramId :

    167

    GRIB_shortName :

    2t

    GRIB_stepType :

    instant

    GRIB_stepUnits :

    1

    GRIB_totalNumber :

    0

    GRIB_typeOfLevel :

    surface

    GRIB_units :

    K

    long_name :

    2 metre temperature

    standard_name :

    unknown

    units :

    K

    array([278.26782, 277.99854, 277.55438, 277.62317, 278.46   , 278.24545,
           278.44894, 278.7466 , 278.65573, 278.58252, 278.44833, 278.60593,
           278.95447, 278.04535, 278.8974 , 278.27567, 277.86798, 277.90875,
           278.1934 , 277.8908 , 277.46985, 277.5852 , 277.58664, 277.5549 ,
           277.7196 , 277.47736, 277.54263, 277.76074, 277.97852, 277.31335,
           277.6454 , 277.77972, 277.50485, 277.5234 , 278.55896, 278.3081 ,
           278.21347, 277.6573 , 277.52722, 277.3569 , 277.6035 , 277.99054,
           278.4326 , 277.97855, 277.41168, 278.4711 , 278.33304, 278.20682,
           278.14206, 278.04953, 278.21262, 278.46283, 278.4858 , 279.0404 ,
           278.9546 , 278.50568, 278.87714, 278.47153, 278.11234, 278.0975 ,
           278.048  , 278.03516, 278.30048, 278.45847, 279.1602 , 279.6753 ,
           280.1556 , 280.04617, 280.04797, 280.22263, 279.90283, 279.7982 ,
           279.96432, 280.79327, 280.98715, 280.6522 , 280.2949 , 279.8483 ,
           279.81482, 280.11774, 280.26666, 280.35   , 280.30566, 280.6055 ,
           280.293  , 280.1313 , 280.25003, 280.88766, 281.28616, 281.49414,
           281.4392 , 281.51828, 281.2786 , 281.23727, 281.1772 , 281.86725,
           280.9513 , 281.13928, 281.70062, 282.04172, 281.73676, 281.58932,
           281.4739 , 281.64487, 281.92972, 281.8969 , 282.02878, 281.938  ,
           281.93707, 282.45807, 283.31937, 283.92056, 283.94632, 283.76746,
           283.69562, 283.24496, 283.26202, 283.37985, 283.15475, 283.41003,
    ...
           288.29382, 288.4852 , 287.9779 , 287.3797 , 287.38   , 287.23395,
           287.3066 , 286.91574, 287.06384, 287.36084, 287.4526 , 287.43784,
           286.93607, 286.90067, 286.50034, 286.23233, 286.29877, 286.4569 ,
           286.75824, 286.80762, 286.76312, 286.8206 , 285.87756, 285.48767,
           284.99835, 284.95145, 285.22034, 284.62405, 285.39865, 285.6204 ,
           285.52252, 285.44907, 284.67593, 284.79007, 284.03882, 284.13568,
           284.11737, 283.5954 , 282.9895 , 283.17352, 282.77475, 283.71854,
           283.5197 , 283.57617, 283.94583, 283.58572, 283.6869 , 283.25446,
           282.92294, 282.87662, 283.1113 , 283.05737, 282.68387, 282.35422,
           282.7335 , 281.77182, 281.92133, 281.60953, 281.90515, 281.97043,
           281.08734, 281.59256, 281.80066, 281.34253, 281.13397, 280.7475 ,
           280.75348, 280.3979 , 280.0536 , 280.23886, 279.65857, 279.49475,
           279.2009 , 279.86053, 279.85587, 280.00473, 280.1448 , 280.25507,
           280.15628, 279.93848, 279.86407, 279.3353 , 279.50824, 279.35938,
           279.4443 , 278.88782, 278.8686 , 278.85416, 278.81525, 278.72217,
           278.2837 , 278.3242 , 278.1177 , 278.3143 , 278.55502, 277.93918,
           278.36438, 278.45737, 278.3188 , 278.17505, 278.48364, 277.4214 ,
           278.44415, 279.06763, 279.01282, 279.2145 , 278.32074, 278.2451 ,
           277.9478 , 277.3528 , 277.33508, 277.89883, 277.86685, 275.9882 ],
          dtype=float32)

• Attributes: (7)

  Conventions :

  CF-1.7

  GRIB_centre :

  ecmf

  GRIB_centreDescription :

  European Centre for Medium-Range Weather Forecasts

  GRIB_edition :

  1

  GRIB_subCentre :

  0

  history :

  2024-09-02T04:48 GRIB to CDM+CF via cfgrib-0.9.10.4/ecCodes-2.26.0 with {"source": "../../../../../admp-scratch/data/arco-job-76964210-9c34-4488-a458-d3511cc8a37a-inputs/pre-reanalysis_era5_single_levels-sfc:1-sst-20150131-000000.grib", "filter_by_keys": {}, "encode_cf": ["parameter", "time", "geography", "vertical"]}

  institution :

  European Centre for Medium-Range Weather Forecasts