Position

Basic Example

An example of a position requested via earthkit-data:

import earthkit.data

request = {
    "class": "od",
    "stream" : "enfo",
    "type" : "pf",
    "date" : -1,  # Note: date must be within the last two days 
    "time" : "0000",
    "levtype" : "sfc",
    "expver" : "0001", 
    "domain" : "g",
    "param" : "164/167/169",
    "number" : "1",
    "step" : "0"
    "feature" : {
        "type" : "position",
        "points": [[-9.10, 38.78]],
    },
    "format": "covjson",
}

ds = earthkit.data.from_source("polytope", "ecmwf-mars", request, stream=False, address='polytope.ecmwf.int')

The following will return a position starting yesterday at 00Z with step 0, for the parameters 164/167/169 at the point given. This data will be returned for ensemble member 1.

"polytope" refers to the underlying service being used to return the data. "ecmwf-mars" is the dataset we are looking to retrieve from. Setting stream=False returns all the requested data to us once it is available. address points to the endpoint for the polytope server.

Required Fields

For a position within the feature dictionary two fields are required

• type
• points

For a position type must be position.

points must be a nested list with a points containing a latitude and a longitude.

Optional Fields

axes can also be provided which defines the spatial axes on which the request is made. For example if the user provides points in the order longitude, latitude they can add axes : ["longitude", "latitude"].