如何返回每个年度最大值所在的季节？

Question

I have a daily netcdf dataset. I want to get each year maximum value, and return the season of the maximum value is in.

I have tried the xarray.DataArray.idxmax, below is the example, it can return the coordinate label of the maximum value along a dimension.

    array = xr.DataArray(
    [
        [2.0, 1.0, 2.0, 0.0, -2.0],
        [-4.0, np.NaN, 2.0, np.NaN, -2.0],
        [np.NaN, np.NaN, 1.0, np.NaN, np.NaN],
    ],
    dims=["y", "x"],
    coords={"y": [-1, 0, 1], "x": np.arange(5.0) ** 2},
)
array.max(dim="x")
<xarray.DataArray (y: 3)>
array([2., 2., 1.])
Coordinates:
  * y        (y) int64 -1 0 1
array.argmax(dim="x")
<xarray.DataArray (y: 3)>
array([0, 2, 2])
Coordinates:
  * y        (y) int64 -1 0 1
array.idxmax(dim="x")
<xarray.DataArray 'x' (y: 3)>
array([0., 4., 4.])
Coordinates:
  * y        (y) int64 -1 0 1

I know xarray.DataArray.idxmax can return the day of the all years. but i can't turn this day to each year's season is. The most difficult thing for me is winter, because winter spans between in two years.

How can I achieve that?

Answer 1

You tagged the question with cdo, and the cdo answer to the first part is fairly straightforward, getting the maximum in the year is just

cdo yearmax in.nc out.nc 

That is the first part of your question. But in terms of the season it occurs in, How are you defining your seasons? DJF, MAM, JJA, and SON? Can you clarify this in your question? Or would knowing the month be adequate (or even the date itself?).