indices:
  nzero:
    reference: SMHI
    period:
      allowed:
        annual:
        monthly:
        seasonal:
      default: annual
    output:
      var_name: nzero
      standard_name:
      long_name: Number of zero-crossing days (days when Tmin < 0 degC < Tmax)
      units: days
      cell_methods:
        - time: sum over days
      proposed_cell_methods:
        - time: level_crossing within days
        - time: sum over days
    input:
      low_data: tasmin
      high_data: tasmax
    index_function:
      name: count_level_crossings
      parameters:
        threshold:
          kind: quantity
          long_name: Threshold value for daily air temperature
          standard_name: air_temperature
          data: 0.
          units: degree_Celsius