Add new variable to data object in cds toolbox

Question

I'd like to compute the daily climatology and standard deviation of a variable (in this case pressure on two levels).

I'm able to do this, but currently can't create a single data object which I can download as a netcdf.

My code currently outputs a data object area_ave_c which is the climatology, and area_ave_s which has the standard deviations.

I can get the function to return either one of these objects, but ideally I would like to merge them and return one data object (downloaded as a netcdf) which contains both variables.

import cdstoolbox as ct


@ct.application(title='Retrieve Data')
@ct.output.download()



def retrieve_sample_data():
    data = ct.catalogue.retrieve(
        'reanalysis-era5-pressure-levels',
        {
            'product_type': 'reanalysis',
            'pressure_level': [
                '1','2',
            ],
            'year': [            '1979', '1980', '1981'
                    ],
            
            'month': [
                '01','02','12',
            ],
            'day': [
            '01', '02', '03',
            '04', '05', '06',
            ],
            'time': [
                '00:00',
            ],
            "grid": [1, 1],
            "area":[90,-180,60,180],
        }
    )
    
    climatology = ct.climate.climatology_mean(data,frequency='dayofyear')
    std_deviation = ct.climate.climatology_std(data,frequency='dayofyear')

    area_ave_c = ct.geo.spatial_average(climatology)
    area_ave_s = ct.geo.spatial_average(std_deviation)

    return (area_ave_s, area_ave_c)

The return line throws a bug currently, but I would like to download both data objects and running the code twice to output them sequentially is wasteful (as it gets all the data twice).

Answer 1

It turns out that you can return two objects from the retrieve_sample_data() function, and you download them by just calling ct.output.download() twice in the preamble before the function. So my code now reads:

import cdstoolbox as ct

@ct.application(title='Retrieve Data')

@ct.output.download()
@ct.output.download()

def retrieve_sample_data():
etc etc