Reading xarray goes16 data directly from S3 without downloading into the system

Question

Reading xarray goes16 data directly from S3 without downloading into the system. the issue is that I cannot concatenate S3Files. I am recalling 24 files from S3 and want to read and extract the data for these files for the time range:

This is the code:

import datetime as dt
import xarray as xr
import fsspec
import s3fs

fs = fsspec.filesystem('s3', anon=True)

urls1=[]

for i in range (2):
    urls = [
        's3://' + f
        for f in fs.glob(f"s3://noaa-goes16/ABI-L2ACMC/2022/001/{i:02}/*.nc")
    ]
    urls1 = urls1+ urls

with fs.open(urls1[0]) as fileObj:
    ds = xr.open_dataset(fileObj, engine='h5netcdf')

however, i run into the issue I/O operation on closed file.

Answer 1

Similarly to most file object interfaces in python, opening a file-like object with a context manager closes the file on exit. So in the following example:

# use fs.open to create an S3File object
with fs.open(urls1[0], mode="rb") as fileObj:
    # open the netcdf for reading, but don't load the data - instead, just
    # establish a lazy-load connection to the underlying S3File object
    ds = xr.open_dataset(fileObj, engine='h5netcdf')

# <--
# exit the context, thereby closing the S3File object

# attempt to access the data again, after the stream is closed
ds.load()  # raises IOError

Instead, you should either load all the data within the context manager:

with fs.open(urls1[0], mode="rb") as fileObj:
    with xr.open_dataset(fileObj, engine='h5netcdf') as ds:
        ds = ds.load()

Or, if you're planning to use the dataset in later code without loading:

fileObj = fs.open(urls1[0], mode="rb")
ds = xr.open_dataset(fileObj, engine='h5netcdf')

# other data operations

# be sure to close the connections when you're done
ds.close()
fileObj.close()