issue_comments: 527553471

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https://github.com/pydata/xarray/issues/3277#issuecomment-527553471 https://api.github.com/repos/pydata/xarray/issues/3277 527553471 MDEyOklzc3VlQ29tbWVudDUyNzU1MzQ3MQ== 2448579 2019-09-03T17:15:22Z 2019-09-03T17:15:22Z MEMBER

Yikes. Thanks @p-d-moore .

Looks like the rolling mean changes the chunks

```

print(dat_chunk.chunks) ((7653,), (20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20))

print(dat_mean.chunks) ((5, 7648), (20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20)) ```

A workaround is to do dat_mean = dat_mean.chunk({'day': None}) and then calculate the rolling std

 
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