I still think that we don't need to define all the year, year_trim, mon, and day variables..., all can be produced by a single call to ``date.strftime``.
```python
if 'wavelength' in kwargs:
    if kwargs['wavelength'] == '34':
        file_prefix =  'tcz'
else:
    file_prefix = 'tca'

final_url = urlparse.urljoin(baseurl,date.strftime('%Y/%m/' + file_prefix + '%y%m%d'))
```
This way, we have just one final_url to change if they change in the future, and a lot less variables created that we don't use.