SSL Certificates error on macOS Catalina

[StegmannJCSDA]

Running ./setup_pycrtm.py --install $PWD/lib/ --rtpath $PWD/lib/ --jproc 1 and effectively downloading the CRTM tarball from scratch produces the following Python error on macOS Catalina:

Traceback (most recent call last): File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/urllib/request.py", line 1317, in do_open encode_chunked=req.has_header('Transfer-encoding')) File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/http/client.py", line 1229, in request self._send_request(method, url, body, headers, encode_chunked) File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/http/client.py", line 1275, in _send_request self.endheaders(body, encode_chunked=encode_chunked) File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/http/client.py", line 1224, in endheaders self._send_output(message_body, encode_chunked=encode_chunked) File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/http/client.py", line 1016, in _send_output self.send(msg) File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/http/client.py", line 956, in send self.connect() File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/http/client.py", line 1392, in connect server_hostname=server_hostname) File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/ssl.py", line 412, in wrap_socket session=session File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/ssl.py", line 853, in _create self.do_handshake() File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/ssl.py", line 1117, in do_handshake self._sslobj.do_handshake() ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1056)

[StegmannJCSDA]

This was fixed by adding the following lines to setup_pycrtm.py:

    import urllib.request
    import ssl
    from contextlib import closing
...
    with closing(urllib.request.urlopen('http://ftp.emc.ncep.noaa.gov/jcsda/CRTM/REL-2.3.0/crtm_v2.3.0.tar.gz',context=context)) as r:
            with open('crtm_v2.3.0.tar.gz', 'wb') as f:
                shutil.copyfileobj(r, f)

So far this change has only been merged into my own fork.