Error:curl error: Problem with the SSL CA cert (path? access rights?)

[paapu88]

Was trying to run copy pasted example from metno examples:

import xarray
import numpy as np

opendap_url = "https://thredds.met.no/thredds/dodsC/aromearcticlatest/"+\
              "archive/arome_arctic_det_2_5km_latest.nc"
#Ask for time=0 to make the calculation smaller, height0=0 to remove the 4th dimension
ds = xarray.open_dataset(opendap_url).isel(time=0,height0=0)

# Formula to calculate pressure from hybrid: p(n,k,j,i) = ap(k) + b(k)*ps(n,j,i)"
ap = ds.ap
b = ds.b
surface_pressure = ds.surface_air_pressure

# Note that k = 0 is top of atmosphere (ToA), and k = 64 is surface
pressure_at_k = (ap + (b*surface_pressure))
temperature_at_k = ds.air_temperature_ml
R = 287.058
g = 9.81

height_at_k = xarray.full_like(pressure_at_k, fill_value=0)

max_k = len(height_at_k.hybrid) -1
# Compute the height of the lowest model level
height_at_k.values[max_k,:,:] = (R*temperature_at_k.isel(hybrid=max_k))/g
height_at_k.values[max_k,:,:] *= np.log(surface_pressure / (pressure_at_k.isel(hybrid = max_k)))

# Loop over the rest of the model levels
for hybrid in range(max_k - 1,-1,-1):
    height_at_k.values[hybrid,:,:] = (R*temperature_at_k.isel(hybrid=hybrid))/g
    height_at_k.values[hybrid,:,:] *= np.log((pressure_at_k.isel(hybrid = hybrid + 1)) / \
                                             (pressure_at_k.isel(hybrid = hybrid)))
    height_at_k.values[hybrid,:,:] += height_at_k.isel(hybrid=hybrid + 1)

but got error Error:curl error: Problem with the SSL CA cert (path? access rights?)

google says this is server side error due to outdated SSL certificate(s) for cURL installed on the server.

terveisin, Markus

[johtoblan]

Hi Markus!

We believe this error to be in the netcdf4 dependency for xarray. We have a found a possible solution to be to create a file in your home directory called .ncrcand add this line: HTTP.SSL.CAINFO=/etc/ssl/certs/ca-certificates.crt

Please retry this and let me know if this does not solve the issue

[cskarby]

Hello Markus!

Please check Johannes reply above for a suggest fix!

I just wanted to add that the certificates on thredds.met.no are configured according to recommended practice - the scan results are available on https://www.ssllabs.com/ssltest/analyze.html?d=thredds.met.no&hideResults=on

As the server is passing the SSL test with no warnings in the section "Certification Paths", it seems to be a problem on the client side. Please try the proposed workaround, or upgrade your software libraries. It may have been fixed in more recent releases of NetCDF.

[paapu88]

I tested with xarray version xarray==2023.1.0 and now it works.

So it was my problem had nothing to do with your site, sorry for a false alarm.

My guess is that my version of xarray or some other package was too old.