  Context: Solar sectoral Rossby waves have only recently been unambiguously
identified in Helioseimsic and Magnetic Imager (HMI) and Michelson Doppler
Imager (MDI) maps of flows near the solar surface. So far this has not been
done with the Global Oscillation Network Group (GONG) ground-based
observations, which have different noise properties.
  Aims: We utilize 17 years of GONG++ data, to identify and characterize solar
Rossby waves using ring-diagram helioseismology. We compare directly with HMI
ring-diagram analysis.
  Methods: Maps of the radial vorticity are obtained for flows within the top 2
Mm of the surface for 17 years of GONG++. The data is corrected for systematic
effects including the annual periodicity related to the $B_0$ angle. We then
compute the Fourier components of the radial vorticity of the flows in the
co-rotating frame. We perform the same analysis on the HMI data that overlap in
time.
  Results: We find that the solar Rossby waves have measurable amplitudes in
the GONG++ sectoral power spectra for azimuthal orders between $m=3$ and
$m=15$. The measured mode characteristics (frequencies, lifetimes and
amplitudes) from GONG++ are consistent with the HMI measurements in the overlap
period from 2010 to 2018 for $m\le9$. For higher-$m$ modes the amplitudes and
frequencies agree within two sigmas. The signal-to-noise ratio of modes in
GONG++ power spectra is comparable to HMI for $8\le m\le11$, but is lower by a
factor of two for other modes.
  Conclusions: The GONG++ data provide a long and uniform data set to study
solar global-scale Rossby waves from 2001.
