  Context. Several upcoming helioseismology space missions are very limited in
telemetry and will have to perform extensive data compression. This requires
the development of new methods of data compression.
  Aims. We give an overview of the influence of lossy data compression on local
helioseismology. We investigate the effects of several lossy compression
methods (quantization, JPEG compression, and smoothing and subsampling) on
power spectra and time-distance measurements of supergranulation flows at disk
center.
  Methods. We applied different compression methods to tracked and remapped
Dopplergrams obtained by the Helioseismic and Magnetic Imager onboard the Solar
Dynamics Observatory. We determined the signal-to-noise ratio of the travel
times computed from the compressed data as a function of the compression
efficiency.
  Results. The basic helioseismic measurements that we consider are very robust
to lossy data compression. Even if only the sign of the velocity is used,
time-distance helioseismology is still possible. We achieve the best results by
applying JPEG compression on spatially subsampled data. However, our
conclusions are only valid for supergranulation flows at disk center and may
not be valid for all helioseismology applications.
