The DMC has developed procedures to create, on-the-fly, the most continuous data series possible from the highest quality data available in the DMC archive. In order to deal with the problems associated with multiple quality indicators and to differentiate these data from the SEED records supplied by the network operators, all data that has gone through this process will be marked as ‘M’ quality data (M standing for merged).
The new process for creating ‘M’ quality data is to join archival ‘Q’,‘D’, and ‘R’ data at the sample level such that a continuous waveform results. The ‘M’ quality data will NOT replace the original data in the archive as we consider it of utmost importance to preserve the original recordings as delivered. Instead, ‘M’ quality is generated dynamically and is the default. We will always give users the option to specifically request one of the original waveform streams (Q, D, or R) when desired.
Our first rollout of ‘M’ quality data was for our BREQ_FAST email request mechanism. When users specify a .QUALITY of ‘B’ (best), they will receive an ‘M’ quality data stream.
Though there may be some software programs that cannot read this data quality yet, users can rest assured that the most recent release of rdseed v4.8 and later can recognize and process ‘M’ quality data. Other software at the IRIS DMC has also been adapted to ‘M’ quality.
by Rick Benson (IRIS Data Management Center)