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All targets regarding availability refer to the number of observations received by NWP centres from the network (Table 1). For each station, 6-hourly totals (section 4.1) and daily totals (section 4.2) are computed based on the quality monitoring information received from all the NWP Centres (section 5) and stored in the WDQMS Database. This task is performed on a daily basis, so that availability information of the observing network is accessible in near-real time. It is worth noting that in the WDQMS context “observations received” means the observations that were made available to the assimilation system of each NWP centre and are considered as a good proxy for the observations disseminated on the GTS. Moreover the results are aggregated across NWP centres (section 5.2) to help reduce potential differences between the number of observations available on the GTS and the number of the observations seen by the individual assimilation systems.
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