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Number of Expected Observations (based on OSCAR/Surface)
For each station, the expected 6-hourly and daily totals (i.e. the number of observations the station should exchange internationally via GTS/WIS during the defined period) are extracted from OSCAR/Surface by using the “Schedule” element, and used as a reference (Table 2). In this context, the schedule of observations is obtained for all the stations recorded in OSCAR/Surface that meet the following criteria: stations that are declared operational or partially operational on the level of the GOS/Regional Basic Synoptic Network (RBSN) affiliation; have an observation of the variable of interest; have the “international exchange” field set to “yes” (currently only for surface); are valid at the date of the defined period. For the upper-air, the schedule is obtained for all stations that are of station class Upper-air/Radiosonde. In case an observation has no entry in "Deployments" in OSCAR/Surface, a default schedule is assumed, which is 3 hourly observations for surface and 2 observations per day for upper-air stations, one in each interval, the 00 and 12 UTC interval. All the metadata used in WDQMS is updated daily, which means that any update on the station metadata recorded in OSCAR/surface will be reflected on the performance maps the next day.
The availability performance reports are generated by comparing the 6-hourly and daily totals against the respective expected values for each observed variable (Table 2). A performance report is generated individually for each NWP Centre and time interval. For the 6-hourly totals, four reports are generated daily for each of the NWP centres.
GBON Availability is also compared against GBON requirements. According to the draft provisions, the expected frequency of observations is hourly for surface-based and 12-hourly for upper-air observations.
The availability performance reports based on GBON targets are generated by comparing availability against expected values calculated for the different periods using the frequency rules mentioned above. This means that for surface observations, the expected
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observations are 6, 24 and 24
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times the number of days in the month for the 6-hourly
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, daily, and monthly periods, respectively.
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The GBON requirements for upper-air observations
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only
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apply to the daily
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and monthly aggregations, with a total of
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expected observations being 2 and twice the number of days in the month, respectively.
Table 1 - AvailabilityAnchor Table1 Table1
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