Hello, my question regards to availability. Centres consider synop or bufr to make statistics for surface and upper air?
And is there a definition of cut off time in the categories 6 hour daily or alert?
Your questions are quite pertinent and are addressed in the WDQMS User Guide that is about to be released. Meanwhile, I'll try to answer your questions below.
First, the Centres are providing monitoring information based on their assimilation systems, which means that the statistics computed for each station, interval and variable, will include mainly the observations used in the assimilation system (either TAC or BUFR) because observation duplicates are not considered in WDQMS. On the quality maps for surface observations, the 6-hourly intervals for a particular monitoring centre allow you to see the details of individual observations that contribute for the average value displayed on the map. This means that it is possible to check the O-B value, the usage (Status, i.e., used or not used because it was rejected by/before the assimilation) and the type of report (Type, i.e., TAC or BUFR) of a particular observation (identified by date and time) by hovering the mouse over each dot in the time series. For the upper-air, this information is provided on the 6-hourly availability maps for a single NWP Centre. Clicking on a dot on the map shows a pop-up with detailed information about the station data availability over the selected period. For the 6-hourly periods, details of the observations received such as Layer (Trop - from surface up 100hPa- and Stra -from 100hPa up balloon burst), Variable and observation type (TAC or the new high resolution BUFR reports) and status (used / not used, “used” meaning that at least one level/variable was assimilated) are provided.
Second, the interval categories are defined as follows. The 6-hourly intervals are centred on the main synoptic hours: 00 (21 UTC ≤ t < 03 UTC); 06 (03 UTC ≤ t < 09 UTC); 12 (09 UTC ≤ t < 15 UTC); and 18 (15 UTC ≤ t < 21 UTC), where t refers to observation time. The daily interval is the union of the four 6-hourly intervals as defined above, therefore is the 24-hour period within the interval 21 UTC ≤ t < 21 UTC, where t is the observation time and the lower “21UTC” limit is the day before. The alert maps represent a 5-day moving average, therefore rely on daily values for a 5 day period.
I hope this helps, but please do not hesitate to contact me if you need any further clarification. The future release of WDQMS web tool will include a link to the Use Guide that I referred to.
In fact NCEP is not providing this information to WDQMS (that is why is shows as Type: n/a) as they don't currently pass info into their DA database on whether the observation source was TAC or BUFR. I have contacted NCEP and they told me that the majority of data they are using is still TAC.