The WDQMS operational web tool monitors the performance of some of the WIGOS observing components, namely the GOS land-based surface and upper-air (radiosonde) stations, the GBON surface and upper-air land-based stations, and the GCOS surface and upper-air land stations. The monitoring of the GOS networks covered in the near-real-time NWP monitoring module is based on NWP monitoring information provided by some global NWP centres. The GBON monitoring is also based on the near-real-time monitoring information provided by the four global NWP centres. The GCOS monitoring module is based on data collected from the GCOS monitoring centres and includes the monitoring of the climate observing networks GSN and GUAN.
2.1. Near-real time NWP monitoring
The NWP module of the WDQMS web tool monitors the performance of all surface and upper-air (radiosonde) land stations documented in WMO’s database OSCAR/Surface, based on near-real-time monitoring information provided by DWD, ECMWF, JMA and NCEP. The system collects 6-hourly quality monitoring (QM) reports (CSV files in a commonly agreed format containing information for each observing station based on data assimilation results) from these four WIGOS Monitoring Centres and stores the data in the WDQMS database at ECMWF. Figure 1 shows a diagram of the QM data flow for the NWP module of the WDQMS web tool, where the database fed by the NWP QM reports and the web-based application constitute the back and front end of the QM system, respectively.
Figure 1 - Quality Monitoring (QM) data flow in the NWP module of the WDQMS web tool.
2.1.1. Surface-land observations
This module displays stations with the following criteria in OSCAR/Surface:
- Stations of Facility Type seaFixed, lakeRiverFixed, lakeRiverMobile, landFixed, landMobile, landOnIce or airFixed;
- One or more observations out of surface pressure, temperature, humidity or wind;
- The declared status of a program affiliated with the variable displayed is either operational or partly operational;
- The “international exchange” field set to “yes” on the variable;
- The reporting schedule indicates that the variable is reported during the period for which data is displayed.
ECMWF, DWD, NCEP and JMA are providing quality monitoring reports of land surface observations based on feedback from their data assimilation (DA) systems on a daily basis. These reports include qualitative and quantitative (Observation-minus-Background, O-B, departures) information covering the following observed physical quantities: surface pressure (or geopotential height for some high-altitude stations), 2-metre temperature, 2-metre relative humidity and 10-metre wind (meridional and zonal components). The qualitative information includes a description on the usage (Status, i.e., used or not used on the assimilation) and the type of report (i.e., the Traditional Alphanumeric Code -TAC-, or the Binary Universal Format for the Representation of Meteorological Data -BUFR) of each of the above mentioned physical quantities. It is worth noting that surface pressure is the most important in situ observed quantity for global NWP forecasting, and in some cases the only observed surface quantity over land used in the global atmospheric data assimilation, e.g. in the JMA global atmospheric data assimilation system (JMA, 2019). ECMWF’s atmopsheric 4D-Var also assimilates relative humidity over land at nighttime (Owens and Hewson, 2018). Based on these reports (four daily, centred at the main synoptic hours, 00, 06, 12 and 18UTC), it is possible to infer the performance of the land surface network both in terms of availability and quality.
2.1.2. Upper-air land observations
This module displays stations with the following criteria in OSCAR/Surface:
- The declared status of a program affiliated with the variable pressure profile is either operational or partly operational;
- Station class Upper-air Radiosonde or PILOT;
- “international exchange” field set to “yes” on the pressure profile variable;
- The reporting schedule of pressure profile indicates that the variable is reported during the period for which data is displayed.
All the four WIGOS Monitoring Centres - ECMWF, DWD, JMA and NCEP- are providing quality monitoring reports for upper-air observations. Like the surface reports, these include qualitative as well as quantitative information. The quantitative information provided is obtained by aggregating the O-B departures into two main categories: layer between the first pressure level up to 100 hPa inclusive (Trop); and the layer from 100 hPa up to the last reported level (Stra). The quantitative information for the aforementioned layers consists of both the mean and standard deviation of O-B departures over the layer for the following observed physical quantities: upper-air temperature, upper-air humidity and upper-air wind. Provision of these data reports (four daily, centred at the main synoptic hours, 00, 06, 12 and 18UTC), typically happens 24 hours after the actual observation. The availability, quality and completeness of these conventional profiling observations can be easily assessed based on the information provided by the monitoring reports. It is worth mentioning that for the high-resolution BUFR reports, two messages are disseminated on the Global Telecommunication System (GTS): a preliminary message containing the measurements from the surface up to 100h Pa (TTAA=IUK header - I, Observational data Binary coded, U, upper-air message and K, radiosonde from fixed land station up to 100 hPa) and the final message containing the entire sounding from surface to balloon burst (TTAA=IUS, header - I, Observational data Binary coded, U, upper-air message and S, radiosonde from fixed land station up to balloon burst). ECMWF, JMA and DWD use the full BUFR message (i.e., IUS bulletin), and only if the full one is not available they use the IUK bulletin. Therefore, all NWP monitoring reports reflect this, i.e., the ascent report that contains the highest level will be used to calculate the statistics (i.e., IUS bulletin). This is a case of duplicates, however, if a radiosonde is launched 30 mins after the one that went wrong (i.e., burst at quite low altitudes), both will be used because they are not considered duplicates in those circumstances.
2.2. GBON monitoring
The GBON module monitors the compliance of all land-based surface and upper-air GBON-affiliated stations – as documented in OSCAR/Surface - with the GBON baseline requirements. Data availability at station level is calculated using the near-real-time monitoring data provided by the four NWP centres and stored in the WDQMS database at ECMWF.
2.2.1. Surface-land observations
This module displays stations with the following criteria in OSCAR/Surface:
- Station class GBON surface station;
- Station is not closed.
The 6-hourly monitoring reports provided by DWD, ECMWF, JMA and NCEP contain qualitative and quantitative (Observation-minus-Background, O-B, departures) information on the following observed variables: surface pressure (or geopotential height for some high-altitude stations), 2-metre temperature, 2-metre relative humidity and 10-metre wind (meridional and zonal components). This data is then aggregated and used to determine the station data availability per variable and time interval. It is based on the data availability that GBON station-level compliance is assessed. The station will only be compliant if it reports the required measurements at the required frequency, i.e., hourly for all the above-mentioned quantities.
2.2.2. Upper-air land observations
This module displays stations with the following criteria in OSCAR/Surface:
- Station class GBON upper-air station;
- Station is not closed.
The upper-air monitoring reports provided by the four NWP centers include qualitative as well as quantitative information for upper-air temperature, upper-air humidity, and upper-air wind aggregated into two main categories: the layer between the first pressure level and 100 hPa inclusive (Trop); and the layer from 100 hPa up to the last reported level (Stra). A radiosonde is deemed complete if an NWP centre obtains measurements for all the variables up to and above 100hPa, with the exception of humidity above 100hPa. Only complete soundings will be used to determine the station data availability. The assessment of GBON station-level compliance is done based on the data availability. The station will only be compliant if it reports the required measurements at the required frequency, i.e., complete soundings twice a day.
2.3. GCOS monitoring
The GCOS module of the WDQMS web tool monitors the performance of both surface and upper-air components of the climate observing system. The surface component is based on the routine monitoring of CLIMAT reports done by DWD and JMA in their capacities as GSN monitoring centres. The system collects a file provided monthly by DWD with information on availability and completeness of CLIMAT data for all the GSN stations recorded in OSCAR/Surface. The upper-air component is based on the routine monitoring of TEMP reports done by DWD and ECMWF in their capacities as GUAN monitoring centres. The system monitors the performance of all upper-air (radiosonde) land stations that are part of the GUAN as documented in WMO’s database OSCAR/Surface, based on monthly monitoring information provided by DWD. The system collects two files monthly containing the availability and quality monitoring information separately.
2.3.1. Surface-land observations
This module displays all stations reported by the DWD GSN reporting. DWD provides a monthly monitoring statistics report, which includes information on the availability and completeness of the CLIMAT reports sent by all the surface land stations that are part of GSN. The availability results are obtained by checking the collected monthly CLIMAT messages against the list of stations affiliated to the GSN and registered in OSCAR/Surface. For a station to be classified as reporting it needs to have sent a CLIMAT message that includes information of at least one of the following variables: monthly mean temperature, monthly precipitation amount, mean daily maximum temperature and mean daily minimum. The completeness is obtained from the information - not mandatory though - provided on the number of days of the month missing for some observed variables. The variables included in GSN completeness monitoring are: daily mean surface pressure, daily mean air temperature, daily maximum air temperature, daily minimum air temperature, daily mean water vapour, total daily precipitation and total daily sunshine duration. Provision of the data report (monthly), typically happens on the 22nd of the following month.
2.3.2. Upper-air land observations
This module displays all stations reported by the DWD GUAN reporting. DWD is providing the monthly statistics reports for both availability and quality monitoring categories. The availability results for the GCOS upper-air stations are based on DWD data assimilation system, whereas the quality results provided by DWD are based on the O-B departures from ECMWF data assimilation system. The availability reports contain information on all GCOS upper-air stations regarding the number of radiosonde soundings that reach the 30hPa level in the reported month. The quality reports contain the root mean square of O-B departures calculated for the sounding profiles of the following observed quantities: upper-air temperature, upper-air humidity and upper-air wind. Provision of these data reports (monthly), typically happens 2 days after the end of the month. It is worth noting that contrary to the NWP monitoring, the monitoring of the GUAN stations only covers the radiosonde observations provided in the new Binary Universal Form for Representation of meteorological data (BUFR) reports.