GBON Compliance App
About the GBON Compliance App
1. Purpose
The GBON Compliance App is the WMO’s monitoring tool for the quarterly assessment of Members’ compliance with the regulations for the Global Basic Observing Network (GBON), as set out in the Manual on the WMO Integrated Global Observing System (WMO-No. 1160).
The App provides information on GBON implementation and compliance at both station level and Member level, for surface and upper-air observations.
2. How GBON compliance is monitored
The GBON Compliance App combines information from two WMO systems:
· WDQMS provides station-level information on observation availability.
· OSCAR/Surface provides information on stations affiliated with GBON and relevant station metadata, including the WIGOS Station Identifier, station name and station type.
The GBON compliance criteria are set out in Section 10.4 of the Guide to the WMO Integrated Global Observing System (WMO-No. 1165) and are established and kept under review by INFCOM.
The Guide defines the criteria for station-level availability and quality at the monthly level, while the Member-level GBON compliance assessment is undertaken on a quarterly basis. The GBON Compliance App therefore applies the relevant station-level criteria over the quarterly assessment period for the purpose of the quarterly compliance assessment.
The App presents global GBON implementation aggregated by geographic area on its main page. As a result, the status shown on the global page may differ from the compliance information presented on an individual Member’s page, where compliance is assessed at Member or sub-region level.
3. Station-level compliance
Station-level compliance is assessed in accordance with Section 10.4.2 of WMO-No. 1165. The assessment applies to both surface and upper-air observations and currently focuses on observation availability at Numerical Weather Prediction (NWP) centers.
GBON target number of observations per day and Daily Cap
The GBON target number of observations per day corresponds to the standard GBON temporal-resolution requirement:
· Surface stations: 24 observations per day (hourly reporting)
· Upper-air stations: 2 observations per day (twice-daily reporting)
These values also define the Daily Cap: the maximum number of observations from a station that can be counted as contributions towards compliance on any given day.
Observations exceeding the Daily Cap are not counted towards the station’s compliance assessment.
GBON target number of observations for the quarter
GBON target number of observations for the quarter is the expected number of observations for the quarter, calculated as:
GBON target number of observations per day × number of days in the quarter
Registration and affiliation
A station must be registered in OSCAR/Surface and affiliated with GBON on at least one day during the quarter to be considered a GBON station for that quarter.
Observations are counted from the date on which the station becomes affiliated with GBON in OSCAR/Surface.
Availability
Availability at NWP centers is currently the only criterion used for the station-level compliance assessment.
For each station, the total number of observations received during the quarter is compared with the GBON target number of observations for the quarter.
The station is considered compliant when the number of observations received during the quarter, after applying the Daily Cap, is equal to or greater than 80% of the GBON target number of observations for the quarter.
For example, for a surface station operating throughout a 90-day quarter:
GBON target number of observations for the
quarter = 24 × 90 = 2,160
Minimum required for compliance = 80% × 2,160 = 1,728 observations
Upper-air observation completeness
For upper-air stations, only complete observations are counted towards availability.
An upper-air observation is considered complete when it reaches 100 hPa or above and includes the required variables:
· air temperature;
· humidity; and
· horizontal wind.
The completeness check is therefore applied before observations are counted towards the station’s availability.
Variables used for the assessment
For the current availability assessment:
· Surface stations: compliance is assessed using the surface pressure variable.
· Upper-air stations: compliance is assessed using air temperature, humidity and horizontal wind.
For surface stations, the use of surface pressure for the current compliance assessment does not mean that surface pressure is the only variable required under GBON. It reflects the current implementation of the GBON Compliance App.
Other compliance criteria
The following additional criteria are under development or review and are not currently used in the station-level compliance assessment:
· Vertical resolution — criteria are under development and subject to review.
· Timeliness — criteria are under development and subject to review.
· Quality — criteria are under development and subject to review.
Compliant Stations
The term “Compliant Station” is used throughout the App to refer to a station that meets the applicable GBON compliance criteria.
4. Member-level compliance
Member-level compliance is assessed in accordance with Section 10.4.3 of WMO-No. 1165.
A Member is considered compliant for surface and/or upper-air GBON when the Member operates a number of Compliant Stations equal to or greater than the applicable GBON target number of stations for the respective observing system.
GBON target number of stations
The GBON target number of stations represents the number of stations required to meet the GBON horizontal-resolution requirement for a Member.
The methodology for determining the target is broadly based on the Member’s land surface area and, for small island developing States and coastal States, its Exclusive Economic Zone, divided by the square of the required horizontal resolution.
The GBON target numbers presented in the App were established through the January 2022 GBON Global Gap Analysis as the initial composition of GBON and were subsequently refined based on National GBON Gap Analyses.
The methodology is described in Section 10.2.3 of WMO-No. 1165. Further information is provided in Circular Letter 18876/2022/I/WIGOS/ONM/GBON of 15 August 2022.
GBON gap
The GBON gap represents the difference between the applicable GBON target number of stations and the number of Compliant Stations.
For Members with multiple independent geographical sub-regions, the gap is calculated separately for each sub-region and then summed.
A surplus of Compliant Stations in one sub-region cannot compensate for a gap in another sub-region. Similarly, a surplus of stations for one Member cannot compensate for a gap for another Member.
The App supports the display of GBON gaps by sub-region.
Important: GBON compliance is assessed against the applicable target for each Member and, where relevant, each independent geographical sub-region. Surpluses cannot be transferred between sub-regions or between Members.
5. Exemptions
The GBON compliance assessment takes into account exemptions granted to Members under Article 9 of the WMO Convention, as described in Section 10.4.5 of WMO-No. 1165.
Exemptions may apply to two types of requirements:
Horizontal-resolution requirement
An exemption may be requested at Member or sub-region level.
Where an exemption has been granted, compliance with the horizontal-resolution requirement is assessed against the agreed reduced target number of stations, rather than the original GBON target.
The reduced target used for the compliance assessment is indicated on the Member’s page.
Temporal-resolution requirement
An exemption may be requested at station level for the number of observations required per day.
Where an exemption has been granted, the station’s compliance with the temporal-resolution requirement is assessed against the agreed reduced number of observations per day, rather than the generic GBON target of 24 observations for surface stations or 2 observations for upper-air stations.
The reduced target used for the compliance assessment is indicated in the station pop-up on the Member’s page.
6. GBON target percentages
For transparency, the App also indicates observations as a percentage of the GBON target number of observations for the quarter, both at the station level and at the Member level.
At the station level, the percentage represents the number of observations counted towards the station's availability assessment as a percentage of the GBON target number of observations for the quarter. The GBON target number of observations for the quarter is based on the generic GBON temporal-resolution requirement of 24 observations per day for surface stations and 2 observations per day for upper-air stations.
At the Member level, the percentage is calculated by summing the observations received from the number of GBON stations corresponding to the nominal GBON target number of stations for the Member, selecting the stations that contribute the highest number of observations. These observations are then compared with the nominal GBON target number of observations for the quarter for that number of stations.
For Members with multiple independent geographical sub-regions, the percentage is calculated separately for each sub-region and then aggregated. The number of stations included in each sub-region is limited to the applicable nominal GBON target for that sub-region. Consequently, observations or stations in excess of the applicable target in one sub-region cannot compensate for a gap in another sub-region.
The GBON target percentages are intended to show the actual observation contribution against the standard GBON temporal-resolution requirement. They are distinct from the compliance assessment where an exemption applies.
Where a station has an approved temporal-resolution exemption, its compliance is assessed against the reduced target specified by the exemption, while its GBON target percentage continues to be calculated against the generic GBON target.
Similarly, where a Member or sub-region has an approved horizontal-resolution exemption, its compliance is assessed against the reduced target number of stations specified by the exemption. The Member-level GBON target percentage, however, continues to be calculated against the nominal GBON target number of stations and the corresponding nominal GBON target number of observations for the quarter.
Therefore, a station may be considered compliant even when its GBON target percentage is below 80%. Similarly, a Member may be considered compliant even when its Member-level GBON target percentage is below 80%.
7. Further information
The GBON Compliance App is based on the applicable WMO regulatory and guidance framework. For details of the GBON compliance criteria and methodologies, please refer to:
· Manual on the WMO Integrated Global Observing System(WMO-No. 1160)
· Guide to the WMO Integrated Global Observing System(WMO-No. 1165)
· Circular Letter 18876/2022/I/WIGOS/ONM/GBON, 15 August 2022
8. GBON compliance assessment: overview
The following diagram illustrates the main data flow and assessment logic used by the GBON Compliance App.