ISO 19289:2015

Overview

ISO 19289:2015 - Air quality - Meteorology - Siting classifications for surface observing stations on land provides a practical, standardized method to describe how the local environment affects meteorological and air‑quality measurements. Rather than replacing sensor exposure rules, the standard defines a siting classification (classes 1–5) for each measured parameter (temperature, humidity, precipitation, wind, radiation, etc.) to document representativeness at small scales and to support operational metadata and uncertainty estimation.

Key points:

• Each parameter measured at a site receives its own class (1–5); a site has no single universal class.
• Class 1 = reference (high representativeness); Class 5 = environment likely unsuitable for wide‑area representativeness.
• Classification is used to condense metadata, aid network managers, and improve siting decisions while keeping operational metadata practical.

Key Topics and Requirements

• Per‑parameter classification: temperature/humidity, precipitation, surface wind, global/diffuse/direct radiation each have defined siting criteria and class descriptions.
• Temperature/humidity guidance: recommended sensor screen heights (1.25–2.0 m) and class‑based minimum distances from heat sources, water bodies and shading (examples: Class 1 >100 m from heat/reflective surfaces; Class 2 >30 m).
• Siting uncertainty: where applicable the classification is accompanied by an estimated uncertainty due to siting (to be included in the measurement uncertainty budget), derived from bibliographic studies or comparative tests.
• Documentation cadence: visual checks recommended annually; complete reclassification at least every five years or when the environment changes.
• Special flags: complex terrain or urban sites may get an “S” flag (e.g., 4S) to indicate specific environments or applications.
• Scope limits: distant natural relief (>1 km) is generally not considered; a 500 m station move test helps judge representativeness of local relief.

Practical Applications and Users

ISO 19289:2015 is practical for:

• National and regional meteorological services
• Air quality monitoring network managers and operators
• Environmental agencies and regulators
• Research institutions and consultants performing site audits and data quality assessment
• Instrument manufacturers and data users who need reliable metadata and uncertainty inputs

Use cases:

• Classifying existing stations to document local influences and support data quality control
• Prioritizing site upgrades or relocations to improve representativeness
• Adding siting‑related uncertainty to measurement uncertainty budgets for reporting and modeling
• Streamlining metadata for operational networks while preserving essential siting information

Related Standards

• ISO 19289:2015 is identical to the WMO Guide to Meteorological Instruments and Methods of Observations (WMO‑No. 8) Annex 1B and was prepared jointly by ISO and WMO. This alignment helps ensure compatibility across meteorological and air‑quality data systems.

By applying ISO 19289:2015, organizations can standardize how siting influences are reported, improve network comparability, and make siting metadata both actionable and operationally efficient.