2. Representativeness of observations

Often, the environment surrounding a station or instrument distorts the results and alters their representativeness, particularly when a site is supposed to represent a relatively large area (for example, between 100 and 1,000 km ² for synoptic stations).

• In the Guide to Meteorological Instruments and Methods of Observation (WMO No. 8, also known as the CIMO Guide), the WMO sets out the clearance rules applicable to different sensors. But what should be done when the conditions described are not met?

  • There are indeed sites that do not comply with these ideal clearance rules. In 2010, based on Météo-France practices since 1998, the WMO defined a classification of the environment of measurement sites to determine their representativeness on a small scale, based...