Instruments and Methods of Observation Programme

Setting technical standards, quality control procedures and guidance for the use of meteorological instruments and observation methods in order to promote development documentation and worldwide standardization.

IMOPThe Instruments and Methods of Observation Programme (IMOP) works under the guidance of the Commission for Instruments and Methods of Observation (CIMO) to ensure the accuracy of weather observation by facilitating the creation of international standards and, thus, the compatibility of measurements. One of the principal challenges for the Programme today is in the integration and new technologies. The transition from manual observations to automatic and, now, remote-sensing wind profiler and satellite observations requires the development of guidelines on the use and performance of these and, possibly, conducting intercomparisons to assess their relative performance.

The ever growing demand for higher resolution meteorological observations in both time and space, such as for nowcasting and severe weather forecasting, and for the optimization of financial resources have obliged meteorological services to use observational data from various different sources – different systems as well as different providers – including external and private data providers. In addition, national security issues make these observations extremely sensitive.

Thus, the goals of the  Instruments and Methods of Observation Programme include:

  • the promotion of standards,
  • development and publication of guides on instruments and methods of observation,
  • instrument intercomparisons, and
  • the organization of capacity building activities such as training workshops and technical conferences.

The Programme actively collaborate with instrument manufacturers – primarily through the Association of Hydro-meteorological Equipment Industry (HMEI) – the scientific community and other international organisations.  Over the years, where synergies exist, it has partnered with other international organizations to achieve common goals. These include the Bureau International des Poids et Mesures (BIPM), the International Organization for Standardization (ISO) and the direct involvement of CIMO experts into metrology research such as with the European Metrology Research Programme (EMRP).


Marko Korosec/Chased by the StormThe International Cloud Atlas

​An major project currently being carried out by IMOP, which has caught the imagination of the public, is the updating of the International Cloud Atlas. The aim is to produce a user-friendly, digital-based product that is an authoritative, comprehensive and up-to-date source of reference and which is also of interest and accessible to a wide audience. There are proposals to recognize new clouds, including those produced from human activities like aviation.

The roots of the International Cloud Atlas date back to the 19th century. The International Meteorological Conference published the first International Cloud Atlas containing 28 coloured pictures in 1896. The existing Cloud Atlas has two volumes and was originally published in 1956. Volume I is a detailed technical manual of standards. Volume II contains around 220 plates of photographs of clouds and certain other meteors (such as precipitation types, haze, rainbows, and lightning) . Each photograph is accompanied by explanatory text to enable the pictures in Volume II to be understood without the detailed technical definitions and descriptions contained in Volume I, and has been revised and updated on several occasions, most recently in 1987 with the addition of new photographs.

The new International Cloud Atlas will be published in 2017. To celebrate the event, Members have chosen “Understanding Clouds” as the theme for World Meteorological Day (23 March) in 2017 and WMO has also launched a cloud photography competition for the 2017 WMO calendar.

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