Climate observations are sourced from the numerous meteorological and related observational networks and systems (GOS) that underpin applications such as weather and climate monitoring and forecasting, air pollution modeling and environmental impact assessments. The WMO Integrated Global Observing System (WIGOS), together with the WMO Information System (WIS), once fully operational will be the basis for all Members and WMO Programmes to provide and enable access to accurate, reliable and timely weather, climate, water and related environmental observations and products.
Climate observations are defined based on a number of important criteria. Firstly, climate observations need to account for the full range of elements that describe the climate system – not just those that describe the atmosphere. Extensive observations of the ocean and terrestrial-based systems are required. Secondly, an observation at any point in time needs a reference climate against which it can be evaluated, i.e. a reference climatological period must be selected. In this regard, the observations from a station that only exists for a short period (i.e. from days to a few years) or which relocates very frequently will generally be of less value than those observations from a station whose records have been maintained to established standards over many years. Thirdly, a climate observation should be associated – either directly or indirectly - with a set of data (Metadata) describing the conditions in which climate observations were collected and that will provide users with information, often implicitly, on how the observation should be interpreted and used. The Global Climate Observing System (GCOS) has a mandate to ensure that high quality sustained observations on global climate system are identified based on Essential Climate Variables, ECVs, obtained and made widely available for climate research and global climate monitoring. A set of monitoring principles provide guidance for the implementation and operation of observation networks necessary for global climate monitoring