Thermal metrology for climate: a review of projects, activities and open issues

Over the last decade, an increasing collaboration has been established between the metrology and the meteorology and climate communities. The International Committee for Weights and Measures and the World Meteorological Organization of the United Nations are jointly cooperating and driving the growing liaisons between national institutes of metrology and national meteorological and hydrological services. Thermal quantities play a key role among the Essential Climate Variables defined by the Global Climate Observing System in the terrestrial, atmospheric and marine domains. Improved understanding of ongoing and future climate variability and change through accurately monitoring temperature evolution requires metrological rigor to also enable early detection of trends. This is achieved through developing new measurement techniques and novel instruments; understanding uncertainty components both for laboratory calibration and for field conditions; accurately evaluating quantities of influence; and developing guidelines, best practices and recommendations. This paper reports an overview of the projects and activities involving the thermal metrology community under a growing collaboration with the researchers in climate and meteorology. A general vision on open issues and future perspectives is also presented.