Global climate - Night marine air temperature [in: State of the Climate in 2023]

Two night marine air temperature (NMAT) datasets are routinely updated and used for analysis in this section: UAHNMAT (Junod and Christy 2020) and CLASSnmat (Cornes et al. 2020). These datasets are evaluated in combination with the HadSST4 dataset (Kennedy et al. 2019). Since these datasets are not spatially interpolated, they each have slightly different spatial coverage. In this evaluation the data have been masked to allow comparisons to be made over the common coverage areas, and to the common period of 1900–2023. NMAT and sea-surface temperature (SST) data are expected to follow each other closely across large spatial scales and over longer time periods. As such, the NMAT data are used here to evaluate the more widely used SST data, which are considered in more detail in section 3b.