In 2016, the Global Climate Observing System (GCOS) included Land Surface Temperature (LST) in its list of Essential Climate Variables (ECVs). LST is an important variable within the Earth climate system that describes processes such as the exchange of energy and water between the land surface and atmosphere, and influences the rate and timing of plant growth. Accurately understanding LST at the global and regional level helps to evaluate land surface–atmosphere exchange processes in models and, when combined with other physical properties such as vegetation and soil moisture, provides a valuable metric of surface state.

The LST_cci project provides an accurate view of temperatures across land surfaces globally over the past 20 to 25 years and meets the GCOS requirements for climate applications by developing techniques to merge archived data from a variety of satellites into a combined long-term satellite record for climate.

Among others, LST_cci aims to provide the following:

• An expected accuracy and precision of all the LST ECV Products of < 1 K
• A first assessment of the stability of LST ECV Products
• A first global LST Climate Data Record (CDR) with record length over 25 years
• A first passive microwave LST time series > 20 years
• Intercalibration and temporal corrections of level-1 data for CDRs
• Retrieval algorithm consistency across LST ECV products and CDRs
• Independent and rigorous product validation and inter-comparison (KIT responsibility)