"Land surface air temperature" refers to the measure of how hot or cold the air is just above the ground. It helps us understand the temperature of the air that we feel on land. Full definition
Land surface air temperatures there effectively stopped warming around 1998. (wattsupwiththat.com)
They then infill the Arctic and Southern Oceans with land surface air temperature data. (wattsupwiththat.com)
They analyzed improved ocean sea surface temperatures, a more comprehensive set of land surface air temperature product, and two additional years of data that were not available to the IPCC Fifth Assessment Report. (usclivar.org)