Observed temperature changes in the troposphere and stratosphere from 1979 to 2018

Temperature observations of the upper-air atmosphere are now available for more than 40 years for both ground- and satellite-based observation systems. Recent years have seen substantial improvements in long-standing discrepancies between data sets through major reprocessing efforts. The advent of GNSS radio occultation observations in 2001 has led to further improvements in vertically-resolved temperature measurements, enabling a detailed analysis of upper troposphere/lower stratosphere trends. This paper presents the current state of atmospheric temperature trends from the latest available observation records. We analyze observations from merged operational satellite measurements, radiosondes, lidars, and GNSS radio occultation, spanning a vertical range from the lower troposphere to the upper stratosphere. The focus is on assessing climate trends and their significance, and on identifying the degree of consistency between the different observational systems. Results show a robust cooling of the stratosphere of about 2–3 K, and a robust warming in the troposphere of about 0.6–0.8 K over the last four decades. Consistent results are found between the analyzed satellite-based layer average temperatures and vertically-resolved radiosonde records. The overall latitude-altitude trend patterns are found to be consistent between GNSS RO and radiosonde records. Significant warming of the troposphere is clearly revealed in the GNSS RO measurements with trends of 0.25–0.35 K per decade in this shorter time period. The enhanced consistency of the latest upper-air data sets will help to improve our understanding of climate changes and their drivers and underlines the need for sustaining long term climate data records of essential climate variables