edu.ucar.opensky::articles:22715 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-25T15:33:54.623736 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7zc83wj https://doi.org/10.15142/T33H26 https Related Dataset #1 USU Na Lidar Data The long-term trends of nocturnal mesopause temperature and altitude revealed by Na lidar observations between 1990 and 2018 at mid-latitude 2019-05-17T00:00:00Z publication https://n2t.org/ark:/85065/d7zc83wj https://doi.org/10.1029/2018JD029828 Yuan, T. author Solomon, Stanley C. author She, C. author Krueger, D. author Liu, Hanli author UCAR/NCAR - Library publisher The mesopause, a boundary between mesosphere and thermosphere with the coldest atmospheric temperature, is formed mainly by the combining effects of radiative cooling of CO2, and the vertical adiabatic flow in the upper atmosphere. A continuous multidecade (1990-2018) nocturnal temperature database of an advanced Na lidar, obtained at Fort Collins, CO (41°N, 105°W), and at Logan, UT (42°N, 112°W), provides an unprecedented opportunity to study the long-term variations of this important atmospheric boundary. In this study, we categorize the lidar-observed mesopause into two categories: the "high mesopause" (HM) above 97 km during nonsummer months, mainly formed through the radiative cooling, and the "low mesopause" (LM) below 92 km during nonwinter months, generated mostly by the adiabatic cooling. These lidar observations reveal a cooling trend of more than 2 K/decade in absolute mesopause temperature since 1990, along with a decreasing trend in mesopause height: The HM is moving downward at a speed of ~ 450 ± 90 m/decade, while the LM has a slower downward trend of ~ 130 ± 160 m/decade. However, since 2000, while the height trend (- 470 ± 160 m/decade for the HM and 150 ± 290 m/decade for the LM) is consistent, the temperature trend becomes statistically insignificant (- 0.2 ± 0.7 K/decade and -1 ± 0.9 K/decade for the HM and the LM, respectively). A long-term study by Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) also indicated the similar mesopause changes, mostly caused by stratosphere-lower mesosphere cooling and contraction. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2019 American Geophysical Union. None eng geoscientificInformation