Publication Date:
2019
Description:
Abstract
We present midlatitude solar response and linear trend from CSU/USU Na lidar nocturnal temperature observations between 1990 and 2017. Along with the nightly‐mean temperatures (_Ngt), we also use the corresponding 2‐hour‐means centered at midnight (_2MN), resulting in vertical trend profiles similar in shapes as those previously published. The 28‐year trend from _Ngt (_2MN) dataset starts from a small warming at 85 km, to cooling at 87 (88) km, reaching a maximum of 1.85±0.53(1.09±0.74 ) at 92 (93) km, and turns positive again at 102 (100) km. The 6‐mo winter trend is much cooler than the 4‐mo summer trend with comparable solar response varying around 5±1K/100SFU throughout the profile (85‐105 km) with higher summer values. We explore the observed summer/winter trend difference in terms of observed gravity wave heat flux heating rate at a nearby station and the long‐term trend of gravity wave variance at a midlatitude. Between 89 and 100 km, the lidar trends are within the error‐bars of the Leibniz Middle Atmosphere (LIMA) summer trends (1979‐2013), which are nearly identical to the lidar‐Ngt trend. We address the need of long dataset for reliable analysis on trend, the extent of trend uncertainty due to possible tidal bias, the effect of a Pinatubo/episodic function, and the impact of stratospheric ozone recovery.
Print ISSN:
2169-9380
Electronic ISSN:
2169-9402
Topics:
Geosciences
,
Physics
