Temperature Control of the Variability of Tropical Tropopause Layer Cirrus Clouds

Abstract

This study examines the temperature control of variability of tropical tropopause layer (TTL) cirrus clouds (i.e., clouds with bases higher than 14.5 km) by using 8 years (2006–2014) of observations from the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC). It is found that the temporal variability of vertical structure of TTL cirrus cloud fraction averaged between 15°N and 15°S can be well explained by the vertical temperature gradient below ~17.5 km but by the local temperature above for both seasonal and interannual time scales. It is also found that the TTL cirrus cloud fraction at a given altitude is best correlated with the temperature at a higher altitude and this vertical displacement increases with a decrease of the cirrus altitude. It is shown that the TTL cirrus cloud fractions at all altitudes are significantly correlated with tropical cold point tropopause (CPT) temperature. The plausible mechanisms that might be responsible for the observed relations between TTL cirrus fraction and temperature‐based variables are discussed, which include ice particle sediments, cooling associated with wave propagations, change of atmospheric stability, and vertical gradient of water vapor mixing ratio. We further examine the spatial covariability of TTL total cirrus cloud fraction and CPT temperature for the interannual time scale. It is found that the El Niño–Southern Oscillation and quasi‐biennial oscillation are the leading factors in controlling the spatial variability of the TTL cirrus clouds and temperatures.

The Impact of Cloud Radiative Effects on the Tropical Tropopause Layer Temperatures

“…The cloud radiative effects over the western Pacific were about twice of those averaged over 20 • N-20 • S. Figure 2 (right) shows the cloud radiative effects of TTL cirrus, which was derived as the difference of the radiative heating rates for the whole skies with and without the TTL cirrus. The TTL cirrus is clouds with cloud base height higher than 14.5 km [51,52]. The TTL cirrus introduces heating in the TTL, with a maximum heating of 0.09 K/day (0.17 K/day) near 110 hPa over the tropics (western Pacific).…”

Observed changes in Brewer–Dobson circulation for 1980–2018

“…Holton 1990, Holton et al 1995, Appenzeller et al 1996. The BDC directly modulates the tropical tropopause temperatures, tropical tropopause layer cirrus, and stratospheric water vapor, all of which are associated with climate change processes (Birner 2010, Dessler et al 2013, Fu 2013, Tseng and Fu 2017.…”

An Investigation of Optically Very Thin Ice Clouds from Ground-Based ARM Raman Lidars

“…The launch of the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on-board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) has offered an unprecedented global representation of ice cloud occurrence and optical depth [19]. Many studies have leveraged CALIPSO's capability to characterize ice clouds, providing new insights into the global ice cloud observations [5,[20][21][22][23][24][25][26][27].…”