Aerosol impacts on cloud thermodynamic phase change over East Asia observed with CALIPSO and CloudSat measurements

Abstract

Impacts of aerosols on subfreezing cloud thermodynamic phase change over East Asia are studied by using 4 year combined CloudSat radar and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar measurements. The mean occurrence frequencies of supercooled-liquid, mixed-phase, and glaciated clouds over East Asia are 10.4%, 10.3%, and 16.9%, respectively. Over northwest of East Asia (32-44°N, 75-100°E), subfreezing clouds are dominated by glaciated clouds with a mean relative cloud fraction (RCF) of~60% and over southeast (16-32°N, 95-120°E) are dominated by supercooled-liquid clouds with a mean RCF of~50%. Although cloud top temperature (CTT) differences contribute largely to the thermodynamic phase differences, northwest of East Asia has~20% larger glaciated (smaller mixed-phase) RCFs than those of southeast at the same CTT. Seasonal anomalies of glaciated and mixed-phase RCFs correlate well with the seasonal variations of dust occurrence frequency. In addition, subfreezing clouds associated with mineral dust contain approximately 5%, 10%, and 20% larger glaciated (smaller mixed-phase) RCFs than those associated with polluted dust, smoke, and background aerosols at any given CTT. It is suggested that dust impacts on subfreezing clouds over East Asia by providing abundant effective ice nuclei to glaciate mixed-phase clouds, although the impacts of large-scale dynamics and water supply mechanisms cannot be ruled out.

Distinct impact of different types of aerosols on surface solar radiation in China

“…The six aerosol types include clean marine, smoke (biomass burning), dust, polluted dust (mixtures of dust and smoke), polluted continental, and clean continental [ Omar et al ., , ; Tesche et al ., ]. These CALIPSO data have been widely used by many researchers [ Huang et al ., ; Huang et al ., ; Thorsen and Fu , ; Zhang et al ., ]. This level 2 lidar vertical feature mask product is available online at the NASA Langley Atmospheric Science Data Center website (https://eosweb.…”

Effects of atmospheric dynamics and aerosols on the fraction of supercooled water clouds

“…Some studies have investigated the impact of different aerosol types on cold phase clouds over East Asia (Zhang et al, 2015) or at a global scale (Choi et al, 2010;Tan et al, 2014). However, studies of the statistical relationship between cloud phase changes and meteorological parameters have received far less attention, especially at a global scale.…”

“…For example, based on laboratory experiments and field measurements, mineral dust from arid regions has been widely recognized as an important source of IN in mixed-phase clouds because of its nucleation efficiency and abundance in the atmosphere. In addition to dust, some studies have also verified the potential ice nucleation ability of polluted dust and smoke at cold temperatures (Niedermeier et al, 2011;Cziczo et al, 2013;Tan et al, 2014;Zhang et al, 2015). For dynamical process, Naud et al (2006) assessed the impact of large-scale ascent on the cloud phase and found that the areas of greatest large-scale ascent are not glaciated at cloud top as much as areas of moderate ascent.…”

“…Generally speaking, the changes of cloud phase composition in mixed-phase clouds is complicatedly controlled by several factors other than temperature, e.g., ice nuclei (IN) (Choi et al, 2010;Tan et al, 2014;Zhang et al, 2015) or dynamical processes (Trembly et al, 1996;Shupe et al, 2008). Some special aerosols suspended in the atmosphere can change the cloud phase by acting as IN in the heterogeneous ice nucleation process of mixed-phase clouds via different nucleation modes (e.g., deposition, immersion freezing, contact and condensation freezing) (Lohmann and Feichter, 2005).…”

East Asian Study of Tropospheric Aerosols and their Impact on Regional Clouds, Precipitation, and Climate (EAST‐AIRCPC)

“…Nevertheless, studies of cloud thermodynamic phase changes and the vertical structures of mixed and ice‐phase clouds over East Asia from both observations and model simulations are still sparse (Fan et al, ; J. Liu et al, ). The impacts of aerosols on cold‐phase cloud thermodynamic phase changes over East Asia were studied using four years of combined measurements from the CloudSat radar and the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar (Zhang et al, ). Seasonal anomalies of glaciated and mixed‐phase clouds correlate well with the seasonal variations in the frequency of dust occurrence.…”