Characterizing Marine Boundary Layer Clouds Using CALIPSO Observations

Abstract:

Clouds play important roles in Earth’s climate system. Marine boundary layer clouds strongly affect Earth’s radiation budget. They exert a net radiative cooling effect on climate due to their high albedo. In this presentation, we will examine the 3D characteristics of marine boundary layer clouds using observations from the CALIOP lidar onboard CALIPSO satellite. CALIOP is a two-wavelength (532 nm and 1064 nm) polarization-sensitive (at 532 nm) elastic backscatter lidar that provides high vertical resolution cloud profiles giving accurate estimates of cloud boundaries. Different from passive remote sensors, CALIOP can detect even thin marine boundary layer clouds in columns with multiple cloud layers. With its 70-meter footprint diameter, CALIOP has high sensitivity to detect small-scale marine boundary layer clouds. Specifically, we will examine cloud fraction, cloud top and cloud thickness partitioned by cloud opacity. Further we will investigate how characteristics such as cloud thermodynamic phase are different between Arctic and tropical marine boundary clouds. Results from CALIOP will be compared with those from passive remote sensors such as MODIS. As part of our preparations for a future CALIPSO Level 3 cloud product, we also examine which of the five Level 2 CALIOP cloud products best characterizes marine boundary layer. This research will produce a more accurate representation of marine boundary layer clouds that could be used to evaluate the representation of such clouds in global climate models.