Abstract
Abstract. Detailed and accurate vertical distributions of cloud properties (such as cloud fraction, cloud phase, and cloud water content) and their changes are essential to accurately calculate the surface radiative flux and to depict the mean climate state. Surface and space-based active sensors including radar and lidar are ideal to provide this information because of their superior capability to detect clouds and retrieve cloud microphysical properties. In this study, we compare the annual cycles of cloud property vertical distributions from space-based active sensors and surface-based active sensors at two Arctic atmospheric observatories, Barrow and Eureka. Based on the comparisons, we identify the sensors' respective strengths and limitations, and develop a blended cloud property vertical distribution by combining both sets of observations. Results show that surface-based observations offer a more complete cloud property vertical distribution from the surface up to 11 km above mean sea level (a.m.s.l.) with limitations in the middle and high altitudes; the annual mean total cloud fraction from space-based observations shows 25–40 % fewer clouds below 0.5 km than from surface-based observations, and space-based observations also show much fewer ice clouds and mixed-phase clouds, and slightly more liquid clouds, from the surface to 1 km. In general, space-based observations show comparable cloud fractions between 1 and 2 km a.m.s.l., and larger cloud fractions above 2 km a.m.s.l. than from surface-based observations. A blended product combines the strengths of both products to provide a more reliable annual cycle of cloud property vertical distributions from the surface to 11 km a.m.s.l. This information can be valuable for deriving an accurate surface radiative budget in the Arctic and for cloud parameterization evaluation in weather and climate models. Cloud annual cycles show similar evolutions in total cloud fraction and ice cloud fraction, and lower liquid-containing cloud fraction at Eureka than at Barrow; the differences can be attributed to the generally colder and drier conditions at Eureka relative to Barrow.
Highlights
The Arctic has changed dramatically in recent decades, and causes of these changes and their feedbacks to the global climate system are under intense investigation
The Arctic is warming at a higher rate than that of the global average, a phenomenon known as Arctic amplification (Solomon et al, 2007; Serreze and Francis, 2006); Arctic sea ice extent has been decreasing dramatically (Serreze et al, 2015), and this trend is expected to continue (Holland and Bitz, 2003; Overland and Wang, 2013)
Based on the comparison performed here, this study proposes blended products of cloud property vertical distributions from surface and space-based cloud observations at those two Arctic sites to serve as a best estimate cloud product for model and reanalysis evaluation
Summary
The Arctic has changed dramatically in recent decades, and causes of these changes and their feedbacks to the global climate system are under intense investigation. Radar reflectivity from CloudSat has been used to generate high-vertical-resolution longwave and shortwave radiative flux profiles and corresponding heating rates (L’Ecuyer et al, 2008); assessing the product’s accuracy shows that CloudSat’s weakness in detecting low clouds introduces the largest uncertainty. This product has been improved by the inclusion of complementary cloud and aerosol information mainly from space-based lidar observations (Henderson et al, 2013). Blanchard et al (2014) investigated the difference in cloud fraction and vertical distribution at Eureka, Canada, in the Arctic from surface and space-based combined radar– lidar observations from 2006 to 2010. The conclusions will likely be valid for other spacebased radar and lidar instruments, e.g., the ATmospheric backscatter LIDar (ATLID) and the CPR onboard the EarthCARE mission (Hélière et al, 2007)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
