Validation of CERES-MODIS and CALIPSO/CloudSat Arctic cloud properties using ARM NSA observations

 

Authors

Xiquan Dong — University of Arizona
Patrick Minnis — NASA - Langley Research Center
Baike Xi — University of Arizona
Kathryn Giannecchini — University of North Dakota

Category

Cloud Properties

Description

Cloud fraction derived from CALIPSO/CloudSat, MODIS, and MMCR at the ARM NSA site at Barrow, Alaska, for January 2007–December 2008.
Studies of cloud properties in the Arctic are often affected by complex snow and ice cover that make it difficult to differentiate between clouds and ground cover using satellite remote sensing techniques. In this study, the Arctic cloud fraction and microphysical properties derived from NASA CERES team (CERES-MODIS) and CloudSat/CALIPSO have been compared with the DOE ARM NSA observations from January 2007 through December 2008. The ARM cloud properties used in this study include monthly means of cloud fraction, cloud base and top heights, and cloud liquid water path derived from the ARM ceilometers, millimeter-wavelength cloud radar (MMCR), and microwave radiometer (MWR) measurements at the ARM NSA site. The NASA CERES-MODIS cloud properties are retrieved by the 4-channel VISST (Visible Infrared Solar-Infrared Split-window Technique), an updated version of the 3-channel visible infrared solar-infrared method described by Minnis et al. (1995). The cloud properties from CloudSat/CALIPSO are Level 2B data products, including cloud base and top heights determined by both 94-GHz radar and lidar with a vertical resolution of 240 m, with LWP retrieved from the 94-GHz radar. To match the surface and satellite observations/retrievals, the ARM surface observations have been averaged into 1 hour centered at the satellite overpass, and the satellite observations have been averaged within a 1°x1° grid box around the Barrow site. Preliminary results have revealed that the CERES-MODIS derived effective cloud height (2.349 km) and CloudSat/CALIPSO derived cloud base (2.77 km) and top (4.471 km) heights are within the ARM ceilometer- and MMCR-derived cloud base (0.929 km) and top (5.388 km) heights. The ARM ceilometer- and MMCR-derived CFs have an excellent agreement (0.724 vs. 0.74), whereas the CERES-MODIS- and CloudSat/CALIPSO-derived CFs are slightly lower (0.665) and higher (0.825), respectively. The LWP values derived from ARM, CERES-MODIS, and CloudSat/CALIPSO are close to each other (76, 66, 57 gm-2) with a general trend of increasing from winter to late summer/early fall.