High Spectral Resolution Lidar and CALIPSO measurements from the ARCTAS field campaign

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) was deployed on the NASA B-200 aircraft and measured profiles of aerosol extinction, backscatter, and depolarization during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign. The HSRL flights were heavily focused on CALIPSO validation, addressing one of the primary objectives of ARCTAS to evaluate and improve the accuracy of satellite-based observations. Additionally, the HSRL flights were also aimed at providing vertically and horizontally resolved aerosol information for use in conjunction with observations from other aircraft and models. During the ARCTAS spring component (April 2008) the HSRL was based out of Barrow, AK and collected 60 flight hours over 15 science flights (12 CALIPSO validation flights). For the summer component (June/July 2008) the HSRL was based out of Yellowknife, Canada and acquired 58 flight hours over 16 science flights (10 CALIPSO validation flights). In both spring and summer phases the HSRL also made coordinated measurements with the NASA P-3, the NASA DC-8, the NOAA P3, the Canadian Convair-580 operated under contract to the DOE, and the DOE ARM NSA site. This poster uses the established and well calibrated HSRL measurements to assess the CALIPSO level 1 attenuated backscatter during ARCTAS. The level 1 attenuated backscatter products were compared in the free troposphere, essentially measuring the calibration between the two instruments, and found differences between the HSRL and CALIPSO 532 nm calibrations to be less than 4% on average for the ARCTAS campaign. The HSRL measurements also show that the arctic aerosols are frequently diffuse and extend up to at least 7 km, often higher in the spring campaign. This lack of a strong aerosol gradient combined with a strong daytime background results in CALIPSO detecting fewer aerosol features than the HSRL. For the features that were detected by CALIPSO a preliminary comparison of CALIPSO level 2 aerosol profile products (532 nm aerosol backscatter, extinction, and lidar ratio) was performed both statistically and on a profile-by-profile basis. Overall we found that CALIPSO underestimates the aerosol extinction and backscatter compared to HSRL using the version 2 dataset and expect better agreement with the version 3 dataset. Investigations are underway to understand the differences. In addition, specific comparisons were made on near-coincident profiles of smoke plumes in both spring and summer missions, show good agreement between HSRL and CALIPSO.