A New Retrieval Algorithm of the Thermal Infrared Optical Depth of Dust based on the Combined CALIOP and IIR Observations

Mineral dust significantly affects both shortwave solar (SW) and longwave thermal infrared (LW) radiation, which however remains uncertain. Although dust optical properties and cooling effect at the top of atmosphere (TOA) in SW range have been extensively studied for decades, dust properties and warming effect in LW range have been understudied. In this study, we develop a new way to retrieve dust optical depth in the thermal infrared (DOD_TIR) by integrating the Infrared Radiometer (IIR) and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), both onboard CALIPSO. The IIR provides brightness temperature (BT) observations in three TIR bands centered at 8.65,10.6 and 12.05 μm, respectively. . In addition, the impact of the radiometric and ancillary data uncertainty on DOD_TIR retrieval will be evaluated by using the linear perturbation method.