Abstract
This study investigates the direct comparison of backscatter coefficient profiles at 1064 nm which were measured by CALIOP (Cloud–Aerosol Lidar with Orthogonal Polarization) and by ground–based ceilometers located in coastal and non–coastal regions. The study uses data recorded between 2013 and 2016 to investigate the challenges involved in performing such a comparison in different environments. The standard Level 2 CALIOP Aerosol Profile version 4 product is evaluated against data from two ground–based Jenoptik CHM15K ceilometers: One at Mace Head (western Ireland) and the other at Harzgerode (central Germany). A statistical analysis from a series of CALIOP overpasses within 100 km distance from the ground–stations is presented considering different along–track averages in CALIOP data (5 km, 15 km, 25 km, 35 km, and 100 km) at the closest approach. The mean bias calculated from the correlative measurements between CALIOP and the ground–based ceilometers shows negative bias for 80% of the cases analyzed at Mace Head and positive bias for 68% of the cases investigated at Harzgerode, considering both daytime and nighttime measurements in cloud–free scenarios. The correlation of these results with HYSPLIT shows that different air samples play a role in the comparison. To our knowledge, this is the first study that addresses the limitations and capabilities in comparing CALIOP data with ground–based ceilometers at 1064 nm wavelength in different environments.
Highlights
Aerosol scattering and absorbing properties have a direct impact on the global radiative budget and an indirect impact on cloud formation and microphysics [1]
In order to demonstrate the methodology described in the previous section, two particular cases are discussed for Mace Head, Ireland and two for Harzgerode, Germany
53 CALIPSO overpasses occurred within a 100 km ground track offset distance from an operating ceilometer in the coastal site of Mace Head, Ireland, and 50 occurred from the non–coastal site of Harzgerode, Germany
Summary
Aerosol scattering and absorbing properties have a direct impact on the global radiative budget and an indirect impact on cloud formation and microphysics [1]. The tropospheric aerosols possess a substantial spatial and temporal variability, which leads to significant uncertainties in the estimation of radiative forcing in climate change studies [2]. The aerosol radiative forcing has a strong dependence on its vertical distribution. On the other hand, exhibit a more significant forcing when their mass is above cloud layers [3]. A better understanding of aerosol vertical (and horizontal) distribution and lifetime in the atmosphere is essential to investigate climate change and to improve forecast and dispersion models [4]. Aerosol and cloud properties can be observed either by in–situ or remote sensing instruments.
Sign-in/Register to view highlights & summary 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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
