Periodic Reporting for period 1 - GRASP-ACE (Development of GRASP radiative transfer code for the retrieval of aerosol microphysics vertical-profiles from space measurements and its impact in ACE mission)
Reporting period: 2018-03-01 to 2020-02-29
The main objective of this proposal is the development and implementation of the joint inversion in GRASP for space polarimeter + lidar instruments to retrieve independent and accurate vertical profiles of aerosol microphysical properties. Such an approach is critical for future space missions such as ACE and ACCP, and will allow aerosol microphysics vertical-profiles, particularly for absorption properties. To fulfill this objective we divide the goals in:
1. Study of capabilities of the joint inversion through new mathematical developments and sensitivity test analyses.
2. Evaluation of the GRASP joint inversion from field campaign data and their advantages over the classical stand-alone 3β+2α lidar inversion.
3. Exploring merging data of different satellite missions for implementing GRASP joint inversion.
4. Defining synergies in ground-based networks for the evaluation of aerosol microphysics satellite products.
The consortium to be created in this proposal fits with the general scope of Marie Curie RISE call to promote international and inter-sectorial collaborations as we proposed staff exchange among the institutions to share knowledge and ideas from the last research developments in aerosol sciences. We propose a set of secondments, workshop and training activities that will also foster a shared culture of research and innovation to promote creativity and to help creative ideas into innovative research, product and services.
We also carried out theoretical development of the solution of the ill-posed problem for the combination of multiangle and multiwavelength polarimeter measurements and multiwavelength lidar. For obtaining aerosol microphysical properties (retrieved) from aerosol optical (measured) properties we need to solve an ill-posed problem that requires analyses. Current GRASP version already incorporates a numerical module based on least squares analyses for polarimeter measurements. We evaluated the capabilities of the inversion module for space lidar and polarimetry signal and implement more equations to fulfill the inversion.
The development of a joint inversion that allows the retrieval of aerosol microphysical and optical properties vertically resolved combining multi-angle and multi-wavelength polarimetry with backscattering lidar measurements open new possibilities not explored until now. Such configuration is critical for space systems because the stand-alone 3β+2α lidar inversion faces with the limitations of deploying cost-effective space lidar systems capable of obtaining accurate extinction measurements. The joint inversion has already been implemented in GRASP and during the next two years of project we will perform an evaluation stage using airborne measurements. The success of the joint inversion development will made GRASP suitable for obtaining aerosol microphysics and optical properties from the polarimeter and backscattering lidar planned in the upcoming Aerosol-Clouds-Convection-Precipitation (ACCP) NASA mission.
The GRASP software has been used within the H2020 Aerosols, Clouds and Trace gases Research Infraestructure (ACTRIS-2) through the combination of ground-based sun photometry and backscattering lidar measurements to obtain aerosol microphysics and optical properties vertically-resolved. In the GRASP-ACE project we have extended such applications, and particularly for nighttime when no sun-photometry measurements are available. The approaches proposed are based on combining backscattering lidar measurements with moon aureole and direct moon measurements with moon-photometers. Also, the continuity with closed daytime retrievals with sun-photometry was studied. The results were very promising in the day-to-night continuity studies. These results are being taken as reference for future evaluations of satellite missions such as ACCP using extensive lidar networks such as EARLINET-ACTRIS or MPLNET which operate many lidar instruments, most of them being only backscattering lidar. Other approaches will be studied during the next two years of the GRASP-ACE project such as those that use sun-photometry measurements with spectroradiometers or with polarization capabilities.