Development of retrieval techniques for aerosol microphysical characterization from multi-wavelength space-borne lidar and radiometric measurements

Project Information

ACE_GFAT

Grant agreement ID: 659398

DOI

10.3030/659398

Project closed

EC signature date 6 March 2015

Start date 1 February 2016

End date 31 January 2018

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 158 121,60

EU contribution

€ 158 121,60

Coordinated by

UNIVERSIDAD DE GRANADA
Spain

Periodic Reporting for period 1 - ACE_GFAT (Development of retrieval techniques for aerosol microphysical characterization from multi-wavelength space-borne lidar and radiometric measurements)

Reporting period: 2016-02-01 to 2018-01-31

Summary of the context and overall objectives of the project

The main goal of the ACE_GFAT project was to study the optimum capabilities of a lidar system to be deployed in the upcoming Aerosols – Clouds – Ecosystems (ACE) NASA space mission. To that end, during this project we continue the collaboration started by Dr. Daniel Perez-Ramirez (coordinator of the project) with NASA Goddard Space Flight Center (Greenbelt, Maryland, USA) and expanded the collaborations with secondments at the University of Lille (France). The studies have focussed on the evaluation of different lidar capabalities for obtaining vertical profiles of aerosol microphysical properties from space lidar measurements and also on studying the yields of different lidar space systems. The proposed studies are of relevance for the society because will help to better understand the mechanisms of formation of clouds and the interaction of aerosols with radiation. Also, the studies performed during the ACE_GFAT project are being essential to define the feasibility of space lidar system in terms of costs/risks, which directly impact on society as such space programs rely mostly on public taxes.

The overall objective of the ACE_GFAT projectwas successfully obtained through the different objectives:

• Simulations of Multi-Wavelength lidar for ACE
• High temporal-resolution of aerosol microphysical properties
• Combination of backscattering lidar and ground-based measurements

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Scientific Tasks
• Using the the Goddard Earth Observing System Model, Version 5 (GEOS-5) different aerosol situations were used as baseline for simulating space-borne lidar signals. We simulated different lidar systems candidates for the ACE mission. The first study was the satellite yield and we found important differences when vaying telescope diameter. Later, the simulated lidar signals were used as inputs in the regularization and Linear Estimation (LE) inversion codes to study their capabablity to reproduce GEOS-5 reference data. These studies were also done adding noise to the lidar signals. The results revealed that retrievals are only possible when fine mode dominates, and also indicating shortcomings for very small particles (typically below 0.05 μm).
• The high temporal-estimation of aerosol microphysical properties using spectral aerosol optical depth (AODs) as inputs were studied by combining LE and Spectral Deconvolution Algorithm (SDA). Our simulations revealed that independent retrievals of coarse and fine mode aerosol properties were not possible. Indeed, we found out a good retrieval of fine mode radius and volume using spectral deconvolution algorithm. Our final approach demonstrated that combining LE and SDA provide feasible retrievals of particle radius and volume for the entire aerosol size distributions and also good estimates of fine mode properties when fine mode contribution to total aerosol is larger than 70%.
• The combination of ground-based backscattering lidar with other remote sensing instrumentation was studied for the retrieval of aerosol microphysical properties vertical profiles during nighttime. Studies were done combining measurements of backscattering lidar and moon/star photometry at the University of Granada. Also, combinations with additional information provided by all sky cameras capable of measuring moon aureoles are in course

Training Activities I: Secondments
• Secondments at NASA Goddard Space Flight Center (USA): The coordinator, Dr. Daniel Perez-Ramirez did two secondments with funding of NASA Goddard Space Flight Center.
• Secondments at the University of Lille (France): Two short secondments were done at the Laboratory of Atmospheric Optics.

Training Activities II: Attendance to Conferences
• Dr. Daniel Perez Ramirez attended to the following conferences: European Geosciences Union General Assembly - Vienna (Austria) 2016, SPIE Remote Sensing - Edimburgh (United Kingdom), September 2016 and American Geophysical Union Fall Meeting 2017 - New Orleans (USA). He also submitted part of his research to other conferences although he did not attended in person (e.g. the American Geophysical Union Fall Meeting 2016, International Lidar Radar Conference 2017 and European Lidar Conference 2018) .

Transferable Skills:

Dr. Daniel Perez Ramirez have been teaching at undergraduate level in the University of Granada with classes in Thermodynamics, Physics for Telecommunication Engineer, Advance Physics in Arquictecture) and in Basic Experimental Techniques. He also participated in the master with classes in Advances Methods for Characterizing Atmospheric Aerosols. Dr. Perez-Ramirez is also co-directing a Phd in the use of lidar data and the characterization of aerosols microphysical properties combining passive and active remote sensing.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

"During this project we have study the different capabilities of space-borne lidars to retrieve aerosols microphysical properties. Several shortcomings have been found in the retrievals, mainly associated with the undetermination of the ill-possed problem. This finding is pushing forward in the optimization of the stand-alone lidar inversion. Such optimization is being developed using the background of more robust retrievals typically obtained by AERONET network and also in the coherence with the assumptions in aerosols properties in global models.

The results of the ACE_GFAT project are also pushing ahead in a joining inversion for space-borne retrievals of aerosol microphysical properties vertical-profiles. Such approach would combine polarimetry and lidar measurements and will solve the issues related with the undetermined problems. The success of these new developments has a direct socio-economical impact because the combination of space remote sensing instruments will allows the scientific community to obtain reliable aerosol parameters without the need of very sophisticated lidar systems. For example, in the joint inversion scheme lidar extinction measurements might be unnecesseraty. Note that in our analyses during ACE_GFAT project we found extinction measurements are the most difficult and noisy, and also errors in extinction measurements induce the larger errors in the retrievals.

As a result of this progress beyond the state of the art during the ACE_GFAT Marie Skolodowska-Curie project, Dr. Daniel Perez Ramirez is coordinating a recently funded Marie Sklodowska-Curie Research Innovative and Staff Exchange (RISE) action entitled "" Development of GRASP radiative transfer code for the retrieval of aerosol microphysics vertical profiles from space measurements and its impact in the ACE mission (GRASP-ACE)"". The GRASP-ACE project include several European beneficiaries such as the University of Granada (Spain), University of Valladolid (Spain), University of Lille (France), Free University of Berlin (Germany), CNRS (France) and the company GRASP.SAS (France). Partner institutions also participated, mainly from thid countries, such as NASA Goddard Space Flight Center (USA), University of Maryland Baltimore County (USA), General Institute of Physics of the Russian Academy of Sciences (Rusia) and Stephanov Institute of Physics of the Belarus Academy of Sciences.

All these new possibilities within the GRASP-ACE project have been created thanks to the the ACE-GFAT project with put in contact different institutions and open new possibilities of collaboration.
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SummaryResults