From March 17th till 28th, I (Athina Argyrouli) was hosted at the University of Hertfordshire under the supervision of Dr. Detlef Müller. The major goal of this two-week secondment was to get training on the inversion algorithm for retrieving aerosol microphysical properties by using optical data from a Raman lidar (with 3β+2α capabilities). During the first week of my stay, I got familiar with a training version of the software. I received training in how to retrieve volume concentration, number concentration, surface-area concentration, effective radius and the complex refractive index of aerosols with using synthetic optical data. That was basically the first step to understand whether a mathematical solution retrieved through the inversion is also acceptable from the physical point-of-view. The idea of using simulated data gave me an overview of the discrepancy which can be introduced to the solution of an ill-posed problem because of instability reasons. During this first week, Dr. Müller offered me some face-to-face sessions about the fundamentals behind the inversion process with respect Mie scattering theory.
The second week of my visit was devoted on the latest version of the software (research grade) which will be used to retrieve aerosol microphysical properties with data from two forthcoming field campaigns planned for May-July 2014 in Greece, the so-called HygrA-CD campaign in Athens and a second one taking place in Crete island. For practicing reasons, I retrieved microphysical properties of aerosols from a set of lidar data analyzed by Dr. Rodanthi-Elisavet Mamouri, former Ph.D. student in LRSU group of NTUA. Dr. Müller gave me the opportunity to introduce my project (i.e., challenges and scientific objectives) to him, so as I focus on the key parameters which will give added value to my research goals. I am very thankful to Dr. Müller for his valuable advice and suggestions towards the successful development of my Ph.D. thesis. Last but not least, I would like to thank both Dr. Müller and his Ph.D. student, Felix Ameseder, for their hospitality which made my stay in the UK during these two weeks pleasant. Special thanks to Felix Ameseder who has been taken the pictures of Dr. Müller and myself; in front of the Center for Atmospheric and Instrumentation Research and in Dr. Müller's office at the end of a Whiteboard Session.