Atmospheric measurements including AirCore measurements

• Main Author: Mandrakis, Vasileios
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bern
• Subjects: 530 Physics; 550 Earth sciences & geology; Hagen; Sodankylä
• Online Access: http://boristheses.unibe.ch/4077/; http://boristheses.unibe.ch/4077/1/22mandrakis_v.pdf; https://doi.org/10.48549/4077

This thesis describes the AirCore sampling technique which is able to retain a continuous vertical profile of air that extends from the ground until the mid-stratosphere. The majority of the data that are presented in the following pages were recorded from various sensors that are attached on the AirCore. These data were acquired during two intensive AirCore sampling campaigns in Sodankylä, Finland during June of 2019, and in Traînou, France in 2020. Chapter 1 describes some of the main techniques that we use today to measure the concentration of greenhouse gases in the atmosphere. Whether it is for ground-based observations, commercial flights or intensive scientific aircraft campaigns, onboard instruments on ships and unmanned vehicles, the information we derive about the vertical distribution of greenhouse gases is limited to a maximum altitude which is much lower compared to the altitude at which an AirCore is able to sample. In Chapter 2, the stratification of the atmosphere is presented and the most important characteristics of each layer are described. The main focus is given on the two layers that a typical AirCore flight covers, namely the troposphere and the stratosphere. The typical pressure and temperature profiles with changing altitude are shown in this chapter. Chapter 3 provides important information related to fluid dynamics. It starts with the description of the laminar and the turbulent flow, two regimes that can affect significantly the sampling conditions during an AirCore flight or the measurement of the sample during the analysis. We can decide about the type of flow regime by calculating the dimensionless Reynolds number, which is the next definition provided in this chapter. One of the most important variables, especially during the analysis of the sample, is how fast we measure the total sampled volume of the AirCore, which is given by the volumetric flow rate. Next in this chapter, the Hagen-Poiseuille law for fluid flow along a tube is described, which explains the parabolic velocity ...