Infl uence of particulate matter on observed albedo reductions on Plaine Morte glacier, Swiss Alps Master’s Thesis Faculty of Science University of Bern presented by Eva Bühlmann 2011 Supervisor: Prof. Dr. Margit Schwikowski Paul Scherrer Institute and Oeschger Centre for Climate Change Research Co-Supervisor: Prof. Dr. Martin Hoelzle Department of Geosciences,University of Fribourg Advisor: Pierre-Alain Herren Paul Scherrer Institute and Oeschger Centre for Climate Change Research II Moulin on Plaine Morte glacier, Eva Bühlmann, 2010 III IV Table of contents Table of contents Summary . XI Zusammenfassung . .XIII 1. Introduction . .1 1.1. State of knowledge and research motivation . 2 1.2. Research questions . 5 1.3. Project design . 5 1.4. Thesis outline . 6 2. Basic terms, concepts and processes . .7 2.1. Energy balance and albedo of glaciers . 7 2.2. Cryoconite . 7 2.3. Atmospheric transport and deposition mechanisms of PM . 8 2.4. Sources of PM and their identifi cation . 8 2.5. Carbonaceous fraction of soot . 9 3. Study site . 11 3.1. Geographical setting . 11 3.2. Climate and meteorology . 11 3.3. Glaciology and hydrology . 11 3.4. Geology . 13 4. Methods . 15 4.1. Fieldwork . 15 4.1.1. Sampling procedure . 15 4.2. Albedo and spectral refl ectance measurements . 15 4.3. Sample extraction and preparation . 17 4.4. Standard snowpit analyses . 18 4.4.1. Reconstruction of snowpack . 18 4.4.2. Ion chromatography (IC) . 18 4.4.3. Isotope ratio mass spectrometry (IR-MS) . 19 4.5. Mineral dust analyses . 20 4.5.1. X-ray diff raction (XRD) . 20 4.5.2. Inductively coupled plasma mass spectrometry (ICP-MS) . 21 4.6. Analyses of potential darkening agents . 21 4.6.1. Loss on ignition (LOI) . 21 4.6.2. Microscopic assay of biogenic matter and microorganisms . 22 4.6.3. Thermo-optical OC/EC analysis . 24 4.7. Data processing of albedo measurements . 25 4.7.1. Broadband albedo . 25 4.7.2. Spectral refl ectance . 26 5. Results and interpretations . 27 V Table of contents 5.1. Results of snowpack investigation . 27 5.1.1. Reconstruction of snowpack formation . 27 5.1.2. General characterisation of the snowpack on 1 June . 28 5.1.3. Impurities in snowpack . 29 5.2. Biogeochemical analysis of cryoconite . 33 5.3. Broadband albedo and spectral refl ectance . 37 6. Discussion . 41 6.1. Snowpack investigation . 41 6.1.1. Snowpack characterisation . 41 6.1.2. Identifi cation of dust events . 42 6.1.3. Budget of impurities in snow . 44 6.2. Cryoconite composition . ..