Microphysical Properties of Ice Crystal Precipitation and Surface-Generated Ice Crystals in a High Alpine Environment in Switzerland
AbstractDuring the Cloud and Aerosol Characterization Experiment (CLACE) 2013 field campaign at the High Altitude Research Station Jungfraujoch, Switzerland, optically thin pure ice clouds and ice crystal precipitation were measured using holographic and other in situ particle instruments. For cloud particles, particle images, positions in space, concentrations, and size distributions were obtained, allowing one to extract size distributions classified by ice crystal habit. Small ice crystals occurring under conditions with a vertically thin cloud layer above and a stratocumulus layer approximately 1 km below exhibit similar properties in size and crystal habits as Antarctic/Arctic diamond …
Coarse-mode mineral dust size distributions, composition and optical properties from AER-D aircraft measurements over the tropical eastern Atlantic
Mineral dust is an important component of the climate system, affecting the radiation balance, cloud properties, biogeochemical cycles, regional circulation and precipitation, as well as having negative effects on aviation, solar energy generation and human health. Dust size and composition has an impact on all these processes. However, changes in dust size distribution and composition during transport, particularly for coarse particles, are poorly understood and poorly represented in climate models. Here we present new in situ airborne observations of dust in the Saharan Air Layer (SAL) and the marine boundary layer (MBL) at the beginning of its transatlantic transport pathway, from the AE…
Aircraft and ground measurements of dust aerosols over the west African coast in summer 2015 during ICE-D and AER-D
During the summertime, dust from the Sahara can be efficiently transported westwards within the Saharan air layer (SAL). This can lead to high aerosol loadings being observed above a relatively clean marine boundary layer (MBL) in the tropical Atlantic Ocean. These dust layers can impart significant radiative effects through strong visible and IR light absorption and scattering, and can also have indirect impacts by altering cloud properties. The processing of the dust aerosol can result in changes in both direct and indirect radiative effects, leading to significant uncertainty in climate prediction in this region. During August 2015, measurements of aerosol and cloud properties were condu…
Advances in understanding mineral dust and boundary layer processes over the Sahara from Fennec aircraft observations
Abstract. The Fennec climate programme aims to improve understanding of the Saharan climate system through a synergy of observations and modelling. We present a description of the Fennec airborne observations during 2011 and 2012 over the remote Sahara (Mauritania and Mali) and the advances in the understanding of mineral dust and boundary layer processes they have provided. Aircraft instrumentation aboard the UK FAAM BAe146 and French SAFIRE (Service des Avions Français Instrumentés pour la Recherche en Environnement) Falcon 20 is described, with specific focus on instrumentation specially developed for and relevant to Saharan meteorology and dust. Flight locations, aims and associated met…
Mixed-Phase Clouds: Progress and Challenges
Mixed-phase clouds represent a three-phase colloidal system consisting of water vapor, ice particles, and coexisting supercooled liquid droplets. Mixed-phase clouds are ubiquitous in the troposphere, occurring at all latitudes from the polar regions to the tropics. Because of their widespread nature, mixed-phase processes play critical roles in the life cycle of clouds, precipitation formation, cloud electrification, and the radiative energy balance on both regional and global scales. Yet, in spite of many decades of observations and theoretical studies, our knowledge and understanding of mixed-phase cloud processes remains incomplete. Mixed-phase clouds are notoriously difficult to represe…