Regional Saharan dust modelling during the SAMUM 2006 campaign

Published under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported LicenseThe regional dust model system LM-MUSCAT-DES was developed in the framework of the SAMUM project. Using the unique comprehensive data set of near-source dust properties during the 2006 SAMUM field campaign, the performance of the model system is evaluated for two time periods in May and June 2006. Dust optical thicknesses, number size distributions and the position of the maximum dust extinction in the vertical profiles agree well with the observations. However, the spatio-temporal evolution of the dust plumes is not always reproduced due to inaccuracies in the dust source placement by the model. While simulated winds and dust distributions are well matched for dust events caused by dry synoptic-scale dynamics, they are often misrepresented when dust emissions are caused by moist convection or influenced by small-scale topography that is not resolved by the model. In contrast to long-range dust transport, in the vicinity of source regions the model performance strongly depends on the correct prediction of the exact location of sources. Insufficiently resolved vertical grid spacing causes the absence of inversions in the model vertical profiles and likely explains the absence of the observed sharply defined dust layers.Peer reviewe

Interactions between the atmosphere, cryosphere, and ecosystems at northern high latitudes

The Nordic Centre of Excellence CRAICC (CRyosphere-Atmosphere Interactions in a Changing Arctic Climate), funded by NordForsk in the years 2011–2016, was the largest joint Nordic research and innovation initiative to date, aiming to strengthen research and innovation regarding climate change issues in the Nordic Region. CRAICC gathered more than 100 scientists from all Nordic countries in a virtual Centre with the objectives to identify and quantify the major processes controlling Arctic warming and related feedback mechanisms, to outline strategies to mitigate Arctic warming and to develop Nordic Earth System modelling with a focus on the short-lived climate forcers (SLCF), including natural and anthropogenic aerosols. The outcome of CRAICC is reflected in more than 150 peer-reviewed scientific publications, most of which are in the CRAICC special-issue of the journal Atmospheric Chemistry and Physics. This manuscript presents an overview on the main scientific topics investigated in the Centre and provides the reader a state-of-the-art comprehensive summary of what has been achieved in CRAICC with links to the particular publications for further detail. Facing the vast amount of outcomes we are not claiming to cover all results from CRAICC in this manuscript but concentrate here on the main results which are related to the feedback loops in the climate change-cryosphere interaction scheme affecting the Arctic amplification.The Nordic Centre of Excellence CRAICC (CRyosphere-Atmosphere Interactions in a Changing Arctic Climate), funded by NordForsk in the years 2011–2016, was the largest joint Nordic research and innovation initiative to date, aiming to strengthen research and innovation regarding climate change issues in the Nordic Region. CRAICC gathered more than 100 scientists from all Nordic countries in a virtual Centre with the objectives to identify and quantify the major processes controlling Arctic warming and related feedback mechanisms, to outline strategies to mitigate Arctic warming and to develop Nordic Earth System modelling with a focus on the short-lived climate forcers (SLCF), including natural and anthropogenic aerosols. The outcome of CRAICC is reflected in more than 150 peer-reviewed scientific publications, most of which are in the CRAICC special-issue of the journal Atmospheric Chemistry and Physics. This manuscript presents an overview on the main scientific topics investigated in the Centre and provides the reader a state-of-the-art comprehensive summary of what has been achieved in CRAICC with links to the particular publications for further detail. Facing the vast amount of outcomes we are not claiming to cover all results from CRAICC in this manuscript but concentrate here on the main results which are related to the feedback loops in the climate change-cryosphere interaction scheme affecting the Arctic amplification.The Nordic Centre of Excellence CRAICC (CRyosphere-Atmosphere Interactions in a Changing Arctic Climate), funded by NordForsk in the years 2011–2016, was the largest joint Nordic research and innovation initiative to date, aiming to strengthen research and innovation regarding climate change issues in the Nordic Region. CRAICC gathered more than 100 scientists from all Nordic countries in a virtual Centre with the objectives to identify and quantify the major processes controlling Arctic warming and related feedback mechanisms, to outline strategies to mitigate Arctic warming and to develop Nordic Earth System modelling with a focus on the short-lived climate forcers (SLCF), including natural and anthropogenic aerosols. The outcome of CRAICC is reflected in more than 150 peer-reviewed scientific publications, most of which are in the CRAICC special-issue of the journal Atmospheric Chemistry and Physics. This manuscript presents an overview on the main scientific topics investigated in the Centre and provides the reader a state-of-the-art comprehensive summary of what has been achieved in CRAICC with links to the particular publications for further detail. Facing the vast amount of outcomes we are not claiming to cover all results from CRAICC in this manuscript but concentrate here on the main results which are related to the feedback loops in the climate change-cryosphere interaction scheme affecting the Arctic amplification.Peer reviewe

Impact of Vegetation Fires on the Composition and Circulation of the Atmosphere

Vegetation fires are a significant source for atmospheric trace gases and aerosol particles (APs) on both local and global scale. The biomass burning APs affect cloud formation as well as microphysical and chemical processes in clouds. They influence the radiation budget directly and via altered cloud properties. Finally, this results in changes of the atmospheric energy budgets and circulation. The joint research project EFEU addressed these topics with a combined experimental and numerical approach of eight different research groups. Three series of experiments were carried out at the laboratory oven facility at MPI Mainz. Characteristic vegetation from different burning regions was investigated, e.g., Musasa (Africa), aleppo pine (Mediterranian), spruce (boreal) and peat (Indonesia). Trace gases and a wide range of AP parameters were measured, including size distributions as well as morphological, chemical, hygroscopic and radiative properties. Experimental results indicate that hygroscopic properties and drop nucleating abilities are rather similar for APs from burns of different types of hard wood but different to APs from other burning material such as maize or peat. Generally, the soluble fraction of the APs is quite small and their EC content fairly high. Radiative properties (single scattering albedo) are well correlated with the burn conditions (flaming/smoldering). For the numerical studies of the complex impact of biomass burning emissions on the atmosphere a suite of independent models was employed. Ranging from the microscale to the regional scale they complement each other in terms of spatial and temporal resolution as well as complexity of the processes described. Modelling efforts covered a detailed description of the microphysics including the ice phase, the evolution of individual biomass burning plumes, effects of radiative transport on chemistry and dynamics as well as regional atmospheric budgets of trace constituents, water and energy. Main results are: Precipitation is initiated only via the ice phase in the clouds explored. The dilution of an individual plume was predicted successfully and realistic heating and photolysis rates were simulated. Total particulate matter was correctly calculated for the Indonesian case study using emission factors and sizes of the burning areas