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Phosphorus burial in the ocean over glacial-interglacial time scales
(2008)Biogeosciences DiscussionsThe role of nutrients and their impact on primary productivity and the fluctuations in atmospheric CO2 over glacial-interglacial periods are intensely debated. One of the cornerstones is the role of phosphorus (P; in the form of phosphate). Suggestions as to the importance of P evolved from an earlier proposal that P actively participated 5 in changing productivity rates and therefore climate change, to the most recent one that changes ...Working Paper -
Single ice crystal measurements during nucleation experiments with the depolarization detector IODE
(2008)Atmospheric Chemistry and Physics DiscussionsIn order to determine the efficiency of aerosol particles of several types to nucleate ice,an Ice Optical DEpolarization detector (IODE) was developed to distinguish betweenwater droplets and ice crystals in ice nucleation chambers. A laser beam polarizedlinearly (power: 50 mW, wavelength: 407 nm) is directed through the chamber. The scattered light intensity from particles is measured at a scattering angle ofΘ=175◦inboth polarization ...Working Paper -
Oxygen isotopic signature of CO2 from combustion processes
(2008)Atmospheric Chemistry and Physics DiscussionsFor a comprehensive understanding of the global carbon cycle precise knowledge ofall processes is necessary. Stable isotope (13C and18O) abundances provide infor-mation for the qualification and the quantification of the diverse source and sink pro-cesses. This study focuses on theδ18O signature of CO2from combustion processes, which are widely present both naturally (wild fires), and human induced (fossil fuelcombustion, biomass burning) ...Working Paper -
Can we reconstruct Arctic sea ice back to 1900 with a hybrid approach?
(2008)Climate of the Past DiscussionsThe variability and trend of Arctic sea ice since the mid 1970s is well documented and linked to rising temperatures. However, much less is known for the first half of the 20th century, when the Arctic also underwent a period of strong warming. For studying this period in atmospheric models, gridded sea ice data are needed as boundary conditions. Current data sets (e.g., HadISST) provide a historical climatology, but may not be suitable ...Working Paper -
Radiation transfer in stratus clouds at the BSRN Payerne site
(2008)Atmospheric Chemistry and Physics DiscussionsClouds represent a major source of uncertainty in understanding climate change, because potential changes in the way they affect the atmospheric and surface energy budget are difficult to predict. It is therefore important to determine how clouds affect radiation. Stratiform clouds in particular have an important effect on climate as they cover large areas. This article presents results of radiation transfer calculations with MODTRANTM ...Working Paper -
Modelling of cirrus clouds – Part 1a: Model description and validation
(2008)Atmospheric Chemistry and Physics DiscussionsA double–moment bulk microphysics scheme for modelling cirrus clouds including ex-plicit impact of aerosols on different types of nucleation mechanism is described. Pro-cess rates are formulated in terms of generalised moments of the underlying a priorisize distributions in order to allow simple switching between various distribution types.5The scheme has been implemented into a simple box model and into the anelastic non-hydrostatic model ...Working Paper -
Hydroxyl radicals in the tropical troposphere over the Suriname rainforest: comparison of measurements with the box model MECCA
(2008)As a major source region of the hydroxyl radical OH, the Tropics largely control the oxidation capacity of the atmosphere on a global scale. However, emissions of hydrocarbons from the tropical rainforest that react rapidly with OH can potentially deplete the amount of OH and thereby reduce the oxidation capacity. The airborne GABRIEL field campaign in equatorial South America (Suriname) in October 2005 investigated the influence of the ...Working Paper