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Exploiting the weekly cycle as observed over Europe to analyse aerosol indirect effects in two climate models
(2009)Atmospheric Chemistry and Physics DiscussionsA weekly cycle in aerosol pollution and meteorological quantities is observed over Eu-rope. In the present study we exploit this effect to analyse aerosol-cloud-radiationinteractions. A weekly cycle is imposed on anthropogenic emissions in two generalcirculation models that include parameterizations of aerosol cycles and cloud micro-physics. It is found that the simulated weekly cycles in sulfur dioxide, sulfate, andaerosol optical depth ...Working Paper -
Conditional CO2 flux analysis of a managed grassland with the aid of stable isotopes
(2009)Biogeosciences DiscussionsWorking Paper -
Sensitivity studies of different aerosol indirect effects in mixed-phase clouds
(2009)Atmospheric Chemistry and Physics DiscussionsAerosols affect the climate system by changing cloud characteristics. Using the globalclimate model ECHAM5-HAM, we investigate different aerosol effects on mixed-phaseclouds: The glaciation effect, which refers to a more frequent glaciation due to anthro-pogenic aerosols, versus the de-activation effect, which suggests that ice nuclei become less effective because of an anthropogenic sulfate coating. The glaciation effectcan partly offset ...Working Paper -
Influences of in-cloud aerosol scavenging parameterizations on aerosol concentrations and wet deposition in ECHAM5-HAM
(2009)Atmospheric Chemistry and Physics DiscussionsA diagnostic nucleation scavenging scheme, which determines stratiform cloud scav-enging ratios for both aerosol mass and number distributions, based on cloud droplet,and ice crystal number concentrations, is introduced into the ECHAM5-HAM globalclimate model. This is coupled with a size-dependent in-cloud impaction scavenging parameterization for both cloud droplet-aerosol, and ice crystal-aerosol collisions. Sen-sitivity studies are ...Working Paper -
A case study of eddy covariance flux of N2O measured within forest ecosystems: Quality control and flux error analysis
(2009)Biogeosciences DiscussionsEddy covariance (EC) flux measurements of nitrous oxide obtained by using a 3-D sonic anemometer and a tunable diode laser gas analyzer for N2O were investigated. Two datasets (Sorø, Denmark and Kalevansuo, Finland) from different measurement campaigns including sub-canopy flux measurements of energy and carbon dioxide are5 discussed with a focus on selected quality control aspects and flux error analysis. Although fast response trace gas ...Working Paper -
Objective assessment of ozone in chemistry-climate model simulations
(2009)Atmospheric Chemistry and Physics DiscussionsStratospheric ozone recovery is expected to drive pronounced trends in atmospherictemperature and circulation from the stratosphere to the troposphere in the 21st cen-tury, but coupled chemistry-climate models (CCMs) vary widely in their predictions offuture ozone evolution. In order to assess which models might be expected to better simulate future ozone evaluation, we assess the ability of twelve CCMs to simulateobserved ozone climatology ...Working Paper -
Water vapor δ2H and δ18O measurements using off-axis integrated cavity output spectroscopy
(2009)Atmospheric Measurement Techniques DiscussionsWe present a detailed assessment of a commercially available water vapor isotopeanalyzer (WVIA, Los Gatos Research, Inc.) for simultaneous in-situ measurements ofδ2H andδ18O in water vapor. This method, based on off-axis integrated cavity outputspectroscopy, is an alternative to the conventional water trap/isotope ratio mass spectrometry (IRMS) techniques. We evaluate the analyzer in terms of precision, memoryeffects, concentration ...Working Paper -
Biodiversity for multifunctional grasslands: Equal productivity in high-diversity low-input and low-diversity high-input systems
(2009)Biogeosciences DiscussionsWorking Paper -
Aerosol indirect effects – general circulation model intercomparison and evaluation with satellite data
(2009)Atmospheric Chemistry and Physics DiscussionsAerosol indirect effects continue to constitute one of the most important uncertaintiesfor anthropogenic climate perturbations. Within the international AEROCOM initiative,the representation of aerosol-cloud-radiation interactions in ten different general cir-culation models (GCMs) is evaluated using three satellite datasets. The focus is on stratiform liquid water clouds since most GCMs do not include ice nucleation effects,and none of ...Working Paper -
Contributions from DMS and ship emissions to CCN observed over the summertime North Pacific
(2009)Atmospheric Chemistry and Physics DiscussionsMeasurements of cloud condensation nuclei (CCN) made over the remote North Pa-cific Ocean in July 2002 are analysed with concurrent measurements of aerosol num-ber, mass and composition. Overall the CCN are controlled by the sulphate, includingone case of particle nucleation and growth resulting from dimethyl sulphide oxidation that enhanced CCN concentrations. Hourly CCN concentrations are correlated withconcentrations of sulphate plus ...Working Paper