FEBUKO results

Results of the field campaign 2001 and 2002


Project IfT-1
Project IfT-2
Project BTU
Project ZUF
Project TUD

Project IfT-1
Physico-chemical characterization of air, particles, and cloud water in cloud experiments

Figure IfT1-1: Comparison of the particle mass concentration (PM10) at Goldlauter (GL) and Gehlberg (GB) from BERNER Impactor (IMP) and foil sampler (HVA)
Figure IfT1-2: Size-segregated particle mass concentration from BERNER impactor in Goldlauter (GL) and Gehlberg (GB)
Figure IfT1-3: Comparison of particle nitrate and sulfate concentrations (BERNER Impactor-BI and foil sampler-HVA) from Goldlauter (GL) and Gehlberg (GB) with those from cloud water (CW) at summit (SM)
Figure IfT1-4: Comparison of particle ammonium and oxalate concentrations (BERNER Impactor-BI and foil sampler-HVA) from Goldlauter (GL) and Gehlberg (GB) with those from cloud water (CW) at summit (SM)
Figure IfT1-7: Size distributions at all three measurement stations during the cloud event #1 from 16th/17th Oct. 2002 averaged over the entire measurement period (between 21 p.m. and 4:10 p.m. UTC) The size distributions of Schmücke and Gehlberg have been normalized to the level of Goldlauter.

Project IfT-2
Phase partitioning of biogenic and anthropogenic aerosol components and of volatile organic compounds in clouds: Influence on cloud formation and consequences after the dispersal of clouds

Figure IfT2-1: Total particle number concentration upwind (GL, total) and downwind (GL, total) the cloud as well as number concentration of interstitial (SM, interstitial), residual particles (SM, residual) and cloud droplets (FSSP > 6 µm) inside cloud for two cloud events. SM, int. + FSSP denotes the sum of interstitial particle and cloud droplet concentration.
Inside cloud, residual particle and cloud droplet concentration are similar, i.e. that one evaporated droplet releases one residual particle. Total aerosol concentrations upwind, downwind and inside cloud are similar, confirming connected flow during the cloud events.
Figure IfT2-2: Mean aerosol size distribution upwind (GL) and downwind (GB) the cloud as well as interstitial (SM, INT) and residual (SM, CVI) particle size distribution inside cloud for two cloud events. SM, INT + CVI denote the sum of interstitial and residual size distribution.
Good agreement between total aerosol size distributions upwind, downwind and inside cloud between 25 and 900 nm. Overlap region of the interstitial and residual number distribution demonstrates the different activation capability of particles of identical size.
Figure IfT2-3: Activation fraction (inside cloud) and number fractions of particles above a certain solubility mass fraction (upwind cloud) as a function of particle size for two cloud events.
Influence of the increase of the solubility number fraction on the steepness of the particle activation fraction confirming the dependence of droplet formation on the particle hygroscopicity. For larger particles a less soluble mass fraction is required to become activated.
Figure IfT2-4: Phase partitioning and atmospheric concentration of aerosol components and gaseous carbonyl compounds for two cloud events.
High phase partitioning for the classical, inorganic CCN constituents, OC and dicarboxylic acids. 50% of BC is found in the droplet phase, i.e. that CCN consist mainly of aged, internally mixed aerosol particles. Low phase partitioning for carbonyl compounds but above their Henry equilibrium, especially for the larger compounds.

Project BTU
Partitioning and modification of organic and reactive compounds in the aerosol and cloudwater phase during cloud processing

Figure BTU-1: Nitrous and nitric acid concentrations in the gas phase at the valley station Goldlauter (Luv) measured by wet denuder - ion chromatography technique (whole FEBUKO campaign; time resolution 30 min).
Figure BTU-2: Chloride, nitrite, nitrate and sulfate concentrations in the aerosol phase at the valley station Goldlauter (Luv) measured by steam jet - ion chromatography technique (whole FEBUKO campaign; time resolution 30 min).

Figure BTU-3: Measurements of inorganic trace species in the aerosol and gas phase at the valley station Goldlauter on 26th and 27th of October 2001 using a wet denuder - steam jet - ion chromatography - system.

Figure BTU-4: Droplet number distributions on 26th and 27th of October 2001 measured by FSSP100 on the top of Mt. Schmücke tower.

Figure BTU-5: Comparison of concentrations of inorganic trace species in the gas and aerosol phase at the valley station Goldlauter (Luv of Mt. Schmücke) and in the cloud water collected simultaneously on the top of Mt. Schmücke tower on 26th and 27th of October 2001.
a) HNO3, aerosol nitrate, cloud water nitrate
b) SO2, aerosol sulfate, cloud water sulfate
c) aerosol chloride, cloud water chloride
d) HNO2, aerosol nitrite, cloud water nitrite

Figure BTU-6: Nitrogen dioxide concentrations at the Luv station Goldlauter (time resolution 30 s) and at the mountain site Schmücke (time resolution 30 min) indicating connected flow between both sites during the cloud events on 26th and 27th of October 2001.

Project ZUF
The Schmücke Mountain as an Atmospheric Flow Reactor. Field and Laboratory Investigations on the Formation of Hydrogen Peroxide in Cloud Drops.

Figure ZUF-1: The Flow Reactor.

The atmosphere as a flow reactor in the Schmücke mountain area. During southwesterly flow and clouds present at the mountain summit, air passing from the valley station Goldlauter over the mountain summit is processed in the cloud and reaches the valley station Gehlberg. To verify that the air mass under investigation is indeed the same at all stations, several tracer experiments have been conducted

Figure ZUF-2a: The measurement sites of the tracer experiment.
Figure ZUF-2b: SF6-Tracer.

SF6 tracer gas was released on October 31, 2001 at 10:00 a.m. at the valley station Goldlauter. Air samples were taken in 10 l polyethylene bags at 13 sites in 5 min intervals. The "Movie" shows SF6 measurement results 10, 15, 20, 25, 30 and 35 min after tracer release, respectively. The results confirm that during southwesterly flow identical air masses are measured at the mountain and valley stations, justifying the assumption of an atmospheric flow reactor.

Figure ZUF-3: Field Measurements.

Hydrogen peroxide concentrations measured in cloud water samples. Results from the entire measurement period. In all samples, hydrogen peroxid was found.

Figure ZUF-4: Field Measurements.

Results from the main cloud event on October 26-27, 2001. Additionally, measured liquid water content (LWC) is presented. A diurnal trend can be observed with hydrogen peroxide maxima during daytime and minima during nighttime. These results encouraged the design of laboratory experiments to investigate whether the presence of hydrogen peroxide in the samples can be attributed to photochemical formation from Fe(III)-oxalato complexes.

Project TUD
Analysis of organic species (aldehydes, ketones and organic acids) in single droplets for investigation of the related aerosol size and the contribution of cloud scavenging.

Figures TUD-1, 2: Concentrations of dicarboxylic acids during field experiment Schmücke 2001 showed a behaviour corresponding to species occuring in hydrophilic aerosols. Their recovery in cloud water on Schmücke was often near 100% while mixing ratios in Gehlberg (leeward) were slightly but significantly lower than in Goldlauter (windward). Wet deposition could be one contribution to this phenomenon as the dependence of recoveries on the liquid water content suggests.

Figure TUD-3: During the field experiment FEBUKO we were able to analyse 30 different carbonyl compounds in cloud water and air sample. For the first time the quantification of 2-,3-Pentanon and 3-Hexanon was achieved because of the improvement of blank values.
In the cloud water phase there could be analysed only polar carbonyl compounds while in the air samples the whole spectrum of carbonyl substances was found.

Last change: 04/05/18