aktualisiertes pdf - DPG-Tagungen

UP 2 Atmosphäre und Klima I
Zeit: Montag 14:15–16:00 Raum: HS 118
Fachvortrag UP 2.1 Mo 14:15 HS 118
Airborne Lidar Measurements of Water Vapour and Humidity
Fluxes during the International H2O Project 2002
— •Christoph Kiemle 1 , Andreas Fix 1 , Harald Flentje 1 ,
Gorazd Poberaj 1 , Martin Wirth 1 , Gerhard Ehret 1 , Michael
Hardesty 2 , and Alan Brewer 2 — 1 Institut fuer Physik der Atmosphaere,
Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), D82234
Oberpfaffenhofen — 2 NOAA Environmental Technical Laboratory, 325
Broadway, Boulder, CO 80305, USA
During the International H2O Project (IHOP 2002) DLR’s 100 Hz
airborne differential absorption lidar (DIAL) enabled two-dimensional
scans of small-scale humidity structures in the boundary layer with unprecedented
spatial resolution. At an aircraft speed of 140 m/s the spatial
(horizontal and vertical) resolution in the humidity field for typical
daytime measurements is 200 m, accepting an average random error of
10 percent. For the first time the DLR DIAL was flown together with
NOAA’s high resolution Doppler lidar (HRDL), both systems pointing
vertically downwards. The dominant turbulent structures of the boundary
layer are well sampled by both lidars. Applying the eddy covariance
technique to both data sets, the upward humidity flux within a cloud-free
convective boundary layer over south-western Kansas was estimated to
0.2+-0.04 g/kg m/s, which corresponds to a latent heat flux of 500+-100
W/m2. The flux is found to be nearly constant with height, i.e. the flux
divergence is zero, the mean boundary layer humidity is constant over
time and the surface evaporation flux equals the entrainment flux at the
boundary layer top, corresponding to the boundary layer growth.
Fachvortrag UP 2.2 Mo 14:30 HS 118
Active Groundbased DOAS-Measurements Of HCHO, NO2
And O3 During FORMAT-Campaigns I And II (Summer
02/03), Milan (Italy) — •Claudia Hak 1 , Achim Bäuerle 1 , Kai-
Uwe Mettendorf 1 , Sebastian Trick 1 , Rainer Volkamer 1,2 ,
Ulrich Platt 1 , and Irene Pundt 1 — 1 Institut für Umweltphysik der
Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg
— 2 now at Massachusetts Institute of Technology, Cambridge, USA
Longpath-DOAS-measurements of formaldehyde (HCHO) and other
pollutants were performed during two field campaigns in the Milan area
(Italy). The campaigns were part of the European project FORMAT
(FORMaldehyde As a Tracer of photooxidation in the troposphere) and
took place in Bresso, in the urban periphery of Milan, and in Alzate, a
village located in a rural area 35 km north of Milan. The covered time
period was 22.07. - 20.08.2002 and 12.09. - 05.10.2003, respectively.
The main aims of the project are to obtain a better knowledge of the
chemistry and distribution of HCHO in the troposphere and the improvement
of analysis techniques for the measurement of formaldehyde. As one
of the largest urban and industrial regions in Europe the metropolitan
area of Milan was chosen. In this area, both pollutant emissions and solar
radiation are high during summer - so HCHO can be photochemically
produced and directly emitted. Here, comparisons of the chemical compositions
of the air of both measurement sites will be shown. The mixing
ratios of the photochemical constituents HCHO, NO2, and O3 during
both observed time spans are studied in consideration of the meteorological
conditions.
Fachvortrag UP 2.3 Mo 14:45 HS 118
The ECHO project intercomparison of different systems for organic
trace gas measurements — •Christoph Holzke 1 and intercomparison
team ECHO 2 — 1 Institut fuer Chemie und Dynamik
der Geosphaere, Institut II: Troposphaere (ICG-II), Forschungszentrum
Juelich, D-52425 Juelich, Germany — 2 different paticipating institutes
Despite their importance for atmospheric chemistry, there is still a large
uncertainty about the exact amount of biogenic VOC (Volatile Organic
Compound) emissions and their contribution to tropospheric chemistry.
The analysis of VOCs in ambient air is a difficult task because of the methodical
complexity. This is one reason for the uncertainties in the quantification
of these emissions. In this paper we present the results of two
intercalibration experiments that were conducted as part of the quality
assurance within the ECHO project (Emission and Chemical Transformation
of Biogenic Volatile Organic Compounds). Since many biogenic
VOCs are not stable in gas cylinders as used for round robin tests, the
intercalibration experiments were done on site in the laboratory. We set
151
up a permeation source to produce a constant flow of a complex mixture
of VOCs with mixing ratios in the range of ppt to ppb. The experiments
focussed on the intercomparison of the quantification of specific biogenic
VOCs and some of their degradation products. The intercomparison covered
the following analytical systems: one on-line GC/FID, two on-line
GC/MS, three off-line GC/MS, one off-line GC/FID/MS (off-line sampling
on adsorption tubes), and four PTR-MS. The time resolution of
the different systems was in the range of 40 minutes to 10 seconds.
Fachvortrag UP 2.4 Mo 15:00 HS 118
Commissioning of the new Ground-Based Microwave Radiometer
RAMAS at Summit, Greenland — •Sven Golchert 1 ,
Axel Kleindienst 1 , Nicole Buschmann 1 , Klaus Künzi 1 , Justus
Notholt 1 , Jérôme de La Noë 2 , Nicola Schneider 2 , Helge
Jønch-Sørensen 3 , Allan Gross 3 , Marianne Sloth 3 , Martyn
Chipperfield 4 , and Steve Arnold 4 — 1 Institut für Umweltphysik,
Universität Bremen, Germany — 2 Observatoire de Bordeaux, Université
Bordeaux 1, France — 3 Danmarks Meteorologiske Institut, Københaven,
Denmark — 4 Institute for Atmospheric Science, University of Leeds,
UK
The new microwave Radiometer for Atmospheric Measurements at
Summit (RAMAS) has taken up preliminary operation at Summit,
Greenland, and is now being prepared for continuous measurements.
RAMAS covers the frequency band from 265 GHz to 280 GHz with an
instantaneous bandwidth of currently 1 GHz. It utilises an SIS/HEMT
mixer-preamplifier to minimise receiver noise. Tropospheric water vapour
content, a major constraint on ground-based microwave radiometry, is exceptionally
low at Summit station (72 ◦ N, 38 ◦ W, 3200 m). This for the
first time in the Arctic will allow for year-round measurements and even
the observation of short-term variations of less pronounced species. The
principal objective of RAMAS is to measure O3, ClO, N2O and HNO3.
This comprises a set of primary species involved in polar ozone chemistry,
and an important dynamical tracer, which will allow for the separation
of chemical and dynamical effects on O3. We present an overview of the
instrument performance in its primary observation goals and first results
about the feasibility of measurements of further species.
Fachvortrag UP 2.5 Mo 15:15 HS 118
Atmospheric carbon dioxide retrieved from ground-based solar
FT-spectroscopy — •Thorsten Warneke 1 , Justus Notholt 1 ,
Astrid Schulz 2 , Voltaire Velazco 1 , and Otto Schrems 2 —
1 Institute of environmental physics, Uni Bremen, Bremen — 2 Alfred Wegener
Institute, Bremerhaven
The spatial distribution and temporal variability of the carbon sources
and sinks is still uncertain and needs to be better quantified for the
prediction of future climate. The measurement of column averaged volume
mixing ratios from the ground is important for the validation of
proposed space-borne CO2-measurements and to provide input data for
inverse models. Ground-based FT-solar absorption spectra in the near
infrared are obtained in Spitsbergen and during two cruises onboard the
research vessel Polarstern on the Atlantic between 50N and 40S. Column
averaged volume mixing ratios and a two layer profile are retrieved. The
precisions of the column averaged volume mixing ratios are better than
0.5
Fachvortrag UP 2.6 Mo 15:30 HS 118
Sauerstoff-A-Banden Messungen zur Bestimmung von Photonenweglängenverteilungen
— •Thomas Scholl, Klaus Pfeilsticker
und Ulrich Platt — Institut für Umweltphysik, Universität
Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg
Hochauflösende spektroskopische Messungen der Sauerstoff-A-Bande
an Himmelsstreulicht nach der DOAS Methode erlauben die Bestimmung
der Weglängenverteilung solarer Photonen bei ihrem Durchgang
durch die Atmosphäre. Die Messung von Weglängenverteilungen erlaubt
Rückschlüsse über die Statistik der Mehrfachstreuung in Wolken. In
Kombination mit parallel durchgeführten Wolkenradarmessungen und
Mikrowellenradiometermessungen lassen sich besonders Rückschlüsse auf
den atmospherischen Strahlungstransport ziehen.
Ein direkter Hinweis dreidimensionaler Effekte von Wolken auf den
Strahlungstransport ergibt aus der Untersuchung der Beziehung zwischen
den unterschiedlichen Momenten der Photonenweglängenverteilung,