Download der Druckvorlage im PDF-Format (1.4 MB - DPG-Tagungen

Umweltphysik Montag
Klima. Die Wasserdampfverteilung in der tropischen oberen Troposphäre
ist dabei von besonderer Bedeutung. Allerdings gibt es dort bisher nur
relativ wenige zuverlässige Messungen.
Wir haben mit Hilfe von in-situ Wasserdampfmessungen, die im Rahmen
des EU Projektes MOZAIC über dem tropischen Atlantik an Bord
von Linienflugzeugen durchgeführt wurden, den Einfluss von Prozessen
im Zusammenhang mit tropischer Konvektion auf die Wasserdampfverteilung
in der oberen Troposphäre untersucht. Die Herkunft der gemessenen
Luft wird mit Rückwärts-Trajektorien bis zu einer konvektiven Wolke
zurückverfolgt, die mit Satellitendaten der Wolkenoberflächentemperatur
identifiziert werden kann.
Vorgestellt wird eine Untersuchung dieser über einen Zeitraum von
mehr als 4 Jahren quasi-kontinuierlich vorliegenden Messungen der relativen
Feuchte in Abhängigkeit von der zeitlichen Entfernung zur Konvektion.
Der Vergleich mit Modellergebnissen zeigt, dass die Abnahme
der relativen Feuchte langsamer verläuft, als dies unter wolkenlosen Bedingungen
der Fall sein müsste.
UP 9.6 Mo 16:30 Galerie 1
Ozone depletion and chlorine activation in the Arctic winter
2001/2002 and earlier winters — •Ingo Wohltmann 1 , Kai Lindner
1 , Klaus F. Künzi 1 ,andOtto Schrems 2 — 1 Institut für Umweltphysik,
Postfach 330440, 28334 Bremen — 2 Alfred-Wegener-Institut für
Polar- und Meeresforschung
Vortex averaged ozone loss rates for the most recent winters and
chlorine activation derived from measurements of the ground based microwave
radiometer RAM of the University of Bremen will be shown.
Results are compared with the 3-D chemical transport model SLIMCAT
and other methods.
The RAM is a microwave radiometer jointly operated by the University
of Bremen and the Alfred Wegener Institute for Polar and Marine
Research (AWI) situated in Ny-˚Alesund, Spitsbergen. The radiometer
measures ozone, ClO and H2O. Vortex averaged ozone loss rates are
obtained by subtracting the diabatic descent from the observed ozone
change using a radiative transfer model. The ozone observations of the
RAM are assumed to be representative for the vortex, so that loss rates
can be estimated from a single observation point. Additionally, corresponding
chlorine monoxide measurements will be shown.
The results of the calculations will be compared with several different
techniques for the determination of ozone loss. Some of the reasons for
the different results of these methods like the altitude resolution and the
calculation of heating rates are discussed.
UP 9.7 Mo 16:30 Galerie 1
NO2-Production by Lightning Estimated with GOME —
•Beirle Steffen, M. Grzegorski, J. Hollwedel, S. Kühl, T.
Wagner, M. Wenig, W. Wilms-Grabe, andU. Platt — Institut
für Umweltphysik, Heidelberg
NO2 is an important trace gas in the troposphere with impact on health
and atmospheric chemistry, e.g. ozone production. Therefore a better
understanding of the various source strengths is desirable.
Among the different sources (industry, biomass burning, aircrafts,
soil emissions, lightning) the latter has the highest uncertainty (2-20
Tg[N]/yr) (Lee et al, 1997). While most studies try to estimate the
NO2 produced by one flash and get a global value by extrapolation, with
satellite measurements another approach is possible.
GOME enables a global view of total NO2 columns. With sophisticated
methods also tropospheric values can be obtained (Leue et al, 2001). The
observation of single lightnings is complicated by the coarse spatial resolution
of GOME (40km*320km) as well as the fact that lightning is
attended by clouds. However, high lightning activity shall influence the
measured NO2 value.
In this study, we relate the NO2 received by GOME with the lightning
activity measured by LIS. We regard a region in Australia, where other
sources like biomass burning and industry are negligible. Between the
monthly means of lightning activity and NO2 a clear correlation can be
seen.
UP 9.8 Mo 16:30 Galerie 1
An Advanced Cloud Product for the Interpretation of Tropospheric
Data fromGOME and SCIAMACHY — •Thomas
Wagner, Chrostoph von Friedeburg, Michael Grzegorski,
Mark Wenig und Ulrich Platt — Institut fuer Umweltphysik, Uni-
Heidelberg, INF 229, 69120 Heidelberg
During the last years advanced algorithms for the analysis of tropospheric
trace gases from satellite have been developed. In particular, it
was possible to determine tropospheric column densities of BrO, NO2,
HCHO, SO2, H2O, O2, and (O2)2 from observations of GOME. However,
all of these data products are strongly affected by clouds, which
(a) shield the atmosphere below the cloud cover and (b) show typically
a larger albedo compared to the earths surface. These effects strongly
limit the quantitative analysis of tropospheric trace gas products. Already
existing cloud algorithms are based on spatially resolved intensity
measurements and on the measurement of the O2-A-band absorption.
However, both quantities show important shortcomings, especially over
snow and ice surfaces. We investigate a large variety of cloud sensitive
parameters measured by GOME including also the polarisation of the
measured light and in particular various absorption bands of the oxygen
dimer O4 (at 360, 380, 477, 577, and 630 nm) as well as the Ring effect.
It turned out that several of these quantities are well suited for the
characterisation of clouds even over bright surfaces. Here present first
results of a GOME cloud product for polar regions.
UP 9.9 Mo 16:30 Galerie 1
Measurements of stratospheric chlorine monoxide and water
vapour in Ny-˚Alesund, Spitsbergen — •Kai Lindner 1 ,
Michael Hoock 1 , Ingo Wohltmann 1 , Klaus F. Künzi 1 ,
and Otto Schrems 2 — 1 Institut für Umweltphysik, Bremen —
2 Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven
The Radiometer for Atmospheric Measurements (RAM) is a passive
microwave radiometer, which measures thermal emission from rotational
lines of water vapour at 22 GHz, ozone at 142 GHz and chlorine monoxide
at 204 GHz. The instrument is jointly operated by the Institute
of Environmental Physics of the University of Bremen and the Alfred-
Wegener-Institute for Polar and Marine Research. The RAM is located
at the primary Arctic NDSC station in Ny-˚Alesund at the Spitsbergen
archipelago.
The RAM is presently the only instrument in the Arctic allowing a
continuous monitoring of stratospheric ozone and related species such as
ClO. We will discuss measurements of stratospheric chlorine monoxide
collected in winter 2000/2001 and we will show measured diurnal cycles
and compare our data to results obtained by other instruments and
models.
In the last decades stratospheric water vapour has increased noticeably
in the lower stratosphere, an effect, which cannot be explained by
current theories. The newly installed water vapour radiometer is operational
since January 1999. We will show preliminary water vapour
measurements, which have been acquired using the total power method.
UP 9.10 Mo 16:30 Galerie 1
Untersuchung des Zerfalls hochgeladener Tropfen mit Hilfe ultraschneller
Mikro-Photographie — •Tobias Achtzehn, René
Müller, Denis Duft und Thomas Leisner — TU Ilmenau, Institut
für Physik, Weimarer Str. 32, 98693 Ilmenau
Die Spaltung elektrisch geladener Tropfen ist ein Prozess, der bei der
Ladungsseparation in Gewitterwolken sowie in verschiedenen technischen
Anwendungen wie Elektrospray - Ionisation, Brennstoff - Einspritzung
oder Tintenstrahldruck eine wichtige Rolle spielt (siehe Vortrag: Stabilität
hochgeladener Mikrotröpfchen und das Rayleigh - Limit). Obwohl
bei Annäherung an das Rayleigh - Limit zuerst die Quadrupol - Mode instabil
wird, spaltet ein verdampfender hochgeladener Tropfen nicht symmetrisch,
sondern gibt ca. 25% seiner Ladung aber weniger als 1% seiner
Masse ab. Wir beobachten diese Instabilität an levitierten Mikropartikeln
mit Hilfe ultraschneller Photografie. Dies erlaubt es, die Dynamik
des Vorgangs von der Quadrupol - Verzerrung bis hin zur Ausbildung
eines ”Taylor - cone” zeitaufgelöst zu beobachten.