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Umweltphysik Montag
Insbesondere werden bei niedrigen N2O-Konzentrationen (< 120 ppb) zu
geringes stratosphärisches Gesamt-NOy, sowiezuwenigNOx durch die
Modelle vorausgesagt. Mögliche Ursachen hierfür werden diskutiert.
UP 11.8 Mo 16:30 Galerie 1
Messung von Photonenweglängen als Test für Strahlungstransportmodelle
— •Thomas Scholl, Oliver Funk, Ulrich Nägele
, Ulrich Platt und Klaus Pfeilsticker — Institut für Umweltphysik,
Im Neuenheimer Feld 229, 69120 Heidelberg
Absorptionsspektroskopische Messungen der Sauerstoff A-Bande an
Himmelstreulicht nach der DOAS Methode erlauben die Bestimmung
der Weglängenverteilung der Photonen. Diese erlauben Rückschlüsse
über die Statistik der Mehrfachstreuung in Wolken. Gleichzeitige Messung
der 3D Wolkenstruktur sowie radiometrische Messungen des Liquid
Water Pass (LWP) ermöglichen Vergleiche der optischen und strukturellen
Eigenschaften realer Wolken mit simulierten 1D Wolken. Ein Test
hierbei ist die Länge der Photonenwege als Funktion der geometrischen
Wolkendicke (H) und dem LWP. Dabei zeigen sich Abweichungen der
klassischen Beziehung prop. H 2 , die durch von einfachen Strahlungstransportmodellen
nicht berücksichtigte Inhomogenitäten der Wolken
zustande kommen. Ziel der Untersuchungen ist eine neue Parametrisierung
des Einflusses von Wolken auf den Strahlungsprozess, die ihrer
fraktalen Eigenschaften Rechung trägt.
UP 11.9 Mo 16:30 Galerie 1
Using a new Radiative Transfer Model to estimate the Effect
of Cirrus Clouds on AMSU-B Radiances. — •Sreerekha
Ravindranathan Thonipparambil, Stefan Buehler, andClaudia
Emde — Institute of Environmental Physics University of Bremen
/FB 1 PO Box 330440,28334 Bremen,Germany
The up-welling atmospheric radiation in the mm-wave spectral range
is influenced by the presence of cirrus clouds. A plane parallel radiative
transfer model which can take into account the effect of multiplescattering
of ice particles in the cirrus has been developed and is used
to simulate the brightness temperature for the AMSU-B channels. The
model uses an iterative procedure to solve the radiative transfer equation.
The formulation of the model is such, that it can easily be adapted
to treat the full Stokes vector instead of just the scalar total intensity.
This will allow the investigation of polarization effects by oriented nonspherical
ice particles. The paper/poster presents the model and demonstrates
how it is tested for convergence. Furthermore, different cirrus
cloud scenarios are studied and the results are presented. The results
confirm that the brightness temperature in this frequency range is greatly
influenced by the cloud’s microphysical properties.
UP 11.10 Mo 16:30 Galerie 1
Stratospheric NO2 measured with GOME — •Mark Wenig,
Steffen Beirle, Jens Hollwedel, Stefan Kraus, Sven Kühl,
Michael Grzegorski, Thomas Wagner, Bernd Jähne, andUlrich
Platt — Institut für Umweltphysik, Universität Heidelberg, Im
Neuenheimer Feld 229, 69120 Heidelberg
The Global Ozone Monitoring Experiment enables a global view of
total NO2 columns. The recently developed algorithm to separate the
tropospheric and stratospheric fraction of NO2 can be used to analyse
the development of the global distribution of stratospheric NO2. This
vertical separation is done by taking advantage of certain characteristics
of the horizontal distribution of NO2 in the stratosphere and some assumption
about tropospheric sources. The resulting image sequences of
stratospheric NO2 VCDs are analyzed in order to make the interesting
information visible. This analysis has been performed on GOME data
from beginning of 1996 to the end of 2000. During this period features
like the Noxon Cliff and its southern equivalent has been visualized.
UP 11.11 Mo 16:30 Galerie 1
Validation of a New Radiative Transfer Model for AMSU —
•John Viju Oommen, Stefan Buehler, andMashrab Kuvatov
— Institute of Environmental Physics/Remote Sensing,University of Bremen,p.o.
box: 330440,28334 Bremen,Germany
The retrieval of atmospheric parameters from microwave satellite data
requires a good forward model for the simulation of radiances and for
the calculation of the Jacobian. Our study presents the validation of the
recently developed ARTS (Atmospheric Radiative Transfer System) forward
model by comparing it to other forward models. It was found that
ARTS agrees with the CIMSS-MWLBL model (which is used as reference
odel for ITWG inter comparison) within 0.05K and 0.02K for AMSU-
06 and AMSU-10 respectively and 0.15K for AMSU-14 and 0.16K for
AMSU-18. Furthermore, simulated radiances based on global radiosonde
data were compared to radiances measured by AMSU-A and AMSU-B.
UP 11.12 Mo 16:30 Galerie 1
Validation Of Retrieved Integrated Water Vapour With An Airborne
Millimeter–Wave Airborne Radiometer Over Arctic Sea
Ice — •Nathalie Selbach 1 , Tim J. Hewison 2 , Georg Heygster
1 , Jungang Miao 2 , Andrew J. McGrath 2 ,andJonathan P.
Taylor 2 — 1 Institut für Umweltphysik, Universität Bremen, Postfach
330440, 28334 Bremen — 2 Met Office, UK
Recently, an algorithm was developed to retrieve Integrated Water
Vapour (IWV) using measurements from the SSM/T2 sensor on the
DMSP satellite over the Antarctic. This expects the surface emissivity
to be the same for the 3 channels centred on the 183.31 GHz water
vapour absorption line. The application of this algorithm was limited
to very dry atmospheres, with IWV