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Abstracts from 2006/2007
20/9/06 Lei Wang: Introduction to Stationary Wave Theory and some implications
The stationary wave is defined as the zonally asymmetric component of the atmospheric climatology. The stationary wave theory will be briefly reviewed in this talk.
Stationary wave models have been successful in explaining the stationary wave field in the atmosphere. As a simple application, the stationary wave response to
topography is studied in a barotropic model. Besides the topography, several factors may contribute to the stationary wave response, such as the interactions with
transient eddies, the basic state, and the stationary wave itself. Their relative contribution can be analyzed through the mixed time-space decomposition (Peixoto and
Oort, 1992). The stationary wave may be sensitive to climate change which affects basic state, dynamics, and forcings. A simple baroclinic model is proposed to
investigate the stationary wave response to climate change. Some preliminary results from this baroclinic model will be discussed.
29/9/06 Guoying Qin: Odd nitrogen observations by ACE: solar storms, ozone depletion and denitrification
Odd nitrogen compounds play a very important role in ozone depletion. In this presentation, the odd nitrogen budget is investigated in both polar and midlatitude
regions, using data from the ACE satellite mission. ACE is notable because it provides comprehensive measurements of all species in the NOy family. The relationship
between NOy enhancements in polar regions and solar activity is explored. Correlations between NOy and O3, and NOy and N2O will be shown, in order to understand the
atmospheric processes. The comparison of the NOy budged with a box model is given to examine the box model.
6/10/06 James Anstey: QBO influence on the NH polar vortex
Accurate modelling of the winter stratospheric polar vortices is required for climate simulations, and the large variability of the NH winter vortex should be
captured realistically in order that the significance of trends in this region can be properly assessed. Wave-mean flow interaction between the extratropical
stratospheric flow and upward propagating waves leads to strong variability, but external factors such as the solar cycle and QBO may play an important role. A
commonly accepted mechanism for the QBO to influence the vortex is the Holton-Tan mechanism, whereby the changing tropical stratospheric winds are believed to alter
the propagation characteristics of planetary waves in such a way that the polar vortex is warmer and weaker during easterly QBO phases, and colder and stronger during
westerly QBO phases. Here we investigate this mode of variability as it appears in the CMAM. The Holton-Tan effect appears, but its significance depends on the length
of the data record, indicating that low frequency variability may be important even when the model contains no solar cycle or imposed trends.
13/10/06 Gordan Stuhne: Global Ocean Modeling with Unstructured Grids
The global oceans are characterized by complex coastal and seafloor geometry and by many scales of motion. For example, the distinctive small-scale geometry of the
Arctic archipelago is probably an important factor determining tidal mixing and sea-ice dynamics around this region, which is critical for the climate system as a
whole.
Numerical simulations of flows with complex boundaries and localized features are most naturally handled using unstructured grid methods. I will describe the
application of such techniques to ocean modeling in embedded spherical geometry. The conservative finite-volume marker-and-cell scheme for triangular grids has been
extended to accommodate spherical prismatic grids and the Coriolis effect.
Numerical simulation results will be presented that relate to the global baroclinic ocean circulation and to the barotropic tides. With respect to the global ocean
circulation, large-scale unstructured grid methods have not yet matched the phenomenological realism produced by Cartesian grid models, which have been extensively
parameterized and tuned over the years. In the case of tidal dynamics, the issues involved are not as complex, and the new methods are shown to compare favorably with
Cartesian grid methods.
20/10/06 Clarck Zhao: Himalayan Snow Accumulation and Indian summer monsoon
Over a century ago, Blanford suggested a negative correlation between the western Himalayan snow cover and the Northwest Indian summer monsoon rainfall, an
observation that formed the basis of the snow-monsoon feedback mechanism and resulted in the first forecast of the intensity of the summer monsoon in India. Recently,
an opposite relationship between Tibetan snow cover and Indian summer monsoon has been proposed. However, the relatively short length of the instrumental observations
in the region restricts the further study of the relationship between the two components of the climate system. In my thesis work, a 196-year record of snow
accumulation extracted from southern Himalayan ice cores is shown to contain a decreasing trend that began in the 1840s, however, the All Indian summer monsoon
rainfall shows no evidence of such trend. It is argued that the negative trend in the snow accumulation is associated with the weakening of trade winds over Pacific
Ocean, which may have resulted in a reduction in the easterly transport of moisture towards Asia, thereby contributing to the decreasing snow accumulation at the
Dasuopu site. Evidence from NCEP reanalysis can show that the negative trend in the snow is associated with long-term changes in the regional Hadley and Walker
circulations over the latter half of the 20th century. The decoupling between the snow accumulation and Indian summer monsoon could be attributed to the extreme height
of the ice core site that effectively decoupled the two due to the highly stratified atmosphere.
27/10/06 Lisa Neef: Not your father's Kalman Filter: Data Assimilation for Unbalanced States
Much research has focused on the control of spurious inertia-gravity waves which are generated by assimilation of measurements, for cases where slow vortical motion
is of primary interest. However, there are many problems in the atmosphere and ocean where the true state contains nonnegligible gravity waves. In those cases,
gleaning information about one variable from observations of another (which is what data assimilation is all about) becomes very difficult, because we can't exploit
the balances that are used in the midlatitude troposphere.
So-called four-dimensional data assimilation schemes have the potential to overcome this problem, because a dynamical model, rather than an educated guess, is used to
develop background correlations. Further, advancements in model resolution and the growing inventory of available observations make capturing true gravity waves within
an assimilation possibility -- with lots of caveats.
Our work examines the problems and issues inherent in data assimilation for unbalanced states, using a low-order model which admits motion of multiple timescales, but
is simple enough to make interpretation of experiments straightforward. This talk will offer some background on data assimilation, and then show some examples of how
and when standard DA algorithms succeed (or fail) at capturing states where the primary motion is contaminated by comparatively fast gravity waves.
3/11/06 Jeff Taylor: An Extended Intercomparison of Simultaneous Ground-Based Fourier Transform Spectrometer Observations at the Toronto Atmospheric
Observatory
Simultaneous measurements of O3, HCl, N2O, and CH4 were recorded by two infrared Fourier Transform Spectrometers of differing resolution over a period of four
months in the summer of 2005. These coincident observations were made at the Toronto Atmospheric Observatory, a complementary site of the Network for the Detection of
Atmospheric Composition Change, and, we believe, provide the longest record of simultaneously recorded ground-based infrared spectra to date. Retrievals performed on
the spectra utilized the SFIT2 optimal estimation algorithm with HITRAN 2004 spectroscopic parameters. The influence of instrument resolution was considered in
relation to the respective averaging kernels, with the predicted influence of multiplicative bias agreeing well with the observed influence for the stratospheric
species. The retrieved column amounts correlated well for the stratospheric gases (R2 > 0.6) but the low variability of the investigated tropospheric species
resulted in poor correlations. The median column differences for all gases observed by the instruments ranged from 0.5% to 3.6%.
10/11/06 Susann Tegtmeier:
Variations of the residual circulation in northern hemispheric winter and their impact on Arctic ozone
Due to variability in the tropospheric wave activity the strength of the residual circulation has a distinct seasonal cycle and significant year to year
variability. We use a reverse domain filling trajectory model based on ECMWF ERA-40 data and the ECMWF operational data to compile a multiannual time series of the
strength and spatial structure of the polar branch of the residual circulation.
Two different approaches are used in the trajectory routine to calculate the vertical movement of air. The first approach is based on the vertical velocity given by
ECMWF, a quantity that is derived from the divergence of the horizontal winds and that tends to be noisy. Therefore, in the second approach we use a radiation transfer
model to calculate the diabatic heating rates from the divergence of the net radiation flux. We compare the derived descent from both methods with measured tracer
distributions from satellite data and Arctic field campaigns. The comparison shows that the second approach results in a much more realistic vertical transport.
Therefore the method based on the diabatic heating rates is used to compile a climatology of the diabatic descent averaged within the polar vortex for the Arctic
winters 1957/58-2003/04. Furthermore the climatology contains information of the spatial structure of the diabatic descent. The influence of the diabatic descent in
the Arctic polar vortex on the total ozone column is calculated for the recent winters since 1990. We show that the interannual variability of the Arctic total ozone
column is in equal shares caused by the dynamical transport processes and by the chemical ozone depletion.
17/11/06 Matt Toohey: On comparing coincident measurements by satellite-based instruments
Each day, a pack (gaggle?, orchestra?) of satellite-based instruments make thousands of measurements of the composition of the earth's atmosphere. Given the
complexity of converting collected radiances into constituent profiles, it is perhaps not surprising that measurements are not always consistent between instruments.
Differences between measurement sets are characterized through comparison, which is crucial for uncovering underlying and correctable discrepancies in the measurement
systems.
The industry standard comparison technique involves comparing means of coincident measurements. This has the advantage that certain effects (such as random instrument
error) "average out" over a large enough data set. Despite this, comparing means can easily hide differences in the data sets. A more informative technique may be to
compare the variances and covariances of the data sets. It turns out that the natural way to compare the second moments of data is closely akin to fitting a straight
line to noisy data: something that is actually more complicated than we usually let our first year laboratory students know.
I'll present some novel techniques for the comparison of satellite instrument measurement sets, with examples focusing on the comparison of data from MLS with ACE-FTS.
We will see that comparison of three independent pieces of data (triple-coincidences) allows the a posteriori estimation of two types of bias and the error variance of
each measurement set.
23/11/06 Thomas Birner: A tale of the little tropopause that wanted to be sharp and the evil step-data asmoothilator
Climatological characteristics of the thermal structure around the tropopause are studied as obtained from high-resolution radiosoundings (about 30 m vertical
resolution) at both, tropical and extratropical sites. Utilizing the tropopause as a common reference level of all profiles in the mean the tropopause manifests itself
as a very strong inversion in the vertical temperature gradient. That is temperature is strongly increasing just above a sharp tropopause in contrast to the isothermal
behaviour as found, e.g., in the U.S. standard atmosphere for midlatitudes.
The climatological characteristics as found in the radiosoundings are compared to output from the free-running CMAM and CMAM in data assimilation mode (CMAM-DA), and
to NCEP reanalysis data. CMAM exhibits a rather realistic inversion in the vertical temperature gradient at the tropopause. However, NCEP shows a much weaker
inversion, even though both models run at similar horizontal and vertical resolution. It is hypothesized that the discrepancy between the models is mainly due to data
assimilation acting to smooth the sharp vertical curvature in temperature at the tropopause. Indeed, CMAM-DA exhibits a much weaker inversion than CMAM that rather
resembles the one found in NCEP.
30/11/06 Yonggang Liu: A Carbon-Cycle Coupled Climate Model: Implications for the "Snowball Earth" Hypothesis
The profound negative carbon isotropic excursions and glaciogenic deposits associated with them found within the ancient Neoproterozoic interval of time (1000 Ma -
545 Ma) have stimulated both speculation and debate concerning the spatial extent of the glaciations, the extremity of the accompanying climate, and the consequences
for biological evolution. Some researchers believe that only a series of "hard snowball Earth" events (in which ice covered all of the continents as well as the entire
surface of the oceans) can explain the observed sedimentary records. Here I will argue that the alternative "slushball Earth" scenario (in which the equatorial oceans
are never entirely ice covered) combined with a special carbon cycle model appropriate for the Neoproterozoic is able to fully explain the available isotopic data. The
results for coupled model integrations demonstrate that the interaction of the physical climate system with the carbon cycle may support mode of glaciation, the
timescale of which is carbon cycle controlled.
15/12/06 Sorin Codoban: Available energy of the middle atmosphere meridional circulation
The available potential energy (APE) diagnostic is a tool for the assessment of the large scale circulations in the atmosphere. In its original form (Lorenz, 1955)
the APE is defined by accounting for the thermal constraints on the parcels' motion. It has been recognized however, that the balance between the mass field, defined
by the potential temperature distribution, and the zonal velocity field, characterized by the angular momentum distribution, acts as a constraint on the evolution of
the flow. To account for these constraints on the fluid motion we have used the pseudoenergy, a wave-activity measure, to derive the energy budget for the cross-stream
circulation.
In this talk I will discuss the features of the newly developed diagnostic in application to the diagnostic of available energy for the mean meridional circulation in
the middle atmosphere of the CMAM.
05/1/06 Constantine Nenkov:
A New Model of Thermal Convection: Implications for the Atmospheres of the Gas Giants
In this talk I will give an overview of the newly developed 3D Anelastic GCM on icosahedral grid in spherical geometry. The idea behind this model is to apply it
for the study and modeling of globally convective planetary atmospheres with large extent, like the atmospheres of Jupiter and Saturn.
I will start with a broad overview of our current understanding about the physics of the four giant planets in our Solar system. This is a quickly evolving research
field with very important implications for both Geophysics and Astrophysics. Then I will briefly describe the numerical technology used in building the model and its
most important features. Here I will show how the model has been tested against established benchmarks, both in the non-rotating and rotating case, as well as results
from critical Rayleigh number searches in a spherically convective fluid shells.
One of the main goals of this research is to attain a better assessment of the qualities and constraints of this new model of thermal convection. If time permits I
will present some results from long-term integrations of the model which have relevance to zonal flow jet formation in the atmospheres of Jupiter and Saturn.
12/1/06 Annemarie Fraser:
Lightning-produced NO2 Observed During MANTRA 2004
Zenith-sky UV-Visible spectrometers are a well established method of measuring stratospheric ozone and NO2 from the ground using DOAS (Differential Optical
Absorption Spectroscopy). The SAOZ (Systeme d'Analyse par Observations Zenitales) instrument was constructed in the late 1980's, and is now deployed in a global
network for measurements of stratospheric concentrations of trace gases important to ozone loss.
In 1998, a similar instrument was assembled at the University of Toronto for deployment in the Canadian High Arctic (the University of Toronto Ground-Based
Spectrometer, UT-GBS). Since then, it has taken part in all four MANTRA balloon campaigns (1998, 2000, 2002, and 2004), as well as seven springtime Arctic campaigns in
Eureka, Nunavut (1999-2001, 2003-2006) and one campaign in Resolute Bay, Nunavut (2002). During MANTRA 2004 and the past two Eureka campaigns, a SAOZ instrument was
part of the ground-based suite of instruments, allowing for the first side-by-side comparisons of the UT-GBS with SAOZ.
My Brewer will occur in two parts. In the first part I'll compare ozone and NO2 data from SAOZ and the UT-GBS during MANTRA 2004. The second part will focus on the
afternoon of August 28, when several thunderstorms passed over the instruments. During the storm, enhanced amounts of ozone and NO2 were observed by both instruments.
By combining these observations with lightning flash data from the Canadian Lightning Detection Network and Doppler radar data from Environment Canada, the production
of NO2 molecules per lightning flash is determined.
19/1/07 Robert Field: Modeling stable water isotope composition using GCMs as a tool to understand the climate signals in ice cores.
The stable water isotope (SWI) composition of ice cores is conventionally assumed to provide a method of temperature reconstruction because of the temperature
dependence of isotope fractionation when water forms in clouds. The isotope fractionation is also influenced, however, by the conditions under which the moisture
originally evaporated and its transport between source and deposition regions. This complicates the use of ice cores as indicators of local climate, but also makes
them useful as proxies of broader circulation patterns. The goal of our work is to better understand what controls the SWI composition of precipitation in the
southwestern Yukon, and in particular, to better-interpret the SWI signal from the Mount Logan ice core.
To this end, we are conducting experiments with the GISS ModelE general circulation model, which is equipped with SWI diagnostics. Preliminary results show that the
model performs well in capturing regional and seasonal SWI variation at selected sites in Canada. In the Yukon, SWI variability is controlled by both the local
temperature as well as large-scale circulation anomalies such as the Pacific North America teleconnection pattern and ENSO. The strength of these relationships is
highly dependent on seasonality, which provides a possible explanation for the lack of circulation signals detected thus far in the Mt. Logan ice core.
26/1/07 Tiffany Shaw: Revisiting the anelastic approximation
In the framework of current climate models one can think of the resolved, unresolved, and turbulent scales as a hierarchy of scales each defined, of course, by the
range of scales to be modelled. In the case of the unresolved scales, which include both convection and gravity wave propagation, one requires a model which filters
sound waves, is non-hydrostatic, and couples many grid boxes in the vertical (column approach). The model used most often for the unresolved scales is the so-called
anelastic model. In this talk I will revisit the derivation of the anelastic equations from the context of fitting them into a model hierarchy while paying close
attention to things which have been swept under the rug as well as to conservation of energy and momentum.
2/2/07 Xiaolu Yu: Modeling 20th Century Climate Using CCSM3: Solar Variability and Its Effect on Modern Climate
20th century climate simulations conducted by National Center for Atmospheric Research (NCAR) using the Community Climate System Model Version 3 (CCSM3) have shown
that the combination of natural and anthropogenic forcings are required to reproduce the time evolution of observed globally averaged surface temperatures. These
simulations include greenhouse gases, ozone, tropospheric and stratospheric aerosol effects, as well as solar variability. In order to assess the interplay between the
influence of solar variability and aerosol as well as other radiative forcings on the current climate, and the interactions of the solar forcing with internal
variability modes, we conducted studies involving two CCSM3 simulations of modern climate since 1870 forced by the total solar irradiance (TSI) reconstructions of Lean
el al. in 2000 and in 2005 respectively. Compared to the old Lean data, the new reconstructed dataset has only one fourth secular irradiance increase since Maunder
Minimum (due to the reduction of contributions from background component) but higher in magnitude almost throughout the past three centuries. Simulated climate forced
by the new solar forcing shows a good fit to observations in both global and hemispheric mean surface temperature, capturing all the important warming and cooling
periods in the 20th century. Strong polar warming, another important feature observed in the last thirty years of the 20th century, is also reproduced by the
simulation.
2/9/07 Rodica Lindenmaier:
Studies of Arctic Middle Atmosphere Chemistry Using Infrared Absorption Spectroscopy
A new high resolution Infrared Fourier Transform Spectrometer (FTS) was installed at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka,
Nunavut in July 2006. The new instrument is being used to measure solar absorption spectra in the mid-infrared from which total columns and some vertical profile
information can be retrieved for a suite of trace gases that are involved in the process of ozone depletion.
It is well known that after the long polar winter, which creates special conditions for chlorine and bromine reactive radicals to develop, the process of rapid ozone
loss begins. This is well understood now in Antarctica, and the ozone hole has the tendency to stabilize. The special conditions present in the Arctic make it harder
to understand the ozone loss. Studies performed in the last years show a cooling tendency in the Arctic and also an increased ozone loss.
This talk will present the first measurements recorded with the new instrument, including preliminary retrievals of ozone in August and September. The performance of
the instrument will be discussed, along with details of the retrieval process, and future plans.
2/16/07 Jane Liu: Long range transport of air pollution: An example of the pollution outflow from the Asian summer monsoon
Long-range transport of air pollution refers to the motion of polluted air mass from a source region to a receptor region over a distance of thousands of
kilometres. The primary objectives of my study are to characterize the pathways for long-range transport of air pollution and to improve our understanding of the
influence of the transport to the distribution of tropospheric ozone.
I shall present some results from a 3-dimensional global chemical transport model, namely GEOS-CHEM. GEOS-CHEM has a function that can tag the transport of air
pollution to a region by its origin and therefore is used to track the outflow of pollution from continents. I shall particularly focus on an example of the pollution
outflow from the Asian summer monsoon in 2000. The influence of the outflow to "the Middle Eastern ozone maximum" will be illustrated.
3/2/07 Dmitry Vyushin: Long range transport of air pollution: An example of the pollution outflow from the Asian summer monsoon
Putting Hasselmann's Model to the Test In 1976 Klauss Hasselmann proposed a conceptual model of climate variability that still stands as one of the corner stones of
modern climate science. In his model he divided climate variability into a slow and a fast component. The atmosphere is considered to be the fast component represented
by white noise. The ocean is a slow component. Oceanic dynamical processes are not taken into account and the ocean's role is only to integrate the atmosphere's white
noise forcing. Mathematically this model can be written as a first order auto-regressive (AR(1)) stochastic process, whose power spectrum saturates at low-frequencies,
i.e. variability stays the same as the frequency decreases from low to ultra-low. However some observations of 20th century climate and longer paleo-climate
reconstructions have power spectra that do not saturate on time scales predicted by Hasselmann's model and keep growing toward ultra low frequencies. Such power
spectra can be parsimoniously described by a power law function which is integrable but diverges at the origin. The reason for the variability build up might be an
internal ocean dynamics and/or external forcings, i.e. solar and volcanic. In my talk I will discuss spatial distribution of the signatures of "non-Hasselmann"
behavior in the atmosphere based on ERA40 reanalysis and GCM simulations.
3/9/07 Dave MacKenzie: Quantifying the transport of tropospheric pollution to the UT/LS
Changes in O3 in the upper troposphere and lower stratsophere (UT/LS) can influence the climate system. We examine the influence of tropospheric pollution on O3 in
the UT/LS. The GEOS-Chem global chemical transport model is used to quantify the transport of pollution to the UT/LS from different source regions in the troposphere.
To assess cross tropopause transport we focus on the correlations between CO and O3. Recent satellite observations provide information on the distribution of CO and O3
in the UT/LS and this data has been assimilated in the model to improve the model simulation of these tracers. Preliminary results of the data assimilation will be
discussed.
3/16/06 Steven Hardiman:
Downward influence of dynamical signals in the stratosphere
There has recently been a lot of work demonstrating that dynamical changes in the stratosphere can influence tropospheric weather and climate. A few mechanisms have
been suggested for how such influence can occur but there remain many unanswered questions.
In this talk I suggest one possible mechanism for the downward influence caused by a stratospheric perturbation, looking at when and why we might expect such a
perturbation to have a large downward influence.
Experiments are carried out first with a 1D quasi-geostrophic beta-channel model and then with a 3D mechanistic circulation model. The existence of multiple stable
states is the likely cause of a large downward influence being seen in certain cases with both models.
3/23/07 Shuang Liang: Atmospheric Predictability with a Simple Model
The prediction of the evolution of a nonlinear dynamic system from an initial condition with some uncertainties can be intrinsically limited by its dynamics. Lorenz
(1969) and Leith (1971) explored the predictability of 2D turbulence and respectively found finite and indefinite predictability, a result of their different
assumptions about the slopes of the energy spectra in the inertial range, and hence the dependence of error growth rate on spatial scale. In the atmosphere, the error
growth rates on the smallest scales are much faster than those on larger scales and saturate quickly. Moreover, observational errors are finite. The Lyapunov exponent
reflects the small-scale growth of infinitesimal errors, and is thus irrelevant to predictability. The Finite Size Lyapunov Exponent accounts for the dependence of
error growth rate on error magnitude. Its successful application in simple low-order systems motivates our attempt to apply it into a simple model of 2D turbulence
(Bartello and Warn, 1988). Energy injection and dissipation are introduced into the model and tuned to generate turbulent flows with different slopes of energy
spectra. The FSLE is applied in these flows to study the corresponding predictability. Some scaling behaviours are compared with the results from a full 2D turbulence
model (Boffetta and Musacchio, 2001).
4/13/07 Carling Hay: Greenland Tip Jets and the Greenland Flow Distortion Experiment
The North Atlantic thermohaline circulation is driven at high latitudes by areas of deep convection. One area of deep convection has been found off the southern tip
of Greenland in the Irminger Sea. It is driven by high wind speed events known as tip jets which are a result of the interaction of weather systems with the high
topography of Greenland.
With the use of the Weather Research and Forecasting Model (WRF), I will examine a tip jet event that occurred on November 29th 2004. During this event, a cyclone
which formed in the Labrador Sea on November 27th 2004 interacted with the high topography of Greenland, thereby diminishing its surface structure. Redevelopment of
the cyclone in the Irminger Sea occurred 6hr later, producing a forward tip jet. I will present the results of this simulation, focusing on the development of the
cyclone and the trajectories of air parcels that interacted with Greenland.
The study of how Greenland affects air flow and weather systems was further studied during the Greenland Flow Distortion Experiment (GFDex). I will present the initial
results from this campaign, highlighting a few case studies.
4/20/07 Mark Parrington:
Analysis of tropospheric composition through the assimilation of observations from the Tropospheric Emission
Spectrometer.
We are studying the chemical and physical processes governing the distribution of tropospheric ozone and carbon monoxide through the assimilation of ozone and CO
observations, from the Tropospheric Emission Spectrometer (TES) on the NASA EOS Aura satellite, into two global models of tropospheric chemistry and transport. The TES
data are assimilated into the GEOS-Chem model and a version of the GFDL AM2 model, with full tropospheric chemistry and dynamics nudged to NCEP reanalyses. We will
show that, although regions of enhanced ozone and CO correlate in both models the abundances can vary significantly. The assimilation of TES data brings the ozone and
CO in both models to a more comparable state which allows us to conduct a detailed analysis of the differences between the chemical and convective schemes utilized in
each model.
5/11/07 Jing Wang: Retrieval of Sulfur Dioxide from the GOME Instrument Using Optimal Estimation and Non-Linear Fitting Methods
We are studying the chemical and physical processes governing the distribution of tropospheric ozone and carbon monoxide through the assimilation of ozone and CO
observations, from the Tropospheric Emission Spectrometer (TES) on the NASA EOS Aura satellite, into two global models of tropospheric chemistry and transport. The TES
data are assimilated into the GEOS-Chem model and a version of the GFDL AM2 model, with full tropospheric chemistry and dynamics nudged to NCEP reanalyses. We will
show that, although regions of enhanced ozone and CO correlate in both models the abundances can vary significantly. The assimilation of TES data brings the ozone and
CO in both models to a more comparable state which allows us to conduct a detailed analysis of the differences between the chemical and convective schemes utilized in
each model.
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