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Abstracts from 2007/2008

21/9/07    Matt Toohey:   Balloon and space-based measurements of HNO3

Between 1998 and 2004, the MANTRA (Middle Atmosphere TRend Assessment) mission performed biennial balloon flights from Vanscoy Saskatchewan, making measurements of the chemical composition of the stratosphere. As the name suggests, part of the mandate of MANTRA was to investigate potential trends in reactive nitrogen species, which are intimately involved in ozone chemistry. Two emission radiometer instruments provided a unique opportunity towards this aim: since they had been flown on similar balloon flights years previously, they provided the opportunity to perform consistent retrievals of HNO3 on data collected with equivalent instrumentation spanning 12 years. For this week's Brewer seminar, I will (re)introduce the radiometer instruments, the technique used to retrieve profiles of HNO3, and place these retrievals into the historical record of HNO3 measurements.



28/9/07    Jeffrey R. Taylor:   A Tale of Two Instruments

Once upon a time there was a spectrometer named Fourier. Fourier lived in a penthouse lab on the 16th floor of a high rise building, known as the Toronto Atmospheric Observatory. Fourier worked hard, all day long, in the blazing sun, making measurements of chemical trace gas concentrations. He yearned for a companion with which to spend his time and share his knowledge of atmospheric composition above Toronto. One day, Fourier met another Canadian instrument named OSIRIS. OSIRIS was a drifter who travelled all around the world making similar measurements of chemical gases. The two instruments bonded over their common interest of measuring ozone (O3) and nitrogen dioxide (NO2) in the stratosphere. Things were going well for years (2002-2006), until they had a bitter disagreement over the partial columns of NO2 during this time period. They sought help by using a chemical box model, but it only served to push them apart. Their last chance is to turn to the new technique of "virtual coincidences". or is it already too late?! Will Fourier and OSIRIS be able to put their differences aside and learn to live happily ever after? Is the technique of "virtual coincidences" powerful enough to correct large disagreements over stratospheric NO2? To learn the answers to all of these questions, come to the Brewer Seminar on Friday.`



5/10/07    James Anstey:   Effects of the QBO on the extratropics in a dynamics-only GCM

The quasi-biennial oscillation (QBO) is a pattern of variability that dominates the variance of equatorial stratospheric winds but fails to be simulated in most GCMs. By increasing the vertical resolution in a dynamics-only incarnation of the Canadian Middle Atmosphere Model (CMAM) we obtain a QBO and consider its effects on the interannual variability of the extratropical middle atmosphere. As might be expected from observations, some improvement to the warm bias of the CMAM's northern hemisphere polar vortex occurs when the QBO allows for equatorial westerly zonal winds to exist in the model's stratosphere (in contrast to the weak tropical easterlies that exist in the QBO's absence). But this cooling is non-robust due to variability that arises on decadal timescales in our 150-year model run. We compare this behaviour to that of the real atmosphere, noting that this version of the CMAM lacks interannually varying sea surface temperatures or external forcings such as the 11-year solar cycle or trends in chemical consituents.



12/10/07    Petra Huck:   Inter- and intra-annual variability in Antarctic ozone depletion

The coupling of dynamics and chemistry in the Antarctic stratosphere is examined to describe inter- and intra-annual variability in Antarctic ozone depletion. Dynamics in the form of planetary-scale atmospheric waves can affect the ozone distribution directly through transport of trace gases. In addition, indirect effects such as heat transport causing temperature changes which in turn modify ozone destruction have to be considered. Planetary waves can change the dynamical conditions in the Antarctic stratosphere and thereby change the conditions necessary for ozone destruction. Chemical ozone depletion depends on the abundance of halogens in the stratosphere, temperature and the availability of sunlight. In particular, low temperatures (< 195 K) are necessary for the formation of polar stratospheric clouds which lead to heterogeneous chemistry and chlorine activation which is a basic requirement for ozone depletion. Based on this theory, statistical models are developed which can then be used to project inter-annual variability and intra-seasonal evolution of Antarctic stratospheric ozone depletion into the future.



19/10/07    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, as well as the challenges it faces both from theoretical and computational point of view. 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.



26/10/07    Lei Wang:   Stationary wave theory, modeling, and applications

The stationary wave, defined as the zonal asymmetries of the atmospheric climatology, is generated by the zonally varying lower boundary, diabatic heating, and other forcings. Atmospheric stationary waves are closely related to regional climate, and consequently changes to the stationary waves resulting from recent global warming might have significant impacts on regional climate change.

The physical interpretation of the stationary wave is highly complicated due to the nonlinear interactions between the surface and the atmosphere, but it is still possible to explain the existed atmospheric zonal asymmetries under a framework in which these complicated processes are neglected. That is, stationary wave models are able to approach observed atmospheric zonal asymmetries with much less computational cost than that of GCMs. This talk will illustrate the construction and the test of a stationary wave model.



2/11/07    Chris Fletcher:   Can the Stratosphere Control the Extratropical Circulation Response to Surface Forcing?

Snow extent anomalies over Siberia have been proposed as potential precursors to stratosphere-troposphere interaction events. However, often these events occur without a clear tropospheric precursor. We assess the role of snow cover in initiating such events in a 100-member ensemble of autumn-winter transient integrations using the Geophysical Fluid Dynamics Laboratory atmosphere/land GCM AM2/LM2. The forcing is a prescribed Siberia region snow mass perturbation, which does indeed induce a stratosphere-troposphere interaction response. On seasonal timescales we demonstrate that the coupling of the stratospheric response to the surface depends on the state of the stratosphere prior to the initiation of the forcing. An initially weak stratospheric polar vortex increases the likelihood of a negative Northern Annular Mode response at the surface. This result could have practical implications for the general problem of the prediction of circulation anomalies arising from surface forcing in the extratropics.



9/11/07    Peter Hitchcock:   Are the Coldest Winters in the Arctic Stratosphere Getting Colder?

Temperatures low enough for the formation of Polar Stratospheric Clouds (PSCs) have become increasingly widespread in the Arctic stratosphere over the past four decades, despite the lack of an apparent cooling trend in the mean temperatures. Since PSCs are strongly implicated in the chemical destruction of ozone, this trend could have troubling consequences. It has been argued that this is a sign of climate change, though details of the mechanism remain unclear. This Friday I will discuss polar stratospheric temperatures in an ensemble of three, 150-year integrations of the Canadian Middle Atmosphere Model (CMAM) which include representations of ozone depletion/recovery and climate change. While the distinct radiative effects of ozone depletion and carbon dioxide increase are clearly seen in the Antarctic temperature extremes, any such effects in the northern hemisphere of the model are overwhelmed by the strong variability of the Arctic vortex.



16/11/07    Robert Field:   Identifying controls on stable water isotope composition with a GCM

In this talk, I will report on our efforts to better understand controls on the stable water isotope composition of precipitation. Since their development in the 1980's, GCMs equipped with stable water isotope diagnostics have been used to identify climatological controls on precipitation δ18O. These studies have been important in identifying controls on δ18O in data-poor regions, and in the absence of complicating factors such as post-depositional effects on snowfall. They are, however, similar to observational studies, in that isotopic variability is not being attributed to a particular control in a strict physical sense because of possible collinearity between explanatory variables.

As an alternative, we are conducting a series of sensitivity experiments using the GISS ModelE GCM, whereby different fractionation processes are systematically disabled to determine the dominant controls of δ18O. Our results show that variability in precipitation δ18O is controlled almost exclusively by atmospheric processes. Surface processes make a negligible contribution, except perhaps in regions adjacent to heavy vegetation where moisture recycling could play an important role.



23/11/07    Jane Liu:   Revisiting "the Tropospheric Middle East Ozone Maximum" with Satellite Observations of Tropospheric Ozone

Previous modelling and observational studies suggest the existence of a seasonal buildup in tropospheric ozone over the Middle East, which is so called the "Middle East Ozone Maximums" (Li et al. 2001 and Kar et al. 2002, Geophyiscal Research Letters). However, more evidences are needed to confirm or reject this suggestion because of its high uncertainty. In this study, we revisited this issue using a chemical transport model, GEOS-CHEM, the newly available tropospheric ozone data from the Tropospheric Emission Spectrometer (TES) satellite, and in-situ ozone sonde data. We found that there is a summer-time ozone enhancement in a narrow layer of altitudes around 400 hPa in the in-situ data. This enhancement disappears in the other seasons. The seasonal variation of the ozone vertical profile in the in-situ data can be mostly captured by both TES and GEOS-CHEM. Spatially, the "Middle East ozone maximum" is visible in the TES images, with some inter-annual variations in its extent.

The seasonal cycle of ozone over the Middle East region was examined by isolating the influence of photochemical production and transport on the ozone budget in the region. A tagged ozone simulation was conducted to track ozone in the region from its origins in Asia, Africa, North America, and European. The results suggest that although long-range transport and in situ chemical production both contribute to the formation of the ozone enhancement, transport appears to be the major source. The majority of transported ozone comes from Asia in the mid-upper troposphere and from African in the middle troposphere. The accumulation of ozone in the region is strongly related to the location and movement of the Arabian anticyclone. The TES data show enhanced ozone extending from North Africa to Central Asia, over a larger area than what GEOS-CHEM predicted, reflecting possible biases in the model transport over these regions.



30/11/07    Tiffany A. Shaw:   Wave-activity conservation laws and their application to subgrid-scale parameterization in climate models

It is common in fluid dynamical applications to consider the fluid state as a disturbance to some specified background reference state. In such cases wave-activity conservation laws play a central role and their most general formulation follows from Hamiltonian geophysical fluid dynamics. In the case of the large-scale circulation of the middle atmosphere the Eliassen-Palm wave activity has been crucial to theoretical analysis. In the case of the mesoscale, whose interaction with the large scales is represented in climate models through subgrid-scale parameterizations, one generally considers three-dimensional disturbances to a horizontally homogeneous but vertically dependent background flow. While such conservation laws have been applied to a horizontally homogeneous background flow in two-dimensions their application to the three-dimensional problem fails because of a degeneracy created by the absence of a potential vorticity gradient. Here we will show how this degeneracy can be overcome and wave-activity conservation laws derived for three-dimensional disturbances to a horizontally homogeneous background flow. The role of the wave-activity fluxes in forcing the large-scale energy and momentum budgets will be briefly discussed and their usefulness in constraining the fluxes of parameterized energy and momentum will also be highlighted.



7/12/07    Yonggang Liu:   A Carbon-Cycle Coupled Climate Model: Implications for the "Snowball Earth" hypothesis

The profound negative carbon isotopic excursions and the 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 explain the available isotopic data. The results of coupled model integrations demonstrate that the interaction of the physical climate system with the carbon cycle may support a cyclic mode of glaciation, the timscale of which is carbon cycle controlled. The model has been proved to be able to excellently explains the younger glaciation event (Marinoan glaciation, ~650 Ma), but for the older one (Sturtian glaciation, ~720 Ma), in which the continents are claimed to be mostly distributed in the low-latitude region, this simple model cannot produce a similar cyclic glaciation. Either more complex mechanism needs to be invoked in the model, or causes other than carbon cycle (e.g., true polar wander) should be found to explain the Sturtian glaciation.



14/12/07    Carling Hay:   Case Study of a Greenland Tip Jet

Standing over 3000m tall in some regions, Greenland's southern tip acts as a large barrier to storm systems traversing the North Atlantic. As a result of the interaction with Greenland, low-pressure systems located in the Irminger Sea between Iceland and Greenland often produce strong low-level winds. These westerly low-level winds are known as tip jets and can have magnitudes in excess of 30 m/s. On November 29th 2004 a lee cyclone in the Irminger Sea produced a tip jet event that was captured by a meteorological buoy positioned off the southwest tip of Greenland. The Weather Research and Forecasting Model (WRF) along with an air parcel trajectory analysis has been used to study the system that produced the tip jet as well as the characteristics of the winds themselves.



11/01/08    Annemarie Fraser:   UV-visible measurements of Ozone and NO2 during the Canadian Arctic ACE Validation Campaigns: 2004-2007

The first four Canadian Arctic ACE validation campaigns were held during polar sunrise at Eureka, Nunavut from 2004 to 2007 in support of validation of the ACE (Atmospheric Chemistry Experiment) satellite mission. Three to five zenith-sky viewing UV-visible spectrometers have taken part in each of the four campaigns.

During my Brewer I'll introduce you to the five UV-visible spectrometers that have taken part in the ACE campaigns, and discuss how their measurements of ozone and NO2 compare. I'll also compare the total columns from the ground-based instruments to integrated total columns from ozonesondes and integrated partial columns from the two instruments on board ACE: ACE-FTS (ACE-Fourier Transform Spectrometer) and ACE-MAESTRO (ACE-Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation).

As an added bonus, I'll show you what the newest instrument, the PEARL-GBS (Polar Environment Atmospheric Research Lab - Ground Based Spectrometer), has been doing since it was permanently installed in Eureka in August 2006.



18/01/08    Peifeng Yan:   The infrared absorption cross-sections of CFC-113

CFC-113 is the third most abundant chlorofluorocarbon in the atmosphere. Its impact on ozone depletion and global warming require accurate measurement of its concentration. Currently, the lack of cross-section measurements is the major limitation for the retrieval of this species from atmospheric spectra. In this work, a CFC-113 spectrum recorded in 2005 at room temperature (294 K) was analyzed to derive a cross-section and was compared with existing data. The temperature-dependence of the peak cross-sections and the temperature-independence of the integrated band strengths were also studied. A thermocouple performance test was performed with carbon monoxide as preparatory work for future CFC-113 temperature measurements. A multi-pass White cell is being commissioned to enable measurements of weak absorption cross-sections features of CFC-113, and measurements of some infrared line parameters of a number of greenhouse gases and atmospheric constituents. These data will be invaluable for retrieval and remote sounding of atmospheric constituents.



25/01/08    Jing Wang:   Retrieval of Sulfur Dioxide from GOME Instrument Using Optimal Estimation Inversion Technique

Sulfur dioxide (SO2) is an important trace gas, both under background conditions and in polluted areas. The purpose of using the previous GOME measurement is to get better monthly retrievals of SO2 and then improve our understanding of the trend of SO2 emission in recent decade. In the talk, I'll present the short timescale retrievals of SO2 from the measurements of Global Ozone Monitoring Experiment (GOME) in UV spectral region for both volcanic and anthropogenic emissions using Optimal Estimation (OE) inverse technique. The results will be compared with the retrieval using Nonlinear Least Squares Fitting method, showing the advantage of OE in both emission sources. And our work has improved the previous retrieval using OE in anthropogenic emission by applying better fitting window, which is validated by the measurements from CASTNET (Clean Air Status and Trends Network) in the United States.



08/02/08    Rebekah Martin:   A tale of two tip jets: Case studies of two Greenland tip jets

Since its discovery 10 years ago, the Greenland tip jet has been a focus of study as an orographically induced phenomenon that supports intense air sea interaction. Much of the research on this weather system has been to characterize its structure and the environmental conditions that give rise to it. As a result, its genesis mechanism has not been addressed in depth. We present here the results of mesoscale simulations of two Greenland tip jet events, and discuss some of the factors that were important to their development that should be included in a theory of tip jet formation. Both of these events were classified as strong events based on climatologies developed from reanalysis and satellite data, however their genesis was significantly different, and these cases could be considered as two end members of the spectrum of tip jet events. The first case took place from 17-19 February, 1997, and was one of the cases addressed in the first work on tip jets, while the second occurred over 22-24 January, 2001. Although these cases occurred under slightly different synoptic forcing conditions and had different mature configurations, they highlight similarities between tip jet events that could be extrapolated to occur for most events.

Time permitting I will also review a case study of a reverse tip jet event that occurred in December 2001 for the purposes of even more fun and frivolity.



15/02/08    Rodica Lindenmaier:   Studies of Arctic Middle Atmosphere Chemistry Using Infrared Absorption Spectroscopy: Optimization of Ozone Retrievals

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 stratospheric ozone depletion.

It is well known that, after the long polar winter which creates special conditions for reactive chlorine and bromine radicals to develop, the process of rapid ozone loss begins. This is well understood now in Antarctica where the springtime ozone hole is fairly stable from year to year. Arctic winter/spring total ozone columns show large interannual variability due to large variations from year to year in the area of the Arctic vortex, the strength of the sudden warmings, and the timing of the final vortex breakdown all of which can affect the amount of chemical ozone loss. Long-term observations are essential to address the question of “What is the composition of the Arctic atmosphere above the site and how is it changing with time?” In my research activity I would like to improve our understanding of the processes controlling the Arctic stratospheric ozone budget and its future evolution, using measurements of the concentrations of stratospheric constituents.

This talk will present measurements recorded with the new instrument during its first year of operation, including those from the Canadian Arctic ACE Validation spring campaign in 2007. Particular consideration will be given to optimizing the ozone retrievals. The performance of the instrument will be discussed, along with details of the retrieval process, trace gas measurements, and future plans.



29/02/08    Dmitry Vyushin:   Power-law and long-memory characteristics of the atmospheric general circulation

The question of which statistical model best describes internal climate variability on interannual and longer timescales is key to our ability to predict such variables and detect periodicities and trends in them. For over 30 years the dominant model for background climate variability has been the autoregressive model of the first order (AR1). But recent research has shown that some aspects of climate variability are best described by a "long-memory" or "power-law" model. Such a model fits a temporal spectrum to a single power-law function which thereby accumulates more power at lower frequencies than an AR1 fit. In this study, several power-law model estimators are applied to global temperature data from reanalysis products. The methods employed (detrended fluctuation analysis, Geweke Porter-Hudak estimator, Gaussian semiparametric estimator, and multitapered versions of the last two) agree well for pure power-law stochastic processes. But for the observed temperature record, the power-law fits are sensitive to the choice of frequency range and the intrinsic filtering properties of the methods. The observational results converge once frequency ranges are made consistent and several climate signals have been filtered. Two robust results emerge from the analysis: first, that the tropical circulation features relatively large power-law exponents that connect to the zonal-mean extratropical circulation; and second, that the subtropical lower stratosphere exhibits power-law behaviour that is volcanically forced.



7/03/08    Dave MacKenzie:   Transport of CO and O3 into the UTLS Region

Changes in O3 in the upper troposphere and lower stratosphere (UTLS) can influence the climate system. We examine the influence of tropospheric pollution on O3 in the UTLS. The GEOS-Chem global chemical transport model is used to quantify the transport of pollution to the UTLS from different source regions in the troposphere. To assess cross tropopause transport we focus on the correlations between CO and O3. These results are compared with output from the GMI Combo model and SPURT aircraft data to help describe UTLS mixing.



14/03/08    Zhe Jiang:   Quantifying the impact of aggregation errors and model transport biases on top-down estimates of carbon monoxide emissions using satellite’s observations

We conducted an inverse analysis of atmospheric CO, using the GEOS-Chem model and observations from the MOPITT satellite instrument, to quantify the potential contribution of model transport error and aggregation errors to top-down source estimates. We focus on quantifying CO emissions for September 2000, during the biomass burning season. Using a 4-dimensional variational data assimilation scheme, we optimize the CO emissions on the 2°x2.5° grid of the model. The high-resolution, a posteriori source estimates are compared with estimates obtained from a coarse resolution, analytical Bayesian inversion to quantify the impact of aggregation errors in the coarse resolution inversion on the source estimates. We also carry out the coarse resolution analytical inversion using two different versions of the GEOS-Chem model, driven with different transport fields, to isolate the impact on the source estimates of systematic differences in transport in the models.



4/04/08    Thomas Walker:   Tropospheric Ozone at High Latitudes: An Initial Look

Despite a paucity of pollution sources, the Arctic atmosphere experiences ozone accumulation, which affects the surface air quality and the local radiation budget. We use a global chemical transport model (GEOS-Chem) to study the seasonal cycles in PAN and ozone at high latitude sites, both on the ground and aloft, and compare to in situ datasets where available. We observe an early springtime maximum in both PAN and ozone at the surface. Aloft, we observe a shift in the timing of stratospheric downwelling between the model and observation. A tagged ozone simulation reveals four continental source regions of interest for transport to high latitudes as well as the temporal and spatial distributions of ozone originating in these regions.



11/04/08    Karen Smith:   The transient response to localized surface cooling in a simple AGCM

Terrestrial snow cover constitutes the largest areal component of the cryosphere and experiences the largest spatial and temporal fluctuations of Earth's surface conditions. Consequently, it exerts a strong influence over global climate. In addition to the role of snow cover in the surface energy and moisture budgets, recent studies have shown that the circulation response to the diabatic forcing associated with seasonal snow cover anomalies projects onto the leading mode of extratropical variability, the Northern Annular Mode (NAM). Therefore, snow variability can potentially induce large-scale changes in the circulation. Using an idealized dry, hydrostatic, primitive equation model, the transient response to surface cooling is investigated. We find that responses generated by our simple model differ from snow forcing studies in comprehensive GCMs. The ability of our simple model to capture sudden warming dynamics and stratosphere-troposphere coupled variability is likely an important factor in interpreting our cooling experiments.



18/04/08    Cristen Adams:   UV-visible measurements from the 2008 field campaign at Eureka, Nunavut: Preliminary results and future plans

This spring, I took measurements with two spectrometers at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut, Canada (80N, 86W). The UT-GBS (University of Toronto Ground-Based Spectrometer) and the PEARL-GBS (PEARL Ground-Based Spectrometer) are nearly identical spectrometers that measure in the UV-visible region. During the spring 2008 campaign, both instruments recorded some zenith-sky measurements of scattered sunlight, which yield vertical columns with primarily stratospheric information. I will discuss some preliminary vertical column measurements of ozone and NO2, as well as current progress toward retrieving BrO vertical columns. This spring, we installed a sun-tracker above the PEARL-GBS, with the goal of detecting "bromine explosions", sudden increases in tropospheric bromine in the springtime that are thought to originate from newly forming sea-ice. I will describe the measurements that we are taking for this purpose, and future plans to combine the direct-sun measurements (for tropospheric sensitivity), with the zenith-sky measurements (for stratospheric sensitivity) in order to measure tropospheric and stratospheric partial columns of BrO above Eureka.



2/05/08    Marie-Ève Gagné:   Using airglow to derive temperature and density profileson Mars

Middle-atmospheric (50 - 100 km) temperature measurements of Mars are rare and unreliable because of the high opacity of the atmosphere. The absorption bands of the standard sensors used to infer temperature quantities, i.e. in the thermal infrared region, are mostly saturated due to the high concentration of carbon dioxide (CO2) in the Martian atmosphere, as the main absorption lines of CO2 cover most of this spectral region. Airglow measurements provide a highly promising approach for the determination of temperature and atomic-oxygen density over this altitude range given the strong heritage of this technique for Earth observations. Airglow has been observed during the Mariner 6, 7 & 9 missions to Mars; the presence of atmospheric airglow features in different spectral regions has recently been confirmed by the measurements of SPICAM on board Mars EXpress.

The presentation will review the measurements of middle-atmospheric temperatures and airglow on Mars. The airglow features of the Herzberg I, II & III and Chamberlain bands of the O2 transitions will be explained. Finally, the first simulations of the Martian airglow from those emission bands will be presented. The simulations use profiles from a time-dependent photochemical model that solves for the diurnal changes in composition driven by varying insolation between the ground and 100 km altitude.



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