M. Lopez-Puertas

Instituto De Astrofisica De Andalucia, Granata, Andalusia, Spain

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Publications (99)163.59 Total impact

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    ABSTRACT: The recent 23-30 January and 7-11 March 2012 solar proton event (SPE) periods were substantial and caused significant impacts on the middle atmosphere. These were the two largest SPE periods of solar cycle 24 so far. The highly energetic solar protons produced considerable ionization of the neutral atmosphere as well as HOx (H, OH, HO2) and NOx (N, NO, NO2). We compute a NOx production of 1.9 and 2.1 Gigamoles due to these SPE periods in January and March 2012, respectively, which places these SPE periods among the 12 largest in the past 50 yr. Aura Microwave Limb Sounder (MLS) observations of the peroxy radical, HO2, show significant enhancements of > 0.9 ppbv in the northern polar mesosphere as a result of these SPE periods. Both MLS measurements and Goddard Space Flight Center (GSFC) two-dimensional (2-D) model predictions indicated middle mesospheric ozone decreases of > 20% for several days in the northern polar region with maximum depletions > 60% over 1-2 days as a result of the HOx produced in both the January and March 2012 SPE periods. The SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE) and the Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instruments measured NO and NO2 (~ NOx), which indicated enhancements of over 20 ppbv in most of the northern polar mesosphere for several days as a result of these SPE periods. The GSFC 2-D model was used to predict the medium-term (~ months) influence and showed that the polar middle atmosphere ozone was most affected by these solar events in the Southern Hemisphere due to the increased downward motion in the fall and early winter. The downward transport moved the SPE-produced NOy to lower altitudes and led to predicted modest destruction of ozone (5-9%) in the upper stratosphere days to weeks after the March 2012 event. Total ozone reductions were predicted to be a maximum of 1% in 2012 due to these SPEs.
    Atmospheric Chemistry and Physics 09/2013; 13(9):23251-23293. · 4.88 Impact Factor
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    ABSTRACT: A dedicated mission to investigate exoplanetary atmospheres represents a major milestone in our quest to understand our place in the universe by placing our Solar System in context and by addressing the suitability of planets for the presence of life. EChO -the Exoplanet Characterisation Observatory- is a mission concept specifically geared for this purpose. EChO will provide simultaneous, multi-wavelength spectroscopic observations on a stable platform that will allow very long exposures. EChO will build on observations by Hubble, Spitzer and groundbased telescopes, which discovered the first molecules and atoms in exoplanetary atmospheres. EChO will simultaneously observe a broad enough spectral region -from the visible to the mid-IR- to constrain from one single spectrum the temperature structure of the atmosphere and the abundances of the major molecular species. The spectral range and resolution are tailored to separate bands belonging to up to 30 molecules to retrieve the composition and temperature structure of planetary atmospheres. The target list for EChO includes planets ranging from Jupiter-sized with equilibrium temperatures Teq up to 2000 K, to those of a few Earth masses, with Teq ~300 K. We have baselined a dispersive spectrograph design covering continuously the 0.4-16 micron spectral range in 6 channels (1 in the VIS, 5 in the IR), which allows the spectral resolution to be adapted from several tens to several hundreds, depending on the target brightness. The instrument will be mounted behind a 1.5 m class telescope, passively cooled to 50 K, with the instrument structure and optics passively cooled to ~45 K. EChO will be placed in a grand halo orbit around L2. We have also undertaken a first-order cost and development plan analysis and find that EChO is easily compatible with the ESA M-class mission framework.
    Experimental Astronomy 10/2012; 34(2):311-353. · 2.97 Impact Factor
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    ABSTRACT: Atomic hydrogen is one of the major chemically active species in the mesosphere. It is controlled by various reactions with hydrogen and oxygen compounds. The amount of atomic hydrogen depends on the water vapour abundance, transport processes, and on the solar flux. In this talk we discuss the temporal evolution of atomic hydrogen obtained by two different methodologies.The first one is based on the measurement of highly excited hydroxyl and ozone nighttime abundance, namely by the SCIAMACHY and GOMOS instruments on Envisat. The second dataset is retrieved from the day- to night ratio of ozone as measured by the MIPAS instrument on the same satellite. Both datasets are compared to each other and limitations of the two approaches are addressed by means of HAMMONIA model data. The temporal evolution of atomic hydrogen as indicated by the measurements points to the complex interaction between chemistry and dynamics and the importance for the 11-year solar cycle on the composition of the mesosphere and lower thermosphere.
    07/2012;
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    ABSTRACT: Sophisticated model calculating Titan's non-LTE population of CH 4 vibrational levels. Solar radiation, CH 4 -N 2 collisions, and nu 4 -quanta exchange are the relevant processes. Emission from nu 3 and nu 3 + nu 4 dominate Titan's upper atmosphere 3.3 mum limb radiance. Other weaker CH 4 bands may contribute up to 20-25% to the total limb radiance. Retrieved CH 4 abundance from Cassini-VIMS support well mixed values up to 1000 km.
    Icarus 01/2011; 214:571-583. · 3.16 Impact Factor
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    ABSTRACT: We present observations of the infrared radiative cooling by carbon dioxide (CO2) and nitric oxide (NO) in Earth's thermosphere. These data have been taken over a period of 7 years by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite and are the dominant radiative cooling mechanisms for the thermosphere. From the SABER observations we derive vertical profiles of radiative cooling rates (W m-3), radiative fluxes (W m-2), and radiated power (W). In the period from January 2002 through January 2009, we observe a large decrease in the cooling rates, fluxes, and power consistent with the declining phase of solar cycle 23. The power radiated by NO during 2008 when the Sun exhibited few sunspots was nearly one order of magnitude smaller than the peak power observed shortly after the mission began. Substantial short-term variability in the infrared emissions is also observed throughout the entire mission duration. Radiative cooling rates and radiative fluxes from NO exhibit fundamentally different latitude dependence than do those from CO2, with the NO fluxes and cooling rates being largest at high latitudes and polar regions. The cooling rates are shown to be derived relatively independent of the collisional and radiative processes that drive the departure from local thermodynamic equilibrium (LTE) in the CO2 15 μm and the NO 5.3 μm vibration-rotation bands. The observed NO and CO2 cooling rates have been compiled into a separate data set and represent a climate data record that is available for use in assessments of radiative cooling in upper atmosphere general circulation models.
    Journal of Geophysical Research 03/2010; 115(A3):3309-. · 3.17 Impact Factor
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    ABSTRACT: Stratospheric sudden warmings (SSWs) represent dramatic meteorological disturbances which affect the polar winter atmosphere in a wide altitude range. While the mechanisms of SSWs are well understood in the middle atmosphere, little is known about the polar temperature responses to SSW above 120 km. We used temperature data from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board ESA's Envisat satellite to analyze the temperature responses in the mesosphere and thermosphere up to 170km to a major stratospheric sudden warming (SSW) which occurred in January 2009. The observations show clear signatures of a mesospheric cooling and a thermospheric warming, the latter peaking at 120-140 km. From the analysis of the zonal temperature structure during the SSW a pronounced wave 1 pattern was found in the stratosphere and thermosphere. In the mesosphere, the wave amplitude is significantly damped. The wave amplification above is most likely produced by in situ forced planetary waves in the MLT region. Our observations represent, to our best knowledge, the first experimental evidence for dynamical coupling from the lower atmosphere up to the thermosphere by means of satellite data.
    01/2010;
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    ABSTRACT: Water vapor is a key constituent of the middle atmosphere. It is involved in the ozone chem-istry, it is the precursor of PSCs and PMCs, and it is an infrared cooler in the stratosphere. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard Envisat observes the H2O infrared emissions with high resolution up to the mesopause. We have derived water vapor abundance from MIPAS spectra using the IMK/IAA data processor, which includes the GRANADA non-LTE algorithm. That allows for accurate H2O retrievals in the atmospheric regions where its emissions are affected by non-LTE, i.e., above 50km and particularly in the polar summer. We describe the information gained from MIPAS spectra about the non-LTE processes affecting the H2O infrared emissions, discuss its uncertainties and present MIPAS pole-to-pole distributions of water vapor retrieved from the stratosphere to the upper meso-sphere. We pay special attention to its behavior in the polar summer mesosphere, where the presence of PMCs and particular dynamical events may perturb the H2O vertical distribution. We also compare our results with those from global circulation models and other independent measurements.
    01/2010; 38:88.
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    ABSTRACT: Except for a few reactions involving electronically excited molecular or atomic oxygen or nitrogen, atmospheric chemistry modelling usually assumes that the temperature dependence of reaction rates is characterized by Arrhenius' law involving kinetic temperatures. It is known, however, that in the upper atmosphere the vibrational temperatures may exceed the kinetic temperatures by several hundreds of Kelvins. This excess energy has an impact on the reaction rates. We have used upper atmospheric OH populations and reaction rate coefficients for OH(v=0...9)+O3 and OH(v=0...9)+O to estimate the effective (i.e. population weighted) reaction rates for various atmospheric conditions. We have found that the effective rate coefficient for OH(v=0...9)+O3 can be larger by a factor of up to 1470 than that involving OH in its vibrational ground state only. At altitudes where vibrationally excited states of OH are highly populated, the OH reaction is a minor sink of Ox and O3 compared to other reactions involving, e.g., atomic oxygen. Thus the impact of vibrationally excited OH on the ozone or Ox sink remains small. Among quiescent atmospheres under investigation, the largest while still small (less than 0.1%) effect was found for the polar winter upper stratosphere and mesosphere. The contribution of the reaction of vibrationally excited OH with ozone to the OH sink is largest in the upper polar winter stratosphere (up to 4%), while its effect on the HO2 source is larger in the lower thermosphere (up to 1.5% for polar winter and 2.5% for midlatitude night conditions). For OH(v=0...9)+O the effective rate coefficients are lower by up to 11% than those involving OH in its vibrational ground state. The effects on the odd oxygen sink are negative and can reach −3% (midlatitudinal nighttime lowermost thermosphere), i.e. neglecting vibrational excitation overestimates the odd oxygen sink. The OH sink is overestimated by up to 10%. After a solar proton event, when upper atmospheric OH can be enhanced by an order of magnitude, the excess relative odd oxygen sink by consideration of vibrational excitation in the reaction of OH(v=0...9)+O3 is estimated at up to 0.2%, and the OH sink by OH(v=0...9)+O can be reduced by 12% in the thermosphere by vibrational excitation.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 01/2010; · 5.51 Impact Factor
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    ABSTRACT: Polar mesospheric clouds (PMCs) occur at the coldest regions of the atmosphere near the summer high latitude mesopause where they form a layer of a few kilometers wide, peaking near 83 km and located at latitudes poleward of 50 degrees. They are being discussed as potential early indicators of global change since they are very sensitive to temperature and water vapour concentration in that region. PMCs have been intensively studied by observations from ground, rockets (in situ), and space, as well as by sophisticated models. The observations of PMCs in emission in the infrared is, however, very difficult because of the low icy particle volume concentration and the very cold mesopause temperatures, thus requiring very sensitive instruments for their detection. In this paper we report on the infrared emission (10-12 microns) of polar mesospheric clouds as measured by the MIPAS instrument on Envisat. The shape of MIPAS spectra in this region is very similar to that simulated for ice particle emission at low temperatures (below 150 K) and hence provide a further evidence of the water ice nature of the PMC particles. The simultaneous measurements of temperature from the MIPAS CO2 15 microns region allows us to retrieve the ice particles volume density. 3D (longitude, latitude, altitude) distributions of the ice particles volume density are retrieved from MIPAS spectra. We have analyzed the measurements taken by MIPAS in its NLC, MA and UA modes during the NH and SH seasons from 2005 until 2009. The variability of the zonal mean distribution of ice density, mean altitude of the layer and column ice density are analyzed as function of latitude, season and year.
    01/2010;
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    ABSTRACT: Energetic particle precipitation (EPP) changes the composition of the middle atmosphere from the lower thermosphere down to the middle stratosphere. Particularly, the generation of odd nitrogen lead to accelerated catalytic ozone destruction which could have important implications on the longterm evolution of stratospheric ozone. In this sense, the understanding of EPP impacts is of importance for the evaluation of ozone recovery. Since 2002, MIPAS provides globally vertical distributions of up to 30 trace species, temperature and clouds in the upper troposphere, stratosphere and mesosphere, covering also the polar caps during polar winter. Hence it is an ideal instrument to monitor EPP effects on atmospheric composition. In this overview talk, scientific key results obtained from MIPAS data will be summarized, focusing on composition changes caused by recent solar proton events, inter-annual variability of polar winter NOx descent, and the coupling of the high latitude EPP response with the extra-polar regions.
    01/2010;
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    ABSTRACT: Solar eruptions and geomagnetic activity led to energetic particle precipitation in early 2005, primarily during the January 16-21 period. Production of OH and destruction of ozone have been documented due to the enhanced energetic solar proton flux in January 2005 [e.g., Ver-ronen et al., Geophys Res. Lett., 33, L24811, doi:10.1029/2006GL028115, 2006; Seppala et al., Geophys. Res. Lett., 33, L07804, doi:10.1029/2005GL025571, 2006]. These solar pro-tons as well as precipitating electrons also led to the production of NOx (NO, NO2). Our simulations with the Whole Atmosphere Community Climate Model (WACCM) show that NOx is enhanced by 20-50 ppbv in the polar Northern Hemisphere middle mesosphere ( 60-70 km) by Jan. 18. Both the SCISAT-1 Atmospheric Chemistry Experiment (ACE) NOx mea-surements and Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) nighttime NO2 observations show large increases during this period, in reasonable agreement with WACCM predictions. Such enhancements are considerable for the mesosphere and led to simulated increases in polar Northern Hemisphere upper stratospheric odd nitrogen (NOy) of 2-5 ppbv into February 2005. The largest ground level enhancement of solar cycle 23 occurred on Jan. 20, 2005 with a neutron monitor increase of about 270 percent [Gopalswamy et al., 29th Int. Cosmic Ray Conf., Pune, 00, 101-104, 2005]. We found that protons of energies 300 to 20,000 MeV, not normally included in our computations, led to enhanced stratospheric NOy of less than 1 percent as a result of this GLE. The atmospheric impact of precipitating middle energy electrons (30-2,500 keV) during the Jan. 16-21, 2005 period is also of interest, and an effort is ongoing to include these in WACCM computations. This presentation will show both short-and longer-term changes due to the January 2005 energetic particle precipitation.
    01/2010;
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    ABSTRACT: Solar eruptions in early 2005 led to a substantial barrage of charged particles on the Earth’s atmosphere in a few separate events during the January 16-21 period. Significant production of OH [Verronen et al. 2006] and destruction of ozone [Verronen et al. 2006; Seppala et al. 2006] have been documented due to the enhanced solar proton flux in January 2005. These solar proton events (SPEs) also led to the production of NOx (NO, NO2), when the protons and associated secondary electrons dissociated molecular nitrogen (N2). Our simulations with the Whole Atmosphere Community Climate Model (WACCM) show that mesospheric NOx is enhanced in both the polar Southern (greater than 10 ppbv) and Northern (greater than 40 ppbv) Hemispheres. Envisat MIPAS measurements of nighttime NO2 for the Northern Hemisphere are in reasonable agreement with these predictions. Such enhancements are considerable for the mesosphere and led to increases in Northern Hemisphere polar upper stratospheric odd nitrogen (NOy) greater than 20% in February and March 2005. The largest ground level enhancement (GLE) of solar cycle 23 occurred on January 20, 2005 with a neutron monitor increase of about 270% [Gopalswamy et al. 2005]. Using results from a recent analysis of the proton spectrum derived from neutron-monitor data [Tylka & Dietrich 2009], we found that protons of energies 300 to 20,000 MeV, not normally included in our computations, led to enhanced stratospheric NOy of less than 1% as a result of this GLE. Thus, the primary impact of the January 2005 solar events on the middle atmosphere was through protons with energies less than 300 MeV. This presentation will show both short- and longer-term changes due to the January 2005 solar protons. Gopalswamy, N., et al., Coronal mass ejections and ground level enhancements, 29th International Cosmic Ray Conference Pune, 1, 169-173, 2005. Seppala, A., et al., Destruction of the tertiary ozone maximum during a solar proton event, Geophys. Res. Lett., 33, L07804, doi:10.1029/2005GL025571, 2006. Tylka, A.J. & W.F. Dietrich, A new and comprehensive analysis of proton spectra in ground-level enhanced (GLE) solar particle events, 31st International Cosmic Ray Conference Lodz, paper 0273, 2009. Verronen, P. T., et al., Production of odd hydrogen in the mesosphere during the January 2005 solar proton event, Geophys Res. Lett., 33, L24811, doi:10.1029/2006GL028115, 2006.
    AGU Fall Meeting Abstracts. 11/2009; -1:1245.
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    ABSTRACT: This paper describes a methodology for water vapor retrieval in the mesosphere-lower thermosphere (MLT) using 6.6 μm daytime broadband emissions measured by SABER, the limb scanning infrared radiometer on board the TIMED satellite. Particular attention is given to accounting for the non-local thermodynamic equilibrium (non-LTE) nature of the H2O 6.6 μm emission in the MLT. The non-LTE H2O(ν2) vibrational level populations responsible for this emission depend on energy exchange processes within the H2O vibrational system as well as on interactions with vibrationally excited states of the O2, N2, and CO2 molecules. The rate coefficients of these processes are known with large uncertainties that undermines the reliability of the H2O retrieval procedure. We developed a methodology of finding the optimal set of rate coefficients using the nearly coincidental solar occultation H2O density measurements by the ACE-FTS satellite and relying on the better signal-to-noise ratio of SABER daytime 6.6 μm measurements. From this comparison we derived an update to the rate coefficients of the three most important processes that affect the H2O(ν2) populations in the MLT: a) the vibrational-vibrational (V–V) exchange between the H2O and O2 molecules; b) the vibrational-translational (V–T) process of the O2(1) level quenching by collisions with atomic oxygen, and c) the V–T process of the H2O(010) level quenching by collisions with N2, O2, and O. Using the advantages of the daytime retrievals in the MLT, which are more stable and less susceptible to uncertainties of the radiance coming from below, we demonstrate that applying the updated H2O non-LTE model to the SABER daytime radiances makes the retrieved H2O vertical profiles in 50–85 km region consistent with climatological data and model predictions. The H2O retrieval uncertainties in this approach are about 10% at and below 70 km, 20% at 80 km, and 30% at 85 km altitude.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 01/2009; · 5.51 Impact Factor
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    ABSTRACT: The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment is one of four instruments on NASA’s Thermosphere–Ionosphere–Energetics and Dynamics (TIMED) satellite. SABER measures broadband infrared limb emission and derives vertical profiles of kinetic temperature (Tk) from the lower stratosphere to approximately 120 km, and vertical profiles of carbon dioxide (CO2) volume mixing ratio (vmr) from approximately 70 km to 120 km. In this paper we report on SABER Tk/CO2 data in the mesosphere and lower thermosphere (MLT) region from the version 1.06 dataset. The continuous SABER measurements provide an excellent dataset to understand the evolution and mechanisms responsible for the global two-level structure of the mesopause altitude. SABER MLT Tk comparisons with ground-based sodium lidar and rocket falling sphere Tk measurements are generally in good agreement. However, SABER CO2 data differs significantly from TIME-GCM model simulations. Indirect CO2 validation through SABER-lidar MLT Tk comparisons and SABER-radiation transfer comparisons of nighttime 4.3 μm limb emission suggest the SABER-derived CO2 data is a better representation of the true atmospheric MLT CO2 abundance compared to model simulations of CO2 vmr.
    Advances in Space Research 01/2009; 43(1):15-27. · 1.18 Impact Factor
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    ABSTRACT: Thermospheric infrared radiance at 4.3 μm is susceptible to the influence of solar-geomagnetic disturbances. Ionization processes followed by ion-neutral chemical reactions lead to vibrationally excited NO+ (i.e., NO+(v)) and subsequent 4.3 μm emission in the ionospheric E-region. Large enhancements of nighttime 4.3 μm emission were observed by the TIMED/SABER instrument during the April 2002 and October–November 2003 solar storms. Global measurements of infrared 4.3 μm emission provide an excellent proxy to observe the nighttime E-region response to auroral dosing and to conduct a detailed study of E-region ion-neutral chemistry and energy transfer mechanisms. Furthermore, we find that photoionization processes followed by ion-neutral reactions during quiescent, daytime conditions increase the NO+ concentration enough to introduce biases in the TIMED/SABER operational processing of kinetic temperature and CO2 data, with the largest effect at summer solstice. In this paper, we discuss solar storm enhancements of 4.3 μm emission observed from SABER and assess the impact of NO+(v) 4.3 μm emission on quiescent, daytime retrievals of Tk/CO2 from the SABER instrument.
    Advances in Space Research 01/2009; · 1.18 Impact Factor
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    ABSTRACT: MIPAS, the Michelson Interferometer for Passive Atmospheric Sounding, is a mid-infrared emission spectrometer which is part of the core payload of ENVISAT. It is a limb sounder, i.e. it scans across the horizon detecting atmospheric spectral radiances which are inverted to vertical temperature, trace species and cloud distributions. These data can be used for scientific investigations in various research fields including dynamics and chemistry in the altitude region between upper troposphere and lower thermosphere. The instrument is a well calibrated and characterized Fourier transform spectrometer which is able to detect many trace constituents simultaneously. The different concepts of retrieval methods are described including multi-target and two-dimensional retrievals. Operationally generated data sets consist of temperature, H2O, O3, CH4, N2O, HNO3, and NO2 profiles. Measurement errors are investigated in detail and random and systematic errors are specified. The results are validated by independent instrumentation which has been operated at ground stations or aboard balloon gondolas and aircraft. Intercomparisons of MIPAS measurements with other satellite data have been carried out, too. As a result, it has been proven that the MIPAS data are of good quality. MIPAS can be operated in different measurement modes in order to optimize the scientific output. Due to the wealth of information in the MIPAS spectra, many scientific results have already been published. They include intercomparisons of temperature distributions with ECMWF data, the derivation of the whole NOy family, the study of atmospheric processes during the Antarctic vortex split in September~2002, the determination of properties of Polar Stratospheric Clouds, the downward transport of NOx in the middle atmosphere, the stratosphere-troposphere exchange, the influence of solar variability on the middle atmosphere, and the observation of Non-LTE effects in the mesosphere.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 01/2008; · 5.51 Impact Factor
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    ABSTRACT: SCIAMACHY limb scatter radiance measurements at selected wavelengths in the HARTLEY bands have been used to retrieve ozone profiles in the upper stratosphere and lower mesosphere. Comparisons with profiles measured by a ground based radiometer in Norway, MIPAS on board ENVISAT, HALOE on UARS and MLS on AURA indicate an agreement within 15% between 40 and 55 km and show that the retrieval provides reliable ozone profiles at these altitudes. Above 55 km, an increasing overestimation is observed. Beside the profile comparisons, further retrieval features of the current retrieval (version 1.26) are described.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 01/2008; · 5.51 Impact Factor
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    ABSTRACT: 1] The quality of the retrieved temperature-versus-pressure (or T(p)) profiles is described for the middle atmosphere for the publicly available Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) Version 1.07 (V1.07) data set. The primary sources of systematic error for the SABER results below about 70 km are (1) errors in the measured radiances, (2) biases in the forward model, and (3) uncertainties in the corrections for ozone and in the determination of the reference pressure for the retrieved profiles. Comparisons with other correlative data sets indicate that SABER T(p) is too high by 1–3 K in the lower stratosphere but then too low by 1 K near the stratopause and by 2 K in the middle mesosphere. There is little difference between the local thermodynamic equilibrium (LTE) algorithm results below about 70 km from V1.07 and V1.06, but there are substantial improvements/differences for the non-LTE results of V1.07 for the upper mesosphere and lower thermosphere (UMLT) region. In particular, the V1.07 algorithm uses monthly, diurnally averaged CO 2 profiles versus latitude from the Whole Atmosphere Community Climate Model. This change has improved the consistency of the character of the tides in its kinetic temperature (T k). The T k profiles agree with UMLT values obtained from ground-based measurements of column-averaged OH and O 2 emissions and of the Na lidar returns, at least within their mutual uncertainties. SABER T k values obtained near the mesopause with its daytime algorithm also agree well with the falling sphere climatology at high northern latitudes in summer. It is concluded that the SABER data set can be the basis for improved, diurnal-to-interannual-scale temperatures for the middle atmosphere and especially for its UMLT region.
    Journal of Geophysical Research 01/2008; 113. · 3.17 Impact Factor
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    ABSTRACT: In this paper we present evidence of enhanced N<sub>2</sub>O concentrations in the upper stratosphere/lower mesosphere polar regions after the solar proton events that occurred during October–November 2003. The observations were performed by the MIPAS instrument on the Envisat satellite. Simulations performed using the Canadian Middle Atmospheric Model (CMAM) show that such enhancements are most likely produced by the reaction of N(<sup>4</sup>S) with NO<sub>2</sub>, both of which species are largely enhanced just after the solar proton events in the winter polar night.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 01/2008; · 5.51 Impact Factor
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    ABSTRACT: Satellite observations show that the enormous solar proton events (SPEs) in October–November 2003 had significant effects on the composition of the stratosphere and mesosphere in the polar regions. After the October–November 2003 SPEs and in early 2004, significant enhancements of NO<sub>x</sub>(=NO+NO<sub>2</sub>) in the upper stratosphere and lower mesosphere in the Northern Hemisphere were observed by several satellite instruments. Here we present global full chemistry calculations performed with the CLaMS model to study the impact of mesospheric NO<sub>x</sub> intrusions on Arctic polar ozone loss processes in the stratosphere. Several model simulations are preformed with different upper boundary conditions for NO<sub>x</sub> at 2000 K potential temperature (≈50 km altitude). In our study we focus on the impact of the non-local production of NO<sub>x</sub>, which means the downward transport of enhanced NO<sub>x</sub> from the mesosphere to the stratosphere. The local production of NO<sub>x</sub> in the stratosphere is neglected. Our findings show that intrusions of mesospheric air into the stratosphere, transporting high burdens of NO<sub>x</sub>, affect the composition of the Arctic polar region down to about 400 K (≈17–18 km). We compare our simulated NO<sub>x</sub> and O<sub>3</sub> mixing ratios with satellite observations by ACE-FTS and MIPAS processed at IMK/IAA and derive an upper limit for the ozone loss caused by enhanced mesospheric NO<sub>x</sub>. Our findings show that in the Arctic polar vortex (equivalent lat.>70° N) the accumulated column ozone loss between 350–2000 K potential temperature (≈14–50 km altitude) caused by the SPEs in October–November 2003 in the stratosphere is up to 3.3 DU with an upper limit of 5.5 DU until end of November. Further, we found that about 10 DU, but in any case lower than 18 DU, accumulated ozone loss additionally occurred until end of March 2004 caused by the transport of mesospheric NO<sub>x</sub>-rich air in early 2004. The solar-proton-produced NO<sub>x</sub> above 55 km due to the SPEs of October–November 2003 had a negligibly small impact on ozone loss processes through the end of November in the lower stratosphere (350–700 K≈14–27 km). The mesospheric NO<sub>x</sub> intrusions in early 2004 yielded a lower stratospheric ozone loss of about 3.5 DU, and clearly lower than 6.5 DU through the end of March. Overall, the non-local production of NO<sub>x</sub> is an additional variability in the existing variations of the ozone loss observed in the Arctic.
    ATMOSPHERIC CHEMISTRY AND PHYSICS 01/2008; · 5.51 Impact Factor

Publication Stats

1k Citations
163.59 Total Impact Points

Institutions

  • 1985–2013
    • Instituto De Astrofisica De Andalucia
      Granata, Andalusia, Spain
  • 2010
    • Hampton VA Medical Center
      Hampton, Virginia, United States
  • 1999–2006
    • Spanish National Research Council
      • • Institute of Fundamental Physics
      • • Andalusian Astrophysics Institute
      Madrid, Madrid, Spain
  • 1986
    • University of Oxford
      Oxford, England, United Kingdom