M. López-Puertas

Instituto De Astrofisica De Andalucia, Granata, Andalusia, Spain

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Publications (272)437.33 Total impact

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    ABSTRACT: We use NO, NO2 and CO from MIPAS/ENVISAT to investigate the impact of energetic particle precipitation onto the NOx budget from the stratosphere to the lower mesosphere in the period from October 2003 to March 2004, a time of high solar and geomagnetic activity. We find that in the winter hemisphere the indirect effect of auroral electron precipitation due to downwelling of upper mesospheric/lower thermospheric air into the stratosphere prevails. Its effect exceeds even the direct impact of the very large solar proton event in October/November 2003 by nearly one order of magnitude. Correlations of NOx and CO show that the unprecedented high NOx values observed in the Northern Hemisphere lower mesosphere and upper stratosphere in late January and early February are fully consistent with transport from the upper mesosphere/lower thermosphere and subsequent mixing at lower altitudes; an additional source of NOx due to local production by precipitating electrons at altitudes below 70 km as discussed in previous publications appears unlikely. In the polar summer Southern Hemisphere, we observed an enhanced variability of NO and NO2 on days with enhanced geomagnetic activity but they seem to indicate enhanced instrument noise rather than a direct increase due to electron precipitation. A direct effect of electron precipitation onto NOx can not be ruled out, but if any, it is lower than 3 ppb in the altitude range 40-56 km and lower than 6 ppb in the altitude range 56-70 km.
    Atmospheric Chemistry and Physics 12/2013; 14(1). · 5.51 Impact Factor
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    ABSTRACT: [1] In this paper, observations by thermosphere, ionosphere, mesosphere energetics and dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry from 2002 to 2012 and by Envisat/Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) from 2008 to 2009 are used to study the longitudinal structure of temperature in the lower thermosphere. In order to remove the longitudinal structure induced by tides, diurnally averaged SABER temperatures are used. For MIPAS data, we use averaged temperatures between day and night. The satellite observations show that there are strong longitudinal variations in temperature in the high-latitude lower thermosphere that persist over all seasons. The peak of the diurnally averaged temperature in the lower thermosphere always occurs around the auroral zone. A clear asymmetry between the two hemispheres in the longitudinal temperature structure is observed, being more pronounced in the Southern than in the Northern Hemisphere. In both hemispheres, the longitudinal variation is dominated by the first harmonic in longitude. The total radiative cooling observed by SABER has a structure in longitude that is similar to that of temperature. Modeling simulations using the Thermosphere-Ionosphere-Electrodynamics General Circulation Model reproduce similar features of the longitudinal variations of temperature in the lower thermosphere. Comparison of two model runs with and without auroral heating confirms that auroral heating causes the observed longitudinal variations. The multiyear averaged vertical structures of temperature observed by the two satellite instruments indicate that the impact of auroral heating on the thermodynamics of the neutral atmosphere can penetrate down to about 105 km.
    Journal of Geophysical Research: Space Physics 11/2013; 118(11). · 3.44 Impact Factor
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    Dataset: Funke2012a
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    ABSTRACT: The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere at the terminator in the upper mesosphere and lower thermosphere (70 to 170 km) with an emphasis on vertical distribution of the gases. In particular, measurements of CO2 density vertical profiles have been routinely performed. From these density measurements, kinetic temperature profiles are derived using the hydrostatic equilibrium. A permanent cold layer is observed at the mesopause (± 120 km). A different and independent method is developed here, making use of the information obtained from the rotational structure of the CO2 bands to derive rotational temperature profiles. The rotational temperature profiles are compared to the hydrostatic temperature profiles, and they confirm the presence of the cold layer at the mesopause.
    09/2013;
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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: Observations of Titan atmosphere made with the VIMS instrument on board the Cassini satellite show a strong limb emission around 3.3 μm at high atmospheric altitudes (above 700 km). This emission exhibits the spectral signatures of the strong CH4 bands. A detailed analysis of the spectra reveals an additional strong emission centered at 3.28 μm and peaking at about 950 km. Here we present an analysis of this residual spectra and show that it attributed to emission from heavy aromatic hydrocarbon compounds.
    09/2013;
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    ABSTRACT: In this paper, we analyze the strong unidentified emission near 3.28 μm in Titan’s upper daytime atmosphere recently discovered by Dinelli et al.We have studied it by using the NASA Ames PAH IR Spectroscopic Database. The polycyclic aromatic hydrocarbons (PAHs), after absorbing UV solar radiation, are able to emit strongly near 3.3 μm. By using current models for the redistribution of the absorbed UV energy, we have explained the observed spectral feature and have derived the vertical distribution of PAH abundances in Titan’s upper atmosphere. PAHs have been found to be present in large concentrations, about (2–3) × 104 particles cm−3. The identified PAHs have 9–96 carbons, with a concentration-weighted average of 34 carbons. The mean mass is ∼430 u; the mean area is about 0.53 nm2; they are formed by 10–11 rings on average, and about one-third of them contain nitrogen atoms. Recently, benzene together with light aromatic species as well as small concentrations of heavy positive and negative ions have been detected in Titan’s upper atmosphere. We suggest that the large concentrations of PAHs found here are the neutral counterpart of those positive and negative ions, which hence supports the theory that the origin of Titan main haze layer is located in the upper atmosphere.
    The Astrophysical Journal 06/2013; 770:132. · 6.73 Impact Factor
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    ABSTRACT: During the solar proton events (SPE) on 23-30 January and 7-15 March 2012, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat monitored atmospheric temperature and composition with global coverage. In the Northern Hemisphere, the January SPE started at the end of a polar stratospheric warming period. The SPE effect is superimposed by large-scale subsidence of mesospheric NOx-rich air, which partly masks direct chemical SPE effects. SPE-induced NOx increases by 5, 20, 50, and 100 ppbv at altitudes of 50, 57, 60, and 70 km, respectively, are observed during the January SPE and those by 2, 5, 10, 20, 30, and 35 ppbv at altitudes of 47, 50, 53, 60, 63, and 66 km, respectively, during the March SPE. SPE-related ozone loss is clearly observed in the mesosphere, particularly in the tertiary ozone maximum. A sudden short-term HNO4 increase immediately after the January SPE hints at SPE-triggered HOx chemistry. In the Southern Hemisphere, a large NOx response is observed (increases by 2, 5, 10, 20, and 30 ppbv at 52, 56, 59, 63, and 70 km in January and by 2, 5, 10, 20, 30, and 35 ppbv at 47, 50, 53, 60, 63, and 66 km in March), while the effect on other species seems much less pronounced than in the Northern Hemisphere. SPE-related destruction of mesospheric ozone in the Southern Hemisphere was much more pronounced after the March SPE than the January SPE but in both cases, ozone recovered within about a day.
    Geophysical Research Letters 05/2013; 40(10):2339-2343. · 3.98 Impact Factor
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    ABSTRACT: [1] Ozone profiles in the upper mesosphere (70–100 km) retrieved from nine instruments are compared. Ozone from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument is used as the basis of comparison. Other measurements are from the Halogen Occultation Experiment, the High Resolution Doppler Imager, the Michelson Interferometer for Passive Atmospheric Sounding, the Global Ozone Monitoring by Occultation of Stars, the Atmospheric Chemistry Experiment—Fourier Transform Spectrometer, the Solar Occultation For Ice Experiment, the Optical Spectrograph and InfraRed Imaging System, and the Superconducting Submillimeter-Wave Limb-Emission Sounder. Comparisons of each data set with SABER using coincident profiles indicate agreement in the basic vertical profile of ozone but also some systematic differences in daytime ozone. Ozone from the SABER 9.6 μm channel is higher than the other measurements over the altitude range 60–80 km by 20–50%. Nighttime comparisons indicate better relative agreement (<10% difference). Taking all the data, not limited to coincidences, shows the global and seasonal distributions of ozone in the upper mesosphere from each instrument. The average maximum in ozone mixing ratio is around 90–92 km during daytime and 95 km at night. There is a maximum in ozone density at night (∼90 km) and during some hours of the day. The latitude structure of ozone has appreciable variations with season, particularly in the tropical upper mesosphere. The basic latitude-altitude structure of ozone depends on local time, even when the analysis is restricted to day-only observations.
    Journal of Geophysical Research 05/2013; · 3.17 Impact Factor
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    ABSTRACT: We use the ultra-violett (UV) spectra in the range 230-300 nm from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) to retrieve the nitric oxide (NO) number densities from atmospheric emissions in the gamma-bands in the mesosphere and lower thermosphere. Using 3-D ray tracing, a 2-D retrieval grid, and regularisation with respect to altitude and latitude, we retrieve a whole semi-orbit simultaneously for the altitude range from 60 to 160 km. We present details of the retrieval algorithm, first results, and initial comparisons to data from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Our results agree on average well with MIPAS data and are compatible with previously published measurements from other instruments. For the time of available measurements in 2008-2011, we achieve a vertical resolution of 5-10 km in the altitude range 70-140 km and a horizontal resolution of about 9° from 60° S-60° N. With this we have independent measurements of the NO densities in the mesosphere and lower thermosphere with approximately global coverage.
    Atmospheric Measurement Techniques 04/2013; 6(2):3611-3642. · 3.21 Impact Factor
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    ABSTRACT: We have analyzed limb daytime observations of Titan's upper atmosphere at 3.3 μm, acquired by the visual-infrared mapping spectrometer (VIMS) on Cassini. They were previously studied by García-Comas et al. (2011) to derive CH4 densities. Here, we report an unidentified emission peaking around 3.28 μm, hidden under the methane R branch. This emission is very strong, with intensity comparable to the CH4 bands located in the same spectral region. It presents a maximum at about 950 km and extends from 600 km up to 1250 km. It is definitely pumped by solar radiation since it vanishes at night. Our analysis shows that neither methane nor the major hydrocarbon compounds already discovered in Titan's upper atmosphere are responsible for it. We have discarded many other potential candidates and suggest that the unidentified emission might be caused by aromatic compounds.
    Geophysical Research Letters 01/2013; 40(8):1489. · 3.98 Impact Factor
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    ABSTRACT: The MIPAS instrument on the ENVISAT satellite has provided vertical profiles of the atmospheric composition on a global scale for almost ten years. The MIPAS mission is divided in two phases, the full resolution phase, from 2002 to 2004, and the optimized resolution phase, from 2005 to 2012, which is characterized by a finer vertical and horizontal sampling attained through a reduction of the spectral resolution. While the description and characterization of the products of the ESA processor for the full resolution phase has been already described in previous papers, in this paper we focus on the performances of the latest version of the ESA processor, named ML2PP V6, which has been used for reprocessing the entire mission. The ESA processor had to perform the operational near real time analysis of the observations and its products needed to be available for data assimilation. Therefore, it has been designed for fast, continuous and automated analysis of observations made in quite different atmospheric conditions and for a minimum use of external constraints in order to avoid biases in the products. The dense vertical sampling of the measurements adopted in the second phase of the MIPAS mission resulted in sampling intervals finer than the instantaneous field of view of the instrument. Together with the choice of a retrieval grid aligned with the vertical sampling of the measurements, this made ill-conditioned the retrieval formalism of the MIPAS operational processor. This problem has been handled with minimal changes to the original retrieval approach but with significant improvements nonetheless. The Levenberg-Marquardt method, already present in the retrieval scheme for its capability to provide fast convergence for non-linear problems, is now also exploited for the reduction of the ill-conditioning of the inversion. An expression specifically designed for the regularizing Levenberg-Marquardt method has been implemented for the computation of the covariance matrices and averaging kernels of the retrieved products. The regularization of the Levenberg-Marquardt method is controlled by the convergence criteria and is deliberately kept weak. The resulting oscillations of the retrieved profile are a-posteriori damped by an innovative self-adapting Tikhonov regularization. The convergence criteria and the weakness of the self-adapting regularization ensure that minimum constraints are used and the best vertical resolution obtainable from the measurements is achieved in all atmospheric conditions. Random and systematic errors, as well as vertical and horizontal resolution are compared in the two phases of the mission for all products, namely: temperature, H2O, O3, HNO3, CH4, N2O, NO2, CFC-11, CFC-12, N2O5 and ClONO2. The use in the two phases of the mission of different optimized sets of spectral intervals ensures that, despite the different spectral resolutions, comparable performances are obtained in the whole MIPAS mission in terms of random and systematic errors, while the vertical resolution and the horizontal resolution are significantly better in the case of the optimized resolution measurements.
    Atmospheric Measurement Techniques 01/2013; 6(1):461-518. · 3.21 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: We present in this paper the Generic RAdiative traNsfer AnD non-LTE population Algorithm (GRANADA). This model is able to compute non-LTE populations for vibrational, rotational, spin (i.e., NO and OH), and electronic (i.e., O2) states in a given planetary atmosphere. The model is very flexible and can be used for computing very accurate non-LTE populations or for calculating reasonably accurate but at high speed non-LTE populations in order to implement it into non-LTE remote sensing retrievals. We describe the model in detail and present an update of the non-LTE collisional processes and their rate coefficients for the most important molecules in Earth's atmosphere. In addition, we have applied the model to the most important atmospheric infrared emitters including 13 species (H2O, CO2, O3, N2O, CO, CH4, O2, NO, NO2, HNO3, OH, N2, and HCN) and 460 excited vibrational or electronic energy levels. Non-LTE populations for all these energy levels have been calculated for 48 reference atmospheres expanding from the surface up to 200 km, including seasonal (January, April, July and October), latitudinal (75°S, 45°S, 10°S, 10°N, 45°N, 75°N) and diurnal (day and night) coverages. The effects of the most recent updates of the non-LTE collisional parameters on the non-LTE populations are briefly described. This climatology is available online to the community and it can be used for estimating non-LTE effects at specific conditions and for testing and validation studies.
    Journal of Quantitative Spectroscopy and Radiative Transfer 09/2012; 113(14):1771–1817. · 2.38 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;
  • A. K. Smith, M. Lopez-Puertas, V. Harvey, M. G. Mlynczak
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    ABSTRACT: Multiyear global observations from the SABER and MIPAS satellite instruments show the variations of the secondary maximum of ozone in the upper mesosphere (90-100 km). The ozone concentrations have large diurnal and seasonal cycles and also vary on daily to weekly timescales. We investigate the relative contributions and timescales of photochemistry, temperature dependent chemical reactions, and transport and diffusion of ozone and other trace species. Additional satellite observations from these and other instruments contribute to and constrain the analysis. Simulations with the Whole Atmosphere Community Climate Model reproduce much of the variability but the ozone concentrations in the model are lower than observed. Detailed comparisons between model and observations are used to investigate the processes responsible for the differences. At high latitudes during NH winter, variations in ozone are forced at some times by temperature variations, through temperature dependent chemical reaction rates, and at others by variations in atomic hydrogen concentration.
    AGU Fall Meeting Abstracts. 12/2011;
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    ABSTRACT: Vertical profiles of hydrogen cyanide (HCN) have been retrieved from Cassini/VIMS limb observations in the region from 600 to 1100 km of the Titan's atmosphere by analyzing the 3 μm emission. HCN concentrations show a very good correlation with solar zenith angles, for different latitudes and local times. This would indicate that HCN is in (or close to) photochemical equilibrium in the sounded region.
    10/2011;
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    ABSTRACT: This paper summarizes the work presented in [1]. In that work, we fulfilled a thorough analysis of Titan's methane limb emission at 3.3 μm measured by VIMS in Titan. Methane is, after nitrogen, the most abundant species in Titan's atmosphere. It plays an important role in its chemistry and energy budget and strongly emits during daytime around 3.3 μm. In Titan's upper atmosphere, where pressure is low, that emission is affected by non-local thermodynamic equilibrium. Therefore, its analysis needs from a modeling of the population of the emitting levels considering specifically the mechanisms able to excite and de-excite them. We developed a sophisticated non-LTE model that includes all known excitation mechanisms and calculates the population of 22 CH4 vibrational levels from two isotopes. We simulated VIMS radiance and identified the bands that significantly contribute to the total measured signal. We also retrieved daytime methane abundance from 500 to 1100 km and compared our results with other measurements and results from models.
    10/2011;
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    02/2011;

Publication Stats

3k Citations
437.33 Total Impact Points

Institutions

  • 1985–2013
    • Instituto De Astrofisica De Andalucia
      Granata, Andalusia, Spain
  • 2010
    • Hampton VA Medical Center
      Hampton, Virginia, United States
  • 1998–2009
    • Spanish National Research Council
      • • Andalusian Astrophysics Institute
      • • Institute of Fundamental Physics
      Madrid, Madrid, Spain
  • 2006
    • Aristotle University of Thessaloniki
      Saloníki, Central Macedonia, Greece
  • 2005
    • Air Force Research Laboratory
      Washington, Washington, D.C., United States
  • 2000
    • National Center for Atmospheric Research
      Boulder, Colorado, United States
  • 1986
    • University of Oxford
      Oxford, England, United Kingdom