ALBERT

Description: Large strike-slip faults in the eastern Betics are interpreted to have developed in a transcurrent setting in response to 4-6 mm/yr of Africa-Iberia NW-SE convergence. However, here we show that some of these faults are transfer faults accommodating heterogeneous late Miocene extension. The north–Cabrera dextral fault and other E–W to NE–SW strike-slip faults in the Sorbas basin were transfer faults produced under SW–NE extension. These faults together with related normal faults form the main boundaries of two sedimentary depocenters active between the Serravallian and the Tortonian. The older north Cabrera depocenter extended between the Serravallian and the early Tortonian (approx. 13.8 to 9 Ma), whilst the younger Gacía depocenter formed in response to late Tortonian extension (approx. 9 to 7.5 Ma). The latter formed to the west of the north Cabrera depocenter by a listric fan of normal faults with SW-directed transport that are linked by dextral and sinistral transfer fault segments. These faults root on a low-angle detachment cutting into the exhumed high-pressure Nevado–Filabride complex rocks at ~0.8 km depth. The present work reveals that 1) this extension was partially coeval with and kinematically linked to sinistral displacement along the Carboneras fault farther south in the Níjar basin; 2) this westward-directed extension produced elongated core-complexes and tilted-blocks to the north of the Carboneras fault and magmatic accretion upon thinned continental crust to the south, probably in response to slab tearing or detachment and associated edge delamination of the Iberian continental lithospheric mantle beneath the Betics.

Description: Interpretation of new multichannel seismic reflection profiles indicates that the Palomares margin formed by crustal-scale extension and coeval magmatic accretion during middle to late Miocene opening of the Algero-Balearic basin. The margin formed at the transition between thinned continental crust intruded by arc volcanism and back-arc oceanic crust. Deformation produced during the later positive inversion of the margin offshore and onshore is partitioned between ~N50°E striking reverse faults and associated folds like the Sierra Cabrera and Abubacer anticlines, and N10-20°E sinistral strike-slip faults like Palomares and Terreros faults. Parametric sub-bottom profiles and multibeam bathymetry offshore, structural analysis, available GPS geodetic displacement data and earthquake focal mechanisms jointly indicate that tectonic inversion of the Palomares margin is currently active. The Palomares margin shows a structural pattern comparable to the north Maghrebian margins where Africa-Eurasia plate convergence is accommodated by NE-SW reverse faults, NNW-SSE sinistral faults and WNW-ESE dextral ones. Contractive structures at this margin contribute to the general inversion of the Western Mediterranean since ~7 Ma ago, coeval to inversion at the Algerian margin. Shortening at the Alboran ridge and Al-Idrisi faults occurred later, since 5 Ma, indicating a westward propagation of the compressional inversion of the Western Mediterranean.

Description: The study uses a Monte Carlo radiative transfer model to examine the sensitivity of the UV Erythemal radiation (UVER) enhancement to broken liquid water clouds of the cumulus and stratocumulus type. The model uses monochromatic radiation at 310 nm corresponding approximately to the peak of the product between irradiance and the erythemal curve. All scattering, absorption, extinction coefficients and spectral albedos are tuned to this wavelength. In order of importance, fractional cloud cover, the area of individual cloud patches and cloud thickness exert a strong influence on the enhancement, with smaller contributions from cloud optical depth, cloud base height and solar zenith angle. In order to produce realistic enhancements for our study area located in the Valencia region of Spain (39° 30’ N; 0° 25’W), measurements were obtained from a Landsat image of the region in combination with a spectral Fourier transform model. The Monte Carlo model, as applied to the Fourier transform cloud distribution, produced satisfactory results compared to one year of measured UVER enhancement for the study region provided fractional cloud cover was equal to or greater than 3/10. At smaller cloud fractions, the neglect of cloud patches less than 50 m x 50 m in area by the model created significant discrepancies.

Description: The urban population of South America has grown at 1.05% per year, greater urbanization increasing problems related to air pollution. In most large cities in South America, there has been no continuous long-term measurement of regulated pollutants. One exception is São Paulo, Brazil, where an air quality-monitoring network has been in place since the 1970s. In this paper, we used an air quality-based approach to determine pollutant trends for emissions of carbon monoxide (CO), nitrogen oxides (NO x ), ozone (O 3 ) and coarse particulate matter (PM 10 ), mostly from mobile sources, in the Metropolitan Region of São Paulo (MRSP) for the 2000–2013 period. Mobile sources included light-duty vehicles (LDVs, comprising gasoline- or ethanol-powered cars and motorcycles) and heavy-duty vehicles (HDVs, comprising diesel-powered trucks and buses). Pollutant concentrations for mobile source emissions were measured and correlated with fuel sales by the emission factors. Over the 2000–2013 period, concentrations of NO x , CO, and PM 10 decreased by 0.65, 0.37, and 0.71% month −1 , respectively, whereas sales of gasoline, ethanol, and diesel increased by 0.26, 1.96, and 0.38% month −1 , respectively. LDVs were the major mobile source of CO, whereas LDVs were the major source of NO x and PM 10 . Increases in fuel sales and in the corresponding traffic volume were partially offset by decreases in pollutant concentrations. Between 2000 and 2013, there was a sharp (−5 ppb month −1 ) decrease in the concentrations of LDV-emitted CO, together with (less dramatic) decreases in the concentrations of HDV-emitted NO x and PM 10 (−0.25 and −0.09 ppb month −1 , respectively). Variability was greater for HDV-emitted NO x and PM 10 (R = −0.47 and −0.41, respectively) than for LDV-emitted CO (R = −0.72). We draw the following conclusions: the observed concentrations of LDV-emitted CO decreased at a sharper rate than did those of HDV-emitted NO x and PM 10 ; mobile source contributions to O 3 formation varied significantly, LDVs making a greater contribution during the 2000–2008 period, whereas HDVs made a greater contribution during the 2009–2013 period; and decreases in NO x emissions resulted in increases in O 3 observations.

Description: We examine in detail a one-year global reanalysis of carbon monoxide (CO) that is based on joint assimilation of conventional meteorological observations and Measurement of Pollution in The Troposphere (MOPITT) multispectral CO retrievals in the Community Earth System Model (CESM). Our focus is to assess the impact to the chemical system when CO distribution is constrained in a coupled full chemistry-climate model like CESM. To do this, we first evaluate the joint reanalysis (MOPITT Reanalysis) against four sets of independent observations and compare its performance against a reanalysis with no MOPITT assimilation (Control Run). We then investigate the CO burden and chemical response with the aid of tagged sectoral CO tracers. We estimate the total tropospheric CO burden in 2002 (from ensemble mean and spread) to be 371 ±12% Tg for MOPITT Reanalysis and 291 ± 9 % Tg for Control Run. Our multi-species analysis of this difference suggests that: a) direct emissions of CO and hydrocarbons are too low in the inventory used in this study; and b) chemical oxidation, transport, and deposition processes are not accurately and consistently represented in the model. Increases in CO led to net reduction of OH and subsequent longer lifetime of CH 4 (Control Run: 8.7 years versus MOPITT Reanalysis: 9.3 years). Yet, at the same time, this increase led to 5-10% enhancement of northern hemisphere O 3 and overall photochemical activity via HO X recycling. Such nonlinear effects further complicate the attribution to uncertainties in direct emissions alone. This has implications to chemistry-climate modeling and inversion studies of longer-lived species.

Description: A regional study starting from detailed geological mapping has been carried out in the Malpica-Tui Complex of Galicia in NW Spain. The complex is formed by two units representing pieces of the external edge of Gondwana, subducted and exhumed during the Variscan collision. The study shows that synsubduction and early synexhumation structures in continental subduction channels tends to be obscured and even erased once exhumation is complete. Detailed structural analysis, matched with the knowledge of the history, and available data for other Galician basal units have elucidated the major structures developed during the subduction-exhumation process. The results include evidence of the plate convergence causing early Variscan continental subduction of the Gondwana margin. Subduction was followed by exhumation driven by ductile thrusting within the subduction channel, which, in turn, provoked crustal duplication in the subducted slab and modified the initial tectonometamorphic architecture of the subduction wedge. The next step was accretion to the adjacent continental domains, placing the subduction wedge on top of unsubducted parts of the Gondwana margin via ductile thrusting. Thrusting was preceded by progressive propagation of a train of recumbent folds toward the foreland that affected the previous structural stack. Subsequent transference of oceanic (Rheic) and peri-Gondwanan terranes to the Gondwana margin took place by out-of-sequence thrusting followed by crustal extensional collapse and strike-slip tectonics.

Description: A P-wave seismic velocity model has been obtained for the Central Iberian Zone, the largest continental fragment of the Iberian Variscan Belt. The spatially dense, high-resolution, wide-angle seismic reflection experiment ALCUDIA-WA, was acquired in 2012 across central Iberia, aiming to constrain the lithospheric structure and resolve the physical properties of the crust and upper mantle. The seismic transect, ~310 km long crossed the Central Iberian Zone from its suture with the Ossa-Morena Zone to the southern limit of the Central System mountain range. The energy generated by 5 shots, was recorded by ~900 seismic stations. High amplitude phases were identified in every shot gather for the upper crust (Pg and PiP) and Moho (PmP and Pn). In the upper crust, the P-wave velocities increase beneath the Cenozoic Tajo Basin. The base of the upper crust varies from ~13 km to ~20 km between the southernmost Central Iberian Zone and the Tajo Basin. Lower crustal velocities are more homogeneous. From SW-NE, the travel-time of PmP arrivals varies from ~10.5 s to ~11.8 s, indicating lateral variations in the P-wave velocity and the crustal thickness, reflecting an increase towards the north related with alpine tectonics and the isostatic response of the crust to the orogenic load. The results suggest that the high velocities of the upper crust near the Central System might correspond to igneous rocks and/or high grade metamorphis rocks. The contrasting lithologies and the increase in the Moho depth to the north evidence differences in the Variscan evolution.

Description: [1]  Validation results are reported for the MOPITT (Measurements of Pollution in the Troposphere) “Version 5” (V5) product for tropospheric carbon monoxide (CO) and are compared to results for the “Version 4” product. The V5 retrieval algorithm introduces (1) a method for reducing retrieval bias drift associated with long-term instrumental degradation, (2) a more exact representation of the effects of random errors in the radiances and, for the first time, (3) the use of MOPITT's near-infrared (NIR) radiances to complement the thermal-infrared (TIR) radiances. Exploiting TIR and NIR radiances together facilitates retrievals of CO in the lowermost troposphere. V5 retrieval products based (1) solely on TIR measurements, (2) solely on NIR measurements and (3) on both TIR and NIR measurements are separately validated and analyzed. Actual retrieved CO profiles and total columns are compared with equivalent retrievals based on in-situ measurements from (1) routine NOAA aircraft sampling mainly over North America and (2) the “HIAPER Pole to Pole Observations” (HIPPO) field campaign. Particular attention is focused on the long-term stability and geographical uniformity of the retrieval errors. Results for the retrieved total column clearly indicate reduced temporal bias drift in the V5 products compared to the V4 product, and do not exhibit a positive bias in the Southern Hemisphere which is evident in the V4 product.

Description: ALCUDIA is a 230 km long, vertical incidence deep seismic reflection transect acquired in spring 2007 across the southern Central Iberian Zone (part of the pre-Mesozoic Gondwana paleocontinent) of the Variscan Orogen of Spain. The carefully designed acquisition parameters resulted in a 20 s TWTT deep, 60–90 fold, high-resolution seismic reflection transect. The processed image shows a weakly reflective upper crust (the scarce reflectivity matching structures identified at surface), a thick, highly reflective and laminated lower crust, and a flat Moho located at 10 s TWTT (∼30 km depth). The transect can be divided into three segments with different structural styles in the lower crust. In the central segment, the lower crust is imaged by regular, horizontal and parallel reflectors, whereas in the northern and southern segments it displays oblique reflectors interpreted as an important thrust (north) and tectonic wedging involving the mantle (south). The ALCUDIA seismic image shows that in an intracontinental orogenic crust, far from the suture zones, the upper and lower crust may react differently to shortening in different sectors, which is taken as evidence for decoupling. The interpreted structures, as deduced from surface geology and the seismic image, show that deformation was distributed homogeneously in the upper crust, whereas it was concentrated in wedge/thrust structures at specific sectors in the lower crust. The seismic image also shows the location of late Variscan faults in spatial association with the lower crustal thickened areas.

Description: On 21 August 2009, the Airborne Detector for Energetic Lightning Emissions (ADELE), an array of six gamma-ray detectors, detected a brief burst of gamma rays while flying aboard a Gulfstream V jet near two active thunderstorm cells. The duration and spectral characteristics of the event are consistent with the terrestrial gamma ray flashes (TGFs) seen by instruments in low Earth orbit. A long-duration, complex +IC flash was taking place in the nearer cell at the same time, at a distance of ∼10 km from the plane. The sferics that are probably associated with this flash extended over 54 ms and included several ULF pulses corresponding to charge moment changes of up to 30 C km, this value being in the lower half of the range of sferics associated with TGFs seen from space. Monte Carlo simulations of gamma ray propagation in the Earth's atmosphere show that a TGF of normal intensity would, at this distance, have produced a gamma ray signal in ADELE of approximately the size and spectrum that was actually observed. We conclude that this was the first detection of a TGF from an aircraft. We show that because of the distance, ADELE's directional and spectral capabilities could not strongly constrain the source altitude of the TGF but that such constraints would be possible for TGFs detected at closer range.