719 research outputs found
Analyzing the turbulent planetary boundary layer by remote sensing systems: the Doppler wind lidar, aerosol elastic lidar and microwave radiometer
he planetary boundary layer (PBL) is the lowermost
region of troposphere and is endowed with turbulent
characteristics, which can have mechanical and/or thermodynamic
origins. This behavior gives this layer great importance,
mainly in studies about pollutant dispersion and
weather forecasting. However, the instruments usually applied
in studies of turbulence in the PBL have limitations
in spatial resolution (anemometer towers) or temporal resolution
(instrumentation aboard an aircraft). Ground-based
remote sensing, both active and passive, offers an alternative
for studying the PBL. In this study we show the capabilities
of combining different remote sensing systems (microwave
radiometer – MWR, Doppler lidar – DL – and elastic lidar
– EL) for retrieving a detailed picture on the PBL turbulent
features. The statistical moments of the high frequency distributions
of the vertical wind velocity, derived from DL,
and of the backscattered coefficient, derived from EL, are
corrected by two methodologies, namely first lag correction
and -2=3 law correction. The corrected profiles, obtained
from DL data, present small differences when compared with
the uncorrected profiles, showing the low influence of noise
and the viability of the proposed methodology. Concerning
EL, in addition to analyzing the influence of noise, we explore
the use of different wavelengths that usually include
EL systems operated in extended networks, like the European
Aerosol Research Lidar Network (EARLINET),This work was supported by the Andalusia
Regional Government through project P12-RNM-2409 and by the
Spanish Agencia Estatal de Investigación (AEI) through projects
CGL2016-81092-R and CGL2017-90884-REDT. We acknowledge
the financial support by the European Union’s Horizon 2020
research and innovation program through project ACTRIS-2 (grant
agreement no. 654109)
Experimental techniques for the calibration of lidar depolarization channels in EARLINET
Particle depolarization ratio retrieved from lidar measurements are commonly used for aerosol-typing studies, microphysical inversion, or mass concentration retrievals. The particle depolarization ratio is one of the primary parameters that can differentiate several major aerosol components but only if the measurements are accurate enough. The accuracy related to the retrieval of particle depolarization ratios is the driving factor for assessing and improving the uncertainties of the depolarization products. This paper presents different depolarization calibration procedures used to improve the quality of the depolarization data. The results illustrate a significant improvement of the depolarization lidar products for all the selected lidar stations that have implemented depolarization calibration procedures. The calibrated volume and particle depolarization profiles at 532 nm show values that fall within a range that is generally accepted in the literature
Aerosol backscatter profiles from ceilometers: validation of water vapor correction in the framework of CeiLinEx2015
With the rapidly growing number of automated single-wavelength backscatter
lidars (ceilometers), their potential benefit for aerosol remote sensing
received considerable scientific attention. When studying the accuracy of
retrieved particle backscatter coefficients, it must be considered that most
of the ceilometers are influenced by water vapor absorption in the spectral
range around 910 nm. In the literature methodologies have been proposed to correct for this
effect; however, a validation was not yet performed. In
the framework of the ceilometer intercomparison campaign CeiLinEx2015 in
Lindenberg, Germany, hosted by the German Weather Service, it was possible to
tackle this open issue. Ceilometers from Lufft (CHM15k and CHM15kx, operating
at 1064 nm), from Vaisala (CL51 and CL31) and from Campbell Scientific
(CS135), all operating at a wavelength of approximately 910 nm, were
deployed together with a multi-wavelength research lidar (RALPH) that served
as a reference. In this paper the validation of the water vapor correction is
performed by comparing ceilometer backscatter signals with measurements of
the reference system extrapolated to the water vapor regime. One inherent
problem of the validation is the spectral extrapolation of particle optical
properties. For this purpose AERONET measurements and inversions of RALPH
signals were used. Another issue is that the vertical range where validation
is possible is limited to the upper part of the mixing layer due to incomplete
overlap and the generally low signal-to-noise ratio and signal artifacts
above that layer. Our intercomparisons show that the water vapor correction
leads to quite a good agreement between the extrapolated reference signal and
the measurements in the case of CL51 ceilometers at one or more wavelengths
in the specified range of the laser diode's emission. This ambiguity is due
to the similar effective water vapor transmission at several wavelengths. In
the case of CL31 and CS135 ceilometers the validation was not always
successful. That suggests that error sources beyond the water vapor
absorption might be dominant. For future applications we recommend monitoring
the emitted wavelength and providing “dark” measurements on a regular
basis.</p
Four-dimensional distribution of the 2010 Eyjafjallajökull volcanic cloud over Europe observed by EARLINET
© Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 License.The eruption of the Icelandic volcano Eyjafjallaj ökull in April-May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET). Based on multi-wavelength Raman lidar systems, EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude. In this work we show the four-dimensional (4-D) distribution of the Eyjafjallajökull volcanic cloud in the troposphere over Europe as observed by EARLINET during the entire volcanic event (15 April-26 May 2010). All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio) are stored in the EARLINET database available at www.earlinet.org. A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at www.earlinet.org. During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the upper troposphere down to the local planetary boundary layer (PBL). After 19 April 2010, volcanic particles were detected over southern and south-eastern Europe. During the first half of May (5-15 May), material emitted by the Eyjafjallajökull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. The last observations of the event were recorded until 25 May in Central Europe and in the Eastern Mediterranean area. The 4-D distribution of volcanic aerosol layering and optical properties on European scale reported here provides an unprecedented data set for evaluating satellite data and aerosol dispersion models for this kind of volcanic events.Peer reviewe
Hygroscopic growth of atmospheric aerosol particles based on active remote sensing and radiosounding measurements: selected cases in southeastern Spain
A new methodology based on combining active and passive remote sensing and simultaneous and collocated radiosounding data to study the aerosol hygroscopic growth effects on the particle optical and microphysical properties is presented. The identification of hygroscopic growth situations combines the analysis of multispectral aerosol particle backscatter coefficient and particle linear depolarization ratio with thermodynamic profiling of the atmospheric column. We analyzed the hygroscopic growth effects on aerosol properties, namely the aerosol particle backscatter coefficient and the volume concentration profiles, using data gathered at Granada EARLINET station. Two study cases, corresponding to different aerosol loads and different aerosol types, are used for illustrating the potential of this methodology. Values of the aerosol particle backscatter coefficient enhancement factors range from 2.1 ± 0.8 to 3.9 ± 1.5, in the ranges of relative humidity 60–90 and 40–83%, being similar to those previously reported in the literature. Differences in the enhancement factor are directly linked to the composition of the atmospheric aerosol. The largest value of the aerosol particle backscatter coefficient enhancement factor corresponds to the presence of sulphate and marine particles that are more affected by hygroscopic growth. On the contrary, the lowest value of the enhancement factor corresponds to an aerosol mixture containing sulphates and slight traces of mineral dust. The Hänel parameterization is applied to these case studies, obtaining results within the range of values reported in previous studies, with values of the γ exponent of 0.56 ± 0.01 (for anthropogenic particles slightly influenced by mineral dust) and 1.07 ± 0.01 (for the situation dominated by anthropogenic particles), showing the convenience of this remote sensing approach for the study of hygroscopic effects of the atmospheric aerosol under ambient unperturbed conditions. For the first time, the retrieval of the volume concentration profiles for these cases using the Lidar Radiometer Inversion Code (LIRIC) allows us to analyze the aerosol hygroscopic growth effects on aerosol volume concentration, observing a stronger increase of the fine mode volume concentration with increasing relative humidity
Combination of KIR2DS4 and FcγRIIa polymorphisms predicts the response to cetuximab in KRAS mutant metastatic colorectal cancer
Cetuximab is a standard-of-care treatment for RAS wild-type metastatic colorectal cancer (mCRC) but not for those harbor a KRAS mutation since MAPK pathway is constitutively activated. Nevertheless, cetuximab also exerts its effect by its immunomodulatory activity despite the presence of RAS mutation. The aim of this study was to determine the impact of polymorphism FcγRIIIa V158F and killer immunoglobulin-like receptor (KIR) genes on the outcome of mCRC patients with KRAS mutations treated with cetuximab. This multicenter Phase II clinical trial included 70 mCRC patients with KRAS mutated. We found KIR2DS4 gene was significantly associated with OS (HR 2.27; 95% CI, 1.08–4.77; P = 0.03). In non-functional receptor homozygotes the median OS was 2.6 months longer than in carriers of one copy of full receptor. Multivariate analysis confirmed KIR2DS4 as a favorable prognostic marker for OS (HR 6.71) in mCRC patients with KRAS mutation treated with cetuximab. These data support the potential therapeutic of cetuximab in KRAS mutated mCRC carrying non-functional receptor KIR2DS4 since these patients significantly prolong their OS even after heavily treatment. KIR2DS4 typing could be used as predictive marker for identifying RAS mutated patients that could benefit from combination approaches of anti-EGFR monoclonal antibodies and other immunotherapies to overcome the resistance mediated by mutation in RAS.This clinical trial was approved and supported by Merck S.L., an affiliate of Merck KGaA, Darmstadt. Germany [research project number 2010-023580-18, date: 05-06-2014
Contribution of EARLINET/ACTRIS to the summer 2013 Special Observing Period of the ChArMEx project: monitoring of a Saharan dust event over the western and central Mediterranean
In the framework of the Chemistry-Aerosol Mediterranean
Experiment (ChArMEx; http://charmex.lsce.ipsl.fr/) initiative, a
field campaign took place in the western Mediterranean Basin
between 10 June and 5 July 2013 within the ADRIMED (Aerosol
Direct Radiative Impact on the regional climate in the
MEDiterranean region) project. The scientific objectives of
ADRIMED are the characterization of the most common
‘Mediterranean aerosols’ and their direct radiative forcing (column
closure and regional scale). During 15–24 June a multiintrusion
dust event took place over the western and central
Mediterranean Basin. Extra measurements were carried out by
some EARLINET/ACTRIS (European Aerosol Research Lidar
Network /Aerosols, Clouds, and Trace gases Research
InfraStructure Network, http://www.actris.net/) lidar stations in
Spain and Italy, in particular on 22 June in support to the flight
over southern Italy of the Falcon 20 aircraft involved in the
campaign. This article describes the physical and optical properties
of dust observed at the different lidar stations in terms ofdust plume centre of mass, optical depth, lidar ratio, and particle
depolarization ratio. To link the differences found in the
origin of dust plumes, the results are discussed on the basis
of back-trajectories and air- and space-borne lidars. This work
puts forward the collaboration between a European research
infrastructure (ACTRIS) and an international project (ChArMEx)
on topics of interest for both parties, and more generally for the
atmospheric community.Published4698-47114A. Clima e OceaniJCR Journalrestricte
Modelos de crecimiento y producción en España: historia, ejemplos contemporáneos y perspectivas
En el presente trabajo se presenta una revisión sobre los modelos forestales desarrollados en España durante los últimos años, tanto para la producción maderable como no maderable y, para la dinámica de los bosques (regeneración, mortalidad). Se presentan modelos tanto de rodal completo como de clases diamétricas y de árbol individual. Los modelos desarrollados hasta la fecha se han desarrollado a partir de datos procedentes de parcelas permanentes, ensayos y el Inventario Forestal Nacional. En el trabajo se muestran los diferentes submodelos desarrollados hasta la fecha, así como las plataformas informáticas que permiten utilizar dichos modelos. Se incluyen las principales perspectivas
de desarrollo de la modelización forestal en España.In this paper we present a review of forest models developed in Spain in recent years for both timber and non timber production and forest dynamics (regeneration, mortality). Models developed are whole stand, size (diameter) class and individual-tree. The models developed to date have been developed using data from permanent plots, experimental
sites and the National Forest Inventory. In this paper we show the different sub-models developed so far and the friendly use software. Main perspectives of forest modeling in Spain are presented.The models described in this paper were funded by
different regional, national and European projects, and
some of them were elaborated by the authors. This
work was funded by the Spanish Government by the
SELVIRED network (code AGL2008-03740) and the
strategic project «Restauración y Gestión Forestal»
(code PSE-310000-2009-4)
Determinants of the current and future distribution of the West Nile virus mosquito vector Culex pipiens in Spain
Changes in environmental conditions, whether related or not to human activities, are continuously modifying the geographic distribution of vectors, which in turn affects the dynamics and distribution of vector-borne infectious diseases. Determining the main ecological drivers of vector distribution and how predicted changes in these drivers may alter their future distributions is therefore of major importance. However, the drivers of vector populations are largely specific to each vector species and region. Here, we identify the most important human-activity-related and bioclimatic predictors affecting the current distribution and habitat suitability of the mosquito Culex pipiens and potential future changes in its distribution in Spain. We determined the niche of occurrence (NOO) of the species, which considers only those areas lying within the range of suitable environmental conditions using presence data. Although almost ubiquitous, the distribution of Cx. pipiens is mostly explained by elevation and the degree of urbanization but also, to a lesser extent, by mean temperatures during the wettest season and temperature seasonality. The combination of these predictors highlights the existence of a heterogeneous pattern of habitat suitability, with most suitable areas located in the southern and northeastern coastal areas of Spain, and unsuitable areas located at higher altitude and in colder regions. Future climatic predictions indicate a net decrease in distribution of up to 29.55%, probably due to warming and greater temperature oscillations. Despite these predicted changes in vector distribution, their effects on the incidence of infectious diseases are, however, difficult to forecast since different processes such as local adaptation to temperature, vector-pathogen interactions, and human-derived changes in landscape may play important roles in shaping the future dynamics of pathogen transmission.info:eu-repo/semantics/acceptedVersio
Long-range-transported Canadian smoke plumes in the lower stratosphere over northern France
Long-range-transported Canadian smoke layers in the stratosphere over
northern France were detected by three lidar systems in August 2017. The
peaked optical depth of the stratospheric smoke layer
exceeds 0.20 at 532 nm, which is
comparable with the simultaneous tropospheric aerosol optical depth. The
measurements of satellite sensors revealed that the observed stratospheric
smoke plumes were transported from Canadian wildfires after being lofted by
strong pyro-cumulonimbus. Case studies at two observation sites, Lille (lat
50.612, long 3.142, 60 m a.s.l.) and Palaiseau (lat 48.712, long 2.215,
156 m a.s.l.), are presented in detail. Smoke particle depolarization
ratios are measured at three wavelengths: over 0.20 at 355 nm, 0.18–0.19 at
532 nm, and 0.04–0.05 at 1064 nm. The high depolarization ratios and their
spectral dependence are possibly caused by the irregular-shaped aged smoke
particles and/or the mixing with dust particles. Similar results are found by
several European lidar stations and an explanation that can fully resolve
this question has not yet been found. Aerosol inversion based on lidar
2α+3β data derived a smoke effective radius of about
0.33 µm for both cases. The retrieved single-scattering albedo is
in the range of 0.8 to 0.9, indicating that the smoke plumes are absorbing.
The absorption can cause perturbations to the temperature vertical profile,
as observed by ground-based radiosonde, and it is also related to the ascent
of the smoke plumes when exposed in sunlight. A direct radiative
forcing (DRF) calculation is performed using the obtained optical and
microphysical properties. The calculation revealed that the smoke plumes in
the stratosphere can significantly reduce the radiation arriving at the
surface, and the heating rate of the plumes is about 3.5 K day−1. The
study provides a valuable characterization for aged smoke in the
stratosphere, but efforts are still needed in reducing and quantifying the
errors in the retrieved microphysical properties as well as radiative forcing
estimates.</p
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