96 research outputs found
Multiwavelength fluorescence lidar observations of smoke plumes
A five-channel fluorescence lidar was developed for the study of atmospheric
aerosol. The fluorescence spectrum induced by 355 nm laser emission is
analyzed in five spectral intervals using interference filters. Central
wavelengths and the widths of these five interference filters are,
respectively, as follows: 438 and 29, 472 and 32, 513 and 29, 560 and 40, and 614 and 54 nm. The relative
calibration of these channels has been performed using a tungsten–halogen
lamp with a color temperature of 2800 K. This new lidar system was operated during summer–autumn 2022, when strong forest fires occurred in the Moscow
region and generated a series of smoke plumes analyzed in this study. Our
results demonstrate that, for urban aerosol, the maximal fluorescence
backscattering is observed in a 472 nm channel. For the smoke, the maximum is
shifted toward longer wavelengths, and the fluorescence backscattering
coefficients in 472, 513 and 560 nm channels have comparable values.
Thus, from the analysis of the ratios of fluorescence backscattering in
available channels, we show that it is possible to identify smoke layers.
The particle classification based on single-channel fluorescence capacity
(ratio of the fluorescence backscattering to the elastic one) has limitations
at high relative humidity (RH). The fluorescence capacity indeed
decreases when water uptake of particles enhances the elastic scattering.
However, the spectral variation of fluorescence backscattering does not
exhibit any dependence on RH and can be therefore applied to aerosol
identification.</p
Study on the influence of different error sources on sky radiance measurements and inversion-derived aerosol products in the frame of AERONET
Comunicación presentada en: 2012 European Aerosol Conference (EAC-2012), B-WG01S2P30, celebrada del 2 al 7 de septiembre de 2012 en Granada.Financial support from the Spanish MICINN under
projects with ref. CGL2009-09740, CGL2011-23413,
CGL2010-09480-E and CGL2011-13085-E is gratefully
acknowledged
PHOTONS/AERONET sunphotometer network overview. Description – Activities - Results
Fourteenth International Symposium on Atmospheric and Ocean Optics/Atmospheric Physics celebrado del 24 al 30 de junio de 2007 en Buryatia, Russia
An algorithm to retrieve ice water content profiles in cirrus clouds from the synergy of ground-based lidar and thermal infrared radiometer measurements
The algorithm presented in this paper was developed to retrieve ice water
content (IWC) profiles in cirrus clouds. It is based on optimal estimation
theory and combines ground-based visible lidar and thermal infrared (TIR)
radiometer measurements in a common retrieval framework in order to retrieve
profiles of IWC together with a correction factor for the backscatter
intensity of cirrus cloud particles. As a first step, we introduce a method
to retrieve extinction and IWC profiles in cirrus clouds from the lidar
measurements alone and demonstrate the shortcomings of this approach due to
the backscatter-to-extinction ambiguity. As a second step, we show that TIR
radiances constrain the backscattering of the ice crystals at the visible
lidar wavelength by constraining the ice water path (IWP) and hence the IWC,
which is linked to the optical properties of the ice crystals via a realistic
bulk ice microphysical model. The scattering phase function obtained from the
microphysical model is flat around the backscatter direction (i.e., there is
no backscatter peak). We show that using this flat backscattering phase
function to define the backscatter-to-extinction ratio of the ice crystals in
the retrievals with the lidar-only algorithm results in an overestimation of
the IWC, which is inconsistent with the TIR radiometer measurements. Hence, a
synergy algorithm was developed that combines the attenuated backscatter
profiles measured by the lidar and the measurements of TIR radiances in a
common optimal estimation framework to retrieve the IWC profile together with
a correction factor for the phase function of the bulk ice crystals in the
backscattering direction. We show that this approach yields consistent lidar
and TIR results. The resulting lidar ratios for cirrus clouds are found to be
consistent with previous independent studies.</p
The AERONET-Europe calibration facility: access within the ACTRIS project
Comunicación presentada en: 2012 European Aerosol Conference (EAC-2012), B-WG01S2P30, celebrada del 2 al 7 de septiembre de 2012 en Granada.This work has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement N. 262254. Financial support from the Spanish Ministry of Science (MICINN) under projects with ref. CGL2009-09740, CGL2011-23413, CGL2010-09480-E and CGL2011-13085-E as well as from Junta de
Castilla y León are gratefully acknowledged
Pointing error and field of view of AERONET CIMEL-318 sun photometers
Resumen de la comunicación oral presentada en: 1st Iberian Meeting on Aerosol Science and Technology – RICTA 2013, celebrado del 1 al 3 de julio de 2013 en Évora, Portugal
Interiorized Feminism and Gendered Nostalgia of The ‘Daughter Generation’ in Ning Ying's Perpetual Motion
This is the author's accepted manuscript. The original publication is available at http://dx.doi.org/10.1386/jcc.5.3.253_1Ning Ying’s 2006 film Wuqiong dong/Perpetual Motion can be regarded as her first attempt to explore the genre of ‘women’s film’. Deviating from her previous neo-realist style, this film seeks to cultivate an alternative cinematic practice through developing a heavy-handed negative aesthetics. Ning Ying interiorizes the filmic exploration of female subjectivity in an enclosed time and space, which is constantly haunted by a spectral aesthetics characterized by audio-visual allusions to loss, grave, ruins and ghosts. However, the film’s radical content and alternative aesthetics are, ironically, packaged in prevailing consumer aesthetics and commodity fetishism on and off the silver screen. All these competing drives and accounts render the film a contested narrative constantly oscillating between avant-garde feminism and domestic melodrama, and between a register of disintegrating sisterhood and a celebrity scandal of adultery. This article examines the discursive and aesthetic innovations, contradictions and limits of Ning Ying’s cinematic feminism
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
Parental and infant characteristics and childhood leukemia in Minnesota
<p>Abstract</p> <p>Background</p> <p>Leukemia is the most common childhood cancer. With the exception of Down syndrome, prenatal radiation exposure, and higher birth weight, particularly for acute lymphoid leukemia (ALL), few risk factors have been firmly established. Translocations present in neonatal blood spots and the young age peak of diagnosis suggest that early-life factors are involved in childhood leukemia etiology.</p> <p>Methods</p> <p>We investigated the association between birth characteristics and childhood leukemia through linkage of the Minnesota birth and cancer registries using a case-cohort study design. Cases included 560 children with ALL and 87 with acute myeloid leukemia (AML) diagnoses from 28 days to 14 years. The comparison group was comprised of 8,750 individuals selected through random sampling of the birth cohort from 1976–2004. Cox proportional hazards regression specific for case-cohort studies was used to compute hazard ratios (HR) and 95% confidence intervals (CIs).</p> <p>Results</p> <p>Male sex (HR = 1.41, 95% CI 1.16–1.70), white race (HR = 2.32, 95% CI 1.13–4.76), and maternal birth interval ≥ 3 years (HR = 1.31, 95% CI 1.01–1.70) increased ALL risk, while maternal age increased AML risk (HR = 1.21/5 year age increase, 95% CI 1.0–1.47). Higher birth weights (>3798 grams) (HRALL = 1.46, 1.08–1.98; HRAML = 1.97, 95% CI 1.07–3.65), and one minute Apgar scores ≤ 7 (HRALL = 1.30, 95% CI 1.05–1.61; HRAML = 1.62, 95% CI 1.01–2.60) increased risk for both types of leukemia. Sex was not a significant modifier of the association between ALL and other covariates, with the exception of maternal education.</p> <p>Conclusion</p> <p>We confirmed known risk factors for ALL: male sex, high birth weight, and white race. We have also provided data that supports an increased risk for AML following higher birth weights, and demonstrated an association with low Apgar scores.</p
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