scholarly journals Evaluation of LIRIC Algorithm Performance Using Independent Sun-Sky Photometer Data at Two Altitude Levels

2020 ◽  
Vol 12 (5) ◽  
pp. 842
Author(s):  
María J. Granados-Muñoz ◽  
José Antonio Benavent-Oltra ◽  
Daniel Pérez-Ramírez ◽  
Hassan Lyamani ◽  
Juan Luis Guerrero-Rascado ◽  
...  
Keyword(s):  
Volume Concentration ◽  
Observational Period ◽  
Lidar System ◽  
Algorithm Performance ◽  
Microphysical Properties ◽  
A Value ◽  
Large Databases ◽  
Self Consistency ◽  
System Operating ◽  
Good Agreement

This work evaluates the Lidar-Radiometer Inversion Code (LIRIC) using sun-sky photometers located at different altitudes in the same atmospheric column. Measurements were acquired during an intensive observational period in summer 2012 at Aerosols, Clouds, and Trace gases Research InfraStructure Network (ACTRIS)/Aerosol Robotic Network (AERONET) Granada (GRA; 37.16°N, 3.61°W, 680 m above sea level (a.s.l.)) and Cerro Poyos (CP; 37.11°N, 3.49°W, 1820 m a.s.l.) sites. Both stations operated AERONET sun-photometry, with an additional lidar system operating at Granada station. The extended database of simultaneous lidar and sun-photometry measurements from this study allowed the statistical analysis of vertically resolved microphysical properties retrieved with LIRIC, with 70% of the analyzed cases corresponding to mineral dust. Consequently, volume concentration values were 46 μm3/cm3 on average, with a value of ~30 μm3/cm3 corresponding to the coarse spheroid mode and concentrations below 10 μm3/cm3 for the fine and coarse spherical modes. According to the microphysical properties’ profiles, aerosol particles reached altitudes up to 6000 m a.s.l., as observed in previous studies over the same region. Results obtained from comparing the LIRIC retrievals from GRA and from CP revealed good agreement between both stations with differences within the expected uncertainties associated with LIRIC (15%). However, larger discrepancies were found for 10% of the cases, mostly due to the incomplete overlap of the lidar signal and/or to the influence of different aerosol layers advected from the local origin located between both stations, which is particularly important in cases of low aerosol loads. Nevertheless, the results presented here demonstrate the robustness and self-consistency of LIRIC and consequently its applicability to large databases such as those derived from ACTRIS-European Aerosol Research Lidar Network (EARLINET) observations.

Standardisation of von Willebrand Factor in Therapeutic Concentrates: Calibration of the 1st International Standard for von Willebrand Factor Concentrate (00/514)

2002 ◽  
Vol 88 (09) ◽  
pp. 380-386 ◽  
Author(s):  
Dawn Sands ◽  
Andrew Chang ◽  
Claudine Mazurier ◽  
Anthony Hubbard
Keyword(s):  
Von Willebrand Factor ◽  
International Study ◽  
Expert Committee ◽  
International Standard ◽  
A Value ◽  
Significant Difference ◽  
Factor Concentrate ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Good Agreement

SummaryAn international study involving 26 laboratories assayed two candidate von Willebrand Factor (VWF) concentrates (B and C) for VWF:Antigen (VWF:Ag), VWF:Ristocetin Cofactor (VWF:RCo) and VWF:Collagen binding (VWF:CB) relative to the 4th International Standard Factor VIII/VWF Plasma (4th IS Plasma) (97/586). Estimates of VWF:Ag showed good agreement between different methods, for both candidates, and the overall combined means were 11.01 IU/ml with inter-laboratory variability (GCV) of 10.9% for candidate B and 14.01 IU/ml (GCV 11.8%) for candidate C. Estimates of VWF:RCo showed no significant difference between methods for both candidates and gave overall means of 9.38 IU/ml (GCV 23.7%) for candidate B and 10.19 IU/ml (GCV 24.4%) for candidate C. Prior to the calibration of the candidates for VWF:CB it was necessary to calibrate the 4th IS Plasma relative to local frozen normal plasma pools; there was good agreement between different collagen reagents and an overall mean of 0.83 IU per ampoule (GCV 11.8%) was assigned. In contrast, estimates of VWF:CB in both candidates showed large differences between collagen reagents with inter-laboratory GCV’s of 40%. Candidate B (00/514) was established as the 1st International Standard von Willebrand Factor Concentrate by the WHO Expert Committee on Biological Standardisation in November 2001 with assigned values for VWF:Ag (11.0 IU/ampoule) and VWF:RCo (9.4 IU/ampoule). Large inter-laboratory variability of estimates precluded the assignment of a value for VWF:CB.

Heat-flow experiments in liquid 4He with a variable cylindrical geometry

1987 ◽  
Vol 174 ◽  
pp. 209-231 ◽  
Author(s):  
H. Gao ◽  
G. Metcalfe ◽  
T. Jung ◽  
R. P. Behringer
Keyword(s):  
Cylindrical Geometry ◽  
Small Scale ◽  
Onset Of Convection ◽  
Aspect Ratios ◽  
A Value ◽  
Prandtl Numbers ◽  
Convection Rolls ◽  
Flow Experiments ◽  
Increasing Function ◽  
Good Agreement

This paper first describes an apparatus for measuring the Nusselt number N versus the Rayleigh number R of convecting normal liquid 4He layers. The most important feature of the apparatus is its ability to provide layers of different heights d, and hence different aspect ratios [Gcy ]. The horizontal cross-section of each layer is circular, and [Gcy ] is defined by [Gcy ] = D/2d where D is the diameter of the layer. We report results for 2.4 [les ] [Gcy ] [les ] 16 and for Prandtl numbers Pr spanning 0.5 [lsim ] Pr [lsim ] 0.9 These results are presented in terms of the slope N1 = RcdN/dR evaluated just above the onset of convection at Rc. We find that N1 is only a slowly increasing function of [Gcy ] in the range 6 [lsim ] [Gcy ] [lsim ] 16, and that it has a value there which is quite close to 0.72. This value of N1 is in good agreement with variational calcuations by Ahlers et al. (1981) pertinent to parallel convection rolls in cylindrical geometry. Particularly for [Gcy ] [lsim ] 6, we find additional small-scale structure in N1 associated with changes in the number of convection rolls with changing [Gcy ]. An additional test of the linearzied hydrodynamics is given by measurements of Rc. We find good agreement between theory and our data for Rc.

scholarly journals Aerosol retrieval from multiangle, multispectral photopolarimetric measurements: importance of spectral range and angular resolution

2015 ◽  
Vol 8 (6) ◽  
pp. 2625-2638 ◽  
Author(s):  
L. Wu ◽  
O. Hasekamp ◽  
B. van Diedenhoven ◽  
B. Cairns
Keyword(s):  
Refractive Index ◽  
Spectral Range ◽  
Angular Resolution ◽  
Single Scattering ◽  
Microphysical Properties ◽  
Aerosol Retrieval ◽  
Spectral Ranges ◽  
Shortwave Infrared ◽  
Aerosol Properties ◽  
Good Agreement

Abstract. We investigated the importance of spectral range and angular resolution for aerosol retrieval from multiangle photopolarimetric measurements over land. For this purpose, we use an extensive set of simulated measurements for different spectral ranges and angular resolutions and subsets of real measurements of the airborne Research Scanning Polarimeter (RSP) carried out during the PODEX and SEAC4RS campaigns over the continental USA. Aerosol retrievals performed from RSP measurements show good agreement with ground-based AERONET measurements for aerosol optical depth (AOD), single scattering albedo (SSA) and refractive index. Furthermore, we found that inclusion of shortwave infrared bands (1590 and/or 2250 nm) significantly improves the retrieval of AOD, SSA and coarse mode microphysical properties. However, accuracies of the retrieved aerosol properties do not improve significantly when more than five viewing angles are used in the retrieval.

Device Modeling of a-Si:H Alloy Solar Cells: Calibration Procedure for Determination of Model Input Parameters

1998 ◽  
Vol 507 ◽  
Author(s):  
M. Zeman ◽  
R.A.C.M.M. Van Swaaij ◽  
E. Schroten ◽  
L.L.A. Vosteen ◽  
J.W. Metselaar
Keyword(s):  
Solar Cell ◽  
Material Properties ◽  
Calibration Procedure ◽  
Model Parameters ◽  
Model Input ◽  
A Value ◽  
Input Parameters ◽  
Simulated Material ◽  
Good Agreement

ABSTRACTA calibration procedure for determining the model input parameters of standard a-Si:H layers, which comprise a single junction a-Si:H solar cell, is presented. The calibration procedure consists of: i) deposition of the separate layers, ii) measurement of the material properties, iii) fitting the model parameters to match the measured properties, iv) simulation of test devices and comparison with experimental results. The inverse modeling procedure was used to extract values of the most influential model parameters by fitting the simulated material properties to the measured ones. In case of doped layers the extracted values of the characteristic energies of exponentially decaying tail states are much higher than the values reported in literature. Using the extracted values of model parameters a good agreement between the measured and calculated characteristics of a reference solar cell was reached. The presented procedure could not solve directly an important issue concerning a value of the mobility gap in a-Si:H alloys.

scholarly journals Comparison between two lidar methods to retrieve microphysical properties of liquid-water clouds

2018 ◽  
Vol 176 ◽  
pp. 01032 ◽  
Author(s):  
Cristofer Jimenez ◽  
Albert Ansmann ◽  
David Donovan ◽  
Ronny Engelmann ◽  
Jörg Schmidt ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Liquid Water ◽  
High Temporal Resolution ◽  
Lidar System ◽  
Microphysical Properties

Since 2010, the Raman dual-FOV lidar system permits the retrieval of microphysical properties of liquid-water clouds during nighttime. A new robust lidar depolarization approach was recently introduced, which permits the retrieval of these properties as well, with high temporal resolution and during daytime. To implement this approach, the lidar system was upgraded, by adding a three channel depolarization receiver. The first preliminary retrieval results and a comparison between both methods is presented.

scholarly journals Inter-comparison of ABL height estimates from different profiling sensors and models in the framework of HyMeX-SOP1

2021 ◽  
Author(s):  
Donato Summa ◽  
Fabio Madonna ◽  
Noemi Franco ◽  
Bendetto De Rosa ◽  
Paolo Di Girolamo
Keyword(s):  
Friction Velocity ◽  
Hydrological Cycle ◽  
Weather Conditions ◽  
Raman Lidar ◽  
Lidar System ◽  
Combined Application ◽  
Radiosonde Station ◽  
Atmospheric Dynamic ◽  
Thermodynamic Variables ◽  
Good Agreement

Abstract. This paper reports results from an inter-comparison effort involving different sensors/techniques used to measure the Atmospheric Boundary Layer (ABL) height. The effort took place in the framework of the first Special Observing Period of the Hydrological cycle of the Mediterranean Experiment (HyMeX-SOP1). Elastic backscatter and rotational Raman signals collected by the Raman lidar system BASIL were used to determine the ABL height and characterize its internal structure. These techniques were compared with co-located measurements from a wind profiler and radiosondes and with ECMWF-ERA5 data. In the effort we consider radiosondes launched in the proximity of the lidar site, as well as radiosondes launched from the closest radiosonde station included in the Integrated Global Radiosonde archive (IGRA). The inter-comparison effort considers data from October 2012. Results reveal a good agreement between the different approaches, with values of the correlation coefficient R2 in the range 0.52 to 0.94. Results clearly reveals that the combined application of different techniques to distinct sensors’ and model datasets allow getting accurate and cross-validated estimates of the ABL height over a variety of weather conditions. Furthermore, correlations between the ABL height and other atmospheric dynamic and thermodynamic variables as CAPE, friction velocity and relative humidity are also assessed to infer possible mutual dependences.

scholarly journals Lidar observation and model simulation of a volcanic-ash-induced cirrus cloud during the Eyjafjallajökull eruption

2012 ◽  
Vol 12 (6) ◽  
pp. 15675-15707 ◽  
Author(s):  
C. Rolf ◽  
M. Krämer ◽  
C. Schiller ◽  
M. Hildebrandt ◽  
M. Riese
Keyword(s):  
Volcanic Ash ◽  
Model Simulation ◽  
Cirrus Cloud ◽  
Backward Trajectories ◽  
Microphysical Properties ◽  
Ice Nuclei ◽  
A Value ◽  
Lidar Measurements ◽  
Before And After ◽  
Western Germany

Abstract. Heterogeneous ice formation induced by volcanic ash from the Eyjafjallajökull volcano eruption in April 2010 is investigated based on the combination of a cirrus cloud observed with a backscatter lidar over Jülich (Western Germany) and model simulations along backward trajectories. The microphysical properties of the cirrus cloud could only be represented by the microphysical model under the assumption of an enhanced number of efficient ice nuclei originating from the volcanic eruption. The ice nuclei (IN) concentration determined by lidar measurements directly before and after cirrus cloud occurrence implies a value of around 0.1 cm−3 (in comparison clean IN conditions: 0.01 cm−3). This leads to a cirrus cloud with rather small ice crystals having a mean radius of 12 μm and a modification of the ice particle number (0.08 cm−3 instead of 3 × 10−4 cm−3 under clean IN conditions). The effectiveness of ice nuclei was estimated by the use of the microphysical model and the backward trajectories based on ECMWF data, establishing a freezing threshold of around 105% relative humidity with respect to ice in a temperature range from −45 to −55 °C. Only with these highly efficient ice nuclei was it possible for the cirrus cloud to be formed in a slightly supersaturated environment.

Low frequency acoustic thermometry in the range 4.2–20 K with implications for the value of the gas constant

1979 ◽  
Vol 365 (1722) ◽  
pp. 349-370 ◽  
Keyword(s):  
Low Frequency ◽  
Acoustic Thermometry ◽  
A Value ◽  
New Information ◽  
Thermodynamic Temperatures ◽  
Good Agreement ◽  
Gas Thermometry

Six acoustic isotherms have been plotted in the range 4.2–20 K. When thermodynamic temperatures are calculated from their intercepts on the basis of Batuecas’s value of the gas constant ( R = 8.31441 J mol -1 K -1 ), no significant systematic departure from the results of Berry’s gas thermometry is discernible. If one assumes Berry’s work to be thermodynamically correct and the present work to be thermodynamically linear, a value of the gas constant is implied only (7 ± 27 (lσ)) R / 10 6 higher than that of Batuecas, but 152 R / 10 6 lower than that of Quinn, Colclough & Chandler (Q. C. C.). Such a value is close to that expected from a forthcoming revision of the work of Q. C. C. and is in line with recent criticisms of Rowlinson et al . of their value. If this expectation is borne out gas and acoustic thermometry will be in good agreement in this range. Final results are quoted on the basis of Batuecas’s value of the gas constant and in terms of R to facilitate their recalculation as new information on the value of the gas constant becomes available.

scholarly journals Analysis of CO2 Facilitation Transport Effect through a Hybrid Poly(Allyl Amine) Membrane: Pathways for Further Improvement

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 367
Author(s):  
Bouchra Belaissaoui ◽  
Elsa Lasseuguette ◽  
Saravanan Janakiram ◽  
Liyuan Deng ◽  
Maria-Chiara Ferrari
Keyword(s):  
Facilitated Transport ◽  
Transport Parameters ◽  
Material Synthesis ◽  
Transport Models ◽  
Transport Modelling ◽  
Selective Layer ◽  
Membrane Performance ◽  
A Value ◽  
Partial Pressures ◽  
Good Agreement

Numerous studies have been reported on CO2 facilitated transport membrane synthesis, but few works have dealt with the interaction between material synthesis and transport modelling aspects for optimization purposes. In this work, a hybrid fixed-site carrier membrane was prepared using polyallylamine with 10 wt% polyvinyl alcohol and 0.2 wt% graphene oxide. The membrane was tested using the feed gases with different relative humidity and at different CO2 partial pressures. Selected facilitated transport models reported in the literature were used to fit the experimental data with good agreement. The key dimensionless facilitated transport parameters were obtained from the modelling and data fitting. Based on the values of these parameters, it was shown that the diffusion of the amine-CO2 reaction product was the rate-controlling step of the overall CO2 transport through the membrane. It was shown theoretically that by decreasing the membrane selective layer thickness below the actual value of 1 µm to a value of 0.1 µm, a CO2 permeance as high as 2500 GPU can be attained while maintaining the selectivity at a value of about 19. Furthermore, improving the carrier concentration by a factor of two might shift the performances above the Robeson upper bound. These potential paths for membrane performance improvement have to be confirmed by targeted experimental work.

scholarly journals Maritime Aerosol Optical and Microphysical Properties in the South China Sea Under Multi-source Influence

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chi Zhang ◽  
Hua Xu ◽  
Zhengqiang Li ◽  
Yisong Xie ◽  
Donghui Li
Keyword(s):  
South China Sea ◽  
South China ◽  
Volume Concentration ◽  
The South China Sea ◽  
Skewed Distribution ◽  
The South ◽  
China Sea ◽  
Microphysical Properties ◽  
Wide Range ◽  
Fine Mode

AbstractThe South China Sea hosts a wide range of aerosol pollutants with the uneven development of socio-economic and complicated meteorology system. To fill the gap of the maritime aerosol characteristics over the sea, we selected the multi-year ground-based measurements of Taiping Site and Dongsha Site to investigate the optical and microphysical properties. In Taiping, the vast majority of aerosol optical depths (AODs) are less than 0.2, but that of Dongsha shows the wider distribution of AODs from 0 to 0.6. Angstrom Exponent frequency distribution in Taiping peaks at the range of 0.75–1.25 but that has the left-skewed distribution in Taiping Island. Moreover, there is a variation in the coarse-mode volume concentration in Taiping Island but less variation in the fine mode. The seasonal maritime aerosol properties of Taiping and Dongsha have been analyzed that can be employed as a maritime look up table (LUT) kernel in coupled atmospheric retrieval and correction algorithms.

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