Simple Optical Models for Diagnosing Surface–Atmosphere Shortwave Interactions

Abstract A technique is developed for diagnosing effective surface and atmospheric optical properties from climate model shortwave flux diagnostics. These properties can be used to distinguish the contributions of surface and atmospheric optical property changes to shortwave flux changes at the surface and top of the atmosphere. In addition to the four standard shortwave flux diagnostics (upward, downward, surface, and top of atmosphere), the technique makes use of surface-down and top-up fluxes over a zero-albedo surface obtained from an auxiliary online shortwave calculation. The simple model optical properties, when constructed from the time-mean fluxes, are effective optical properties, useful for predicting the time-mean response to optical property changes. The technique is tested against auxiliary online shortwave calculations at four validation albedos and shown to predict the monthly mean surface absorption with an rms error of less than 2% over the globe. The reasons for the accuracy of the technique are explored. Less accurate techniques that make use of existing shortwave diagnostics are presented and compared.

Download Full-text

Influence of Additive Firing on the Surface Characteristics, Streptococcus mutans Viability and Optical Properties of Zirconia

Materials ◽

10.3390/ma14051286 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1286

Author(s):

Wonjoon Moon ◽

Joo Hyang Park ◽

Han-Ah Lee ◽

Bum-Soon Lim ◽

Shin Hye Chung

Keyword(s):

Surface Roughness ◽

Contact Angle ◽

Optical Properties ◽

Optical Property ◽

Streptococcus Mutans ◽

Surface Characteristics ◽

Repetitive Firing ◽

Secondary Caries ◽

Clinically Significant ◽

Property Changes

The purpose of this study was to observe whether the repetitive firing of dental zirconia caused changes in surface characteristics, S. mutans viability, and optical properties of zirconia. Dental zirconia blocks were sintered and randomly distributed into seven experimental groups: F0–F6. Except for F0, which only went through sintering, the additive firing was performed in order for F1–F6. Surface roughness, contact angle, S. mutans viability by fluorescence, and translucency parameter were measured. They were all highest after sintering (F0) and decreased after additive firings (F1–F6). The additive firing of zirconia after sintering decreased surface roughness, contact angle, S. mutans viability, and translucency. The number of firings after the first firing was not found to be critical in surface characteristics, S. mutans viability, and optical property. Changes in surface characteristics might have led to a decrease in S. mutans viability, while the change of translucency was not clinically significant. This implies that additive firing may prevent secondary caries under zirconia restorations, not compromising esthetic appearance.

Download Full-text

Numerical Simulation on Spatial-Frequency Domain Imaging for Estimating Optical Absorption and Scattering Properties of Two-Layered Horticultural Products

Applied Sciences ◽

10.3390/app11020617 ◽

2021 ◽

Vol 11 (2) ◽

pp. 617

Author(s):

Dong Hu ◽

Yuping Huang ◽

Qiang Zhang ◽

Lijian Yao ◽

Zidong Yang ◽

...

Keyword(s):

Optical Properties ◽

Optical Property ◽

Optical Absorption ◽

Spatial Frequency ◽

Estimation Accuracy ◽

Property Estimation ◽

Spatial Frequencies ◽

Stepwise Method ◽

Horticultural Products ◽

Layered Samples

Spatial-frequency domain imaging (SFDI) is a wide-field, noncontact, and label-free imaging modality that is currently being explored as a new means for estimating optical absorption and scattering properties of two-layered turbid materials. The accuracy of SFDI for optical property estimation, however, depends on light transfer model and inverse algorithm. This study was therefore aimed at providing theoretical analyses of the diffusion model and inverse algorithm through numerical simulation, so as to evaluate the potential for estimating optical absorption and reduced scattering coefficients of two-layered horticultural products. The effect of varying optical properties on reflectance prediction was first simulated, which indicated that there is good separation in diffuse reflectance over a large range of spatial frequencies for different reduced scattering values in the top layer, whereas there is less separation in diffuse reflectance for different values of absorption in the top layer, and even less separation for optical properties in the bottom layer. To implement the nonlinear least-square method for extracting the optical properties of two-layered samples from Monte Carlo-generated reflectance, five curve fitting strategies with different constrained parameters were conducted and compared. The results confirmed that estimation accuracy improved as fewer variables were to be estimated each time. A stepwise method was thus suggested for estimating optical properties of two-layered samples. Four factors influencing optical property estimation of the top layer, which is the basis for accurately implementing the stepwise method, were investigated by generating absolute error contour maps. Finally, the relationship between light penetration depth and spatial frequency was studied. The results showed that penetration depth decreased with the increased spatial frequency and also optical properties, suggesting that appropriate selection of spatial frequencies for a stepwise method to estimate optical properties from two-layered samples provides potential for estimation accuracy improvement. This work lays a foundation for improving optical property estimation of two-layered horticultural products using SFDI.

Download Full-text

Advantages of using a fast urban canopy model as compared to a full mesoscale model to simulate the urban heat island of Barcelona

10.5194/gmd-2016-10 ◽

2016 ◽

Cited By ~ 3

Author(s):

M. García-Díez ◽

D. Lauwaet ◽

H. Hooyberghs ◽

J. Ballester ◽

K. De Ridder ◽

...

Keyword(s):

Simple Model ◽

Land Surface ◽

Climate Model ◽

Mesoscale Model ◽

Urban Climate ◽

Urban Canopy ◽

Forecast Model ◽

Reanalysis Data ◽

Urban Canopy Model ◽

Canopy Model

Abstract. As most of the population lives in urban environments, the simulation of the urban climate has become a key problem in the framework of the climate change impact assessment. However, the high computational power required by these simulations is a severe limitation. Here we present a study on the performance of a Urban Climate Model (UrbClim), designed to be several orders of magnitude faster than a full-fledge mesoscale model. The simulations are validated with station data and with land surface temperature observations retrieved by satellites. To explore the advantages of using a simple model like UrbClim, the results are compared with a simulation carried out with a state-of-the-art mesoscale model, the Weather Research and Forecasting model, using an Urban Canopy model. The effect of using different driving data is explored too, by using both relatively low resolution reanalysis data (70 km) and a higher resolution forecast model (15 km). The results show that, generally, the performance of the simple model is comparable to or better than the mesoscale model. The exception are the winds and the day-to-day correlation in the reanalysis driven run, but these problems disappear when taking the boundary conditions from the higher resolution forecast model.

Download Full-text

Using Fundamental Optical Property Sensors for Characterization of Biogeochemical Materials and Processes in Marine Waters

Marine Technology Society Journal ◽

10.4031/002533208786861308 ◽

2008 ◽

Vol 42 (1) ◽

pp. 75-83 ◽

Cited By ~ 2

Author(s):

Casey Moore

Keyword(s):

Optical Properties ◽

Optical Property ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Natural Waters ◽

Harmful Algal Bloom ◽

Light Level ◽

Ecosystem Dynamics ◽

Wide Range ◽

Biogeochemical Parameters

Over the past ten years, efforts to characterize the optical properties of Earth's natural waters have largely merged with the need to better understand underlying biological and chemical processes. Fundamental optical properties such as light level, absorption, scattering and fluorescence are now being utilized with increasing effectiveness to specify particulate and dissolved in-water components in a wide range of applications, including detection of harmful algal blooms, studying ecosystem dynamics, monitoring the effect of industrial and agricultural pollutants, and understanding carbon sequestration processes in the oceans. A diverse offering of commercial optical sensing products capable for research, routine measurements, and in some cases, operational monitoring are now available. These technologies have provided the scientific community with a set of tools for developing, testing, and placing into practice analytical and semi-analytical methods to infer specific biogeochemical parameters and processes. As a result, new, more specialized sensors are now emerging. New sensors couple basic optical property measurements with processing algorithms to provide specific indicators for Harmful Algal Bloom (HAB) identification, carbon products, nutrients, and particle size distributions. The basic measurement methods are described and examples of devices incorporating them are provided to illustrate their use in modern oceanographic research and monitoring.

Download Full-text

Microscopic correlates of macroscopic optical property changes during thermal coagulation of myocardium

10.1117/12.17605 ◽

1990 ◽

Cited By ~ 26

Author(s):

Sharon L. Thomsen ◽

Steven L. Jacques ◽

Stephen T. Flock

Keyword(s):

Optical Property ◽

Thermal Coagulation ◽

Property Changes

Download Full-text

The Preparation and Characterization of Novel Nonlinear Optical Active Dye

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.750-752.899 ◽

2013 ◽

Vol 750-752 ◽

pp. 899-902

Author(s):

Lin Feng Li ◽

Hong Yao Xu

Keyword(s):

Optical Properties ◽

Optical Property ◽

Nonlinear Optical ◽

Nonlinear Optical Property ◽

Condensation Reaction ◽

Nonlinear Optical Properties ◽

532 Nm ◽

Triazine Dye

A novel nonlinear optical active triazine dye 2-(4-methyl-4-amino-azobenzene )-4-sodium sulfanilate-6-chloro-1,3,5-triazine was synthesized by condensation reaction and characterized by FTIR, 1HNMR, respectively. Their nonlinear optical properties were investigated using 5 ns pulse at 532 nm, which showed excellent nonlinear optical property.

Download Full-text

Sensitivity of aerosol radiative effects to different mixing assumptions in the AEROPT 1.0 submodel of the EMAC atmospheric-chemistry–climate model

Geoscientific Model Development ◽

10.5194/gmd-7-2503-2014 ◽

2014 ◽

Vol 7 (5) ◽

pp. 2503-2516 ◽

Cited By ~ 23

Author(s):

K. Klingmüller ◽

B. Steil ◽

C. Brühl ◽

H. Tost ◽

J. Lelieveld

Keyword(s):

Optical Properties ◽

Radiative Transfer ◽

Black Carbon ◽

Atmospheric Chemistry ◽

Radiative Forcing ◽

Climate Model ◽

Mixing Rule ◽

Aerosol Optical Properties ◽

Internal Mixing ◽

Aerosol Radiative

Abstract. The modelling of aerosol radiative forcing is a major cause of uncertainty in the assessment of global and regional atmospheric energy budgets and climate change. One reason is the strong dependence of the aerosol optical properties on the mixing state of aerosol components, such as absorbing black carbon and, predominantly scattering sulfates. Using a new column version of the aerosol optical properties and radiative-transfer code of the ECHAM/MESSy atmospheric-chemistry–climate model (EMAC), we study the radiative transfer applying various mixing states. The aerosol optics code builds on the AEROPT (AERosol OPTical properties) submodel, which assumes homogeneous internal mixing utilising the volume average refractive index mixing rule. We have extended the submodel to additionally account for external mixing, partial external mixing and multilayered particles. Furthermore, we have implemented the volume average dielectric constant and Maxwell Garnett mixing rule. We performed regional case studies considering columns over China, India and Africa, corroborating much stronger absorption by internal than external mixtures. Well-mixed aerosol is a good approximation for particles with a black-carbon core, whereas particles with black carbon at the surface absorb significantly less. Based on a model simulation for the year 2005, we calculate that the global aerosol direct radiative forcing for homogeneous internal mixing differs from that for external mixing by about 0.5 W m−2.

Download Full-text

Interference Phenomena in Deformed Single Crystals of Ice

Journal of Glaciology ◽

10.1017/s002214300001323x ◽

1971 ◽

Vol 10 (59) ◽

pp. 269-286 ◽

Cited By ~ 1

Author(s):

G. J. Readings ◽

J. T. Bartlett

Keyword(s):

Optical Properties ◽

Simple Model ◽

Single Crystals ◽

Uniaxial Compression ◽

Basal Plane ◽

Quantitative Agreement ◽

Optic Axis ◽

Interference Fringes ◽

Alternative Hypotheses ◽

Active Contribution

AbstractWhen rectangular single crystals of ice were subjected to uniaxial compression parallel to their Long axes and viewed between crossed polarizers, interference fringes were often observed. Some of these interference bands were associated with grain boundaries formed as a result of “kinking”. These can be explained in terms of the known anisotropic optical properties of ice and the change in the orientation of the optic axis across the boundary. This case has been analysed in detail with the aid of Jones’ calculus and good quantitative agreement exists between the theory and the experimental observations.Other interference bands were observed parallel to the trace of the basal plane on the surface of some deformed crystals. Alternative hypotheses for the explanation of this phenomenon have been considered and it seems probable that these bands are a result of slight random misorientations between adjacent slip lamellae. Applying Jones’ calculus to a simple model of such a deformed crystal indicates that the required misorientations are of the order of 1º If this explanation is correct, it implies that dislocations with non-basal Burgers vectors (probablyc[0001]) make an active contribution to the deformation.

Download Full-text