Carynelisa Haspel (nee Erlick) | The Hebrew University of Jerusalem (original) (raw)

Papers by Carynelisa Haspel (nee Erlick)

Atmospheric Chemistry and Physics Discussions

European pollutants are known to affect the Eastern Mediterranean (EM). However, there has been n... more European pollutants are known to affect the Eastern Mediterranean (EM). However, there has been no previous study explicitly locating the European sources, characterizing their transport pathways, and quantifying their contribution to local concentrations in the EM. In the current study, spatially tagged carbon monoxide was used 5 as a tracer for pollutant transport from Europe to the EM over five consecutive years (2003)(2004)(2005)(2006)(2007) using the global chemical transport model MOZART-4. The model results were compared against NOAA/GMD ground station data and remotely sensed data from the Terra/MOPITT satellite and found to agree well. European anthropogenic emissions were found to significantly influence EM surface concentrations, while Eu-10 ropean biomass burning (BB) emissions were found to have only a small impact on EM surface concentrations. Over the five simulated years, only two European biomass burning episodes contributed more than 10 ppb to surface CO concentrations in the EM. CO enhancement in the EM during the summer was attributed to synoptic conditions prone to favorable transport from Turkey and Eastern Europe towards the EM 15 rather than increased emissions. We attribute the apparently misleading association between CO emitted from European BB and CO enhancements over the EM to typical summer synoptic conditions caused by the lingering of an anticyclone positioned over the Western and Central Mediterranean Basin that lead to forest fires in the area. Combined with a barometric trough over the eastern part of the Mediterranean Basin, this 20 generates a prevailing transport of air masses from Eastern Europe to the EM shore.

Applied Optics

In this study, we performed a series of sensitivity tests in order to elucidate the convergence t... more In this study, we performed a series of sensitivity tests in order to elucidate the convergence tendency of the scattering order formulation (SOF) of the discrete dipole approximation (DDA). Using both the original formulation of the SOF and a new marching SOF, the progression of orders of scattering marches, along with the propagation of the incident plane wave through the scatterer, allow dipoles that come into steady-state oscillation with the incident wave earlier to more quickly advance to the next order of scattering that is local to them. Using the original SOF, we found that for cases in which the simulations converge (rods and very small spheres), there are a number of different possible convergence tendencies, among them convergence behavior that resembles the decaying oscillations of a damped harmonic oscillator. For the cases in which the original SOF does not converge, we did not find an indication that the lack of convergence is due to a numerical issue, such as round-off error, or that the divergence could be alleviated by increasing the dipole resolution or by decreasing the size of the marching step in the marching SOF. For cases in which the original SOF does not converge, with both the original SOF and the marching SOF, we found that the calculated extinction cross section exhibits oscillations about the correct value, but with increasing amplitude rather than with decreasing amplitude.

Scientific reports, Jan 10, 2017

The urbanization of the shores of the Gulf of Aqaba has exposed the marine environment there, inc... more The urbanization of the shores of the Gulf of Aqaba has exposed the marine environment there, including unique fringing coral reefs, to strong anthropogenic light sources. Here we present the first in situ measurements of artificial nighttime light under water in such an ecosystem, with irradiance measured in 12 wavelength bands, at 19 measurement stations spread over 44 square km, and at 30 depths down to 30-m depth. At 1-m depth, we find downwelling irradiance values that vary from 4.6 × 10(-4) μW cm(-2) nm(-1) 500 m from the city to 1 × 10(-6) μW cm(-2) nm(-1) in the center of the gulf (9.5 km from the city) in the yellow channel (589-nm wavelength) and from 1.3 × 10(-4) μW cm(-2 )nm(-1) to 4.3 × 10(-5) μW cm(-2) nm(-1) in the blue channel (443-nm wavelength). Down to 10-m depth, we find downwelling irradiance values that vary from 1 × 10(-6) μW cm(-2 )nm(-1) to 4.6 × 10(-4) μW cm(-2) nm(-1) in the yellow channel and from 2.6 × 10(-5) μW cm(-2) nm(-1) to 1.3 × 10(-4) μW cm(-2) nm...

ABSTRACT We present results from a simple 2D model of the mesospheric electric field for several ... more ABSTRACT We present results from a simple 2D model of the mesospheric electric field for several thunderstorm charge configurations. The model assumes a simple dipole structure with a screening charge above cloud-top. The charge centers are modeled as horizontal disks with a Gaussian charge density distribution. We solve the Poisson equation numerically, using a second order central finite difference scheme. A relaxation method is used over a grid of 90 x 300 points with a 1-km interval. We convert the computed electric potential at each grid point to the electric field and compare it to the breakdown field, thus mapping the regions where there exists a possibility for sprite initiation. This model allows the study of various thunderstorm cell configurations, with multiple cells and with different polarities. Four main charge configurations are examined: (1) a summer thunderstorm cell, (2) a winter cell, (3) simultaneous lightning from two summer cells, and (4) a summer cell with an inverse dipole. The results highlight the difference in the charge moment change (CMC) threshold needed for sprite generation in winter and summer cells. The effects of the presence of neighboring thunderclouds at different relative stages of development are presented, particularly with respect to the likelihood of sprite formation and the displacement of sprites from the parent flash. In addition, we show how the orientation of the electric field changes with altitude, potentially explaining the optical observations of sprite tendril curvature toward the cloud.

The effect of absorbing aerosols on clouds is investigated using a sequence of models. A size- an... more The effect of absorbing aerosols on clouds is investigated using a sequence of models. A size- and composition-resolved microphysical parcel model is used to look at the extent to which absorbing material from a continental air mass (dust, black carbon, and organic carbon) inside of cloud drops influences the amount of solar radiation absorbed by a marine stratocumulus cloud. Using the parcel model results, the shortwave properties of clouds are perturbed in a radiative-convective model (RCM) in order to look at the influence of such absorption on the global-mean atmospheric temperature profile. The shortwave properties of clouds are then perturbed in the SKYHI general circulation model (GCM) in order to look at possible feedbacks of such absorption on cloud amount. Comparison of the results from the RCM and GCM give an indication of whether absorption of solar radiation in clouds as a result of the presence of continental type absorbing aerosols is likely to cause a warming or cool...

Geochmica et Cosmochimica Acta

Proceedings of the National Academy of Sciences of the United States of America, Jan 17, 2013

The cycling of atmospheric aerosols through clouds can change their chemical and physical propert... more The cycling of atmospheric aerosols through clouds can change their chemical and physical properties and thus modify how aerosols affect cloud microphysics and, subsequently, precipitation and climate. Current knowledge about aerosol processing by clouds is rather limited to chemical reactions within water droplets in warm low-altitude clouds. However, in cold high-altitude cirrus clouds and anvils of high convective clouds in the tropics and midlatitudes, humidified aerosols freeze to form ice, which upon exposure to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. Here we simulate an atmospheric freeze-drying cycle of aerosols in laboratory experiments using proxies for atmospheric aerosols. We find that aerosols that contain organic material that undergo such a process can form highly porous aerosol particles with a larger diameter and a lower density than the in...

Fauna norvegica, 2012

. Insights from chironomid oviposition is useful to visual pest control. Fauna norvegica 31: 65-7... more . Insights from chironomid oviposition is useful to visual pest control. Fauna norvegica 31: 65-70. Efficient visual pest control is still in its infant stages. Although being non-invasive, environmentally friendly and potentially cost effective, we still have not cracked the way to efficiently use it against epidemic vector-carrying and crop-infesting insects. Chironomid ovipostion can provide insights to key factors in visual pest control by investigating the behavior under confined and unconfined conditions. Under confined condition, due to limited amount of oviposition sites and increase of egg density in highly preferred locations, females oviposit in less suitable sites. Intensity and polarization of light reflected from the oviposition sites were found to be important as guiding cues for the females. However, in the open outdoor where oviposition sites are unlimited, oviposition followed the polarization signal only, and the intensity was ignored as a cue. By applying this approach to reduce chironomid population in a natural reservoir we show that it may be used to divert ovipositing females to egg traps reflecting highly and horizontally polarized light. The potential of using color, intensity and polarization as a basis for building oviposition traps and applying it to pest control in the future, is discussed.

$Research paper thumbnail of Estimation of the porosity and refractive index of sol–gel silica films using high resolution electron microscopy$

Solar Energy Materials and Solar Cells, 2014

ABSTRACT The relationship between the refractive index and the porosity of silica based anti-refl... more ABSTRACT The relationship between the refractive index and the porosity of silica based anti-reflective coatings (ARCs) has been studied. The coatings were prepared with the traditional Stöber method. The refractive index was evaluated by fitting vis–NIR transmittance spectra to Fresnel׳s coefficient of reflection using the transfer matrix method. The porosity was assessed by a novel method based on image processing of high resolution scanning electron microscope (SEM) images. Results were compared to the commonly used Yoldas and Maxwell–Garnett mixing rules. Our results showed better agreement with the Yoldas mixing rule than with the Maxwell–Garnett mixing rule, which was explained as being due to the presence of elongated crack shaped pores in the ARCs rather than randomly dispersed spherical shaped pores, as was evident in the SEM images. Furthermore, we found that despite the presence of the elongated cracks, the coating appears to behave towards light like a homogenous medium. This somewhat surprising result calls for further research. Lastly, we have shown that it is reasonable to assume that the ARC is vertically homogeneous in terms of its porosity and effective refractive index.

Journal of Geophysical Research: Atmospheres, 2014

Porous glassy particles are a potentially significant but unexplored component of atmospheric aer... more Porous glassy particles are a potentially significant but unexplored component of atmospheric aerosol that can form by aerosol processing through the ice phase of high convective clouds. The optical properties of porous glassy aerosols formed from a freeze-dry cycle simulating freezing and sublimation of ice particles were measured using a cavity ring down aerosol spectrometer (CRD-AS) at 532 nm and 355 nm wavelength. The measured extinction efficiency was significantly reduced for porous organic and mixed organic-ammonium sulfate particles as compared to the extinction efficiency of the homogeneous aerosol of the same composition prior to the freeze-drying process. A number of theoretical approaches for modeling the optical extinction of porous aerosols were explored. These include effective medium approximations, extended effective medium approximations, multilayer concentric sphere models, Rayleigh-Debye-Gans theory, and the discrete dipole approximation. Though such approaches are commonly used to describe porous particles in astrophysical and atmospheric contexts, in the current study, these approaches predicted an even lower extinction than the measured one. Rather, the best representation of the measured extinction was obtained with an effective refractive index retrieved from a fit to Mie scattering theory assuming spherical particles with a fixed void content. The single-scattering albedo of the porous glassy aerosols was derived using this effective refractive index and was found to be lower than that of the corresponding homogeneous aerosol, indicating stronger relative absorption at the wavelengths measured. The reduced extinction and increased absorption may be of significance in assessing direct, indirect, and semidirect forcing in regions where porous aerosols are expected to be prevalent.

Journal of the Optical Society of America A, 2012

A full Mie scattering subroutine is employed to calculate what we call the linear polarization ph... more A full Mie scattering subroutine is employed to calculate what we call the linear polarization phase function (LPPF; percent polarization and e-vector orientation of radiation as a function of scattering angle) that results from refraction of the direct solar beam from air into water followed by single scattering by spherical hydrosols. The separate effects of refraction at the air-water interface, hydrosol size, the real and imaginary parts of the hydrosol refractive index, and absorption by the surrounding medium (water) on the LPPF are investigated. All of the above factors are found to alter the LPPF, changing the value of the maximum percent polarization (P(max)), the location of P(max), the number of fluctuations in the LPPF, or the location of the neutral points (points of 0 percent polarization), though absorption by the surrounding medium is found to have only a minimal effect. The character and extent of the influence on the LPPF is found to depend on the scattering regime (Rayleigh, Mie, or geometric optics). We conclude that in calculating underwater polarization, it is important to take into consideration Mie scattering even in relatively clear waters. We also find a coupling between the partial polarization and the e-vector orientation, which suggests that for some polarization-based visual tasks, only one of these would suffice. Other implications for aquatic animal polarization vision are discussed.

Journal of Geophysical Research, 2011

1] Aerosol-cloud interactions, such as aerosol loading in convective clouds resulting in either p... more 1] Aerosol-cloud interactions, such as aerosol loading in convective clouds resulting in either precipitation suppression or cloud invigoration, in higher cloud tops, and in longer-lived clouds, are well known. Here we investigate a new aerosol-cloud interaction, the effect of aerosol loading on Bénard cells, on the stratocumulus cloud fraction, and ultimately on the climate over glacial-interglacial cycles, using a two-dimensional model running a million year continuous simulation. This radiative effect is observed only in marine boundary layer stratocumulus clouds that have a convective cellular structure. Recent research suggests that aerosols can switch the direction of convection in Bénard cells (from open cells to closed cells) by suppressing precipitation and therefore dramatically change the cloud fraction. The effect investigated in this work differs from previously known aerosol effects on convective clouds by its intensity and magnitude and has never been taken into account in past climate simulations. The results show that accounting for the aerosol-Bénard cell effect alone contributes a negative radiative forcing, affecting both the Northern Hemisphere mean annual surface temperature and ice volume. Adding the aerosol-Bénard cell effect to the direct radiative effect of dust and to the effect of dust on snow and ice albedo shows that the aerosol-Bénard cell effect plays a significant role in glacial-interglacial climate change, strengthening the earlier glacial cycles and creating a larger glacialinterglacial surface temperature amplitude while preserving the continental ice volume amplitude. Because of the model limitations, there are a number of uncertainties involved. However, the results serve to give a preliminary evaluation of the aerosol-Bénard cell effect at least qualitatively if not quantitatively.

Journal of Geophysical Research, 2003

Journal of Aerosol Science, 1998

Atmospheric Chemistry and Physics, 2012

Pollutants from global sources are known to affect the Eastern Mediterranean Shore (EMS). However... more Pollutants from global sources are known to affect the Eastern Mediterranean Shore (EMS). However, there has been no previous study explicitly locating the Euro-pean sources, characterizing their transport pathways, and quantifying their contribution to local concentrations in the EMS. In the current study, spatially tagged carbon monoxide was used as a tracer for pollutant transport from Europe to the EMS over five consecutive years (2003–2007) using the global chemical transport model MOZART-4. The model results were compared against NOAA/GMD ground station data and remotely sensed data from the Terra/MOPITT satellite and found to agree well on monthly basis but do not agree on daily basis. On synoptic scale, there is agreement between MOZART and GMD during July to August. A budget analysis reveals the role of CO from hydrocarbon oxidation on CO concentration during summer. European anthropogenic emissions were found to significantly influence EM surface concentrations, while European biomass burning (BB) emissions were found to have only a small impact on EM surface concentrations. Over the five simulated years, only two Euro-pean biomass burning episodes contributed more than 10 ppb to surface CO concentrations in the EM. CO enhancement in the EM during the summer was attributed to synoptic conditions prone to favorable transport from Turkey and Eastern Europe towards the EM rather than increased emissions. We attribute the apparently misleading association between CO emitted from European BB and CO enhancements over the EM to typical summer synoptic conditions caused by the lingering of an anticyclone positioned over the Western and Central Mediterranean Basin that lead to forest fires in the area. Combined with a barometric trough over the eastern part of the Mediterranean Basin, this generates a prevailing transport of air masses from Eastern Europe to the EMS. Synoptic scale variations are shown to change the transport pathways from Europe towards the EMS having an overall small affect. CO concentration over the EMS can be describe as having 3 components: the seasonal cycle, the cycle of CO produced from hydrocarbon oxidation and a synoptic variation .

Photochemistry and Photobiology, 1995

Information on column ozone and the earth's reflectivity obtained from satellite-based data allow... more Information on column ozone and the earth's reflectivity obtained from satellite-based data allows estimates of the long-term behavior in erythemal irradiance at any location, including the attenuation provided by clouds. Year-to-year changes in cloudiness over specific geographic regions make a major contribution to interannual variability in irradiance at the ground. Although the general decline in column ozone amounts acted to increase erythemal irradiance over the period November 1978 to April 1993, these changes tend to be obscured by the erratic variability associated with cloudiness. The noise introduced into a time series of erythemal irradiance by clouds effectively widens the error bars assigned to derived trends. This behavior could complicate attempts to establish links between any observed changes in the biosphere and measured changes in the ozone layer.

$Research paper thumbnail of Effective Refractive Indices of Water and Sulfate Drops Containing Absorbing Inclusions$

Journal of the Atmospheric Sciences, 2006

... Ackerman, TP, and OB Toon, 1981: Absorption of visible radiation in atmosphere containing mix... more ... Ackerman, TP, and OB Toon, 1981: Absorption of visible radiation in atmosphere containing mixtures of absorbing and nonabsorbing particles. Appl. ... Myhre, G., F. Stordal, K. Restad, and I. Isaksen, 1998: Estimates of the direct radiative forcing due to sulfate and soot aerosols. ...