Papers by Alexander Kostinski
Atmosphere
The reason why ice nucleation is more efficient by contact nucleation than by immersion nucleatio... more The reason why ice nucleation is more efficient by contact nucleation than by immersion nucleation has been elusive for over half a century. Six proposed mechanisms are summarized in this study. Among them, the pressure perturbation hypothesis, which arose from recent experiments, can qualitatively explain nearly all existing results relevant to contact nucleation. To explore the plausibility of this hypothesis in a more quantitative fashion and to guide future investigations, this study assessed the magnitude of pressure perturbation needed to cause contact nucleation and the associated spatial scales. The pressure perturbations needed were estimated using measured contact nucleation efficiencies for illite and kaolinite, obtained from previous experiments, and immersion freezing temperatures, obtained from well-established parameterizations. Pressure perturbations were obtained by assuming a constant pressure perturbation or a Gaussian distribution of the pressure perturbation. Th...
Geophysical Research Letters
The deep space climate observatory (DSCOVR) spacecraft resides at the first Lagrangian point abou... more The deep space climate observatory (DSCOVR) spacecraft resides at the first Lagrangian point about one million miles from Earth. A polychromatic imaging camera onboard delivers nearly hourly observations of the entire sunlit face of the Earth. Many images contain unexpected bright flashes of light over both ocean and land. We construct a yearlong time series of flash latitudes, scattering angles and oxygen absorption to demonstrate conclusively that the flashes over land are specular reflections off tiny ice platelets floating in the air nearly horizontally. Such deep space detection of tropospheric ice can be used to constrain the likelihood of oriented crystals and their contribution to Earth albedo. These glint observations also support proposals for detecting starlight glints off faint companions in our search for habitable exoplanets.
Spatial Correlations Among Aerosol Particles
ABSTRACT Aerosol particles are usually assumed to be distributed in space in a perfectly random m... more ABSTRACT Aerosol particles are usually assumed to be distributed in space in a perfectly random manner (i.e. according to a Poisson process) when calculating, for example, attenuation of radiation or evolution of the supersaturation during cloud activation. However, the presence of spatial correlations can have a significant impact on such processes, but is rarely, if ever, explicitly considered. We show that classifying the positions of aerosol particles as a Poisson process is often in error, and demonstrate that small scale clustering of aerosol particles does occur. We will also discuss the consequences of these findings.
Response of a Vapor Field to Injection of Aerosols: Characteristic Time Scale
Aqua, CALIPSO, and TERRA satellite data all indicate lower frequency of cloud occurrence at mid-level altitudes in the North Atlantic Ocean, (45N-49N, 25W-5W)
The altitude corresponding to cloud glaciation and release of latent heat is often an input in cl... more The altitude corresponding to cloud glaciation and release of latent heat is often an input in climate models and is important in many other problems such as interpreting satellite retrievals. Our findings, that mid-level clouds (in this study ~3-7 km ) are rare under some conditions, may render the precise glaciation level statistically unimportant for some of these studies: the majority of clouds will be far from the uncertain point of glaciation and easily designated, while clouds that are at mid-level, if in a low-density region/season, will be rare and not require precise designation. Indeed in some cases no mid-level clouds are seen for significant regions and spans of time: complementary use of CALIPSO and Aqua-MODIS, A-train satellites with a 1-2 minute lag between them, show that there are no mid-level clouds for N. Atlantic (45N-49N, 25W-5W), 2006-2008, September 15-30, day/afternoon (11:45-15:40 UTC) and night/morning (1:30-5:00 UTC). This example is further verified by data from TERRA-MODIS, covering the same region at different overpass times than the A-train satellites, the latter having near-polar orbits rather a near-circular orbit. TERRA-MODIS does retrieve some mid-level clouds, but they account for less than 1% of cloud-top phases retrieved. (See figure below for relevant histograms.) Studies of various regions and seasons will be presented in addition to these findings. This type of study, extended globally and annually, will present valuable data for modeling and interpretation of climatic trends.
Polarimetric Matched Image Filter (PMIF) For Pol-Sar Image Interpretation Of Ocean Surface Scatter
International Geoscience and Remote Sensing Symposium, 'Remote Sensing: Moving Toward the 21st Century'., 1988
Optimization Procedures For Scattering Matrices In The Coherent And Partially Coherent Cases
12th Canadian Symposium on Remote Sensing Geoscience and Remote Sensing Symposium,, 1989
Statistical Analysis And Somk Polarimetric Signatures Of A Polarimetric Synthetic Aperturk Radar Image
International Geoscience and Remote Sensing Symposium, 'Remote Sensing: Moving Toward the 21st Century'., 1988
Formulation Of The Proper Equations For Developing Standards In Coherent Dual Polarisation SAR Imaging
International Geoscience and Remote Sensing Symposium, 'Remote Sensing: Moving Toward the 21st Century'., 1988
The Polarimetric Matched Filter In Pol-sar Image Interpretation
12th Canadian Symposium on Remote Sensing Geoscience and Remote Sensing Symposium,, 1989
Parimetric Matched Filter For Coherent Imaging
12th Canadian Symposium on Remote Sensing Geoscience and Remote Sensing Symposium,, 1989
Pollution Effects on Condensation Evaporation and Cloud Coverage of Warm Cumulus Cloud
ABSTRACT Aerosols can affect cloud lifetime and dimensions in opposing ways. It was shown that th... more ABSTRACT Aerosols can affect cloud lifetime and dimensions in opposing ways. It was shown that the cloud's lifetime can increase due to rain suppression or decrease due to enhanced evaporation. A numerical cloud model is used to study the pollution effects on moderate-sized, coastal, convective clouds. The results show that polluted convective clouds produce larger rain drops, due to a more efficient collection process. The evaporation process is more significant at the margins of the polluted clouds (compared to the clean cloud) and it is mostly from the small droplets mode in the size distribution. We measure the overall effect on the integrated cloud coverage.
<title>Some necessary conditions on Mueller matrices</title>
Polarization Analysis and Measurement, 1992
Physical Review Letters, 2012
Data from four Fermi-detected gamma-ray bursts (GRBs) is used to set limits on spectral dispersio... more Data from four Fermi-detected gamma-ray bursts (GRBs) is used to set limits on spectral dispersion of electromagnetic radiation across the universe. The analysis focuses on photons recorded above 1 GeV for Fermi detected GRB 080916C, GRB 090510A, GRB 090902B, and GRB 090926A because these high-energy photons yield the tightest bounds on light dispersion. It is shown that significant photon bunches in GRB 090510A, possibly classic GRB pulses, are remarkably brief, an order of magnitude shorter in duration than any previously claimed temporal feature in this energy range. Although conceivably a > 3σ fluctuation, when taken at face value, these pulses lead to an order of magnitude tightening of prior limits on photon dispersion. Bound of ∆c/c < 6.94 x 10 −21 is thus obtained. Given generic dispersion relations where the time delay is proportional to the photon energy to the first or second power, the most stringent limits on the dispersion strengths were k1 < 1.61 x 10 −5 sec Gpc −1 GeV −1 and k2 < 3.57 x 10 −7 sec Gpc −1 GeV −2 respectively. Such limits constrain dispersive effects created, for example, by the spacetime foam of quantum gravity. In the context of quantum gravity, our bounds set M1c 2 greater than 525 times the Planck mass, suggesting that spacetime is smooth at energies near and slightly above the Planck mass.
Physical Review Letters, 2013
We address the question of distance record-setting by a random walker in the presence of measurem... more We address the question of distance record-setting by a random walker in the presence of measurement error, δ, and additive noise, γ and show that the mean number of (upper) records up to n steps still grows universally as Rn ∼ n 1/2 for large n for all jump distributions, including Lévy flights, and for all δ and γ. In contrast to the universal growth exponent of 1/2, the pace of record setting, measured by the pre-factor of n 1/2 , depends on δ and γ. In the absence of noise (γ = 0), the pre-factor S(δ) is evaluated explicitly for arbitrary jump distributions and it decreases monotonically with increasing δ whereas, in case of perfect measurement (δ = 0), the corresponding pre-factor T (γ) increases with γ. Our analytical results are supported by extensive numerical simulations and qualitatively similar results are found in two and three dimensions.
Optics Letters, 2005
Poor axial precision caused, in part, by large depth of focus ͑͒ has been a vexing problem in ext... more Poor axial precision caused, in part, by large depth of focus ͑͒ has been a vexing problem in extraction of particle position from digital in-line holograms. A simple method is proposed to combat this depth-of-focus difficulty. The method is based on decoupling of size and position information. With d , ⌬, and being particle diameter, CCD pixel size, and the wavelength, respectively, our main theoretical result is the reduction of from ϳ d 2 / to ϳ ⌬ 2 / for particles of known size. This result is confirmed in laboratory experiments with holograms of calibrated glass spheres.
Optics Letters, 2006
The spatial phase resulting from the digital reconstruction of an in-line hologram of a particle ... more The spatial phase resulting from the digital reconstruction of an in-line hologram of a particle field is shown to yield a unique pattern that can be used for particle detection. This phase signature is present only when viewed along with the reference light. The existence of the phase pattern is verified computationally and confirmed in laboratory experiments with holograms of calibrated glass spheres. The phase signature provides an alternative to the widely used intensity method for particle detection.
Journal of the Optical Society of America A, 1988
Various aspects of the physics of partially polarized waves are discussed with applications to op... more Various aspects of the physics of partially polarized waves are discussed with applications to optical (lidar) reception problems. We focus on the issue of the optimal intensity reception of partially polarized waves scattered off a fluctuating object (ensemble of scatterers) of known polarization properties (measured Mueller matrix). Expressions for total available intensity and adjustable (polarization-dependent) intensity are derived in a clear and novel manner by using the coherency matrix approach. A general numerical technique is developed and illustrated for the optimization of adjustable intensity as a function of transmitted polarization. Closed-form expressions are derived for two important subcases, and numerical illustrations for the general case are discussed in detail, including the use of relevant experimental data.
Generalized trace condition on the Mueller-Jones polarization matrix
Journal of the Optical Society of America A, 1993
... Clark R. Givens and Alexander B. Kostinski ... 1993; revised manuscript received April 27, 19... more ... Clark R. Givens and Alexander B. Kostinski ... 1993; revised manuscript received April 27, 1993; accepted May 7, 1993 The purpose of this Communication is to derive a generalized trace condition for a Mueller-Jones polarization matrix that is based on the Brosseau-Barakat [Opt. ...
Optimal detection in depolarizing media: extension for partially polarized sources
Journal of the Optical Society of America A, 1992
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Papers by Alexander Kostinski