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arXiv2009

Stability Criteria of 3D Inviscid Shears

The classical plane Couette flow, plane Poiseuille flow, and pipe Poiseuille flow share some universal 3D steady coherent structure in the form of "streak-roll-critical layer". As the Reynolds number approaches infinity, the steady coherent structure approaches a 3D limiting shear of the form ($U(y,z), 0, 0$) in velocity variables. All such 3D shears are steady states of the 3D Euler equations. This raises the importance of investigating the stability of such inviscid 3D shears in contrast to the classical Rayleigh theory of inviscid 2D shears. Several general criteria of stability for such inviscid 3D shears are derived. In the Appendix, an argument is given to show that a 2D limiting shear can only be the classical laminar shear.

physics.flu-dyn↗

arXiv2009

The Greenhouse Effect Does Exist!

In particular, without the greenhouse effect, essential features of the atmospheric temperature profile as a function of height cannot be described, i.e., the existence of the tropopause above which we see an almost isothermal temperature curve, whereas beneath it the temperature curve is nearly adiabatic. The relationship between the greenhouse effect and observed temperature curve is explained and the paper by Gerlich and Tscheuschner [arXiv:0707.1161] critically analyzed. Gerlich and Tscheuschner called for this discussion in their paper.

physics.ao-ph↗

arXiv2010

Single Photon Atomic Sorting: Isotope Separation with Maxwell's Demon

Isotope separation is one of the grand challenges of modern society and holds great potential for basic science, medicine, energy, and defense. We consider here a new and general approach to isotope separation. The method is based on an irreversible change of the mass-to-magnetic moment ratio of a particular isotope in an atomic beam, followed by a magnetic multipole whose gradients deflect and guide the atoms. The underlying mechanism is a reduction of the entropy of the beam by the information of a single-scattered photon for each atom that is separated. We numerically simulate isotope separation for a range of examples, including lithium, for which we describe the experimental setup we are currently constructing. Simulations of other examples demonstrate this technique's general applicability to almost the entire periodic table. We show that the efficiency of the process is only limited by the available laser power, since one photon on average enables the separation of one atom. The practical importance of the proposed method is that large-scale isotope separation should be possible, using ordinary inexpensive magnets and the existing technologies of supersonic beams and lasers.

physics.atom-ph↗

arXiv2010

Subharmonic resonance of global climate to solar forcing

It is shown that, the wavelet regression detrended fluctuations of the monthly global temperature data (land and ocean combined) for the period 1880-2009yy, are completely dominated by one-third subharmonic resonance to annual forcing (both natural and anthropogenically induced). Role of the oceanic Rossby waves and the resonance contribution to the El Nino phenomenon have been discussed in detail.

physics.ao-ph↗

arXiv2010

A Pedagogical "Toy" Climate Model

A "toy" model, simple and elementary enough for an undergraduate class, of the temperature dependence of the greenhouse (mid-IR) absorption by atmospheric water vapor implies a bistable climate system. The stable states are glaciation and warm interglacials, while intermediate states are unstable. This is in qualitative accord with the paleoclimatic data. The present climate may be unstable, with or without anthropogenic interventions such as CO$_2$ emission, unless there is additional stabilizing feedback such as "geoengineering".

physics.soc-ph↗

arXiv2010

The virial theorem and planetary atmospheres

We derive a version of the virial theorem that is applicable to diatomic planetary atmospheres that are in approximate thermal equilibrium at moderate temperatures and pressures and are sufficiently thin such that the gravitational acceleration can be considered constant. We contrast a pedagogically inclined theoretical presentation with the actual measured properties of air.

physics.gen-ph↗

arXiv2010

Chaotic background of large-scale climate oscillations

It is shown that the periodic alteration of night and day provides a chaotic dissipation mechanism for the North Atlantic (NAO) and Southern (SOI) climate oscillations. The wavelet regression detrended daily NAO index for last 60 years and daily SOI for last 20 years as well as an analytical continuation in the complex time domain were used for this purpose.

physics.ao-ph↗

arXiv2010

Tropospheric ozone columns and ozone profiles for Kiev in 2007

We report on ground-based FTIR observations being performed within the framework of the ESA-NIVR-KNMI project 2907 entitled "OMI validation by ground based remote sensing: ozone columns and atmospheric profiles" for the purpose of OMI data validation. FTIR observations were performed during the time frames August-October 2005, June-October 2006 and March-October 2007, mostly under cloud free and clear sky conditions and in some days from early morning to sunset covering the full range of solar zenith angles possible. Ozone column and ozone profile data were obtained for the year 2005 using spectral modeling of the ozone spectral band profile near 9.6 microns with the MODTRAN3 band model based on the HITRAN-96 molecular absorption database. The total ozone column values retrieved from FTIR observations are biased low with respect to OMI-DOAS data by 8-10 DU on average, where they have a relatively small standard error of about 2%. FTIR observations for the year 2006 were simulated by MODTRAN4 modeling. For the retrieval of ozone column estimates and particularly ozone profiles from our FTIR observations, we used the following data sources to as input files to construct the (a priori) information for the model: satellite Aqua-AIRS water vapor and temperature profiles; Aura-MLS stratospheric ozone profiles (version 1.5), TEMIS climatological ozone profiles and the simultaneously performed surface ozone measurements. Ozone total columns obtained from our FTIR observations for year 2006 with MODTRAN4 modeling are matching rather well with OMI-TOMS and OMI-DOAS data where standard errors are 0.68% and 1.11%, respectively. AURA-MLS data which have become available in 2007 allow us to retrieve tropospheric ozone profiles.

astro-ph.EP↗

arXiv2010

Nonlinear and chaotic ice ages: data vs speculations

It is shown that, the wavelet regression detrended fluctuations of the reconstructed temperature for the past 400,000 years (Antarctic ice cores data) are completely dominated by one-third subharmonic resonance, presumably related to Earth precession effect on the energy that the intertropical regions receive from the Sun. Effects of Galactic turbulence on the temperature fluctuations are also discussed. Direct evidence of chaotic response of the atmospheric CO_2 dynamics to obliquity periodic forcing has been found in a reconstruction of atmospheric CO_2 data (deep sea proxies), for the past 650,000 years.

physics.ao-ph↗

arXiv2010

Theoretical Studies of Long Lived Plasma Structures

We construct the model of a long lived plasma structure based on spherically symmetric oscillations of electrons in plasma. Oscillations of electrons are studied in frames of both classical and quantum approaches. We obtain the density profile of electrons and the dispersion relations for these oscillations. The differences between classical and quantum approaches are discussed. Then we study the interaction between electrons participating in spherically symmetric oscillations. We find that this interaction can be attractive and electrons can form bound states. The applications of the obtained results to the theory of natural plasmoids are considered.

physics.plasm-ph↗

arXiv2010

Potential energy of atmospheric water vapor and the air motions induced by water vapor condensation on different spatial scales

Basic physical principles are considered that are responsible for the origin of dynamic air flow upon condensation of water vapor, the partial pressure of which represents a store of potential energy in the atmosphere of Earth. Quantitative characteristics of such flow are presented for several spatial scales. It is shown that maximum condensation-induced velocities reach 160 m/s and are realized in compact circulation patterns like tornadoes.

physics.ao-ph↗

arXiv2011

General Temporal Instability Criteria For Stably Stratified Inviscid Flow

The temporal instability of stably stratified flow was investigated by analyzing the Taylor-Goldstein equation theoretically. According to this analysis, the stable stratification $N^2\geq0$ has a destabilization mechanism, and the flow instability is due to the competition of the kinetic energy with the potential energy, which is dominated by the total Froude number $Fr_t^2$. Globally, $Fr_t^2 \leq 1$ implies that the total kinetic energy is smaller than the total potential energy. So the potential energy might transfer to the kinetic energy after being disturbed, and the flow becomes unstable. On the other hand, when the potential energy is smaller than the kinetic energy ($Fr_t^2>1$), the flow is stable because no potential energy could transfer to the kinetic energy. The flow is more stable with the velocity profile $U'/U'''>0$ than that with $U'/U'''<0$. Besides, the unstable perturbation must be long-wave scale. Locally, the flow is unstable as the gradient Richardson number $Ri>1/4$. These results extend the Rayleigh's, Fjørtoft's, Sun's and Arnol'd's criteria for the inviscid homogenous fluid, but they contradict the well-known Miles-Howard theorem. It is argued here that the transform $F=ϕ/(U-c)^n$ is not suitable for temporal stability problem, and that it will lead to contradictions with the results derived from the Taylor-Goldstein equation. However, such transform might be useful for the study of the Orr-Sommerfeld equation in viscous flows.

physics.flu-dyn↗

arXiv2012

Microburst applications of brightness temperature difference between GOES Imager channels 3 and 4

This paper presents a new application of brightness temperature difference (BTD) between Geostationary Operational Environmental Satellite (GOES) imager channels 3 and 4. It has been found recently that the BTD between GOES infrared channel 3 (water vapor) and channel 4 (thermal infrared) can highlight regions where severe outflow wind generation (i.e. downbursts, microbursts) is likely due to the channeling of dry mid-tropospheric air into the precipitation core of a deep, moist convective storm. Case studies demonstrating effective operational use of this image product are presented for two significant marine transportation accidents as well as a severe downburst event over the Washington, DC metropolitan area in April 2010.

physics.ao-ph↗

arXiv2010

A stability criterion for two-fluid interfaces and applications

We derive here a new stability criterion for two-fluid interfaces. This criterion ensures the existence of "stable" local solutions that do no break down too fast due to Kelvin-Helmholtz instabilities. It can be seen both as a two-fluid generalization of the Rayleigh-Taylor criterion and as a nonlinear version of the Kelvin stability condition. We show that gravity can control the inertial effects of the shear up to frequencies that are high enough for the surface tension to play a relevant role. This explains why surface tension is a necessary condition for well-posedness while the (low frequency) main dynamics of interfacial waves is unaffected by it. In order to derive a practical version of this criterion, we work with a nondimensionalized version of the equations and allow for the possibility of various asymptotic regimes, such as the shallow water limit. This limit being singular, we have to derive a new symbolic analysis of the Dirichlet-Neumann operator that includes an infinitely smoothing "tail" accounting for the contribution of the bottom. We then validate our criterion by comparison with experimental data in two important settings: air-water interfaces and internal waves. The good agreement we observe allows us to discuss the scenario of wave breaking and the behavior of water-brine interfaces. We also show how to rigorously justify two-fluid asymptotic models used for applications and how to relate some of their properties to Kelvin-Helmholtz instabilities.

math.AP↗

arXiv2010

Successful modeling of the environmental changes' influence on forests' vegetation over North Eurasia

Modeling of forests' vegetation in North Eurasia has been performed for 1982-2006 on the basis of remote sensing data. Four meteorological parameters and one parameter, characterizing geomagnetic field disturbance level, were used for this aim. It was found out that revealed formula is adequate both for coniferous evergreen and coniferous deciduous forests for accuracy to a coefficient. The most proper parameters' combination gives the correlation coefficients ~ 0.9 between modeling parameter and original data rows. These results could solve problems of climate-forests feedbacks' investigations and be useful for dendrological aims.

physics.ao-ph↗

arXiv2010

Investigation of Traveling Ionospheric Disturbances during a Midlatitude Spread F Event

During a midlatitude spread F (MSF) event, data was collected to investigate the circumstances that may lead to MSF. Using the Total Electron Content (TEC) derived from the NCAT-SCINDA GPS station and the Continuous Operating Reference Stations (CORS) Traveling Ionospheric Disturbances (TID) were analyzed during a period of MSF over Wallops Island, Virginia. In addition to the TEC analysis, scintillation calculations have been made using the NCAT-SCINDA GPS receiver, USRP receiver and a Narrow Band (NB) receiver. Scintillation levels on the GPS, USRP and NB signals were very low throughout the period of MSF. Analysis of TEC data from multiple CORS sites has shown the presence of medium scale atmospheric gravity waves (AGW) within the MSF event region propagating towards low latitudes with a small eastward component. This is consistent with theories showing AGW may lead to MSF if an oppositely directed neutral wind is present. This study was performed in conjunction with a sounding rocket experiment investigating ionospheric disturbances at multiple scale sizes.

physics.space-ph↗

arXiv2010

Galactic turbulence and paleoclimate variability

The wavelet regression detrended fluctuations of the reconstructed temperature for the past three ice ages: approximately 340000 years (Antarctic ice cores isotopic data), exhibit clear evidences of the galactic turbulence modulation up to 2500 years time-scales. The observed strictly Kolmogorov turbulence features indicates the Kolmogorov nature of galactic turbulence, and provide explanation to random-like fluctuations of the global temperature on the millennial time scales.

astro-ph.GA↗

arXiv2011

Generation of intermediately-long sea waves by weakly sheared winds

The present study concerns the numerical modeling of sea-wave instability under the effect of logarithmic-wind profile in hurricane conditions. The central point of the study is the calculation of the wave growth rate, which is proportional to the fractional input energy from the weakly-sheared (logarithmic) wind to the wave exponentially varying with time. It is shown for hurricane conditions that the Miles-type stability model based on the Charnock's formula with the standard constant coefficient underestimates the growth rate ~5 to 50 times as compared with the model employing the roughness adopted from experimental data for hurricane winds. The drag reduction with wind speed at hurricane conditions coupled with the similar behavior of the dimensionless gravity acceleration, leads to the minimum in the maximal growth rate and the maximum in the most unstable wavelength.

physics.ao-ph↗