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arXiv2010

Total ozone columns and vertical ozone profiles above Kiev in 2005-2008

The study of total ozone columns above Kiev and variations of ozone concentrations in the troposphere at different altitudes above Kiev was carried out using ground-based Fourier Transform InfraRed (FTIR) spectrometric observations that are taken on a routine basis at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine (MAO NASU). This study was performed within the framework of the international ESA-NIVR-KNMI OMI-AO project no.2907 entitled OMI validation by ground-based remote sensing: ozone columns and atmospheric profiles during the time frame 2005-2008. The infrared FTIR spectral observations of direct solar radiation in the wavelength range of 2-12 micron as transmitted through the Earth's atmosphere were performed during the months of April-October of each year. The aim of the project was the validation of total ozone columns and vertical ozone profiles as obtained by the Ozone Monitoring Instrument (OMI)) onboard of the NASA EOS-Aura scientific satellite platform. The modeling of the ozone spectral band shape near 9.6 microns was performing with the MODTRAN code and a molecular band model based on the HITRAN-2004 molecular database. The a-priori information for the spectral modeling consisted of water vapor and temperature profiles from the NASA EOS-Aqua-AIRS satellite instrument, stratospheric ozone profiles from the NASA EOS-Aura-MLS satellite instrument, TEMIS-KNMI climatological ozone profiles and surface ozone concentration measurements performed at the specific times of infrared spectra observations. The troposphere ozone variability was analyzed for two typical episodes: the spring episode of enhanced total ozone columns and the summer episode of enhanced surface ozone concentrations.

astro-ph.EP↗

arXiv2010

Delta-singular vortex dynamics on a rotating sphere and stability of coupled atmospheric centers of action

Existence of a stationary mode for a Hamiltonian dynamic system of two point vortexes with different signs on different latitudes of a uniform rotating sphere complying with observed data is stated. It is shown that such mode realization is possible only in the case when the more intensive cyclonic vortex has greater latitude than that of the anticyclonic vortex. A criterion of exponential instability of the stationary vortex mode taken into account impact of the polar vortexes is obtained. Compliance of the theory to observed data and reanalysis for coupled quasi-stationary systems of cyclonic and anticyclonic atmosphere action centers above oceans in the Northern Hemisphere is considered.

physics.flu-dyn↗

arXiv2011

Stability of Inviscid Parallel Flows between Two Parallel Walls

In this paper, the stability of inviscid parallel flow between two parallel walls is studied. Firstly, it is obtained that the profile of the base flow for this classical problem is a uniform flow. Secondly, it is shown that the solution of the disturbance equation is cr=U and ci=0, i.e., the propagation speed of the disturbance equals the flow velocity and the disturbance in this flow is neutral. Finally, it is suggested that the classical Rayleigh Theorem on inflectional velocity instability is incorrect which states that the necessary condition for instability of inviscid parallel flow is the existence of an inflection point on the velocity profile.

physics.flu-dyn↗

arXiv2010

Recent developments in microburst nowcasting using GOES

Recent testing and validation have found that the Geostationary Operational Environmental Satellite (GOES) microburst products are effective in the assessment and short-term forecasting of downburst potential and associated wind gust magnitude. Two products, the GOES sounder Microburst Windspeed Potential Index (MWPI) and a new two-channel GOES imager brightness temperature difference (BTD) product have demonstrated capability in downburst potential assessment. The MWPI, a diagnostic nowcasting product, is designed to infer attributes of a favorable microburst environment: large CAPE and a convective mixed layer with a steep temperature lapse rate and low relative humidity in the surface layer. These conditions foster intense convective downdrafts due to evaporational cooling as precipitation descends in the sub-cloud layer. More recently, a new application of the brightness temperature difference (BTD) between GOES imager channels 3 and 4 has been developed. It has been found 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. This paper provides an updated assessment of the MWPI and new GOES BTD algorithm, presents case studies demonstrating effective operational use of the microburst products, and presents validation results for the 2010 convective season over the United States Great Plains and Atlantic Coast regions.

physics.ao-ph↗

arXiv2010

Tidal Evolution of Exoplanets

Tidal effects arise from differential and inelastic deformation of a planet by a perturbing body. The continuous action of tides modify the rotation of the planet together with its orbit until an equilibrium situation is reached. It is often believed that synchronous motion is the most probable outcome of the tidal evolution process, since synchronous rotation is observed for the majority of the satellites in the Solar System. However, in the 19th century, Schiaparelli also assumed synchronous motion for the rotations of Mercury and Venus, and was later shown to be wrong. Rather, for planets in eccentric orbits synchronous rotation is very unlikely. The rotation period and axial tilt of exoplanets is still unknown, but a large number of planets have been detected close to the parent star and should have evolved to a final equilibrium situation. Therefore, based on the Solar System well studied cases, we can make some predictions for exoplanets. Here we describe in detail the main tidal effects that modify the secular evolution of the spin and the orbit of a planet. We then apply our knowledge acquired from Solar System situations to exoplanet cases. In particular, we will focus on two classes of planets, "Hot-Jupiters" (fluid) and "Super-Earths" (rocky with atmosphere).

astro-ph.EP↗

arXiv2010

Point symmetry group of the barotropic vorticity equation

The complete point symmetry group of the barotropic vorticity equation on the $β$-plane is computed using the direct method supplemented with two different techniques. The first technique is based on the preservation of any megaideal of the maximal Lie invariance algebra of a differential equation by the push-forwards of point symmetries of the same equation. The second technique involves a priori knowledge on normalization properties of a class of differential equations containing the equation under consideration. Both of these techniques are briefly outlined.

math-ph↗

arXiv2011

A retrieval strategy for interactive ensemble data assimilation

As an alternative to either directly assimilating radiances or the naive use of retrieved profiles (of temperature, humidity, aerosols, and chemical species), a strategy is described that makes use of the so-called averaging kernel (AK) and other information from the retrieval process. This AK approach has the potential to improve the use of remotely sensed observations of the atmosphere. First, we show how to use the AK and the retrieval noise covariance to transform the retrieved quantities into observations that are unbiased and have uncorrelated errors, and to eliminate both the smoothing inherent in the retrieval process and the effect of the prior. Since the effect of the prior is removed, any prior, including the forecast from the data assimilation cycle can be used. Then we show how to transform this result into EOF space, when a truncated EOF series has been used in the retrieval process. This provides a degree of data compression and eliminates those transformed variables that have very small information content. In both approaches a vertical interpolation from the dynamical model coordinate to the radiative transfer coordinate is required. We define an algorithm using the EOF representation to optimize this vertical interpolation

physics.ao-ph↗

arXiv2010

An Internal Wave as a Frequency Filter for Surface Gravity Waves on Water

We consider one-dimensional model of the interaction between surface and the internal gravity water waves. The internal wave is modeled by its basic form: a non-dispersive field with a horizontal current that is uniform over all depth, insignificantly affected by the surface waves, while ignoring surface tension and wind growth/decay effects. The depth is infinite. Approximation for the height of the surface wave on the flow by the "elementary quasi stationary" solutions was found. It was shown that the flow acts as a frequency filter for gravitational waves on water.

physics.ao-ph↗

arXiv2010

The Laboratory Complex for the Calibration of Photometers Using the Optical Method for Determination of the Water Vapor Content in the Earth Atmosphere

We describe the laboratory complex for the calibration of photometers that are used in weather service to measure the water vapor content in the Earth atmosphere. The complex was built up in Pulkovo Observatory and developed within the framework of collaboration between Pulkovo Observatory and Lindenberg Meteorological Observatory (Meteorologisches Observatorium Lindenberg - Richard-Aßmann-Observatorium, Lindenberg, Germany). It is used to obtain calibration dependences for individual devices, and also to develop and compare various methods of construction of calibration dependences. These techniques are based on direct calibration of the photometers, on the use of spectral laboratory transmission functions for water vapor, on calculation methods using spectroscopical databases for individual lines. We hope that when the parameters of the equipment are taken into account in detail and new results for the absorptive power of water vapor are used, the accuracy of determination of the water vapor content in the atmosphere of 1-2% may be attained.

astro-ph.IM↗

arXiv2011

Analysis of the application of the optical method to the measurements of the water vapor content in the atmosphere - Part 1: Basic concepts of the measurement technique

We retrieved the total content of the atmospheric water vapor (or Integrated Water Vapor, IWV) from extensive sets of photometric data obtained since 1995 at Lindenberg Meteorological Observatory with star and sun photometers. Different methods of determination of the empirical parameters that are necessary for the retrieval are discussed. The instruments were independently calibrated using laboratory measurements made at Pulkovo Observatory with the VKM-100 multi-pass vacuum cell. The empirical parameters were also calculated by the simulation of the atmospheric absorption by water vapor, using the MODRAN-4 program package for different model atmospheres. The results are compared to those presented in the literature, obtained with different instruments and methods of the retrieval. The reliability of the empirical parameters, used for the power approximation that links the water vapor content with the observed absorption, is analyzed. Currently, the total (from measurements, calibration, and calculations) errors yield the standard uncertainty of about 10% in the total column water vapor. We discuss the possibilities for improving the accuracy of calibration to ~1% as indispensable condition in order to make it possible to use data obtained by optical photometry as an independent reference for other methods (GPS, MW-radiometers, lidar, etc).

physics.ao-ph↗

arXiv2011

The Weather and its Role in Captain Robert F. Scott and his Companions' Deaths

A long debate has ensued about the relationship of weather conditions and Antarctic exploration. In no place on Earth is exploration, human existence, and scientific research so weather dependent. By using an artificial neural network simulation, historical (Heroic Age) and modern weather data from manned and automated stations, placed at different locations of the Ross Ice Shelf, and the Ross Island, I have examined minimum near surface air temperatures. All modern meteorological data, as well as historical data of Cherry-Garrard, high correlations between temperatures at different locations, and artificial neural network retrodiction of modern and historical temperature data, point out the oddity of Captain Scott's temperature recordings from February 27 - March 19, 1912. I was able to show that in this period the actual minimum near surface air temperature was on the average about 13°F(7°C) above that reported by Captain Scott and his party. On the basis of the mentioned evidence I concluded that the real minimum near surface air temperature data was altered by Lt. Bowers and Captain Scott to inflate and dramatize the weather conditions.

physics.hist-ph↗

arXiv2011

Assessment of a GOES microburst product for two early cold season convective storms

This paper presents an assessment of the new Geostationary Operational Environmental Satellite (GOES) imager channel 3 - 4 brightness temperature difference (BTD) product for two early cold season severe convective storm events that occurred over the Mid-Atlantic region on 17 November and 1 December 2010. Both of these events involved squall lines that produced strong downbursts as they tracked over the Tidal Potomac River and Chesapeake Bay regions. 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. These two cases demonstrate effective operational use of this image product for cold-season convective storm events.

physics.ao-ph↗

arXiv2011

Turbulent viscosity variability in self-propelled body wake model

We study the influence of turbulent viscosity variability on the properties of self-propelled body wake model. In addition to the already known integrals of motion obtained with constant turbulent viscosity, we obtain new ones. The presence of new integrals of motion leads, in particular, to changes in the behavior of the width and profile of the wake leading to its conservation.

physics.flu-dyn↗

arXiv2018

Trajectories of Rubber Balloons used in Balloon Releases: Theory and Application

Balloon releases are one of the main attractions of many fairs. Helium filled rubber balloons are released to carry postcards over preferably long distances. Although such balloons have been considered in atmospheric sciences and air safety analysis, there is only scarce literature available on the subject. This work intends to close this gap by providing a comprehensive theoretical overview and a thorough analysis of real-life data. All relevant physical properties of a rubber balloon are carefully modelled and supplemented by weather observations to form a self-contained trajectory simulation tool. The analysis of diverse balloon releases provided detailed insight into the flight dynamics and potential optimisations. Helium balloons are found to reach routinely altitudes above 10 km. Under optimal conditions, they could stay more than 24 hours airborne while reaching flight distances close to 3000 km. However, external weather effects reduce the typical lifetime to 2-5 hours.

physics.pop-ph↗

arXiv2011

Böögg Bang drives global climate change

The Böögg is a large model of a snowman, constructed of inflammable materials and filled with explosives. During the traditional festival of Sechseläuten, which takes place each spring in Zurich, Switzerland, the Böögg is placed atop a wooden pyre, which is set alight. According to popular legend, the time that elapses until the Böögg's head explodes (the "head-bang" time) is said to give a rough forecast of local weather conditions prevailing during the following summer. However, recent research has questioned the validity of this prediction. To study the Böögg's predictive powers, we analyzed the Böögg head-bang time record from 1965-2010 within the context of global climate change. Our analysis shows that the Böögg head-bang time is a good predictor not of short-term local weather, as might be expected from the legend, but of the behavior of the entire global climate system.

physics.pop-ph↗

arXiv2011

Enstrophy bounds and the range of space-time scales in the hydrostatic primitive equations

The hydrostatic primitive equations (HPE) form the basis of most numerical weather, climate and global ocean circulation models. Analytical (not statistical) methods are used to find a scaling proportional to $(Nu\,Ra\,Re)^{1/4}$ for the range of horizontal spatial sizes in HPE solutions, which is much broader than currently achievable computationally. The range of scales for the HPE is determined from an analytical bound on the time-averaged enstrophy of the horizontal circulation. This bound allows the formation of very small spatial scales, whose existence would excite unphysically large linear oscillation frequencies and gravity wave speeds.

nlin.CD↗

arXiv2011

Gamma Background Measurements at BEO Moussala

Recent measurements of radiation gamma background at high mountain altitude, namely at Basic Environmental Observatory Moussala (42°10' 45" N; 23° 35'07"E, 2925m a.s.l.) are carried out. The measurements are fulfilled with several different devices, namely IGS-421 gamma probe and MDU Liulin spectrometer. The used instrumentation with their characteristics is described. The obtained results are compared with previously obtained measurements carried out with NaI SAPHYMO gamma probe. In addition the measurements are compared with TLD data. The obtained results from measurements are widely discussed. The contribution of galactic cosmic rays to dose rate is estimated on the basis of a numerical model. The model is based on a full Monte Carlo simulation of cosmic ray induced nuclear-electromagnetic-muon cascade in the atmosphere. The simulation is carried out with CORSIKA 6.52 code using FLUKA 2006 and QGSJET II hadron interaction models. The application of the model is briefly discussed.

physics.ao-ph↗

arXiv2012

Ostwald ripening and the kinetics of rain initiation

A central problem in cloud physics is understanding the kinetics of the growth of water droplets. It is believed that there exists a 'condensation-coalescence bottleneck' in the growth of intermediate size droplets. Here the Lifshitz-Slezov theory of Ostwald ripening is applied to the kinetics of the growth of rain drops. The analysis shows that kinetic barriers to rain initiation are not significant. It is also shown that Ostwald ripening can greatly enhance the apparent collision efficiency of droplets falling under gravity.

physics.ao-ph↗