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arXiv2013

Novel measures based on the Kolmogorov complexity for use in complex system behavior studies and time series analysis

We have proposed novel measures based on the Kolmogorov complexity for use in complex system behavior studies and time series analysis. We have considered background of the Kolmogorov complexity and also we have discussed meaning of the physical as well as other complexities. To get better insights into the complexity of complex systems and time series analysis we have introduced the three novel measures based on the Kolmogorov complexity: (i) the Kolmogorov complexity spectrum, (ii) the Kolmogorov complexity spectrum highest value and (iii) the overall Kolmogorov complexity. The characteristics of these measures have been tested using a generalized logistic equation. Finally, the proposed measures have been applied on different time series originating from: the model output (the biochemical substance exchange in a multi-cell system), four different geophysical phenomena (dynamics of: river flow, long term precipitation, indoor 222Rn concentration and UV radiation dose) and economy (stock prices dynamics). Results which are obtained offer deeper insights into complexity of the system dynamics behavior and time series analysis when the proposed complexity measures are applied.

nlin.CD↗

arXiv2013

On the reliability of Seasonal Climate Forecasts

Seasonal climate forecasts are being used increasingly across a range of application sectors. A recent UK governmental report asked: How good are seasonal climate forecasts on a scale of 1-5 (where 5 is very good), and how good can we expect them to be in 30 years time? Seasonal climate forecasts are made from ensembles of integrations of numerical models of climate. We argue that goodness should be assessed primarily in terms of the probabilistic reliability of these ensemble-based forecasts and that a 5 should be reserved for systems which are not only reliable overall, but where, in particular, small ensemble spread is a reliable indicator of low ensemble forecast error. We study the reliability of regional temperature and precipitation forecasts of the current operational seasonal forecast system of the European Centre for Medium-Range Weather Forecasts, universally regarded as a world leading operational institute producing seasonal climate forecasts. A wide range of goodness rankings, depending on region and variable (with summer forecasts of rainfall over Northern Europe performing exceptionally poorly) is found. Finally, we discuss the prospects of reaching 5 across all regions and variables in 30 years time.

physics.ao-ph↗

arXiv2013

Uncovering MIT wind myths through micro-climatological CFD analysis

Popular campus myths of unusually strong pedestrian level winds are investigated with a Computational Fluid Dynamics (CFD) approach. The numerical simulations confirm the existence of the reported phenomena and provide a qualitative explanation of their physical mechanisms.

physics.ao-ph↗

arXiv2013

Some considerations on skewness and kurtosis of vertical velocity in the convective boundary layer

Data of skewness $S$ and kurtosis $K$ of vertical velocity in the convective boundary layer from different datasets have been analysed. Vertical profiles of $S$ were found to be grouped into two classes that display different slopes with height: one is nearly constant and the other is increasing. This behaviour can be explained using a simple model for the PDF of vertical velocity and assuming two distinct vertical profiles of updraft area fraction from literature. The possibility of describing the explicit dependence of $K$ on $S$ was revised critically, also considering the neutral limit as well as the limit for very small non-dimensional height. It was found that the coefficients of the relationship depends on both the Obukhov length scale $L$ and inversion height $z_i$.

physics.ao-ph↗

arXiv2013

Cosmogenic 7Be in ground level air in Rostov-on-Don (Russia) (2001-2011)

The deposition flux of cosmogenic 7Be in the industrial city Rostov-on-Don (Russia) from 2001 to 2011 has been measured. The variations of annual 7Be deposition flux appear to be mainly correlated with the number of the meteorological parameters and solar activity. For the first time correlations of the volume activity of cosmogenic 7Be with such meteorological parameters as temperature, precipitation, wind speed, atmospheric pressure, relative humidity are identified.

physics.ao-ph↗

arXiv2013

A record of atmospheric 210Pb accumulation in the industrial city

The deposition flux of total atmospheric 210Pb in the industrial city Rostov-on-Don, Russia from 2002 to 2010 has been measured. The variations in annual 210Pb deposition flux appear to be mainly correlated with the number of rains and significant amount of anthropogenic 210Pb, polluted into the surface layer of air in the home-heating period. The average 210Pb deposition is 1.75 mBq/m3. Several meteorological parameters which are strongly associated with the fluctuations of concentrations of 210Pb are identified. These results are useful to provide typical information on the atmosphere radioactivity in an industrial city.

physics.ao-ph↗

arXiv2013

Intraseasonal characterization of tropospheric O3 in the North of the Buenos Aires Province: determining four months cycle and teleconnection evidence

Tropospheric ozone (O3T) is a secondary pollutant whose formation involved primarily solar radiation, NOx and volatile organic compounds. The North of the Buenos Aires Province has great agricultural-industrial activity; therefore, O3T study is an important issue in the area. In this paper, we present the first results tend to estimate and characterize O3T in San Nicolás de los Arroyos, North of Buenos Aires. Due to a lack of in situ data, we analyse the observations of the instrument OMI (Ozone Monitoring Instrument) of land remote sensing satellite AURA (GSFC/NASA). The data cover the years 2004-2013. Applying the multitaper technique (MTM), very suitable for short and noisy data series, spectral analysis is performed on a grid corresponding 1° in latitude by 1.5° in longitude, centred South of the Province of Santa Fe. The most remarkable result is the emergence of a significant peak (95%) of four months cycle. To test the validity of this signal in San Nicolás, daily solar radiation data (Q) were analysed in the area. The application of MTM to the daily values of Q, yields a spectral peak of 120 days. It is concluded that atmospheric opacity on the site has four months variations that modify the solar radiation at the troposphere, and consequently, the production rate of O3T. Evidence that these variations are due to teleconnection process originated in the Maritime Continent are presented.

physics.ao-ph↗

arXiv2013

Modeling of Atmospheric Flow Around a Coastal Cape: Lee Side Story

The current research focuses on mesoscale dynamics of the atmospheric circulation around an idealized coastal cape representing typical summertime circulation along the northwest coast of the U.S., studied using a mesoscale coupled ocean-atmosphere modeling system. The orographic wind maximum features a strong NW flow extending a few hundred kilometers downstream and seaward of the cape, which closely follows mesoscale orographic low pressure developed in the lee of the cape. Both wind maximum and the lee trough experience a pronounced diurnal cycle, marked by maximum northwest flow and minimum pressure in the local evening hours (its opposite phase during morning hours), and confirmed by observations from limited buoy and coastal stations. Vertical structure of the atmospheric boundary layer over the coastal ocean on the lee side of the cape indicated the downward propagation of potential temperature and wind features during the course of the day, as opposed to the traditional surface-driven development of the atmospheric boundary layer. Momentum analysis showed the local pressure gradients near the surface vary greatly depending on the relative location about the cape. Strong perturbations in relative vorticity downwind of the cape supported the hypothesis that mountain dynamics have a key role in establishing wind regime around the cape. The sensitivity studies indicated the importance of coastal terrain elevation on the formation and the strength of the lee trough and wind maximum. Higher coastal topography was found to cause greater separation of the upwelling front (jet) from the coast downwind of the cape.

physics.ao-ph↗

arXiv2013

Phase relation between global temperature and atmospheric carbon dioxide

The primary ingredient of Anthropogenic Global Warming hypothesis is the assumption that atmospheric carbon dioxide variations are the cause for temperature variations. In this paper we discuss this assumption and analyze it on basis of bi-centenary measurements and using a relaxation model which causes phase shifts and delays.

physics.ao-ph↗

arXiv2014

On the linear operation of cloned dynamical systems and its Lyapunov exponents

The cloned dynamical system theory is introduced and the Lyapunov exponents of this system are qualitatively proven to be same as the original dynamical system. This property indicates that these two systems have the same error propagation speed in the phase space, and thus we can interpret the phenomenon as why the ensemble mean method sometimes is not effective.

nlin.CD↗

arXiv2013

Polytropic process and tropical Cyclones

We show a parallelism between the expansion and compression of the atmosphere in the secondary cycle of a tropical cyclone with the fast expansion and compression of wet air in a bottle. We present a simple model in order to understand how the system (cyclone) draws energy from the air humidity. In particular we suggest that the upward (downward) expansion (compression) of the warm (cold) moist (dry) air follows a polytropic process, $PV^β$= constant. We show both experimentally and analytically that $β$ depends on the initial vapor pressure in the air. We propose that the adiabatic stages in the Carnot-cycle model for the tropical cyclone be replaced by two polytropic stages. These polytropic processes can explain how the wind wins energy and how the rain and the dry bands are produced inside the storm.

physics.ao-ph↗

arXiv2013

Revealing Relationships among Relevant Climate Variables with Information Theory

A primary objective of the NASA Earth-Sun Exploration Technology Office is to understand the observed Earth climate variability, thus enabling the determination and prediction of the climate's response to both natural and human-induced forcing. We are currently developing a suite of computational tools that will allow researchers to calculate, from data, a variety of information-theoretic quantities such as mutual information, which can be used to identify relationships among climate variables, and transfer entropy, which indicates the possibility of causal interactions. Our tools estimate these quantities along with their associated error bars, the latter of which is critical for describing the degree of uncertainty in the estimates. This work is based upon optimal binning techniques that we have developed for piecewise-constant, histogram-style models of the underlying density functions. Two useful side benefits have already been discovered. The first allows a researcher to determine whether there exist sufficient data to estimate the underlying probability density. The second permits one to determine an acceptable degree of round-off when compressing data for efficient transfer and storage. We also demonstrate how mutual information and transfer entropy can be applied so as to allow researchers not only to identify relations among climate variables, but also to characterize and quantify their possible causal interactions.

physics.data-an↗

arXiv2013

Global Regularity for an Inviscid Three-dimensional Slow Limiting Ocean Dynamics Model

We establish, for smooth enough initial data, the global well-posedness (existence, uniqueness and continuous dependence on initial data) of solutions, for an inviscid three-dimensional {\it slow limiting ocean dynamics} model. This model was derived as a strong rotation limit of the rotating and stratified Boussinesg equations with periodic boundary conditions. To establish our results we utilize the tools developed for investigating the two-dimensional incompressible Euler equations and linear transport equations. Using a weaker formulation of the model we also show the global existence and uniqueness of solutions, for less regular initial data.

math.AP↗

arXiv2013

Downscaling of global solar irradiation in R

A methodology for downscaling solar irradiation from satellite-derived databases is described using R software. Different packages such as raster, parallel, solaR, gstat, sp and rasterVis are considered in this study for improving solar resource estimation in areas with complex topography, in which downscaling is a very useful tool for reducing inherent deviations in satellite-derived irradiation databases, which lack of high global spatial resolution. A topographical analysis of horizon blocking and sky-view is developed with a digital elevation model to determine what fraction of hourly solar irradiation reaches the Earth's surface. Eventually, kriging with external drift is applied for a better estimation of solar irradiation throughout the region analyzed. This methodology has been implemented as an example within the region of La Rioja in northern Spain, and the mean absolute error found is a striking 25.5% lower than with the original database.

physics.ao-ph↗

arXiv2013

Influence of solar and cosmic-ray variability on climate

We analyze solar, geomagnetic and cosmic ray flux data along with rainfall and temperature data for almost five solar cycles. We provide evidence of significant influence of solar variability on climate. Specifically, we demonstrate association between lower (higher) rainfall and higher (lower) temperatures with increasing (decreasing) solar activity and decreasing (increasing) cosmic ray intensities. We propose a plausible scenario that accounts the results of our analysis.

physics.ao-ph↗

arXiv2013

Wavelet-based cascade model for intermittent structure in terrestrial environments

A wavelet-like model for distributions of objects in natural and man-made terrestrial environments is developed. The model is constructed in a self-similar fashion, with the sizes, amplitudes, and numbers of objects occurring at a constant ratios between parent and offspring objects. The objects are randomly distributed in space according to a Poisson process. Fractal supports and a cascade model are used to organize objects intermittently in space. In its basic form, the model is for continuously varying random fields, although a level-cut is introduced to model two-phase random media. The report begins with a description of relevant concepts from fractal theory, and then progresses through static (time-invariant), steady-state, and non-steady models. The results can be applied to such diverse phenomena as turbulence, geologic distributions, urban buildings, vegetation, and arctic ice floes. The model can be used as a basis for synthesizing realistic terrestrial scenes, and for predicting the performance of sensing and communication systems in operating environments with complex, intermittent distributions of scattering objects.

physics.data-an↗

arXiv2013

Qualitative Analysis of the Time-Frequency Signature Induced by a Reflected L-Band Signal from Time Evolving Sea Surfaces

Passive remote sensing techniques have become more and more popular for detection and characterization purposes. The advantage of using the Global Navigation Satellite Systems (GNSS) are the well known signals emitted and the availability in most areas on Earth. In the present paper, L-Band signals (including GNSS signals) are considered for oceanographic purposes. The main interest in this contribution is the analysis of the signal reflected by an evolving sea surface using time-frequency transforms. The features which occur in this domain are examined in relation to the physical phenomena: interaction of the electromagnetic waves with the moving sea surface.

physics.ao-ph↗

arXiv2013

Moist convection scheme in Model E2

This documentation describes the version of the Del Genio - Yao cumulus parameterization used in the NASA Goddard Institute for Space Studies Model E2 GCM. This version was used for the official GISS submissions to the CMIP5 archive.

physics.ao-ph↗