Earth and Atmospheric Sciences

Using the two-layer moist-convective rotating shallow water model, we study the process of relaxation (adjustment) of localized large-scale pressure anomalies in the lower equatorial troposphere, and show that it engenders coherent structures strongly resembling the Madden Julian Oscillation (MJO) events, as seen in vorticity, pressure, and moisture fields. We demonstrate that baroclinicity and moist convection substantially change the scenario of the quasi-barotropic “dry” adjustment, which was established in the framework of one-layer shallow water model and consists, in the long-wave sector, in the emission of equatorial Rossby waves, with dipolar meridional structure, to the West, and of equatorial Kelvin waves, to the East. If moist convection is strong enough, a dipolar cyclonic structure, which appears in the process of adjustment as a Rossby-wave response to the perturbation, transforms into a coherent modon-like structure in the lower layer, which couples with a baroclinic Kelvin wave through a zone of enhanced convection and produces, at initial stages of the process, a self-sustained slowly eastward-propagating zonally- dissymmetrical quadrupolar vorticity pattern. At the same time, a weaker quadrupolar structure of opposite sign arises in the upper layer, the whole picture similar to the active phase of the MJO events. The baroclinic Kelvin wave then detaches from the dipole, which keeps slow eastward motion, and circumnavigates the Equator, catching up and interacting with the dipole.

The Mediterranean basin is characterized by large concentrations of aerosols from both natural and anthro-pogenic sources. These aerosols affect tropospheric photo-chemistry by modulating the photolytic rates. Three simulations of the atmospheric composition at basin scale have been performed with the CHIMERE chemistry-transport model for the period from 6 June to 15 July 2013 covered by the ADRIMED campaign, a campaign of intense measurements in the western Mediterranean basin. One simulation takes into account the radiative effect of the aerosols on photo-chemistry, the second one does not, and the third one is designed to quantify the model sensitivity to a bias in the ozone column. These simulations are compared to satellite and ground-based measurements, with a particular focus on the area of Lampedusa. Values of the aerosol optical depth (AOD) are obtained from the MODIS instrument on the AQUA and TERRA satellites as well as from stations in the AERONET network and from the MFRSR sun photometer deployed at Lampedusa. Additional measurements from instruments deployed at Lampedusa either permanently or exceptionally are used for other variables: MFRSR sun photometer for AOD, diode array spectrometer for actinic fluxes, LIDAR for the aerosol backscatter, sequential sampler for speciation of aerosol and Brewer spectrophotometer for the total ozone column. It is shown that CHIMERE has a significant ability to reproduce observed peaks in the AOD, which in Lampe-dusa are mainly due to dust outbreaks during the ADRIMED period, and that taking into account the radiative effect of the aerosols in CHIMERE considerably improves the ability of the model to reproduce the observed day-today variations of the photolysis rate of ozone to O 2 and O(1 D), J (O 1 D), and that of NO 2 to NO and O(3 P), J (NO 2). While in the case of J (O 1 D) other variation factors such as the strato-Published by Copernicus Publications on behalf of the European Geosciences Union. 1220 S. Mailler et al.: Impact of aerosols on photolysis rates at Lampedusa spheric ozone column are very important in representing correctly the day-today variations, the day-today variations of J (NO 2) are captured almost completely by the model when the optical effects of the aerosols are taken into account. Finally, it is shown that the inclusion of the direct radia-tive effect of the aerosols in the CHIMERE model leads to reduced J (O 1 D) and J (NO 2) values over all the simulation domain, which range from a few percents over continental Europe and the northeast Atlantic Ocean to about 20 % close to and downwind from Saharan dust sources. The effect on the modelled ozone concentration is 2-fold: the effect of aerosols leads to reduced ozone concentrations over the Mediterranean Sea and continental Europe, close to the sources of NO x , but it also leads to increased ozone concentrations over remote areas such as the Sahara and the tropical Atlantic Ocean.

The structure of Mars’ annular polar vortex is not similar to that of its counterpart on Earth and is characterised by a potential vorticity (PV) low in the vicinity of the winter pole, rather than PV monotonically increasing towards the pole. A number of persistent asymmetric high-PV patches around the central low are also typical for the Martian polar vortex. The simplest vertically averaged model of the Mars atmosphere (a rotating shallow water model on the polar tangent plane) with inclusion of diabatic effects is used to get clues for understanding this surprising behaviour. The standard parameterisation of radiative relaxation is applied, together with a simple parameterisation of latent heat release due to spatially inhomogeneous CO2 deposition. The parametrisation of inhomogeneous deposition is new in this type of models, and includes dependence on the concentration of condensation nuclei, which are considered as a passive tracer. Linear stability analysis of the zonally and time averaged Mars’ winter polar vortex is performed, and thus identified unstable modes are used for initialisation of high-resolution numerical simulations of their nonlinear evolution in four different configurations (adiabatic, diabatic with only radiative relaxation, only deposition, and both radiative relaxation and deposition), in order to identify the role of each process. It is shown that the combined effect of radiative relaxation and inhomogeneous deposition can account for the observed, formally unstable structure of the polar vortex, including the patches of high potential vorticity. https://doi.org/10.1016/j.icarus.2018.05.026

A simple two-layer model, the moist-convective rotating shallow water, which allows for low-cost high-resolution numerical simulations of the dynamics of the moist atmosphere in the presence of topography, is used to identify and understand dynamical processes governing the evolution of easterly waves propagating on the background of a low-latitude easterly jet crossing a land-sea boundary, a setup crudely representing the African Easterly Jet over the West-African plateau and the Atlantic ocean. We perform a thorough linear stability analysis and identify the unstable modes of the jet, which we use then for initialisation of fully nonlinear numerical simulations. In this way, we determine nonlinear evolution of unstable perturbations of the jet, both in the “dry” and moist-convective environments and highlight essential differences between the two cases. We identify a mechanism of formation of intense lower-layer cyclonic vortices at the northern flank of the jet and determine the influence of the land-sea contrast upon this process.

The dispersion of heavier-than-air aerosol clouds is of great relevance to the analysis and assessment of hazards in the chemical and petrochemical industries. There are many simple mathematical models for heavy gas dispersion but, in most cases, two-phase dynamics are either ignored or treated in a very simple way, without any convincing scientific justification. In fact almost all of those models which do treat two-phase phenomena rely on the “homogeneous equilibrium” assumption, whether they be for jet dispersion, for gravity dominated dispersion, or for any other aspect of a two-phase release.Here we test the homogeneous equilibrium model against a more sophisticated aerosol approach, in the context of two-phase ammonia clouds released in dry and moist air. It is shown that the simpler model does indeed provide a good description for some envisaged release situations, and guidance is given on where the homogeneous equilibrium model is not likely to be adequate. The homogeneous equilibrium model seems to be adequate for evaluating the dispersion of heavier-than-air clouds containing droplets smaller than 100 μm.

We report a discovery of steady long-living slowly eastward moving large-scale coherent twin cyclones, the equatorial modons, in the shallow water model in the equatorial beta-plane, the archetype model of the ocean and atmosphere dynamics in tropics. We start by constructing analytical asymptotic modon solutions in the non-divergent velocity approximation and then show by simulations with a high-resolution numerical scheme that such configurations evolve into steady dipolar solutions of the full model. In the atmospheric context, the modons persist in the presence of moist convection, being accompanied and enhanced by specific patterns of water-vapour condensation. https://doi.org/10.1063/1.5080415

The process of geostrophic adjustment of localized large-scale pressure anomalies in the standard adiabatic shallow-water model on the equatorial beta-plane is revisited, and it is shown that the standard scenario of generation of westward-moving Rossby and eastward-moving Kelvin waves, which underlies the classical Gill theory of tropical circulation due to a localized heating, is not unique. Depending on the strength and aspect ratio of the initial perturbation, the response to the initial perturbation in the western sector can be dominated by inertia-gravity waves. The adjustment in the diabatic moist-convective shallow water model can be totally different and produces, depending on parameters, either Gill-like response or eastward-moving coherent dipolar structures of the type of equatorial modons, which do not appear in the “dry” adjustment, or vortices traveling, respectively, northwest in the Northern and southwest in the Southern hemispheres. (Physics of Fluids 31, 081702 (2019); https://doi.org/10.1063/1.5110441)

Atmospheric jets and vortices which, together with inertia-gravity waves, constitute the principal dynamical entities of large-scale atmospheric motions, are well described in the framework of one-or multi-layer rotating shallow water models, which are obtained by vertically averaging of full "primitive" equations. There is a simple and physically consistent way to include moist convection in these models by adding a relaxational parameterization of precipitation and coupling precipitation with convective fluxes with the help of moist enthalpy conservation. We recall the construction of moist-convective rotating shallow water model (mcRSW) model and give an example of application to upper-layer atmospheric vortices.

Cosmic Bitcasting emerges from the idea of connecting the human body with the universe by creating a wearable interface that can provide sensory feedback on the invisible cosmic radiation that passes through our bodies. The project proposes the creation of an open-source, wearable detector, that can detect secondary muons generated by cosmic rays hitting the Earth's atmosphere that penetrate the human body by triggering a series of embedded actuators (light, sound and vibration).

In the last three decades, India has been facing the unusual weather condition that the affects the social-ecological balance. The summers are getting hotter; winters colder, drought, stronger storms, heat waves, floods, cloud burst, cyclones, and anomalous seasonal weather frequency and intensity have been historical expectations. Indian climate is affected by winds coming from the Indian Ocean as well as cold, dry northern winds along with atmospheric Hedley and Farrell cell wind and variation in these atmospheric winds. The change in solar radiation may impact these wind patterns, and extreme climatic events that happened globally. To better understand the impact and trend of solar and atmospheric disparities and associated climatic factors such as mean solar radiation, atmospheric pressure, precipitation, wind speed & wind direction and temperature, on extreme climatic conditions in Western India, selected the confluence area of Hedley and tropical wind. They divert at 30°N-25°N latitude as a variation of ITCZ, would be beneficial to understand the actual reason behind the increasing the extreme climatic condition. The city Kota is situated at 25°N latitude under the state of Rajasthan, India, selected for the study.

After the industrial revolution in 18 th century, Carbon dioxide (CO2) concentration has been increases rapidly and predicted the impact of global warming. Atmosphere is made up of various gasses and overall compositions of gasses are constant for the development of the ecosystem. Minor variation in the atmospheric composition, impacted the Earth weather and climate pattern. As increase in CO2 and other greenhouse gases absorbed the sun radiation and increase the temperature of earth. During the Paleo-climatic studies it was observed that climate change happened several times in geological past. Atmospheric concentration varies due to various natural reasons. The CO2 concentration was much higher and oxygen was very low during early atmospheric condition. The concentration of CO2 were varies from 7000 part per million (PPM) to 350 PPM, Oxygen (O2) varies 1% to 35%, sea level 450 m high to (-)50 m low from present sea level and Earth average temperature varies between 29°C to 11°C. Sun brightness was varying 95% to 100% compared to present. Earth had faced various warm and cold phases during the geological past. Presently we are (human) living in small time cycle of Earth and its need of study regarding the future climate of earth. Regarding this, trying to discuss Paleo-climatic variation throughout the Geological time, affecting factors and observed that average atmospheric concentration of CO2, O2, Earth's average temperature and sea level was much higher than present level. Based on observed data, prepared the impact of CO2 & O2 on flora, fauna & natural disaster. Also prepared the line diagram and suggested that atmospheric concentration of CO2, O2, Earth's average temperature and sea level would be increased naturally in future and affect the ecosystem by various natural way.

El presente texto reflexiona acerca del concepto de atmósfera, en el contexto de la crisis climática actual, cuya complejidad se exacerba por su carácter global y urgente. Si bien dicha noción se puede entender a través de datos cuantitativos resultantes de la medición sobre un objeto corporal, la ontología que Félix Guattari desarrolló en sus últimos escritos nos provee de un sistema en el que cada entidad real presupone la convivencia de registros tanto corpóreos como incorpóreos, y tanto reales como posibles, y por tanto un entendimiento puramente corporal sería insuficiente. El sistema de Guattari invita a aceptar la multiplicación de las manifestaciones y de las potencias del objeto atmosférico, y señala la dificultad de articular y conciliar distintos tipos de valores inherentes que presenta.

'Pencil-and-paper' climate modelling is extracted from the comprehensive previous research on the inherently complex natural processes. A major goal is to mediate between general scientific knowledge and the widespread scepticism by identifying the driving forces, seeking simple descriptions, uncovering reproducibility, and thus contributing to transparency. The results of the shortcut model are in outstanding agreement with earlier measurement data and simulation studies. Two observations are fundamentally novel requiring scrutinization by the natural sciences community: (1) near-proportionality of atmospheric infrared absorption to particle densities and (2), temperature impact from human energy consumption. Independently, the presented framework allows for straightforward climate projections and risk assessment. As result, future economic growth is demanded to zero, even in a renewables (Green Growth) world.

The characteristics of valley and mountain winds are uncertain due to various factors e.g. synoptic winds, diurnal cycle, shapes of valleys, and neighboring oceans. The 3-D winds (from airborne Doppler lidar and a mesoscale model) are used to shed light on the horizontal and vertical structures of the mountain and valley winds in central California. The results are presented from WRF simulations which were performed to evaluate the mesoscale model and to study the processes affecting the observed wind features in the Salinas valley. Such results are compared with various observations and show the modeling limitations in mountainous regions.

p El conocimiento actual del hielo lo muestra como un conductor protónico. Esto significa que los portadores son protones pero en primera instancia asociados a defectos. Es decir, no son protones libres en el sentido de un conductor electrónico. En este trabajo se exponen mediciones realizadas en la superficie del hielo tanto mono como policristalino. La técnica usada es de corriente alterna para evitar cargas de polarización electródica. Los resultados muestran una movilidad Hall del orden de 10-5 (m²/Vs). Al aumentar la temperatura, se observa claramente que, a cierta temperatura (~-8°C), existe un cambio de pendiente (energía de activación) que podría indicar el comienzo de la capa desordenada (mal llamada capa cuasiliquida) en la superficie con el consiguiente aumento de movilidad. Se hicieron tratamientos a la superficie tanto térmicos como mecánicos y se hacen hipótesis sobre su influencia en la movilidad Hall. Palabras Claves: hielo, Efecto Hall, conductividad eléctrica, superficies. What we know about ice, shows it as a protonic conductor. This means that those that carry are protons, but, in first instance, associated to defects. This is, they are not free protons in an electronic conductor sense. On this work are expound meditions made on the surface of the ice mono as well as polycrystalline. The technique used is of alternating current to avoid charges of electrodic polarization. The results shows a Hall mobility of the order of the 10-5 (m²/Vs). As the temperature increase, we already observe that on determinated temperature (~-8°C), there is a change of slope (energy of activation) that could indicate the beginning of a mess sheet (wrong called: cuasiliquid sheet) on the surface, with the following increase of mobility. Were made treatments to the surface on thermical as well on mechanical, and are formulated hypotesis about its influence on the Hall mobility.

A mechanistic understanding of the North American Monsoon (NAM) is suggested by incorporating local- and synoptic-scale processes. The local-scale mechanism describes the effect sea surface temperature (SST) in Gulf of California (GC) and how it contributes to the low-level moisture during the 2004 NAM. Before NAM onset, the strong low-level temperature inversion exists over the GC, but this inversion weakens with increasing GC SST and generally disappears once SSTs exceed 29.5°C, allowing the moist air, trapped in the MBL, to mix with free tropospheric air. This leads to a deep, moist layer that can be transported toward the NAM regions to produce thunderstorms. The synoptic scale mechanism is based on climatologies from 1983 to 2010 and explains that the warmest SSTs moving up the coast contributes to NAM convection and atmospheric heating, and consequently advancing the position of the anticyclone and the region of descent northward.

In order to improve microphysical properties of ice clouds, this study develops self-consistent second order polynomial mass- and projected area-dimension (m-D and A-D) expressions that are valid over a much larger size range, compared to traditional power laws. Such expressions can easily be reduced to power laws for the size range of interest, in order to use in cloud and climate models. This was done by combining field measurements of individual ice particle m and D with airborne optical probe measurements of D, A and estimates of m. The resulting m-D and A-D expressions are functions of temperature and cloud type (synoptic vs. anvil), and are in good agreement with m-D power laws developed from recent field studies. These expressions also appear representative for heavily rimed dendrites occurring over the Sierra Nevada Mountains. By using the m-D field measurements of rimed and unrimed particles, and by developing theoretical methods, an approach was suggested for calculating rimed m and A, which has the benefit of accounting for the degree of riming, and therefore it produces a gradual and continuous growth from unrimed ice particles to graupel. The treatment for riming includes a parameterization for collision efficiency as a function of droplet size and ice particle size using the available numerical studies.

A rimed snow growth model (RSGM) was developed based on the growth processes of vapor diffusion, aggregation, and riming. The RSGM uses a measured radar reflectivity at cloud top for initialization, and then predicts the vertical evolution of size spectra. The RSGM is based on the zeroth- and second- moment conservation equations with respect to mass, and thus conserves the number concentration and radar reflectivity, respectively. The size spectra predicted by the RSGM are in good agreement with observed spectra during Lagrangian spiral descents through frontal clouds. The snowfall rate with the inclusion of riming is significantly greater than that produced by the vapor deposition and aggregation alone. Snowfall rates are found to be sensitive to the cloud drop size distribution.

Scientific research of
University Center for Space Research and Technologies includes
The scope of activities of University Center for Space Research and Technologies (UCSRT) includes fundamental and applied research in the field of theoretical and experimental physics, space physics, geophysics, atmospheric physics, space, astrophysics, cosmology, space- materials science, development of mathematical models of processes in the near and distant space. At the Center, research and educational activities are performed in the field of space research and technologies, which have applications in electronics, telecommunications, geophysics, meteorology, ecology, archeology and other fields. The Center performs also research on properties of materials for space technologies.
Main educational activities of the Center are master's Program on “Space research” and Module 1 “Aerospace engineering” (small aero-spacecraft) of the master’s Program “Aerospace engineering and communications”, but its members lead also many courses of undergraduate programs in physics and engineering physics.
Scientific research fields of
University Center for Space Research and Technologies includes:

Space Physics:

1.Elementary particles physics and Early Universe
I. Breaking of dynamic symmetry
II. Quantum field theory.
III. Kaon physics.
IV. Phenomenology of antisymmetric tensor particles.
V. Neutrino oscillations
VI. Early universe
VII. Quantum field theory with a fundamental length.
VIII.Experimental Particle Physics

2. Space Impact on the Environment
I. Solar Impact on Global Climate Changes
II. Solar terrestrial relations and solar forcing of the climate.
III. Orbital Variations of the Earth’s Orbit and their influence over Glacial Periods
IV. Cosmic Rays Impact on the Global Climate Changes
V. Solar Modulation of the Geomagnetic Activity and the related Processes
VI. Solar and Geomagnetic Activity Impact on Human Health 
3. Solar physics
I. Solar Activity
II. Variations of Solar Irradiance
III. Structure and processes in the Solar Corona
IV. Heliospheric physics
V. Studies of the Solar Corona from Space Probes
VI. Studies of the Solar Corona from Stratospheric Flights
VII. Research of Solar Eclipses

4. Space Weather
Study of variations of the flux of dangerous high-energy particles in the Space.

5. Study of Asteroids and Comets interactions with the Sun and Earth
I. Study of collisions of asteroids and comets with the Sun and planets and their consequences.
II. Search for new asteroids and comets.

6. Variations of Cosmic Rays Flux and Production of Cosmogenic Isotopes

7. Applications of Space Research and Technologies in Archaeological and historical research.
Applications of space research and technology in archaeological research are a natural bridge between the Natural and Humanitarian Sciences, integration among which is especially necessary for the functioning of the University as unified institution.

I. Applications of Space Technologies in Archaeological and Historical research
-a. Applications of space technology in archaeological research:
The Ground Penetrating Radar (GPR) was developed by NASA to study the lunar ground for the needs of the US space program. Its applications in archeology established GPR as the most powerful arhaeo-geophysics method. The Archaeo-geophysics laboratory of UCSRT is the only laboratory in Bulgaria using GPR to study archaeological objects. It has applied activities.
-b. Applications of space technologies for location and mapping of areas inhabited by ancient people and their migration:
This method has been developed in 2003 by UCSRT team. It uses satellite measurements of the location of archaeology monuments, ancient villages and historical areas from the space, and allows for localization and precise mapping of areas inhabited by ancient people and their migration, even before emerging of any writing culture.

II. Applications of Space Research in Archaeological and Historical research  -а. Applications of space technology for dating of archaeological objects.
Space research is used to develop new methods for dating of archaeological objects.
-b. Study of the influence of cosmic phenomena and processes on the migration of ancient people.
We study the impact of cosmic events and processes on the sea level rising, which have caused migrations of ancient people in the past.
-c. Applications of space technology to study archaeological objects.
RGB-photometry was developed by UCSRT for registration of ground observation of the structure of the far solar corona, which is visible only from the Space coronagraph LASCO. Later, it was adopted for studies of archeological objects and cultural heritage.

The applied research of the Center includes developing of registration systems for IR, UV and visible images for remote observations from airplanes, unmanned aircrafts (UAVs) and satellites, their photometry, study of the solar and cosmic influence on the environment and applications of space research and technologies for archaeological research and exploration. It includes also research and localization of asteroids and dangerous near Earth objects (NEO) as well as evaluation of the damages, which they could cause upon potential collision with Earth.
The scientific outcome of the Center is significantly higher than the average production of the departments in the Faculty of Physics, despite its smaller staff: the results of the research activities of the members of the Center are published in 750 publications in scientific journals, monographs (mostly international), and conference proceedings, from which 560 publications in peer reviewed journals with impact factor.
Their results are presented in 167 reports at international congresses, conferences, symposia and schools, as 23 of them are invited or plenary reports.
They are cited 31290 times from foreign scientists, and research teams. 89 from the papers are cited more than 89 times, each (h-factor 89).
Specialists of the Center lead national and international research projects and programs. They have participated in one European, 10 international, 3 Italian and two Canadian research projects. At the moment they are leading two international research programs of one international scientific union. They review articles in prestigious international journals; are members of the editorial boards of international journals, editors of foreign monographs; evaluate Italian research projects in the fields of physics, astrophysics and Earth sciences; and participate in the appraisal of Italian universities. They chaired scientific organizing committees of five international scientific schools and conferences, and 6 sessions of other international conferences.
Specialists from UCSRT participate in large international collaborations and experiments in elementary particle physics, such as ATLAS, CHORUS, DELPHI, HARP, OPERA and H1.
One PhD student from the University of Bologna, Italy, was trained at the Center within the European program ERASMUS for PhD student exchange.
The only Archaeo-geophysics laboratory in Bulgaria functions at the UCSRT.
The Center sustains intensive international connections and collaborations with Universities and scientific institutions in Australia,  Austria,  Belgium,  Brazil,  Canada, China,  Croatia,  Czech  republic,  Egypt,  France,  Germany,  Hungary, India, Indonesia, Iran, Iraq, Italy, Luxembourg, Portugal, Puerto Rico, Romania, Russia, Slovenia, South Africa, Serbia, Spain, Swisszerland, UK, USA and other countries.

The UCSRT represents Sofia University in the cluster “AERO-SPACE TECHNOLOGIES, RESEARCH AND APPLICATIONS” (CASTRA). The cluster is a national consortium of 20 Bulgarian Universities, Scientific institutes, private companies and enterprises. Its objectives are: to support Bulgaria’s joining to the European Space Agency (ESA), joint participation in national and international programs etc. One of the main activities of the cluster is to support building up of appropriate options for training, professional qualification and personnel growth, creating joint educational centers and developing of modern educational programs for training in the field of “Aero-space technologies, research and applications” and relevant subjects. Joining of Bulgaria to the European Space Agency (ESA), will open the access of the Faculty’s graduates to 17 000 well paid jobs in their professional field. This will increase strongly the motivation of the high-school graduates to study at the Physics Faculty. Bulgaria is the only EU member, which is not yet a member of ESA. Our joining of ESA (which is scheduled for 2015) will open new horizons for developing of the Bulgarian physics and for realization of its specialists. The members of the cluster rely on UCSRT for the training and education of the staff for the Bulgarian space program, as the only specialized University unit in this field in Bulgaria.

University Center for Space Research and Technologies has YouTube channel:
https://www.youtube.com/channel/UCyH3fFqMfKjLLI9jS4xnWHw