Christina Kalogeri

Natural and anthropogenic aerosols in the Eastern Mediterranean and Middle East: Possible impacts

The physical and chemical properties of airborne particles have significant implications on the microphysical cloud processes. Maritime clouds have different properties than polluted ones and the final amounts and types of precipitation are different. Mixed phase aerosols that contain soluble matter are efficient cloud condensation nuclei (CCN) and enhance the liquid condensate spectrum in warm and mixed phase clouds. Insoluble particles such as mineral dust and black carbon are also important because of their ability to act as efficient ice nuclei (IN) through heterogeneous ice nucleation mechanisms. The relative contribution of aerosol concentrations, size distributions and chemical compositions on cloud structure and precipitation is discussed in the framework of RAMS/ICLAMS model. Analysis of model results and comparison with measurements reveals the complexity of the above links. Taking into account anthropogenic emissions and all available aerosol-cloud interactions the model precipitation bias was reduced by 50% for a storm simulation over eastern Mediterranean.

The impact of sea surface currents in wave power potential modeling

The impact of sea surface currents to the estimation and modeling of wave energy potential over an area of increased economic interest, the Eastern Mediterranean Sea, is investigated in this work. High-resolution atmospheric, wave, and circulation models, the latter downscaled from the regional Mediterranean Forecasting System (MFS) of the Copernicus marine service (former MyOcean regional MFS system), are utilized towards this goal. The modeled data are analyzed by means of a variety of statistical tools measuring the potential changes not only in the main wave characteristics, but also in the general distribution of the wave energy and the wave parameters that mainly affect it, when using sea surface currents as a forcing to the wave models. The obtained results prove that the impact of the sea surface currents is quite significant in wave energy-related modeling, as well as temporally and spatially dependent. These facts are revealing the necessity of the utilization of the sea surface currents characteristics in renewable energy studies in conjunction with their meteo-ocean forecasting counterparts.

Wave power estimation by means of spectral wave models and satellite records

ABSTRACT The aim of this work is to study different approaches for the estimation of the energy potential of sea waves. To this end, numerical models and remote sensing, especially satellites, are utilised for the regions of North Atlantic Ocean and the Mediterranean Sea. In particular, two methods are compared: one based on the full wave spectrum and a second utilising simplified formulas based on specific wave parameters and certain approximations. Moreover, an attempt for a qualitative assessment of the wave model WAM over areas of different wave climatology is made by the comparison of relevant wave spectra. The main outcomes of this work show that simplified calculation approaches of wave energy potential overestimate the energy rate of even 10% on average, varying in the cases of shallow or deep waters. Moreover, the performance of the wave model is satisfactory resulting to small statistical errors in the calculation of wave characteristics, a fact that proves the suitability of WAM model for reliable wave energy assessment.

An Integrated Weather and Sea State Forecasting System for the Arabian Peninsula (WASSF)

Saudi Aramco is the oil industry of the Kingdom of Saudi Arabia with several activities related to the environment. In order to optimize daily operations and minimize environmental risks a forecasting system has been employed and setup in operations. The objectives of the system include prevention and mitigation of environmental problems, as well as early warning of local conditions associated with extreme weather events. The management and operations part is related to early warning of weather and dust storms that affect operations of various facilities, whereas the environmental part is mainly focused on air quality and desert dust levels in the atmosphere.

Mathematical and Physical Models for the Estimation of Wind-Wave Power Potential in the Eastern Mediterranean Sea

A new system developed for the accurate estimation of wind and wave power potential in the area of Eastern Mediterranean Sea is presented in this work. Numerical simulation models in conjunction with statistical techniques are utilized. The numerical systems used are based on high resolution models able to resolve in detail the evolution of the environmental parameters that affect the wind-wave power potential. Moreover, dynamical statistical tools (Kalman filters) and recent advances in a relatively new branch of mathematics the Information Geometry are proposed for the bias correction in the modeled data.

Optimization of numerical weather/wave prediction models based on information geometry and computational techniques

The last years a new highly demanding framework has been set for environmental sciences and applied mathematics as a result of the needs posed by issues that are of interest not only of the scientific community but of todays society in general: global warming, renewable resources of energy, natural hazards can be listed among them. Two are the main directions that the research community follows today in order to address the above problems: The utilization of environmental observations obtained from in situ or remote sensing sources and the meteorological-oceanographic simulations based on physical-mathematical models. In particular, trying to reach credible local forecasts the two previous data sources are combined by algorithms that are essentially based on optimization processes. The conventional approaches in this framework usually neglect the topological-geometrical properties of the space of the data under study by adopting least square methods based on classical Euclidean geometry tools. In the pre...

The Effects of Naturally Produced Dust Particles on Radiative Transfer

Mineral dust has a profound effect on the radiative budget and energy distribution of the atmosphere. By absorbing and scattering the solar radiation aerosols reduce the amount of energy reaching the surface. In addition aerosols enhance the greenhouse effect by absorbing and emitting longwave radiation. Desert dust forcing exhibits large regional and temporal variability due to its short lifetime and diverse optical properties further complicate the quantification of the Direct Radiative Effect (DRE). The complexity of the above processes, indicate the need of an integrated approach in order to examine these impacts. To this end the radiative transfer module RRTMG has been incorporated into the framework of the SKIRON model. The updated system was used to perform a 6-year long simulation over the Mediterranean region. As it was found, the most profound effect dust clouds have in areas away from the sources is the surface cooling through the “shading” effect. The long wave radiation forcing below and above the dust cloud is considerable and drives changes in the tropospheric temperature. In general dust particles cause warming near the ground and at mid-tropospheric layers and at the same time cooling of the lower troposphere.

Numerical Wave Modeling and Wave Energy Estimation

In a rapidly evolving operational and research framework concerning the global energy resources, new frontiers have been set for the scientific community working on environmental and renewable energy issues. In particular, new numerical techniques supporting the accurate estimation of renewable energy sources are highly emphasized. In this framework, wave energy – the energy that can be captured from sea waves – provides an alternative option with critical advantages. In the present paper, recent advances and some preliminary results obtained in two European projects will be discussed: Marina Platform and E-wave projects are focusing on the estimation of the wave energy potential in North Atlantic coastline of Europe and in Eastern Mediterranean Sea, respectively. Special emphasis is given to the utilization of numerical atmospheric and wave modeling systems able to accurately monitor the atmospheric and sea conditions in the area of interest. On the other hand, advanced statistical techniques are utilized for the local adaptation of the results and the estimation of the spatial and temporal distribution of the wave energy potential.