Papers by Ekaterina Batchvarova
Air Pollution Modeling and Its Application XIII, 2000
Springer Proceedings in Complexity, 2014
A parameterization of the wind profile for the entire boundary layer is formulated, with emphasis... more A parameterization of the wind profile for the entire boundary layer is formulated, with emphasis on the lowest 200 - 300 m and considering only wind speeds above 3 m s-1 at 10 m height. The friction velocity is taken to decrease linearly through the boundary layer. The wind profile length scale is composed of three component length scales. In the surface layer the first length scale is taken to increase linearly with height with a stability correction following Monin-Obukhov similarity. Above the surface layer the second length scale becomes independent of height but not of stability, and at the top of the boundary layer the third length scale is assumed to be negligible. A simple model for the combined length scale that controls the wind profile and its stability dependence is formulated by inverse summation. The wind profile for a number of stability classes, based on the Monin-Obukhov stability scale, , is illustrated in Figs 1 and 2. () MBL L
International Journal of Environment and Pollution
Measurements from Northern Finland on radiation and turbulent fluxes over a sparse boreal forest ... more Measurements from Northern Finland on radiation and turbulent fluxes over a sparse boreal forest with snow-covered ground were analysed. The measurements represent harsh winter conditions characterised by low sun angles. The absorption of incoming solar radiation in clear skies (turbidity) was found to be a strong function of the solar elevation. At low solar elevation angles, commonly used expressions for turbidity did not fit the measurements well. A simple energy balance type met-processor performed well during daytime, but it was not satisfactory during night time. Simplifications and possible improvements in the energy balance model are discussed.
With the advancement in wind power meteorology and the growth of the modern wind turbines, the ne... more With the advancement in wind power meteorology and the growth of the modern wind turbines, the need to measure and estimate meteorological parameters other than wind speed and direction has become more and more important. The effect on the wind profile, e.g. of the boundary-layer height h, has not (yet) been fully understood and investigated in the wind energy community, nor in the meteorological one. h has a significant effect on the wind profile at heights above 100 m and even lower when the atmospheric conditions are stable, e.g. during nighttime when low-level jets evolve. These heights are already being exploited by large wind turbines. A possible reason for the lack of use of h in wind power meteorology might be that it is interpreted in different fashions and estimated using different techniques. Common sources for the derivation of h are surface turbulence measurements, turbulence profiles, spectral characteristics of turbulence, sodar measurements, radiosoundings, aerosol l...
Predicting the wind at typical heights of present and future wind turbines is a considerable scie... more Predicting the wind at typical heights of present and future wind turbines is a considerable scientific challenge. Presently applied models are accurate within the surface layer. New measurements and instrument synergies are necessary as basis for developing new wind models and understanding the physical processes that form the wind profile in order to describe the wind profile above it. Analysis of the wind and turbulence profiles from a meteorological mast at heights up to 160 meters and wind lidars up to 300 meters at the National test station at Høvsøre, Denmark, shows deviations of the wind profile above 80 meters the from the profile used so far near the surface. It also reveals the importance of the boundary-layer height as a physical parameter for the description of the wind profile. In the Tall Wind project, mast and lidar measurements of wind and fluxes will be combined with monitoring of the boundary-layer height by use of an aerosol lidar. At the main project monitoring ...
Wind lidar measurements of mean wind speed profiles are com-pared to WRF model simulations (Skama... more Wind lidar measurements of mean wind speed profiles are com-pared to WRF model simulations (Skamarock et al., 2008) up to 600 m at a flat coastal site. Two 15-day periods in the autumn of 2010 are modelled using 2 different planetary boundary layer (PBL) schemes (MYNN and YSU) and 2 different vertical resolu-tions. In general the modelled profiles are less sheared than ob-served, which results in an under estimation of the wind speed higher up in the PBL. Both models are not able to reproduce low-level jets satisfactory, which introduces a bias for stable condi-tions.
A Scintec MFAS sodar is in operation since summer 2008 at Ahtopol meteorological observatory (Bul... more A Scintec MFAS sodar is in operation since summer 2008 at Ahtopol meteorological observatory (Bulgarian Black Sea coast) allowing climatological records of the wind profile up to 400 – 600 m height. The simultaneous turbulence observations with ultrasonic anemometers form unique for Bulgaria basis for studies of the structure of the coastal boundary layer. The monitoring will develop further to cover temperature and humidity profiles, ozone and aerosol concentrations, as the site is suitable for atmospheric composition background observations.
Continuous sodar (Scintec MFAS) and ultrasonic anemometer (Typhoon – Obninsk make) measurements w... more Continuous sodar (Scintec MFAS) and ultrasonic anemometer (Typhoon – Obninsk make) measurements were initiated in summer 2008 at the meteorological observatory of Ahtopol at the Black Sea coast (south-east Bulgaria) under a Bulgarian-Russian collaborative programme. These observations of high resolution form the basis for studies of the atmospheric boundary layer turbulence and vertical structure at a coastal site. This sodar is unique in Bulgaria and provides the first continuous high resolution data on the wind profile up to 400 – 500 m above the ground. In addition, the continuous turbulence parameters monitoring allows atmospheric boundary studies needed for different applications. The meteorological observatory at Ahtopol is under development as a background atmospheric composition station in coastal area and the wind data are essential for the studies of gases exchange under breeze conditions. The measurements revealed quite different sea breeze seasons during the years 2008 t...
In view of the great interest and concern worldwide regarding climate change issues, climate serv... more In view of the great interest and concern worldwide regarding climate change issues, climate services are in the focus of attention of many international and European organizations. In particular, World Meteorological Organization (WMO) has established and developed the WMO Integrated Global Observing System (WIGOS) as well as has been working to address the need for improved climate information and to provide an effective interface between scientists, service providers and decision-makers. In 2009, WMO organized the 3rd World Climate Conference during which the development of a new Global Framework for Climate Services (GFCS) is proposed and decided to start. On the other hand, Global Monitoring for Environment and Security (GMES) - the European Union' contribution to the Global Earth Observation System of Systems (GEOSS), has the purpose to deliver information which corresponds to user needs. The processing and dissemination of this information is carried out within the "...
International Journal of Environment and Pollution, 2003
ABSTRACT The application of the bulk Richardson number approach to determine the height of the ma... more ABSTRACT The application of the bulk Richardson number approach to determine the height of the marine atmospheric boundary layer from standard output of Numerical Weather Prediction models is discussed. It is argued that over smooth surfaces like the sea, the critical Richardson number can be expected to be smaller than over land. Based on 4 days of intensive measurements of the height of the marine atmospheric boundary layer over a small island in the Baltic Sea and a Richardson analysis on simultaneous output from the HIRLAM model, the critical Richardson number for the marine atmospheric boundary layer was found to be around 0.05. Use of the generally accepted value of 0.25 resulted in a clear overestimation of the height of boundary layer over the sea.
Advances in Science and Research, 2011
Continuous measurements of the characteristics of atmospheric boundary layer and the characterist... more Continuous measurements of the characteristics of atmospheric boundary layer and the characteristics of breeze circulation were initiated at the meteorological observatory of Ahtopol on the Black Sea coast (south-east Bulgaria) under a Bulgarian-Russian collaborative programme. Research observations started in July 2008 and go on. These observations are the start of high resolution atmospheric boundary layer vertical structure climatology at a Bulgarian Black Sea coastal site. Automatic weather station «MK-15» with an acoustic anemometer (mounted at 4,5m height) and Flat Array Sodar without RASS extension «Scintec» were installed on polygon of Ahtopol. A preliminary analysis was made of the experimental data on the thermodynamic structure of the atmospheric boundary layer in the coastal zone. Vertical profiles of wind speed, direction and spatio-temporal sectional were constructed according to the sodar data. Graphs of temporal variations of the direction and modulus of wind velocity, vertical velocity, the standard deviation of the acoustic temperature and time variation of air temperature (at a height of 2m -standard synoptic measurements) were constructed according MK-15. The momentum u * = −w u and sensible heat H = w T surface turbulent fluxes were calculated from MK-15 raw data. Prevailing weather conditions contributing to breeze circulation in the area were investigated. Blurred pressure field of high pressure with warm air mass, clear and (or) the overcast weather was characterized for treatment cases. The average wind speed near the ground was did not exceed 3 m/s, with a ripple rate of up to 4 m/s according to MK-15. The nature of the wind changed direction during the day has been practically the same (i.e., diurnal repeats) in all cases. The breeze front location was also detected based on standard measurements in the surface layer (mean values of temperature at 2 m and wind speed and direction from MK-15). In the zone of the front the wind speed increased dramatically and the wind direction varied between East and South. The air temperature showed typical for the sea breeze plateau shape in the noon hours. Understanding and parameterizing the turbulent exchange of momentum, heat and moisture between the earth's surface and the atmosphere is an important goal of the observations.
Air Pollution Modeling and Its Application XVII, 2006
Air Pollution Modeling and Its Application XVI, 2004
In this study first results from a low-level source urban tracer SF6 experiment are reported. The... more In this study first results from a low-level source urban tracer SF6 experiment are reported. The experiment was performed in the framework of the Basel UrBan Boundary Layer Experiment BUBBLE - in an area of the city of Basel (Switzerland) named Kleinbasel. Extensive ...
Developments in Environmental Science, 2007
ABSTRACT The parameterisation of the complex structure of the atmosphere over urban areas has lar... more ABSTRACT The parameterisation of the complex structure of the atmosphere over urban areas has large implication in running and testing meso-scale meteorological and air pollution models. The typical size for the urban area is of the order of 20–50km. It is subdivided into a large number of areas (neighbourhoods) reflecting the development of the town, such as the central inner, residential, recreation and industrial parts. The description of the ceaseless adjustments of the flow in the urban area is simplified by introducing neighbourhoods that are complexly interacting with the flow and forming internal boundary layers. On the level of street canyons, the roughness sub-layer, the flow varies in space and time. At a level of 3–5 times, the average building height the flow is in equilibrium with the underlying surface, known as inertial sub-layer. Higher up, the differences in meteorological fields introduced by surface characteristics of different neighbourhoods are blended and the boundary layer is forced by area-aggregated features. Within this framework, the parameterisation of some meteorological quantities is reviewed. Based on tracer experiments, it is found that the ability to predict the crosswind spread of the plume as well as maximum concentrations in the urban environment is within a factor of 2.
Air Pollution Modeling and Its Application XIV, 2001
NATO Science for Peace and Security Series, 2008
ABSTRACT Analysis of meteorological measurements from tall masts in rural and urban areas show th... more ABSTRACT Analysis of meteorological measurements from tall masts in rural and urban areas show that the height of the boundary layer influences the wind profile even in the lowest hundreds of meters. A parameterization of the wind profile for the entire boundary layer is formulated with emphasis on the lowest 200–300 m and presented here. Results are shown from applying the parameterization of the wind profile on independent measurements from an urban experimental campaign that was carried out in Sofia, Bulgaria in 2003.
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Papers by Ekaterina Batchvarova
number of sites with measurements and in particular sites with intensive vertical wind profiles measurements.With
the modern ground based remote sensing technology, new high time resolution information on wind in coastal
areas is retrieved by the operation of sodars, wind Doppler lidars, ceilometers, etc. Here, we present a comparative
study between two coastal sites: Ahtopol , Bulgaria, at the west coast of the Black Sea, and Lamezia Terme in
Italy, located at the Tyrrhenian coast of the Calabrian Peninsula. The characteristics of the onset, duration, wind
direction of sea breeze and the interaction of synoptic and local processes and the development of low level jets
are studied. The comparison is performed considering the role of orography, coast line orientation at the two sites.