WIND
ENGINEERING
SOCIETY
C/o the Institution of Civil Engineers
One Great George Street
Westminster
London SW1P 3AA
Telephone: +44 (0) 20 7665 2234
www.windengineering.org.uk
Evening Technical Meeting
At the
INSTITUTION OF CIVIL ENGINEERS
ONE GREAT GEORGE STREET, LONDON, SW1P 3AA
Wednesday 22 January 2014 at 6.00pm
(Refreshments available from 5.30pm in the Brasserie)
URBAN METEOROLOGY
PRESENTERS:
DR CHRISTOS HALIOS
UNIVERSITY OF READING
Low Level Jets (LLJs)
&
DR BHARATHI BOPPANA
UNIVERSITY OF SOUTHAMPTON
Modelling dispersion and thermal stratification in urban environments
CHAIRMAN: MARK STIRLING
Please note there is no charge and non-members of the Society are always welcome to attend.
For further information or to express an interest in attending, please contact Tim Fuller at the ICE on:
Tel: 020 7665 2234 Email: tim.fuller@ice.org.uk
It is our intention to transmit a webcast of the technical meeting.
Further details of this will be circulated to WES members prior to the event.
SUMMARY
Dr Christos Halios’ presentation on Low Level Jets (LLJs), defined as wind speed maxima within the
lowest several hundred metres above ground, influence the structure and dynamics of the
atmospheric boundary layer. Even though they have significant practical implications for wind
engineering, particularly with the potential wind loading on the structure of tall buildings, relatively
few studies have examined LLJs over urban areas. In this presentation the development of the LLJ
over London is examined during an intense heat island event. Inertial oscillations were observed
over the urban area when the rural boundary layer became stable, but LLJs were not observed over
the urban area due to mixing during the Urban Convective Island when shear was reduced. Intense
wind shear with the form of LLJs over the urban area only emerged when the Urban Boundary Layer
became stable. Due to the presence of the nocturnal jet, day-time wind profiles can still be strongly
sheared in the rapid, morning phase of convective boundary layer growth.
Dr. Christos Halios is a physicist (1997, Department of Physics, University of Athens). He holds an
MSc in Environmental Physics (University of Athens, 2001) and a PhD in Physics (University of
Athens, 2007). During the period 2000-2010 he had been participating in the Group of Boundary
Layer Meteorology and Air Pollution (University of Athens, group leader Prof C. Helmis), and in the
Group Building Environmental Studies (University of Athens, Group Leader Prof. Matheos
Santamouris) studying the Boundary Layer and the Urban microclimate. As a visiting scientist in
Phisicalish Meteorologische Observatorium Davos/World Radiation Center he has worked in the
field of aerosol optical properties/ atmospheric radiation. He has an extensive teaching experience
in Greek Universities and Technical Schools, teaching Atmospheric Science and Physics. Since
2012 he is a core member of the ACTUAL project (University of Reading, PI J. Barlow). He is
Associate Editor of Frontiers in Environmental Physics.
Bharathi Boppana’s presentation on ‘Modelling dispersion and thermal stratification in urban
environments’:
In the past few decades, we have seen a rapid increase in urbanization and the world urban
population is expected to continue to rise up to 72% by 2050 (as per the 2011 UN report). For the
planning and development of sustainable “green” cities and improve the prediction of numerical
weather models, it is necessary to understand and model the influence of various processes such
as heat, moisture etc. on the flow and scalar dispersion (e.g. pollutants) in and above different types
of roughness morphologies. However, it is challenging to obtain a comprehensive set of detailed
spatial information from the field measurements. Computational tools are therefore necessary to
gain deeper insights on the physics and interaction of various processes in urban flows. To meet
this objective, a systematic set of simulations are performed on scalar dispersion and the effects of
heat transfer on generic urban flows. In this talk, I will present the key findings of these
computational studies and discuss its relevance in the context of street-scale urban flows.
Bharathi Boppana is a post-doctoral research fellow in the University of Southampton. She works
with Prof. Ian Castro and Dr. Zheng-Tong Xie in “urban CFD” project that was funded by National
Centre for Atmospheric Sciences. Her research focusses on computational investigation of thermal
stratification effects on flow and scalar dispersion in and above generic urban canopies. Bharathi
received her PhD in Applied Mathematics from the University of Manchester in 2007. Prior to that,
she held Junior Research Fellow position for one year in the Mathematical Modelling Unit at the
National Institute of Advanced Studies, India. Bharathi graduated with an MSc in Civil Engineering